Peptidases in the kidney and urine of rats after castration

Summary The localization of various peptidases in the renal section of the rat was investigated histochemically, and their activities were determined fluorometrically in renal homogenate. The membrane-bound peptidases aminopeptidase A (APA), aminopeptidase M (APM), -glutamyl-transferase (-GT), dipeptidylpeptidase IV (DAP IV), and the lysosomal dipeptidyl peptidases I (DAP I) and II (DAP II) were investigated in male and female (estrus) rats both before and 30 days after castration. In addition, protein excretion and APA, APM, DAP I and DAP IV activities were measured in the urine of these animals. Histochemically, the membrane-bound peptidases are demonstrable mainly in the brush borders of the proximal tubules. In addition, APA and DAP IV are found in the glomeruli, -GT and DAP IV in the thin descending limbs of the loops of Henle, and -GT in the basal labyrinth of the S₂ and S₃ segments. The lysosomal peptidases are most concentrated in the S₁ and S₂ segments of the proximal tubule, in the distal tubule, and in certain cells of the connecting tubule and collecting duct, where they are contained in lysosomes of varying size. Sex differences and castration effects are demonstrable both histochemically and biochemically for the investigated peptidases. Histochemically these effects are most pronounced in the S₃ segments for the membrane-bound peptidases, and in the lysosomes of the proximal tubule for the lysosomal peptidases. Biochemical tests in controls show significantly higher lysosomal peptidase activities in the renal homogenate of females than of males. After castration the lysosomal peptidase activities in males increase, approaching those of females. This appears to have bearing on the sex-dependent proteinuria in rats, for lysosomal peptidases and proteinases are particularly important in the degradation of filtered proteins that are reabsorbed in the proximal tubule. In females high lysosomal peptidase activities correlate with a low proteinuria, while males demonstrate lower lysosomal peptidase activities and a significantly higher proteinuria than females. After castration, the lysosomal peptidase activities and proteinuria in males approach those in females. Renal peptidases are also excreted in the urine, again with sex differences, and so these excreted peptidases contribute to the proteinuria in rats.Supported by the Deutsche Forschungsgemeinschaft (SFB 105)     

The effect of sex hormones on the proximal tubules in the rat kidney

Summary The three segments (S₁, S₂, S₃) of the proximal tubule of the rat kidney were investigated, with special reference to lysosomes, after castration, estradiol application, and at the end of pregnancy. Especially in S₁ and S₂ castration induces an increase of cellular autophagy. The nuclei become smaller; endoplasmic reticulum (ER), ribosomes, and Golgi apparatus are reduced; catabolism predominates. In S₁ more giant lysosomes occur; the total number of lysosomes increases whereas acid phosphatase activity decreases at the same time. Sex differences which exist in untreated animals disappear. Substitution with estradiol causes an activation of the proximal tubule cells: Heterophagy predominates, and cellular autophagy is reduced. Nuclear size is unchanged; ER, ribosomes and Golgi apparatus show a clear increase. Giant lysosomes are absent in S₁. On the whole lysosomes are larger, but less numerous than after castration. Acid phosphatase is highly active. All changes are most evident in S₃. At the end of pregnancy the proximal tubule cells are stressed considerably: Pinocytotic activity increases, and large numbers of cell organelles and many lipid vacuoles can be observed. The basal lamina in S₁ and S₂ becomes thicker. Lysosomes enlarge and increase in number in all segments; giant lysosomes are absent in S₁; acid phosphatase activity is extremely high. The results indicate that sex hormones directly influence the regulation of the proximal tubule cell; moreover, they are indirectly important for the functioning of the kidney via changes in the whole organism.Supported by the Deutsche Forschungsgemeinschaft (SFB 105)Dedicated to Prof. Dr. O. Bucher, Head of the Institute of Histology and Embryology of the University of Lausanne/Switzerland, on the occasion of his 65th birthday     

Sex-dependent changes in the rat kidney after hypophysectomy

Summary Renal changes following hypophysectomy are investigated. Particular attention is given to sex differences in the ultrastructure of proximal tubule cells and in protein excretion.Regardless of gender, hypophysectomy is followed by an increase in urine volume. However, there is a concomitant reduction of proteinuria, which is much more pronounced in males than in females. Partial hypophysectomy with anterior pituitary function preserved also leads to increased urine excretion, but does not alter proteinuria.In both sexes there is a reduction of the tubule circumference, which again is more pronounced in males thereby moderating the sex difference. The proximal tubule cells display a segment- and sex-independent reduction in surface area, a decrease of Golgi areas and reduction of ribosomes. Mitochondrial changes (condensation of cristae) selectively affect the S₃ segment.The changes in the lysosomes and microbodies are segment- and sexdependent. The volume density of microbodies in the S₃ segment increases considerably, particularly in females. The volume density of lysosomes undergoes an increase in the S₁ cells of the males and a decrease in the S₂ cells. In the females the volume density of these organelles shows little change in these tubule segments; a sex-dependent difference is not longer apparent in the S₁ and S₂ segments. By contrast, in S₃, there is an increase in the volume density of lysosomes in both sexes. The present study confirms a connection between the morphology of lysosomes in the proximal tubule and proteinuria. The findings also point to a possible involvement of male sex hormones in the reabsorption of protein in the renal proximal tubule.Supported by the Deutsche Forschungsgemeinschaft (SFB 105)     

Electron microscopic and morphometric studies of the main kidney segment of male and female rats following castration and testosterone substitution

The effect of testosterone on the 3 segments of the renal proximal tubule (S1, S2, S3) of male and female rats was studied by electronmicroscopic and morphometric methods. Only light, granulated and dark lysosomes as well as microbodies (peroxisomes) and dictyosomes (Golgi zones) were investigated. After castration the area density of light lysosomes in the S1 segment increases in males whereas it decreases in females; therefore the sex different pattern of light lysosomes, that is to be seen in normal animals, is reversed. The absolute size and number of light giant lysosomes is also elevated in castrated males in comparison to normal animals as well as to animals substituted by testosterone. - Dark lysosomes of the S1 segments are more numerous in castrated females and less numerous in castrated males than in normal animals. - The distinct sex difference in dark lysosomes of the S2 segment which is demonstrable in normal animals disappears after castration the area density of dark lysosomes increasing in castrated females and decreasing in castrated males. The three species of lysosomes in the S1 segments show no longer a sex difference after substitution with testosterone: substituted males develop the same pattern as normal animals and substituted females are almost comparable with normal males. However, the sex difference in dark lysosomes of the S2 segment is more pronounced after testosterone treatment. - The characteristic pattern of light lysosomes in the S1 and S2 segments as well as the change of the sex different lysosomal pattern after castration and substitution with testosterone, respectively - especially in S1 - seem to be caused by testosterone which results in an inhibition of resorption. Only after castration a sex difference appears in dark lysosomes of the S3 segment (males show more dark lysosomes than females). This sex difference is reversed by testosterone treatment. There are more numerous lysosomes with an non-homogeneous matrix in both sexes after castration which are seldom to be seen in normal and substituted animals. The area density of microbodies shows sex differences in all 3 segments of normal animals. While no significant changes in S1 and S2 are to be seen after castration and substitution, there is a pronounced decrease of the area density of microbodies in S3 of males after castration, so that no sex differences are then available.(ABSTRACT TRUNCATED AT 400 WORDS)     

Quantitative histochemistry of the lysosomal dipeptidyl aminopeptidase II in the proximal tubule of the rat kidney

Summary The activity of the lysosomal dipeptidyl aminopeptidase II (DAP II) was measured by quantitative histochemical methods in the S₁/S₂ segments of the proximal tubule using freeze dried and celloidin mounted cryostat sections (FDC sections) of rat kidney. The methodological studies show that there is a linear relationship between the amount of reaction product and reaction time for the first 5 min, as well as section thickness between 4 and 10 m. Maximal DAP II activities were demonstrated at pH 5.5. The K _m of DAP II was about 2.3 mM. — In addition to the methodological studies, DAP II activity was also measured in the proximal tubule (S₁/S₂ segments) of experimental animals (sham-operated and castrated male and female rats). Sham-operated females showed significantly higher DAP II activities than males. DAP II activity increased significantly in castrated males so that there were no significant differences between castrated males, sham-operated and castrated females. The quantitative histochemical results are largely in agreement with biochemical data published earlier.Supported by the Deutsche Forschungsgemeinschaft (SFB 105)Dedicated to Prof. Dr. T.H. Schiebler, Chairman of the Institute of Anatomy of the University of Würzburg, on the occasion of his 60th birthday     

The postnatal development of the rat kidney,with special reference to the chemodifferentiation of the proximal tubule

Summary New nephron anlages appear in the renal cortex up to the 4th postnatal day (PD). The last anlages to be formed develop into functional nephrons by PD 10, and the cortex appears mature at PD 12 after formation of the cortex corticis. The renal medulla develops by the longitudinal growth of loops of Henle and collecting ducts. The immature medulla cannot be divided into different zones and corresponds structurally to the later inner stripe of the outer zone. The inner zone is formed by PD 8, and the outer stripe of the outer zone by PD 12. The renal medulla is mature at PD 21.From the start of its development, the renal proximal tubule consists of the pars convoluta and pars recta. In both parts the formation of the brush border is accompanied by the simultaneous appearance of brush border enzymes (alkaline phosphatase, -glutamyltranspeptidase, dipeptidylamino-peptidase IV) and lysosomal enzymes (acid phosphatase, acid -galactosidase, N-acetylglucosaminidase, dipeptidylaminopeptidase II) over the full length of the proximal tubule. During the course of proximal tubule maturation, however, the lysosomal enzyme activities decline in the pars convoluta (with constant brush border enzyme activities), while the brush border enzyme activities increase in the pars recta (with constant lysosomal enzyme activities). The two parts further differ in that they exhibit different lysosomal patterns from the outset, the pars convoluta containing numerous large, highly enzyme-active lysosomes arranged in groups, and the pars recta containing only a few very small lysosomes with low enzyme activity. Thus, even in the newborn rat, the lysosomal pattern of the pars recta already corresponds to that of the mature S₃ segment. The S₁ and S₂ segments of the pars convoluta first differentiate between PD 10 and 21, as the groups of large lysosomes are progressively broken up and the extent of the lysosomal apparatus is diminished, this proceeding in a retrograde direction from the end of the immature pars convoluta.Supported by the Deutsche Forschungsgemeinschaft (SFB 105)     

Zur Cytochemie der Lysosomen in der Rattenniere unter normalen und experimentellen Bedingungen

Zusammenfassung Es wird das Vorkommen der sauren Phosphatase (sP) und der -Glucu-ronidase (-Glu) in den Lysosomen von Rattennieren vom 16. Embryonaltag (ET) bis 33. Lebenstag (LT) sowie von erwachsenen unbehandelten, kastrierten und nach der Kastration mit gleich- bzw. gegengeschlechtlichen Hormonen behandelten Tieren untersucht. Bis zur Geburt entwickelt sich die lysosomale sP und -Glu in den einzelnen Nephronabschnitten und Sammelrohren annähernd parallel. Am 1. LT nimmt in den S₁-Segmenten der iuxtamedullären Nephrone Zahl, Durchmesser und Aktivität der sP positiven Lysosomen sprunghaft zu, um zwischen 5. und 9. LT wieder schnell abzunehmen. Die Aktivität der -Glu steigt dagegen kontinuierlich an. Zwischen 24. und 25. LT nimmt die Aktivität der -Glu in den Lysosomen der S₁- und S₃-Segmente ab, die der sP deutlich zu. Geschlechtsunterschiede treten bei der sP zum ersten Mal am 18. LT in den S₃-Segmenten, bei der -Glu am 25. LT in den S₁-Segmenten auf. Das ausdifferenzierte Enzymmuster für sP und -Glu kann erst bei erwachsenen Tieren nachgewiesen werden. Dann fallen bei beiden Geschlechtern unter den Lysosomen der S₁-Segmente zwei Größenklassen besonders auf: a. große Lysosomen (beim Weibchen 7 m, beim Männchen 5 m) und b. kleinere Lysosomen (bei beiden Geschlechtern 2–3 m). Die großen Lysosomen sind bei Weibchen zahlreicher und sP aktiver als bei Männchen. In den S₂-Segmenten (Durchmesser der Lysosomen 1,5–2,5 m) ist die -Glu in den Lysosomen der Männchen aktiver als bei den Weibchen; jedoch sind die Geschlechtsunterschiede in S₂ geringer als in S₁ In den S₃-Segmenten sind sP und -Glu in den Lysosomen weiblicher Nieren aktiver als in denen männlicher Tiere. — In den übrigen Abschnitten des Nephrons und in den Sammelrohren bestehen keine Geschlechtsunterschiede. — Die Lysosomen der Sammelrohre haben eine höhere Aktivität für -Glu als für sP.Durch Kastration werden die Geschlechtsunterschiede geringer, bleiben aber grundsätzlich erhalten; in den S₁-Segmenten können jedoch Lysosomen über 2,5 m nicht mehr nachgewiesen werden. Nach Testosteronbehandlung männlicher Kastrate nimmt die Aktivität der sP und -Glu gegenüber unbehandelten Kastraten ab. Bei kastrierten weiblichen Tieren treten nach Testosteronbehandlung wieder große Lysosomen auf, das Enzymmuster unbehandelter Tiere wird jedoch nicht erreicht. Östradiolbehandlung kastrierter Tiere führt bei beiden Geschlechtern in etwa zu einer Restitution der normalen Enzymverteilung, insbesondere bei den Männchen. Bei den Weibchen sind die Lysosomen größer und reagieren intensiver als bei Normaltieren, die Anzahl der Lysosomen scheint aber geringer zu sein.Insgesamt ergibt sich, daß die Lysosomen und die lysosomalen Enzyme unter dem Einfluß der Geschlechtshormone stehen.

---

On the cytochemistry of lysosomes in the rat kidney under normal and experimental conditions

Summary Acid phosphatase (ap) and -glucuronidase (-glu) have been investigated in the lysosomes of the rat kidney between the 16th embryonic and 33th postnatal day. Furthermore these enzymes were demonstrated in the kidney of adult normal as well as of orchiectomized or ovarectomized rats following treatment with homosexual and heterosexual hormones. — Up till birth, the development of ap and -glu runs nearly parallel to one another in the nephron and in the collecting tubules. At the first day of life an irregular increase with respect to number, diameter, and activity of lysosomes containing ap can be observed in the S₁ segments of the iuxtamedullary nephrons; a decrease occurs between the 5th and 9th postnatal day. On the contrary the -glu activity increases continously. Between the 24th and 25th day of life its activity decreases in the lysosomes of the S₁ and S₂ segments; the ap activity, however, increases. For the first time sex-specific differences concerning the distribution pattern of ap can be revealed around the 18th day of life in the S₃ segments; in the case of -glu ca one week later in the S₁ segments. The final ap and -glu pattern only exists in the kidney of adult animals. Here, in the male and female kidney two classes of lysosomes exhibit striking peculiarities in the S₁ segments: a. big lysosomes (in male 5 m, in female 7 m in diameter) b. small lysosomes (in both sexes 2–3 m in diameter). The big lysosomes are more numerous. Moreover their ap activity is higher in female rats in comparison with the male kidney. In the S₂ segments (lysosomal diameter 1.5–2.5 m) the -glu activity of male rats surpasses that of females. However sex differences in the S₂ are as obvious as in the S₁ segments. In S₃ the strongest ap and -glu reaction appear in female kidneys. — In the other parts of the nephron and in the collecting tubules sexspecific differences have never been observed. — In the lysosomes of the collecting tubules more -glu than ap activity can be detected.Castration induces only a decrease of sex differences, but they do not disappear completely; in the S₁ segments lysosomes being bigger than 2.5 m are absent. In male castrates treated with testosterone the activity of ap and -glu is lowered in comparison with unsubstituted animals. Following application of testosterone the big lysosomes reappear in overectomized rats; but the enzyme pattern of untreated animals will never be obtained. In both sexes treatment of castrated animals with estradiol is accompanied by restitution of the normal ap and -glu pattern especially in males. In the female kidney lysosomes are bigger and more active in comparison with the controls; the number of lysosomes seems to be reduced. Summarizing strong evidence occurs that in the rat kidney lysosomes and lysosomal enzymes are controlled by sex hormones.

     

Sex different cytochrome-c uptake in the proximal tubule of the rat kidney

The present study deals with the dose- and time-dependent uptake of cytochrome c (CYT c) in the proximal tubule of the rat kidney, and shows that there are segment and sex differences in the reabsorption of CYT c. Rats of both sexes were intravenously injected with different doses of CYT c (0.75-9.0 mg per 100 g body weight), and the kidneys were investigated by light and electron microscopy at different times (3 min, 10 min, and 2 h) after the injection. After 3 and 10 min, CYT c was demonstrated in apical vacuoles of different sizes and in some lysosomes of the S1 and S2 segments, whereas after 2 h, CYT c was found only in lysosomes of all three segments of the proximal tubule. At these times, the S1 segment contained more CYT c than the S2 and S3 segments. However, 2 h after the injection of 6 or 9 mg CYT c, the differences between the S1 and S2 segments disappeared almost completely, due to a strong lysosomal accumulation of CYT c in the S2 segment. At all studied times and CYT-c doses, the S3 segment contained less CYT c than the S1 and S2 segments. On the whole, different levels of CYT-c reabsorption were found in the different segments of the proximal tubule, which was saturable with increasing CYT-c doses, i.e. firstly in the proximal and then in the distal parts of the proximal tubule. Two hours after the injection of CYT c, a difference between males and females was observed, with the lysosomes of the S1 and S2 segments of females containing more CYT c than those of males. Thus, more CYT c was reabsorbed in the proximal tubule of females than in that of males.     

Demonstration of the existence of a single morphological type of gonadotrophic cell in Ellobius lutescens (Microtinae) by an ultrastructural analysis of their development under various physiological and experimental conditions

Summary Ultrastructural studies of pituitaries from Ellobius lutescens (immature males and females, adult hypogonadic males, and virgin and pregnant females) show that the gonadotrophic cells are characterized by a lamellar or vacuolar rough endoplasmic reticulum (RER), a spirally-arranged Golgi apparatus, elongated mitochondria and secretory granules of variable density and size (150–500 m). Ultrastructural differences between gonadotrophic cells previously determined by light microscopy correspond to changes in the development of the protein synthetic apparatus and in the intensity of hormonal discharge. Type 2 gonadotrophs always appear to be more active than type 1 gonadotrophs. After castration, all gonadotrophic cells develop into the same form of castration cell, although type 1 gonadotrophs change more slowly than type 2 cells. Treatment with testosterone induces an inverse development of the gonadotrophic cells which take on the appearance of resting cells similar to those found in immature animals, where the two cell types are also identical. Thus, only one morphological type of gonadotrophic cell can be identified in Ellobius lutescens. Moreover, the gonadotrophic cells of the hypogonadic adult male have the same appearance as those of the female two months after castration, which proves that the negative feedback mechanism which regulates gonadotrophic function is defective in adult male Ellobius lutescens.     

The mature mesonephric nephron of the rabbit embryo

Summary Transmission electron micrographs of the mesonephric nephron in 18 day rabbit embryos reveal major cytological structures reappearing in the nephron of the definitive rabbit kidney. The initial segment of the proximal tubule resembles (despite quite different cell proportions) the cell picture of the metanephric S₂-segment. The changes occurring at the end of the terminal proximal segment, the decrease in cell size, flattening of the nuclei, shortening of the brush border and reduction of Golgi profiles and endocytotic organelles largely parallel those between S₂ and S₃. The type of increased basolateral cell face of the proximal and distal tubule cells shows only quantitative differences to their metanephric counterparts. The distal tubule, which cannot be further subdivided (except the macula densa-region) exhibits varying degrees of cell interdigitations with vertically arranged and partially arching lateral ridges. This tubule matches closely the metanephric medullary straight part of the distal tubule, so that the sequence of the first mesonephric nephron segments is similar to the metanephric ones with the exception that the thin limb of Henle is absent. The large macula densa-region is characterized by its cell height and distended infranuclear spaces. The principal cells of the collecting tubule, with a few basal infoldings and intense short lateral interlockings resemble metanephric cells of the outer medullary collecting duct. The mitochondria-rich intercalated cells occur in dark and light contrasting forms and are more frequent than was evident from our SEM-study. The homogeneous cell population of the Wolffian duct is characterized by large glycogen deposits and comparatively smooth cell faces.     

Further studies on the regulation of the Harderian glands of golden hamsters by the thyroid gland

Summary Long-term increased or decreased circulating levels of thyroid hormones significantly modify porphyrin concentrations and morphology in the Harderian glands of male and female hamsters. Administration of T₃ reduced porphyrin concentrations in females; this treatment or decreasing thyroid hormone levels with KClO₄ suppressed the post-castration rise of porphyrins in males. Hypophysectomy led to increased porphyrins in the Harderian glands of males; this rise was suppressed in hypophysectomized males by T₃ or T₄. In females, hypophysectomy reduced porphyrins which were further reduced by daily administration of T₃ or T₄. These modifications in the normal females were identical in castrated males. Mitotic activity in the Harderian glands of females was stimulated by KClO₄ and by hypophysectomy with or without exogenous T₃. In males, castration increased mitotic activity which was suppressed by T₃ and exacerbated by KClO₄. Increased mitotic activity seemingly follows loss of tissue mass. The data show that thyroid hormones act directly on the Harderian glands rather than indirectly through modification of TSH synthesis/release. Female type glands in males are a consequence of loss of gonadal androgens by castration, or by suppression or loss of thyroid hormones by hypophysectomy or by treatment with KClO₄. However, male type glands in females are the result of androgen treatment, and/or increased levels of thyroid hormones via reduced ambient temperatures or of photic input. We conclude that regulation of the Harderian gland appears to be different in the two sexes.Abbreviations T ₃ Triiodothyronine - T ₄ Thyroxine - TSH Thyroid Stimulating Hormone - KClO ₄ Potassium Perchlorate - h hours - ml milliliter - mg milligram - g gram - male - female - castrated male - AP hypophysectomized - CON Control - ALA delta aminole-vulenic acid - HG Harderian Gland     

Testosterone: the culprit for producing splenocyte immune depression after trauma hemorrhage

Studies indicate that, whereas immune functions in males aredepressed, they are enhanced in females after trauma hemorrhage. Moreover, castration of male mice (i.e., androgen depletion) before trauma hemorrhage prevented the depression of cell-mediated immunity. Nonetheless, it remains unknown whether or not testosterone per se isresponsible for producing the immune depression. To study this, femaleC3H/HeN mice (n = 7 animals/group)were pretreated with 5-dihydrotestosterone (DHT) or vehicle for 19 days, then subjected to laparotomy (e.g., trauma) and hemorrhagic shock(blood pressure 35 ± 5 mmHg for 90 min) followed by fluidresuscitation or sham operation. Nontreated males underwent eithertrauma hemorrhage or sham operation. Twenty-four hours thereafter,splenocyte immune functions as well as plasma DHT, estradiol, andcorticosterone levels were measured. DHT-pretreated females hadsignificantly (P < 0.05) increasedDHT levels, comparable to those seen in males. Conversely, estradiollevels in such females were similar to control males. Splenocyteproliferation as well as interleukin-2 and interleukin-3 release werenot depressed in vehicle-treated females, whereas it was in DHT-treatedfemales after trauma hemorrhage, comparable to hemorrhaged males. Thushigh testosterone and/or low estradiol levels appear to beresponsible for producing splenocyte immune depression in males aftertrauma hemorrhage. Agents that block testosterone receptors or increaseestradiol levels may therefore be helpful in improving depressed immunefunctions in male trauma patients.

     

The hypothalamic–hypophyseal–gonadal regulation of hepatic glutathione S-transferases in the rat

Hepatic glutathione S-transferase activities were determined with the substrates 1,2-dichloro-4-nitrobenzene and 1-chloro-2,4-dinitrobenzene. Sexual differentiation of glutathione S-transferase activities is not evident during the prepubertal period, but glutathione conjugation with 1,2-dichloro-4-nitrobenzene is 2–3-fold greater in adult males than in females. Glutathione conjugation with 1-chloro-2,4-dinitrobenzene is slightly higher in adult males than adult females. No change in activity was observed after postpubertal gonadectomy of males or females. Neonatal castration of males results in a significant decrease in glutathione conjugation with 1,2-dichloro-4-nitrobenzene. Hypophysectomy, or hypophysectomy followed by gonadectomy did result in significantly higher glutathione S-transferase activities in both sexes. These increases can be reversed by implanting an adult male or female pituitary or four prepubertal pituitaries under the kidney capsule. Postpubertal sexual differentiation of glutathione S-transferase activities is neither dependent on pituitary sexual differentiation nor pituitary maturation. Prolactin concentrations are inversely related to glutathione S-transferase activities in hypophysectomized rats with or without ectopic pituitaries. Somatotropin exogenously administered to hypophysectomized rats results in decreased glutathione S-transferase activities, whereas prolactin has no effect. Adult male rats treated neonatally with monosodium l-glutamate to induce arcuate nucleus lesions of the hypothalamus have decreased glutathione S-transferase activities towards 1,2-dichloro-4-nitrobenzene and decreased somatotropin concentrations. Our experiments suggests that sexual differentiation of hepatic glutathione S-transferase is a result of a hypothalamic inhibiting factor in the male (absent in the female). This postpubertally expressed inhibiting factor acts on the pituitary to prevent secretion of a pituitary inhibiting factor (autonomously secreted by the female), resulting in higher glutathione S-transferase activities in the adult male than the adult female.     

Sex-specific effects of a parasite evolving in a female-biased host population

Background

Males and females differ in many ways and might present different opportunities and challenges to their parasites. In the same way that parasites adapt to the most common host type, they may adapt to the characteristics of the host sex they encounter most often. To explore this hypothesis, we characterized host sex-specific effects of the parasite Pasteuria ramosa, a bacterium evolving in naturally, strongly, female-biased populations of its host Daphnia magna.

Results

We show that the parasite proliferates more successfully in female hosts than in male hosts, even though males and females are genetically identical. In addition, when exposure occurred when hosts expressed a sexual dimorphism, females were more infected. In both host sexes, the parasite causes a similar reduction in longevity and leads to some level of castration. However, only in females does parasite-induced castration result in the gigantism that increases the carrying capacity for the proliferating parasite.

Conclusions

We show that mature male and female Daphnia represent different environments and reveal one parasite-induced symptom (host castration), which leads to increased carrying capacity for parasite proliferation in female but not male hosts. We propose that parasite induced host castration is a property of parasites that evolved as an adaptation to specifically exploit female hosts.

     

Programmed loss of flight ability in the early adult life of the blowfly Phormia terrae novae as a possible mechanism of intraspecific niche building with respect to the duration of life

• 1.1. The age related flight performance of males and females of the blowfly Phormia terrae novae was studied and the influence of artificially fed glucose determined.
• 2.2. Maximum flight ability—measured as flight distance, duration and initial velocity—was achieved during the first week after emergence, thereafter the flight performance drops precipitously between the 12th and 17th day of adult life.
• 3.3. Males and females, fed and unfed individuals, show no difference in their time course of flight ability.
• 4.4. The possible causes of the programmed loss of flight performance were discussed with regard to histological and enzyme activity changes observed at the same and other species.
• 5.5. The biological significance of this physiological age effect was revealed.

     

Sex Differences in Reactivity of the Sympathoadrenal System in Rat Ontogenesis

Sex differences in reactivity of the sympathoadrenal system were studied in male and female Wistar rats of three age groups (22-day-old, 31-day-old, and adult). An essential increase of catecholamine excretion level in males between the 22nd and 31st day after the birth has been noted both after stress (immobilization water-immersion action) and after injection of ₂-adrenoblockator yohimbine. In females the response to stress and injection of yohimbine practically did not change at this age stage. The sex dimorphism revealed as a higher level of adrenaline excretion in the 22-day-old females, as compared with males, was characterized in older groups by a higher level of its excretion in males. It might be suggested that sex dimorphism in non-reproductive types of behavior can depend on two factors: on differences in the maturity rate between females and males and on direct or mediated effects of sex hormones on physiological processes and related behavioral reactions.     

Physiological Daily Inhalation Rates for Free-Living Pregnant and Lactating Adolescents and Women Aged 11 to 55 Years,Using Data from Doubly Labeled Water Measurements for Use in Health Risk Assessment

The distribution of physiological daily inhalation rates for pregnant and lactating females aged 11 to 55 years was determined according to total daily energy expenditures, energy costs for growth, pregnancy and lactation (maternal milk-energy synthesis and breast-energy output) in free-living females. Such published data were obtained using a methodology based on the disappearance rates of predetermined doses of doubly labeled water (²H₂O and H₂ ¹⁸O) in urine from non-pregnant and non-lactating females (n = 357), as well as saliva from gravid and breastfeeding females (n = 91), monitored by gas-isotope-ratio mass spectrometry over an aggregate period of about 6,000 days. Monte Carlo simulations were necessary to integrate total daily energy requirements of non-pregnant and non-lactating females into energy costs and weight changes at the 9th, 22nd, and 36th week of pregnancy and at the 6th and 27th, postpartum week: 540,000 data were simulated. The present article confirms that physiological daily inhalation rates for under-, normal-, and overweight/obese pregnant and lactating females expressed in m³/day and m³/kg-day are higher than those for males. For instance, in normal-weight subjects, inhalation rates are higher by 18 to 41% throughout pregnancy and 23 to 39% during postpartum weeks: actual values were higher in females by 1.13 to 2.01 m³/day at the 9th week of pregnancy, 3.74 to 4.53 m³/day at the 22nd week and 4.41 to 5.20 m³/day at the 36th week, and by 4.43 to 5.30 m³/day at the 6th postpartum week and 4.22 to 5.11 m³/day at the 27th postpartum week. The highest 99th percentiles were found to be 0.622 m³/kg-day in pregnant females and 0.647 m³/kg-day in lactating females. By comparison, the highest 99th percentile value for individuals aged 2.6 months to 96 years was determined to be 0.725 m³/kg-day in Brochu et al. (2006a) Brochu, P, Ducré-Robitaille, J F and Brodeur, J. 2006a. Physiological daily inhalation rates for free-living individuals aged 1 month to 96 years, using data from doubly labeled water measurements: a proposal for air quality criteria, standard calculations and health risk assessment. Hum Ecol Risk Assess, 12: 675–701. [CSA][Taylor & Francis Online], [Web of Science ®] [Google Scholar]. Air quality criteria and standard calculations based on the latter value for non-carcinogenic toxic compounds should therefore be protective for virtually all pregnant and lactating females. The present article highlights evidence that the current default assumption regarding the total daily air intake used by the Integrated Risk Information System (IRIS) to derive human equivalent concentrations in reference dose calculations is also underestimated compared to some higher 75th and 90th percentiles of physiological daily inhalation rates in pregnant and lactating females.     

Body size and allometric variation in facial shape in children

Objectives

In group‐living primates, it has been reported that the alpha male exhibits high concentrations of cortisol and testosterone in the context of mating competition. We investigated how the presence of females affected salivary cortisol and testosterone levels in males from a small captive group of chimpanzees (Pan troglodytes). Specifically, we assessed whether the presence of females resulted in a rapid increase in salivary cortisol and testosterone levels in the alpha male.

Materials and methods

We compared the social behavior and salivary hormone concentrations of four males before and after the presentation of receptive females. Three times a day, we collected saliva samples, a useful matrix for investigating short‐term hormonal changes, and measured cortisol and testosterone concentration by liquid chromatography–tandem mass spectrometry (LC–MS/MS).

Results

The frequency of inter‐male aggression increased in the presence of females, indicating intense competition among males. Salivary cortisol levels increased in all males in the presence of females; however, the increase was significantly more pronounced in the alpha male. We found a complex three‐way interaction among the presence of females, sampling timings, and male dominance rank in the analysis of salivary testosterone. Contrary to our prediction, a post hoc analysis revealed that salivary testosterone levels decreased after female introduction and that the alpha male did not show a higher level of salivary testosterone.

Conclusions

Our study provides experimental evidence suggesting that the presence of females plays a significant role in the rank‐related variation in the cortisol levels in male chimpanzees. Furthermore, our findings demonstrate the usefulness of salivary hormones for detecting short‐term physiological changes in studies of socioendocrinology.

     

Peptidases in the kidney of male rats following castration and testosterone substitution

The localization of aminopeptidase M (APM), dipeptidyl peptidase I (DAP I), II (DAP II) and IV (DAP IV) in the renal section was investigated histochemically, and their activities were determined fluorometrically in renal homogenate of normal, castrated and testosteron treated male rats.--After castration the activities of the lysosomal DAP II (pars convoluta of the proximal tubule), DAP I (distal and proximal tubule) and of the mainly membrane-bound DAP IV (glomeruli, brush border of the proximal tubule) increase in comparison to normal males, whereas the activities of the brush border-bound APM decrease. After testosteron treatment of castrated animals (0.1, 0.5 and 1.0 mg testosterone proprionate/100 g BW and day; 5-day treatment) the activities of DAP I, II and IV decrease again, so that after treatment with 0.1 mg testosterone proprionate, the activities of DAP I and II approach those in normal males.--The additionally determined urinary protein excretion shows that there is a significant decrease in proteinuria after castration, whereas testosterone treatment of castrated animals is accompanied by an increase of proteinuria.--Our results would suggest that the protein catabolism in the proximal tubule and the proteinuria are interrelated, and that testosterone influences (decreases) the protein catabolism in the proximal tubule. This means that high activities of lysosomal proteinases in the proximal tubule (castrates) are accompanied by a low proteinuria, and low activities of those proteinases (testosterone treated castrated or normal males) by a high proteinuria.     

Genotype and retention of the ejaculatory reflex in castrated male mice

Genotype proves to be an important factor affecting the retention of sexual responsiveness following castration. Male F₁ hybrids between C57BL/6 females and DBA/2 males (B6D2F₁) show very prolonged retention. Experiment 1 used a diallelic design using C57BL/6, DBA/2 and BALB/c strains and showed that heterosis per se is not an adequate explanation of the superior retention of the B6D2F₁ genotype. Experiment 2 showed that neonatal injections of 100 μg TP to B6D2F₁ male mice did not result in better retention of the ejaculatory reflex after castration in adulthood. B6D2F₁ males from both experiments who exhibited the ejaculatory reflex for many months after castration went through a ‘difficult period’ in the first 10 to 12 postcastration weeks. During this time, ejaculation latency increased fourfold, and then returned to the original level. On the other hand, the proportion of males reaching the ejaculatory threshold during this period first declined then increased.