Renal cathepsin-B activities in rats after castration and treatment with sex hormones

The activities of the lysosomal endopeptidase cathepsin B (cath B; CZB-Ala-Arg-Arg-MNA as substrate) and the lysosomal exopeptidase dipeptidylpeptidase II (DAP II; Lys-Ala-2NA as substrate) were fluorometrically determined in the renal homogenate of normal and experimental (castration followed by a 14-day treatment with estradiol and testosterone) rats of both sexes. In addition, methodological investigations of the renal homogenate were performed in order to differentiate cath B from other proteinases. These showed that cath-B activity was highest at around pH 6, was strongly inhibited by 4-hydroxymercuribenzoate and leupeptin, and was activated by dithiothreitol. Trypsin-like activities were not demonstrable under the used incubation conditions. The animal experiments showed that renal cath-B activities (1) were significantly higher in females than in males, (2) increased significantly in males and decreased significantly in females after castration (no significant difference between both sexes), (3) decreased in female and male castrates after treatment with testosterone and increased strongly after treatment with estradiol, and (4) showed an activity pattern similar to that of DAP II. The results are discussed in relation to the sex-dependent and sex-hormone-dependent proteinuria of rats. It is suggested that there is a correlation between protein catabolism in the kidney and proteinuria, i.e. high lysosomal proteinase activities correspond with low proteinuria.     

Variations in sexual dimorphism in the skulls of rats subjected to malnutrition, castration, and treatment with gonadal hormones

Two groups of weanling rats were subjected to malnutrition, one with periodic injections of testosterone (males) and the other with estradiol (females). Two other groups (castrated males or castrated females) received normal feedings. In control animals, the relative weights (mg/gm body weight) of testes, seminal vesicles, and ovaries were greater than in malnourished rats. However, relative weights of those organs in hormone-treated, malnourished animals were greater than in those subjected to malnutrition alone and still greater than in controls. Normal sexual cranial dimorphism (SCD) was decreased 16% by male castration, 23% by malnutrition, and 83% by estradiol treatment in malnourished females. On the other hand, normal SCD was increased 20% by female castration and more than 200% by testosterone treatment in malnourished males. All monosexual comparisons corroborated the bisexual range of distances found. Testicular but not ovarian secretions seemed to influence sexual cranial dimorphism. Malnutrition delayed SCD because of a deficiency of testosterone level in stressed males. It is suggested that estradiol in females may counteract sexual cranial development and that its inhibitory effect may be additive to the testosterone deficit evoked by malnutrition.     

Changes of norepinephrine levels, tyrosine hydroxylase and dopamine-beta-hydroxylase activities after castration and testosterone treatment in vas deferens of adult rats

Norepinephrine levels and tyrosine hydroxylase and dopamine-beta-hydroxylase activities have been used to evaluate the effect of castration and testosterone treatment on the sympathetic innervation of the adult vas deferens. Castration was followed by a decrease in both norepinephrine content and tyrosine hydroxylase activity, even though the changes were not concomitant. Treatment of castrated animals with testosterone reversed the effect of castration on organ weight and norepinephrine content, but only a short-lasting increase in tyrosine hydroxylase activity occurred at the beginning of testosterone treatment. In contrast, the testosterone-induced recovery of norepinephrine content observed at this time was accompanied by a marked increase in dopamine-beta-hydroxylase activity. The results suggest that in rat vas deferens, norepinephrine levels are under androgenic control and that this regulation mainly involves changes in dopamine-beta-hydroxylase activity rather than a modulation of tyrosine hydroxylase.     

LHRH test in ovariectomized women with and without treatment of sex hormones

The modulatory effect of sex hormones on the LHRH test, has been studied on ovariectomized women, randomly divided into groups which received estrogen (E2), progesterone (P) and E2 + P respectively. One group was left untreated. Menstruating women in follicular phase were also studied. The LHRH test was performed on all women and FSH, LH levels were measured in the blood. The LH levels in the blood following the LHRH test showed an increase in all the groups under investigation, including the ovariectomized untreated one. This suggests that, after ovariectomy, the hypophysis does not reach its maximum capacity for gonadotrophin release. The FSH response to the LHRH test was very low in all the groups studied, including the ovariectomized without treatment. It thus could be suggested that FSH needs other stimuli besides LHRH for its physiological release.     

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)     

Sex differences and sex hormones in anxiety-like behavior of aging rats

Sex differences in the prevalence of affective disorders might be attributable to different sex hormone milieu. The effects of short-term sex hormone deficiency on behavior, especially on anxiety have been studied in numerous animal experiments, mainly on young adult rats and mice. However, sex differences in aged animals and the effects of long-term hypogonadism are understudied. The aim of our study was to analyze sex differences in anxiety-like behavior in aged rats and to prove whether they can be attributed to endogenous sex hormone production in males. A battery of tests was performed to assess anxiety-like behavior in aged female, male and gonadectomized male rats castrated before puberty. In addition, the aged gonadectomized male rats were treated with a single injection of estradiol or testosterone or supplemented with estradiol for two-weeks. Female rats displayed a less anxious behavior than male rats in most of the conducted behavioral tests except the light-dark box. Long-term androgen deficiency decreased the sex difference in anxiety either partially (open field, PhenoTyper cage) or completely (elevated plus maze). Neither single injection of sex hormones, nor two-week supplementation of estradiol in gonadectomized aged male rats significantly affected their anxiety-like behavior in the elevated plus maze. In conclusion, our results confirm sex differences in anxiety in aged rats likely mediated by endogenous testosterone production in males. Whether long-term supplementation with exogenous sex hormones could affect anxiety-like behavior in elderly individuals remains to be elucidated.