Sexual maturational changes circulatory inhibin concentration in relation to FSH concentration and testicular size in Suffolk and DLS rams

Developmental patterns in immunoactive inhibin and FSH concentrations in peripheral blood were determined for Suffolk and DLS (Dorset x Leicester x Suffolk) rams born in January Blood samples were taken every 3 to 4 wk when testes were developing during puberty (5 to 44 wk of age) and redeveloping in early adulthood (17 to 23 months of age). Suffolk lambs had a greater average daily gain (195 vs. 143 g/day, P<0.01), and they developed larger testes (P<0.01) than DLS lambs. Inhibin and FSH concentrations peaked at about the same pubertal (8 wk) and early adult (19 or 20 months) ages in both breeds. Elevations in FSH were greater (P< 0.05) in Suffolk than DLS rams at each stage of development. The pubertal inhibin peak was nearly 70% larger (P<0.01) in DLS than Suffolk rams, and the early adult peak was comparable in rams of both breeds, but much smaller (P<0.01) than the pubertal peak. Nonetheless, inhibin was positively correlated (r=0.48 to 0.57) with FSH in both breeds during each developmental stage. Inhibin and testicular size were negatively correlated in Suffolk (r=-0.74) and DLS (r=-0.86) rams during puberty, and positively correlated in DLS rams (r=0.46) in early adulthood. We conclude that 1) inhibin concentrations are higher in juvenile rams at the time Sertoli cell numbers are being established than in adult rams during testicular recrudescence and 2) rises in FSH concentration participate in regulating corresponding rises in inhibin concentration in both stages of testicular development.     

Determinants of male mating success in a natural population of a stream goby of the genus Rhinogobius

The mating success of individually identified males of a stream goby, Rhinogobius sp. CB (cross‐band type), was recorded over one breeding season. One to 3 year‐old males were active in mating, but 3 year‐old males, which accounted for 36% of the population, amounted to c . 70% of the total males guarding eggs in the nest. Three quarters of the breeding males had only one brooding cycle, but the others had two or three. All the latter males changed their nest sites between cycles within a riffle. In 1 and 2 year‐old males, the number of brooding cycles contributed more to the mating success than egg mass size in one brooding cycle. For mating success of 3 year‐old males, the egg mass size in one brooding cycle, which can be enhanced by spawning with a large female or multiple females, was as important as the number of brooding cycles. These male reproductive tactics could be attributed to the age‐related ability of nest construction and mate acquisition.     

5alpha-reductase isoenzymes 1 and 2 in the rat testis during postnatal development

The pubertal initiation of spermatogenesis is reliant on androgens, and during this time, 5alpha-reduced androgens such as dihydrotestosterone (DHT) are the predominant androgens in the testis. Two 5alpha-reductase (5alphaR) isoenzymes (5alphaR1 and 5alphaR2) have been identified, which catalyze the conversion of testosterone to the more potent androgen DHT. The present study aimed to investigate the developmental pattern of 5alphaR isoenzymes and their relationship to the production of 5alpha-reduced androgens in the postnatal rat testis. Both 5alphaR1 and 5alphaR2 isoenzyme mRNAs were measured by real-time polymerase chain reaction, isoenzyme activity levels by specific assays, and testicular androgens by radioimmunoassay after high-performance liquid chromatographic separation. Both 5alphaR1 and 5alphaR2 mRNAs and activity levels were low in the 10-day-old (prepubertal) testis, peaked between Days 20 and 40 during puberty, and then declined to low levels at 60-160 days of age. The developmental pattern of both 5alphaR isoenzyme activity levels was mirrored by the testicular production of 5alpha-reduced metabolites. Although 5alphaR1 was greater than 5alphaR2 at all ages, it is likely, given the substrate preferences of the two, that both isoenzymes contribute to the pubertal peak of 5alpha-reduced androgen biosynthesis. The peak in 5alphaR isoenzymes and 5alpha-reduced metabolite production coincided with the first wave of spermatogenesis in the rat, suggesting a role for 5alpha-reduced metabolites in the initiation of spermatogenesis. This was explored by acute administration of a 5alphaR inhibitor (L685,273) to immature rats. The L685,273 markedly suppressed testicular 5alphaR activity during puberty by 75%-86%. However, a marked increase was observed in testicular testosterone levels (in the absence of changes in LH), and no decrease was observed in the absolute levels of 5alpha-reduced metabolites. Therefore, whether the formation of DHT in the presence of low testosterone levels in the pubertal testis is required for the initiation of spermatogenesis cannot be tested using 5alphaR inhibitors. We conclude that both 5alphaR1 and 5alphaR2 isoenzymes are involved in the peak of 5alpha-reduced androgen biosynthesis in the testis during the pubertal initiation of spermatogenesis.     

Delay in the age of balano-preputial skinfold cleavage and alterations in serum profiles of testosterone, 5 alpha-androstane-3 alpha,17 beta-diol, and gonadotropins in adult rats treated during puberty with luteinizing hormone releasing hormone

Previous work has shown that chronic treatment of intact, immature male rats with luteinizing hormone releasing hormone (LHRH) decreases sex accessory gland weights and results in retardation of the normal developmental increase in the ratio of serum testosterone (T)/5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-Diol) via an apparent enhancement of testicular 5 alpha-reductase or 3 alpha-hydroxysteroid oxidoreductase activities. In the present work, androgen dependent balano-preputial skinfold cleavage was significantly delayed by approximately one week in intact, immature male rats which were treated daily for two weeks with either 1.0 micrograms, 2.5 micrograms or 5.0 micrograms of LHRH during a discrete phase of pubertal development (28-41 days of age). In intact, adult (62 day old) animals which received LHRH treatments during pubertal development, serum T concentrations and sex accessory gland weights were reduced compared to control animal values. Serum 3 alpha-Diol content in the adult rats was either unaltered or increased significantly depending on the LHRH dosage employed during sexual development. Serum luteinizing hormone concentrations were not different between control and LHRH-pretreated adult rats whereas the highest dosage of LHRH employed (5.0 micrograms) during puberty resulted in a significant elevation of adult serum follicle stimulating hormone levels. It is suggested that chronic LHRH treatment of the male rat during puberty results in a perturbation in testicular androgen biosynthetic activities and an impairment of pituitary-testicular hormone feedback mechanisms which persist at least through early adulthood.     

Spermatogenesis parameters and testosterone production at puberty as predictors of testicular functional activity in mice (<Emphasis Type="Italic">Mus musculus</Emphasis>)

The aim of this study was to investigate fertility-associated parameters of spermatogenesis and androgenic status in male laboratory mice at puberty and to assess their prognostic significance in the realization of the definitive testicular function. In three inbred murine strains, BALB/cLac, CBA/Lac and PT, the serum testosterone level, its testicular concentration, epididymal sperm count (sperm reserve) and portion of sperm with abnormal head morphology were evaluated on days 45 (puberty) and 90 (adulthood) of postnatal development. CBA/Lac males were characterized by a lower epididymal sperm count vs. other strains at both ages indicative of poorer spermatogenesis. At the same time, CBA/Lac males had a lower portion of sperm with abnormal head morphology, and this could be considered as a compensatory reaction aimed at improving sperm fertility. Distinct inter-strain differences in the portion of sperm with morphologically abnormal heads were established at both ages, while the inter-strain ratio remained invariable (BALB/cLac > PT > CBA/Lac). Thus, the level of abnormal spermatogenesis in the pubertal period may have a predictive significance for the definitive testicular activity in adult mice. No inter-strain and age-dependent changes were found in serum and testicular testosterone levels except for the PT strain, in which both testosterone levels rose from puberty to adulthood, suggesting a shift of the pubertal testosterone peak towards later times. Our data show that in male laboratory mice the genetic peculiarities of the testicular function manifest themselves during puberty and persist until adulthood.     

Effects of gonadal steroids during pubertal development on androgen and estrogen receptor-alpha immunoreactivity in the hypothalamus and amygdala

Perinatal development is often viewed as the major window of time for organization of steroid-sensitive neural circuits by steroid hormones. Behavioral and neuroendocrine responses to steroids are dramatically different before and after puberty, suggesting that puberty is another window of time during which gonadal steroids affect neural development. In the present study, we investigated whether the presence of gonadal hormones during pubertal development affects the number of androgen receptor and estrogen receptor alpha-immunoreactive (AR-ir and ER alpha-ir, respectively) cells in limbic regions. Male Syrian hamsters were castrated either before or after pubertal development, and 4 weeks later they received a single injection of testosterone or oil vehicle 4 h prior to tissue collection. Immunocytochemistry for AR and ER alpha was performed on brain sections from testosterone-treated and oil-treated males, respectively. Adult males that had been castrated before puberty had a greater number of AR-ir cells in the medial preoptic nucleus than adult males that had been castrated after puberty. There were no significant differences in ER alpha-ir cell number in any of the brain regions examined. The demonstration that exposure to gonadal hormones during pubertal development is associated with reduced AR-ir in the medial preoptic nucleus indicates that puberty is a period of neural development during which hormones shape steroid-sensitive neural circuits.     

Migratory behaviour of ide: a comparison between the lowland rivers Elbe, Germany, and Vecht, The Netherlands

Individual movement patterns of adult ide Leuciscus idus , a Eurasian river‐dwelling cyprinid, in two lowland rivers were measured all year‐round during 1997–2000 to assess migratory behaviour and variation between and within these populations. In the River Elbe, a 1091 km long lowland river with a free flowing stretch of 590 km, 24 ide were implanted with radio transmitters. Fish were hand‐tracked all year‐round once a week in the main study area (75 km), and once per 6 weeks in a larger area (321 km). In the River Vecht, a 190 km long highly regulated river with six weirs and fishways in the Dutch section, 25 ide were implanted with transponders. An array of three automatic detection stations covering the entire river width, registered each individual passage continuously. Within population variation in year‐round movement patterns was very high. In both rivers a similar continuum was found from individuals using a river stretch of only a few km for spawning, feeding and wintering, to individuals migrating >100 km. The populations in the two rivers differed, however, in spawning site fidelity. In the River Vecht spawning site fidelity was observed in all individuals and appeared much stronger than in the River Elbe, where individuals moving downstream >60–90 km tended to adopt new spawning sites in the next year. Moreover, some ide in the River Vecht migrated upstream to wintering habitats in autumn, whereas this was not observed in the River Elbe. The results suggest that ide is a flexible species capable of using a wide variety of movement patterns and scales.     

Testicular functions in mice bearing an autosomal translocation (T 145H)

In the mouse, the autosomal reciprocal translocation T (7; 19) 145 H caused complete male sterility. The spermatogenesis was arrested at prophase or early metaphase I stages during the first meiotic division. The exocrine and endocrine testicular functions of azoospermic males (T 145 H/+) were compared with those of normal male littermates (+/+) at 63 days of age. Testis and epididymis weights in T 145 H/+ were significantly lower than those in +/+. By histological examination, the interstitial cells appeared preponderant but this was probably illusory due to the decrease in seminiferous tubular size and diminished testicular size. Moreover, androgen activity in T 145 H/+ seemed normal judging by weights of androgen target tissues (prostate, seminal vesicles), and plasma testosterone level.     

Effects of gonadal steroids during pubertal development on androgen and estrogen receptor‐α immunoreactivity in the hypothalamus and amygdala

Perinatal development is often viewed as the major window of time for organization of steroid‐sensitive neural circuits by steroid hormones. Behavioral and neuroendocrine responses to steroids are dramatically different before and after puberty, suggesting that puberty is another window of time during which gonadal steroids affect neural development. In the present study, we investigated whether the presence of gonadal hormones during pubertal development affects the number of androgen receptor and estrogen receptor α‐immunoreactive (AR‐ir and ERα‐ir, respectively) cells in limbic regions. Male Syrian hamsters were castrated either before or after pubertal development, and 4 weeks later they received a single injection of testosterone or oil vehicle 4 h prior to tissue collection. Immunocytochemistry for AR and ERα was performed on brain sections from testosterone‐treated and oil‐treated males, respectively. Adult males that had been castrated before puberty had a greater number of AR‐ir cells in the medial preoptic nucleus than adult males that had been castrated after puberty. There were no significant differences in ERα‐ir cell number in any of the brain regions examined. The demonstration that exposure to gonadal hormones during pubertal development is associated with reduced AR‐ir in the medial preoptic nucleus indicates that puberty is a period of neural development during which hormones shape steroid‐sensitive neural circuits. © 2000 John Wiley & Sons, Inc. J Neurobiol 44: 361–368, 2000     

Post-natal patterns of plasma androgen-binding activity in Djungarian (Phodopus sungorus) and golden (Mesocricetus auratus) hamsters

The binding of sex steroids to plasma proteins was examined in post-natal Djungarian and golden hamsters. With dihydrotestosterone or testosterone as ligands, steady-state polyacrylamide gel electrophoresis revealed 2 androgen binding components in the plasma of young Djungarian hamsters of both sexes. The fast-moving component exhibited a low affinity and high capacity for androgens and corresponded to albumin in stained gels. In contrast, the slow moving component was a beta-globulin with high affinity (Ka = 10(9) M-1) and low capacity for androgens, and was identified as a specific sex steroid-binding protein (SBP; also SHBG). This SBP did not bind oestrogens or corticosteroids and was electrophoretically distinct from corticosteroid-binding globulin (CBG). In addition, this protein did not appear to be of testicular origin because it was present in immature females and in immature males that had been castrated for 8 days. Plasma concentrations of SBP in males as measured by a diethyl-aminoethyl-cellulose binding assay were low at birth, became significantly elevated shortly thereafter when plasma androgen values were also elevated, and subsequently fell to low levels during puberty. These changes follow the same general pattern that has been described for other mammals, including humans, during this period of reproductive development. Although the significance of elevated SBP concentrations during prepuberty has yet to be determined, it appears that the increased concentrations of high-affinity androgen binding in the plasma of Djungarian hamsters plays a role in the asynchronous pubertal development of the testes and accessory organs which occurs in this species. The post-natal SBP pattern in females was similar to that observed in males. Plasma SBP levels were low or undetectable in adults of both sexes. As previously described for adult golden hamsters, the plasma of post-natal male and female golden hamsters lacked a specific SBP: androgen binding in this species is apparently limited to albumin and CBG.     

Testicular Ca++ ATPase activity in mice: effects of age and gonadotropin administration

These studies describe a high affinity calcium (Ca++)-dependent ATPase in purified testicular plasma membranes, which exhibits increased activity from weaning age to adulthood. Administration of human chorionic gonadotropin (hCG; 5 IU) increased enzyme activity in 21-day old and pubertal (35 to 40-day old), but not in adult mice. In pubertal mice, these increases in testicular Ca++-ATPase activity were dose-related and evident 60 min after hCG administration. A second challenge dose of 5 IU hCG administered either 24, 48 hrs, or 5 days later, had no additional effect on Ca++ ATPase in purified testicular plasma membranes in these pubertal animals. The present findings indicate that testicular plasma membrane Ca++ATPase activity exhibits a developmental pattern concomitant with increased testicular steroidogenic activity during sexual maturation. Furthermore, enzyme activity is increased by gonadotropic stimulation and exhibits a refractoriness similar to that of androgen biosynthesis to repeated hCG stimulation.     

Inhibin B,follicle stimulating hormone,luteinizing hormone and testosterone during childhood and puberty in males: changes in serum concentrations in relation to age and stage of puberty

Inhibin B is a gonadal dimeric polypeptide hormone that regulates synthesis and secretion of follicle stimulating hormone (FSH) in a negative feedback loop. The aim of the present study was to determine changes in serum inhibin B, gonadotropins and testosterone concentrations during childhood and puberty in males. We studied the relationship between circulating inhibin B, gonadotropins and testosterone in serum of healthy boys during the first two years of life and then in pubertal development. Using a recently developed two-side enzyme-linked immunosorbent assay (ELISA), inhibin B levels were measured in the serum of 78 healthy boys divided into eleven age groups from birth to the end of pubertal development. In addition, serum levels of gonadotropins and testosterone were measured. Serum inhibin B, gonadotropins and testosterone increased during the first months of postnatal life. A peak in serum inhibin B and gonadotropins concentrations was observed around 3-4 months of age. There was a significant positive correlation between serum inhibin B and gonadotropins and testosterone levels during the first 2 years of life. After this early increase, serum inhibin B, gonadotropins and testosterone levels decreased significantly and remained low until puberty followed by an increase beginning with the onset of puberty. Serum levels of inhibin B reached a peak at stage G3 of puberty. Around midpuberty, inhibin B lost its positive correlation with luteinizing hormone (LH) and testosterone from early puberty, and developed a strong negative correlation with FSH, which persisted into adulthood. We conclude that inhibin B plays a key role in the regulation of the hypothalamic-pituitary-gonadal hormonal axis during male childhood and pubertal development. Inhibin B is a direct marker of the presence and function of Sertoli cells and appears to reflect testicular function in boys.     

An association of early puberty with disordered eating and anxiety in a population of undergraduate women and men

Eating and anxiety disorders are more prevalent in females, increase during adolescence, and are associated with early pubertal development. This study examined whether timing of puberty onset is associated with disordered eating and anxiety in a large sample of postpubertal male and female undergraduate students. Self-report questionnaires assessed timing of puberty, disordered eating, anxiety, alcohol use, personality, and sensation seeking. Females scored significantly higher on measures of disordered eating (binge eating, dietary restraint, eating concerns, and weight and shape concerns) and anxiety (state and trait anxiety) than did males. In addition, early maturing women and men scored significantly higher on measures of disordered eating and anxiety than on time or late maturing women and men. Measures of alcohol use, sensation seeking, and personality characteristics differed in males and females but did not vary with pubertal timing. Findings suggest that early puberty is associated with disordered eating and anxiety, and this association may be due to an organizational effect of pubertal hormones. Despite important differences in body fat composition, both males and females experiencing early puberty had an increased incidence of disordered eating. The fact that early puberty was associated with increased eating and anxiety symptoms in both sexes suggests that puberty may influence these symptoms through both biological and psychosocial mechanisms.     

Sex steroids and their involvement in the cortisol-induced inhibition of pubertal development in male common carp,Cyprinus carpio L

The onset and regulation of puberty is determined by functional development of the brain-pituitary-gonad (BPG) axis. Sex steroids produced in the gonads play an important role in the onset of puberty. Stress interferes with reproduction and the functioning of the BPG axis, and cortisol has frequently been indicated as a major factor mediating the suppressive effect of stress on reproduction. Prolonged elevated cortisol levels, implicated in stress adaptation, inhibited pubertal development in male common carp (Cyprinus carpio). Cortisol treatment caused a retardation of pubertal testis development and reduced the LH pituitary content and the salmon GnRHa-stimulated LH secretion in vitro. A reduced synthesis of androgens also was observed. These findings suggest that the cortisol-induced inhibition of testicular development and the maturation of pituitary gonadotrophs are mediated by an effect on testicular androgen secretion. In this study, we combined cortisol treatment with a replacement of the testicular steroid hormones (testosterone and 11-oxygenated androgens) to investigate the role of these steroids in the cortisol-induced suppression of pubertal development. The effect of cortisol on spermatogenesis was independent of 11-ketotestosterone, whereas the effect on the pituitary was an indirect one, involving the testicular secretion of testosterone.     

REGULATION AND KINETICS OF SPERMATOGONIAL PROLIFERATION IN ARENICOLA MARINA (ANNELIDA, POLYCHAETA) I. THE ANNUAL CYCLE OF MITOTIC INDEX IN THE TESTIS

The annual variation in the mitotic index of the testis of Arenicola marina after 48 hr treatment with colchicine has been determined. This mitotic index in the population is distributed log-normally. The mean mitotic index is low in winter but increases during the spring to a maximum in early summer. The mean mitotic index remains high until September when it decreases temporarily. There is a second minor increase in the mean mitotic index prior to spawning.
Decerebration of animals prior to the spring increase in the mitotic index did not prevent this increase occurring in decerebrate animals maintained in the laboratory. Removal of the coelomic gametes was effective in stimulating the testicular mitotic index only when performed during the period of low mitotic activity in early autumn.     

Neuroendocrine dysfunction in polycystic ovary syndrome

Polycystic ovarian syndrome (PCOS) is a common disorder characterized by ovulatory dysfunction and hyperandrogenemia (HA). Neuroendocrine abnormalities including increased gonadotropin-releasing hormone (GnRH) pulse frequency, increased luteinizing hormone (LH) pulsatility, and relatively decreased follicle stimulating hormone contribute to its pathogenesis. HA reduces inhibition of GnRH pulse frequency by progesterone, causing rapid LH pulse secretion and increasing ovarian androgen production. The origins of persistently rapid GnRH secretion are unknown but appear to evolve during puberty. Obese girls are at risk for HA and develop increased LH pulse frequency with elevated mean LH by late puberty. However, even early pubertal girls with HA have increased LH pulsatility and enhanced daytime LH pulse secretion, indicating the abnormalities may begin early in puberty. Decreasing sensitivity to progesterone may regulate normal maturation of LH secretion, potentially related to normally increasing levels of testosterone during puberty. This change in sensitivity may become exaggerated in girls with HA. Many girls with HA-especially those with hyperinsulinemia-do not exhibit normal LH pulse sensitivity to progesterone inhibition. Thus, HA may adversely affect LH pulse regulation during pubertal maturation leading to persistent HA and the development of PCOS.     

Oogonial proliferation and early oocyte dynamics during the reproductive cycle of two Clupeiform fish species

Although oogonial proliferation continues in mature females in most teleosts, its dynamics and the transformation of oogonia to early meiotic oocytes during the reproductive cycle have received little attention. In the present study, early oogenesis was examined throughout the reproductive cycle in two Clupeiform fishes, the Mediterranean sardine, Sardina pilchardus, and the European anchovy, Engraulis encrasicolus. Observations using confocal laser scanning microscopy (CLSM) provided extensive information on markers of oogonial proliferation (mitotic divisions, oogonia nests) and meiotic prophase I divisions of oocyte nests (leptotene, zygotene, pachytene, diplotene) in ovaries of different reproductive phases. In sardine, oogonial proliferation persisted throughout the entire reproductive cycle, whereas in anchovy, it was more pronounced prior to (developing ovaries) and after (resting ovaries) the spawning period. Anchovy exhibited a higher rate of meiotic activity in developing ovaries, whereas sardine exhibited a higher rate in resting ovaries. The observed differences between the two species can potentially be attributed to different seasonal patterns of energy allocation to reproduction and the synchronization between feeding and the spawning season.     

Pubertal orchestration of hormones and testis in primates

The term “Puberty”, socially known as “Adolescence” is the transitional period from juvenile life to adulthood with functional maturation of gonads and genital organs. In this process, some remarkable developmental changes occur in morphology, physiology, and behavior leading to reproductive competence. Despite sufficient levels of gonadotropins (luteinizing hormone [LH] and follicle‐stimulating hormone [FSH]), robust spermatogenesis is not initiated during infancy in primates due to the immaturity of testicular Sertoli cells. Recent studies suggest that developmental competence augmenting functional activities of receptors for androgen and FSH is acquired by Sertoli cells somewhere during the prolonged hypo‐gonadotropic juvenile period. This juvenile phase is terminated with the re‐awakening of hypothalamic Kisspeptin/Neurokinin B/Dynorphin neurons which induce the release of the gonadotropin‐releasing hormone leading to reactivation of the hypothalamo‐pituitary‐testicular axis at puberty. During this period of pubertal development, FSH and LH facilitate further maturation of testicular cells (Sertoli cells and Leydig cells) triggering robust differentiation of the spermatogonial cells, ensuing the spermatogenic onset. This review aims to precisely address the evolving concepts of the pubertal regulation of hormone production with the corresponding cooperation of testicular cells for the initiation of robust spermatogenesis, which can be truly called “testicular puberty.”