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PubMed1979

Age-related changes in the testicular and antler cycles of reindeer, Rangifer tarandus.

A total of 111 male reindeer of various ages was shot in all months of the year to study the relationship between the seasonal changes in testicular activity and the antler cycle. From the changes in testis weight, seminiferous tubular tissue area and plasma testosterone values and the occurrence of spermatogenesis, it is concluded that calves attain physiological puberty in their first year, during which they also complete an antler cycle. The amplitude of the cyclical change in testis weight and plasma testosterone values increases with age and can be correlated with the earlier onset of events in the spermatogenic and antler cycles of older animals. The duration of the spermatogenic and testosterone cycles of reindeer is short, and is inversely related to the long period spent without antlers. It is suggested that testosterone strongly influences the antler cycle of reindeer males.

Aging↗
PubMed2000

Effect of chronic administration of an aromatase inhibitor to adult male rats on pituitary and testicular function and fertility.

The aim of the present study was to evaluate the effects of the administration of a potent non-steroidal aromatase inhibitor, anastrozole, on male reproductive function in adult rats. As anastrozole was to be administered via the drinking water, a preliminary study was undertaken in female rats and showed that this route of administration was effective in causing a major decrease in uterine weight (P<0.02). In an initial study in male adult rats, anastrozole (100 mg/l or 400 mg/l) was administered via the drinking water for a period of 9 weeks. Treatment with either dose resulted in a significant increase ( approximately 10%) in testis weight and increase in plasma FSH concentrations (P<0.01) throughout the 9 weeks. Mating was altered in both groups of anastrozole-treated rats, as they failed to produce copulatory plugs. Histological evaluation of the testes from anastrozole-treated rats revealed that spermatogenesis was grossly normal. In a more detailed study, adult rats were treated with 200 mg/l anastrozole via the drinking water for periods ranging from 2 weeks to 1 year. Plasma FSH and testosterone concentrations were increased significantly (P<0.001) during the first 19 weeks of treatment. However, LH concentrations were increased only at 19 weeks (P<0.001) in anastrozole-treated rats, and this coincided with a further increase in circulating and intratesticular testosterone concentrations (P<0.05). No consistent change in inhibin-B concentrations was observed during the study. Suppression of plasma oestradiol concentrations could not be demonstrated in anastrozole-treated animals, but oestradiol concentrations in testicular interstitial fluid were reduced by 18% (P<0.01). Mating was again inhibited by anastrozole treatment, but could be restored by s.c. injection of oestrogen, enabling demonstration that rats treated for 10 weeks or 9 months were still fertile. Testis weight was increased by 19% and 6% after treatment for 19 weeks and 1 year, respectively. Body weight was significantly decreased (P<0.01) by 19 weeks of anastrozole treatment; after 1 year the animals appeared to have less fat as indicated by a 27% decrease in the weight of the gonadal fat pad. The majority of anastrozole-treated animals had testes with normal spermatogenesis but, occasionally, seminiferous tubules showed abnormal loss of germ cells or contained only Sertoli cells. Ten percent of anastrozole-treated animals had testes that appeared to contain only Sertoli cells, and one rat had 'giant' testes in which the tubule lumens were severely dilated. Morphometric analysis of the normal testes at 19 weeks showed no difference in the number of Sertoli cells or germ cells, or the percentage volumes of the seminiferous epithelium, tubule lumens and interstitium between control and anastrozole-treated rats. On the basis of the present findings, oestrogen appears to be involved in the regulation of FSH secretion and testosterone production, and is also essential for normal mating behaviour in male rats. Furthermore, these data suggest that the brain and the hypothalamo-pituitary axis are considerably more susceptible than is the testis to the effects of an aromatase inhibitor. Anastrozole treatment has resulted in a model of brain oestrogen insufficiency.

Anastrozole↗
PubMed2000

Testicular heat exposure enhances the suppression of spermatogenesis by testosterone in rats: the "two-hit" approach to male contraceptive development.

The objectives of the study were to determine stage-specific changes in the kinetics of germ cell apoptosis induced by administration of exogenous testosterone (T) alone and to examine whether addition of a single testicular heat exposure would enhance the induction of germ cell apoptosis and the suppression of spermatogenesis by T. Adult male rats were implanted with 3-cm SILASTIC brand capsules (Dow Corning Corp.) containing T for up to 6 weeks. Intratesticular T levels declined to 2.9% of control values by 1 week and remained suppressed at 2, 3, and 6 weeks after T administration. The incidence of germ cell apoptosis (expressed as numbers per 100 Sertoli cells) was low in control rats (0-9.52). After T treatment, the mean incidence of apoptosis at stages VII-VIII increased significantly by 1 week (21.43 +/-3.33) and showed further increases by 6 weeks (56.30 +/- 7.47); apoptotic rates remained low at early (I-VI) and later (XII-XIV) stages. To test whether the combination of T with a single testicular heat exposure resulted in more complete suppression of spermatogenesis than either treatment alone, four groups of adult rats received one of the following treatments: 1) a subdermal empty polydimethylsilozane implant, 2) exposure to a single testicular heating (43 C for 15 min) applied on day 14, 3) 3-cm T implant, or 4) 3-cm T implant and a single testicular heat exposure (applied on day 14). All animals were killed at the end of 6 weeks. In the heat-treated group, testis weight and testicular sperm counts were decreased to 65.4% and 28.9% of control levels, respectively. The corresponding values in the T-treated group were 49.7% and 24.9% of control levels, respectively. Notably, addition of heat to T further reduced testis weight to 31.1% of control levels and testicular sperm counts to near zero. Histomorphometric analysis showed that all treatments reduced seminiferous tubular diameter and epithelial and luminal volume, with the greatest decrease after combined T and heat treatment. Heat exposure in animals bearing T implants markedly reduced the number of pachytene spermatocytes and round spermatids through apoptosis, resulting in tubules devoid of mature spermatids. Spermatogonia and preleptotene spermatocytes remained unaffected. These results clearly demonstrate that 1) exogenous T reduces intratesticular T and induces apoptosis mainly at stages VII-VIII within 1-6 weeks; 2) the combined treatment of T and heat markedly inhibits spermatogenesis, resulting in near azoospermia within 6 weeks; and 3) meiosis and spermiogenesis are the most vulnerable phases of spermatogenesis in response to T plus heat treatment. These findings suggest that a combination of hormonal treatment such as T and a physical agent (heat exposure) is more effective in suppressing spermatogenesis than either treatment alone. We hypothesize that combination of two antispermatogenic agents ("two hit") working at separate stages of the spermatogenic cycle will lead to greater male contraceptive efficacy.

Animals↗
PubMed1997

Rescue of testicular function after acute experimental torsion.

PURPOSE: Spermatic cord torsion results in impairment of testicular function. The mechanism of this injury is unclear; however, intracellular Ca++ influx and reactive oxygen species have been implicated in the testicular damage following torsion and reperfusion. In the present study a model of testicular torsion in the rat was used to determine whether testicular function following torsion can be rescued by the administration of antioxidants and Ca++ channel blockers. MATERIALS AND METHODS: Seventy-two animals were divided into 9 groups. Animals underwent 1 hr. or 2 hrs., 720 degrees experimental torsion. Animals received combinations of superoxide dismutase (SOD), catalase, allopurinol, and verapamil. Drugs were administered intravenously during the last 15 minutes of experimental torsion and the first hour of reperfusion. Bilateral testicular function was determined 60 days after experimental torsion by measuring testis weights, daily sperm production (DSP), and testicular venous testosterone concentrations. Ipsilateral values were compared to both control and contralateral values. RESULTS: SOD + catalase and SOD + catalase+verapamil treatments caused significant rescue of tests function following 1 hr. experimental torsion. Mean +/- s.e. testis weights and DSP in control animals were 1.75 +/- 0.6 g. and 18.4 +/- 0.3 x 10(6) sperm/g./d. The same value for testes experiencing 1 hr. experimental torsion were 0.72 +/- 0.6 g. and 2.3 +/- 0.5 x 10(6) sperm/g./d. The values from testes receiving 1 hr. experimental torsion followed by SOD + catalase were 1.45 +/- 0.17 g. and 9.9 +/- 1.8 x 10(6) sperm/g./d. Neither allopurinol nor verapamil added benefit. No significant rescue was seen in testes undergoing 2 hrs. experimental torsion. CONCLUSIONS: Treatment with oxygen radical scavengers provides significant rescue of testicular function after acute experimental torsion.

Allopurinol↗
PubMed1997

Fetal and perinatal influence of xenoestrogens on testis gene expression.

The incidence of reproductive abnormalities in the male has been reported to have increased during the past 50 years. It has been suggested that these changes may be attributable to the presence of chemicals with oestrogenic activity in our environment. The aim of the experiments described in this chapter was to investigate the effects of acute exposure to high levels of xenoestrogens either indirectly during fetal life, or directly during neonatal life, on gene expression in the testis and pituitary. Fetal treatment involved administration of diethylstilbestrol (DES), 4-octylphenol (OP) or vehicle (oil, control) to pregnant rats on days 11.5 and 15.5 post coitum; fetuses were recovered on day 17.5. There was no difference between fetuses from control and treated mothers in either the overall histology of the testes or numbers of Leydig cells as determined by immunohistochemistry with an antibody directed against 3 beta-HSD. However there was a consistent and striking reduction in the amount of P450 17-a hydroxylase C17, 20 lyase (P450c17) and steroidogenic factor 1 (SF-1) detected by immunocytochemistry in testes from treatment groups given the higher doses of OP and DES. Oestrogen receptors (ER alpha) were present in the fetal leydig cells of all animals. Neonatal treatment involved direct injection of oil (control), DES, OP or Bisphenol A (Bis A) on days 2, 4, 6, 8, 10 and 12; pituitaries and testes were recovered on day 18. Testis weights and seminiferous tubule diameters were significantly reduced in animals treated with DES. In these same animals immunocytochemical localisation revealed that the amounts of FSH beta subunit and inhibin alpha subunit were reduced in their pituitaries and testes respectively. OP did not appear to have an acute, measurable effect on testis gene expression but a reduction in testis weight was noted in adult animals given the same treatment regime. The effects observed are consistent with negative feedback by oestrogens on pituitary production of FSH resulting in retarded maturation of seminiferous tubules and reduced Sertoli cell numbers. These studies have demonstrated that administration of high levels of oestrogens can affect gene expression in the testis early in life. However, the relevance of these findings to observations in man await a) a greater understanding of the physiological role(s) of oestrogens in normal males, b) an evaluation of the sources, routes of exposure, concentrations in vivo and bioavailability of xenoestrogens.

Animals↗
PubMed2004

Effects of atrazine on fathead minnow in a short-term reproduction assay.

Atrazine is the most extensively used herbicide in the United States. Part-per-million concentrations of atrazine have been reported in agricultural runoff. It is detectable in surface waters and precipitation throughout the year, and it has been found in groundwater sources of drinking water. Recent studies indicate that atrazine may be a potent endocrine-disrupting compound in frogs exposed to part-per-billion (microg/L) concentrations. For these reasons, the effects of atrazine (5 and 50 microg/L) on several endpoints related to reproductive fitness were examined in fathead minnows (Pimephales promelas) in a 21-d static exposure. Estradiol (0.5 microg/L) was included as a positive-control treatment. Endpoints examined in adult fish during and after the exposures included survival, egg production, number of spawns, eggs/spawn, relative gonad weight, gonad histology, number of nuptial tubercles, and plasma vitellogenin concentration. Eggs produced during the exposures were hatched and reared in control water. The percentages of embryos fertilized and hatched as well as larval survival were evaluated. Decreasing trends were observed in relative testis weight, testis maturity, and percentage embryo fertilization. These trends suggest that further investigation is warranted, but the differences in these and other endpoints were not statistically significant in the atrazine-exposed fish. Nearly all endpoints concerning fish exposed to estradiol were significantly different from atrazine-exposed fish and control fish. These results suggest that atrazine did not have strong estrogenic effects in adult fathead minnows and did not cause overt reproductive toxicity at environmentally relevant concentrations.

Animals↗
PubMed1985

Testosterone response of cryptorchid and hypophysectomized rats to human chorionic gonadotrophin (hCG) stimulation.

The testosterone responses to a single injection of hCG (100 i.u.) in hypophysectomized (hypox.), cryptorchid or sham-operated rats were followed over a 5-day period. In sham-operated rats, hCG induced a biphasic rise in serum testosterone, peaks being observed at 2 and 72 h. Reduced testis weights, elevated FSH and LH levels and reduced serum testosterone levels were found after 4 weeks of cryptorchidism, but hCG stimulation resulted in a normal 2 h peak in serum testosterone. However, the secondary rise at 72 h in cryptorchid rats was significantly lower than sham-operated rats. Reduced testis weight and undetectable serum FSH and LH levels together with decreased testosterone levels were found 4 weeks after hypophysectomy. Serum testosterone levels rose 2 h after hCG in comparison to hypox. controls but this peak was significantly reduced compared with sham-operated rats. The second rise in serum testosterone began on day 2, peaking on day 4 at levels comparable to that seen in sham-operated rats after hCG. The in vitro basal and hCG stimulated secretion of testosterone by cryptorchid testes was greater than that secreted by normal rat testes (518.0 +/- 45.9 and 3337.6 +/- 304.1 pmol per testis per 4 h compared with 223.6 +/- 24.9 and 1312.9 +/- 141.4 pmol per testis per 4 h for normal rat testes). In cryptorchid animals a single injection of 100 i.u. hCG resulted in a pattern of in vitro refractoriness similar to normal rats, lasting from 12 h to 2 days, during which testosterone secretion was reduced to near basal levels. The in vitro basal and hCG-stimulated secretion of testosterone by hypox. rat testes was severely diminished compared with normal rat testes. The temporal pattern of in vitro secretion of testosterone from hypox. rat testes mimicked the in vivo serum testosterone pattern seen in these animals. This study demonstrates important differences in the in vivo and in vitro testosterone response to hCG after testicular damage.

Animals↗
PubMedDate not supplied

Endocrine parameters, hormone receptors, and functions of the testicular interstitium and seminiferous epithelium in estradiol-immunized Ile-de-France rams.

The testicular response of Ile-de-France rams actively immunized against estradiol (E2) was evaluated during both the ovine nonbreeding season (spring) and breeding season (autumn). Plasma concentrations of LH, FSH and testosterone were elevated in E2-immunized rams during both spring and autumn when compared with BSA-immunized controls. Testis weights were significantly elevated by E2 immunization and were characterized by greater interstitial cell volume, including Leydig cells, blood and lymph vessels, greater seminiferous tubule length, and greater numbers of leptotene spermatocytes and round spermatids. Neither Sertoli cell number, Sertoli cell nuclear volume nor testicular FSH receptor number were affected by E2 immunization, but testis weight, Sertoli cell nuclear area, FSH receptor number and LH receptor number were significantly greater in autumn than in spring. A positive effect of E2 immunization on testicular LH receptors was evident in spring but not in autumn. Testicular androgen receptors were suppressed by E2 immunization but were not affected by season. It was concluded that E2 immunization results in moderate stimulation of the ovine testis to increase testosterone secretion and to enhance total daily spermatid production. This effect appears to result from a change in E2 negative feedback and increased pituitary gonadotropin secretion.

Androgen-Binding Protein↗
PubMed2004

Hybrid breakdown caused by substitution of the X chromosome between two mouse subspecies.

Hybrid breakdown is a type of reproductive failure that appears after the F2 generation of crosses between different species or subspecies. It is caused by incompatibility between interacting genes. Genetic analysis of hybrid breakdown, particularly in higher animals, has been hampered by its complex nature (i.e., it involves more than two genes, and the phenotype is recessive). We studied hybrid breakdown using a new consomic strain, C57BL/6J-X(MSM), in which the X chromosome of C57BL/6J (derived mostly from Mus musculus domesticus) is substituted by the X chromosome of the MSM/Ms strain (M. m. molossinus). Males of this consomic strain are sterile, whereas F1 hybrids between C57BL/6J and MSM/Ms are completely fertile. The C57BL/6J-X(MSM) males showed reduced testis weight with variable defects in spermatogenesis and abnormal sperm head morphology. We conducted quantitative trait locus (QTL) analysis for these traits to map the X-linked genetic factors responsible for the sterility. This analysis successfully detected at least three distinct loci for the sperm head morphology and one for the testis weight. This study revealed that incompatibility of interactions of X-linked gene(s) with autosomal and/or Y-linked gene(s) causes the hybrid breakdown between the genetically distant C57BL/6J and MSM/Ms strains.

Animals↗
PubMed1988

The antiandrogen anandron potentiates the castrating effect of the LH-RH agonist buserelin in the rat.

When buserelin (0.04-25 micrograms/kg/day), a potent LH-RH agonist, was administered s.c. daily for 15 days to male rats, prostate weight decreased after a transient increase in the first days of treatment but never as much as after orchidectomy, since testosterone secretion was never totally suppressed. The combination of the pure nonsteroid antiandrogen Anandron (20 mg/kg/day) with even low doses of buserelin led to an immediate decrease in prostate weight that was complete at 15 days. This could be explained (a) by an additivity of effects: inhibition by Anandron of the action of residual testosterone unsuppressed by buserelin on the prostate and prevention by buserelin of the rebound testosterone increase induced by Anandron: (b) by a potentiation by Anadron of the direct castrating effect of buserelin on the testis since testis weight and testosterone secretion were lowered to a greater extent by the combination than by buserelin alone. Anandron might increase the sensitivity of LH-RH receptors to LH-RH agonist in the testes, as has been shown in the pituitary. In contrast, the combination of the antiandrogenic steroid progestin, cyproterone acetate, with buserelin never potentiated the castrating effect of buserelin on testis weight and testosterone and only partially potentiated prostate atrophy. If such actions also exist in the human, the addition of Anandron to LH-RH agonist treatment would not only counter flare-up and adrenal androgen effects on the prostate but would also lower the doses of peptide or the time required for chemical castration.

Administration, Oral↗
PubMed1987

Enhanced spermatogonial stem cell killing and reduced translocation yield from X-irradiated 101/H mice.

The spermatogonial stem cells of 101/H mice have been found to be more sensitive to killing by acute X-ray doses than those of the "standard" C3H/HeH X 101/H F1 hybrid. Duration of the sterile period was longer throughout the 0.5-8.0-Gy dose range tested and "recovered" testis weights, taken after recovery of fertility, were more severely reduced. The shapes of the sterile period dose-response curves were similar, but with the 101/H mice the plateau occurred at 3-5 Gy, rather than at 6 Gy. An equivalent observation was made with the testis weight data. The translocation dose-response curve was bell-shaped, as previously found with the hybrid, but yields were lower at all but the lowest doses. Notably, peak yields occurred at 3-5 Gy, rather than at 6 Gy. The altered stem cell killing and genetic responses may be explained either by a higher proportion of radiosensitive cells in the heterogeneous stem cell population or by a higher ratio of cell killing to recoverable chromosome damage which might imply a reduced repair capacity. The latter finds some support in other data. The pattern of genetic response obtained when an X-ray dose was given in two fractions at various intervals was similar in 101/H and the hybrid mice, suggesting that their kinetics of stem cell repopulation following depletion differ little.

Animals↗
PubMed2001

Heat-shock resistance in experimental cryptorchid testis of mice.

Cryptorchidism is commonly used for research on spermatogenesis. However, there are few comparative investigations about the strain differences in mice, especially in long-term experiments. In the present study, the authors demonstrate its specific dynamics in the MRL/MpJ mouse strain, and discuss the cause of strain differences. In the mouse strains A/J BALB/c, C3H/He, and C57BL/6, after 2 weeks of experimental cryptorchidism, the ratios of the cryptorchid testis weight against the intact one were 0.38+/-0.05, 0.43+/-0.05, 0.38+/- 0.02, and 0.44+/-0.14, respectively. On the other hand, in the MRL/MpJ strain it was shifted to 0.69+/-0.08. The details of this strain difference were compared by calculation of germ cells with the Sertoli cell index at 2 weeks after operation. The indices of spermatogonia in all strains were not significantly different; however, in MRL/MpJ mice remarkable numbers of late spermatocytes and round spermatids were detected. The decrease of the testis weight ratio was similar until 10 days in the C57BL/6 and MRL/MpJ strains, but continued in C57BL/6 until 21 days, whereas in MRL/MpJ mice it plateaued after 10 days. Northern blot analysis for heat shock protein 70-2 using total RNA prepared from the cryptorchid and intact testes at 2 weeks after operation revealed that the expression was decreased in the cryptorchid testis of C57BL/6, but not MRL/MpJ mice. The results suggested that heat-resistant germ cells were present in MRL/MpJ, originating possibly from the genetic background.

Animals↗
PubMedDate not supplied

Acute and long-term effects of a single dose of the fungicide carbendazim (methyl 2-benzimidazole carbamate) on the male reproductive system in the rat.

The effects of carbendazim (methyl 2-benzimidazole carbamate) on the testis, efferent ductules, and sperm were determined in the adult rat after a single oral dose. Two experimental trials were performed: a time response between 2 hours and 32 days after exposure using 0 and 400 mg/kg, and a dose response at 2 and 70 days after exposure using 0 to 800 mg/kg doses. In experiment 1, effects were seen throughout the 32-day period, beginning 8 hours after exposure; the effects included first an increase in testis weight, then decreases in testicular spermatid numbers and in the percentage of morphologically normal cauda sperm. In experiment 2, significant testicular and efferent ductal alterations occurred in animals treated with doses of 100 mg/kg or greater. A dose-dependent increase in testicular weight 2 days after treatment was accompanied by increases in seminiferous tubular diameter and excessive loss of immature germ cells in a stage-dependent manner. There was also a dose-dependent increased incidence of occlusions in the efferent ductules. The occluded ductules were characterized by severe inflammation and exhibited disorganization of the epithelium. At 70 days, there were dose-dependent decreases in mean testis weight and mean seminiferous tubular diameter; however, only minimal long-term effects were seen at 50 mg/kg. In testes exhibiting seminiferous tubular atrophy of greater than 25% (100 mg/kg or greater doses), all of the testes were associated with efferent ductules containing occlusions. Caput sperm numbers were significantly reduced in these testes. Occlusions, abnormal ductules, fibrosis, spermatic granulomas, and mineralization were observed in the ductuli efferents. Long-term effects of carbendazim on the testis were induced primarily by ductal occlusions. Results show that carbendazim produces more severe short- and long-term effects on the male reproductive system than the fungicide benomyl.

Administration, Oral↗
PubMed2002

In utero exposure to diethylstilboestrol or 4-n-nonylphenol in rats: number of sertoli cells, diameter and length of seminiferous tubules estimated by stereological methods.

The effects on testis weight and histopathology were studied in 11-day-old male Wistar rats after prenatal exposure to peanut oil (control), diethylstilboestrol 30 microg/kg b.wt./day, or 4-n-nonylphenol 75 mg/kg b.wt./day from gestational day 11 to 18. Additionally, the diameter and length of seminiferous tubules, and the number of Sertoli cells were investigated with stereological methods. Such unbiased methods have not previously been applied on testis diameter and length or on Sertoli cell number of 11-day-old rats. In the control group, the mean length of the seminiferous tubule was 3.0 m+/-0.6, the mean diameter of the seminiferous tubule was 83 microm+/-6, and the mean number of Sertoli cells was 26.1x10(6)+/-4.6. No differences in testis weight, histopathology, or length or diameter of the seminiferous tubules were observed in the diethylstilboestrol and nonylphenol exposed groups when compared to the control group. In the diethylstilboestrol-treated group, a statistically significant decrease in the number of Sertoli cells was observed (P<0.01) when compared to the control group, whereas nonylphenol had no effect. The result suggests that diethylstilboestrol decreases Sertoli cell proliferation in the foetal testis and furthermore indicate that oestrogens may pose a risk to the reproductive capacity in sensitive species, including man.

Administration, Oral↗
PubMed2003

Seasonal changes in spermatogenesis and testicular steroidogenesis in wild male raccoon dogs (Nyctereutes procynoides).

Testes of 15 wild adult male raccoon dogs (Nyctereutes procynoides) obtained from September 2000 to April 2001 were studied to clarify seasonal changes in spermatogenesis and testicular steroidogenesis. There were marked seasonal variations in the testis weight and size with values relatively low in September and highest in March. Spermatogonia and primary spermatocytes were observed in September, while spermatogonia, spermatocytes and round spermatids were present in January, and all types of spermatogenic cells including mature spermatozoa were found in the mating season (February and March). The number of spermatogenic cells reached their peak values in February and March. In addition, steroidogenic enzymes were immunolocalized using polyclonal antisera raised against bovine adrenal cholesterol side-chain cleavage cytochrome P450 (P450scc), human placental 3beta-hydroxysteroid dehydrogenase (3 betaHSD), porcine testicular 17alpha-hydroxylase cytochrome P450 (P450c17), and human placental aromatase cytochrome P450 (P450arom). P450scc and P450c17 were identified in Leydig cells and spermatids in February, whereas these enzymes were present only in Leydig cells in September. 3betaHSD was found in Leydig cells in September and February with more intense staining in February. The localization of P450arom changed seasonally: no immunostaining in September; more extensive immunostaining in Leydig cells, Sertoli cells, and elongating spermatids in February. These results suggest that seasonal changes in the testis weight and size of wild male raccoon dogs are correlated with changes in spermatogenesis. Seasonal changes in testicular steroidogenesis suggest that the synthesis of androgen and estrogen reaches its peak in the mating season.

Animals↗
PubMed2000

Fertility in rats immunized with steroid-free bovine follicular fluid.

Inhibin is a gonadal hormone that inhibits the release of follicle stimulating hormone (FSH) from the anterior pituitary gland. The objective of this study was to determine whether active immunization of male and female rats against inhibin rich, steroid-free bovine follicular fluid would increase inhibin antibody titre, onset of female puberty, pregnancy rate, litter size, testis weights, testosterone concentration and serum FSH. Immunization of rats with steroid free bovine follicular fluid stimulated production of anti-inhibin antibodies that immunoneutralized endogenous inhibins and increased levels of circulating FSH in immunized males. Inhibin immunoneutralization resulted in early vaginal opening in immunized females compared with controls and pregnancy rates were increased when immunized female rats were mated with immunized males. However, serum testosterone, testis weights and potential litter size remained unchanged. We conclude that methods to immunoneutralize inhibin may have merit as therapeutic procedures to enhance reproductive performance in domestic animals.

Animals↗
PubMed1988

Effects of treatment of neonatal rats with highly purified FSH alone and in combination with LH on testicular function and endogenous hormone levels at various ages.

Factors which play a role in the regulation of testicular size in rats were investigated using neonatal animals treated with exogenous gonadotrophins for 2 or 3 weeks, starting on the day after birth. Effects on testis weight and various aspects of the pituitary-testicular axis were evaluated up to the age of 9 weeks. Daily treatment with human FSH (Metrodin; 0.15 U/g body wt) for 2 or 3 weeks, starting on the first day or 1 week after birth, resulted in enlargement of the testes, increased testicular content of inhibin and a suppression of pituitary and plasma FSH. The relative increase of testis weight decreased after cessation of treatment. Injections of human FSH combined with administration of human LH (Pergonal) for 3 weeks, starting on the first day after birth, resulted in larger testes immediately after treatment. In addition, an increased amount of interstitial tissue was observed in these animals. Pituitary and plasma FSH and LH were suppressed after this treatment, while the growth of the accessory sex organs was significantly stimulated. In animals treated with human FSH during the first 2 or 3 weeks of life, levels of rat FSH in blood samples collected at weekly intervals were significantly suppressed until the animals were killed at the age of 9 weeks. In the animals treated with human FSH and human LH, both FSH and testosterone concentrations were significantly lower than those in control animals between the ages of 4 and 9 weeks. At the age of 9 weeks testicular weights were still higher than those in control animals after these treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1987

Effect of photoperiod on the diurnal rhythm of plasma testosterone, dihydrotestosterone and androstenedione in mature male chickens.

1. The effects of different photoperiods on the concentrations of plasma androgens, testes weight and on the diurnal rhythm of plasma testosterone (T), dihydrotestosterone (DHT) and androstenedione (A) in mature, single comb White Leghorn male chickens were studied. 2. Birds were exposed to either 14 hr of light (lights on at 0600-2000 hr) or to 24 hr of light per day. 3. Blood samples were collected from birds in both groups at 3-hr intervals and plasma levels of T, DHT and A were measured using radioimmunoassays. Following blood collection, birds were weighed, killed and testis weights were recorded. 4. Under 14 hr of light, there was a diurnal rhythm of T and DHT with hormone concentrations peaking at the end of the dark period. There was no obvious rhythm for A. Exposure to 24 hr of light abolished the diurnal rhythm found under 14 hr of light. 5. There was an increase not only in testis weights but also in body weight and hormone concentrations under 24 hr of light. 6. It was concluded that photoperiod plays an important role in controlling the concentration and rhythm of androgens in mature male chickens.

Androgens↗