Effect of uni- and bilateral cryptorchidism on testicular inhibin and testosterone secretion in rats

The effect of uni- and bilateral cryptorchidism on testicular inhibin and testosterone secretion and their relationships to gonadotropins were studied in rats. Mature Wistar male rats weighing approximately 300 g were made either uni- or bilaterally cryptorchid. Testicular inhibin and testosterone content and plasma levels of LH and FSH were examined 2 weeks later. A similar remarkable decrease in testicular inhibin content was found in uni- and bilaterally cryptorchid testes. On the other hand, the testicular testosterone content was significantly decreased only in unilaterally cryptorchid testis with an inverse increase in the contralateral testis. Plasma testosterone levels were normal and plasma LH and FSH increased significantly in both of the cryptorchid groups. These results showed that cryptorchidism impairs both Sertoli and Leydig cell functions. While testosterone production was compensated by increased LH for 2 weeks, neither inhibin secretion nor storage changed in cryptorchid or contralateral testes during the same period.     

Effects of the induction of experimental cryptorchidism and subsequent orchidopexy on testicular function in immature rats

Cryptorchidism surgically induced in 14-day-old rats, was allowed to persist until 35 days when one group was killed to assess testicular function. In a second group the cryptorchid testis was returned to the scrotum surgically (orchidopexy) and subsequently killed at 130 days. A third group remained persistently cryptorchid to 130 days, while in a fourth group two sham operations were performed at 14 and 35 days. At 35 days, cryptorchidism resulted in a significant decline in testis weight due to suppressed spermatogenesis. Sertoli cell function as measured by seminiferous tubule fluid (TF) production after unilateral efferent duct ligation and androgen-binding protein (ABP) production was significantly depressed in the cryptorchid group. Serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were significantly elevated with cryptorchidism but serum testosterone levels were unchanged. Although morphometric measurements showed no change in Leydig cells cross-sectioned area, in vitro human chorionic gonadotropin (hCG)-stimulated testosterone production was significantly increased in the cryptorchid group at higher hCG doses. Similar changes were found in cryptorchid testes at 130 days except that Leydig cell cross-sectional area was now significantly increased. Orchidopexy at 35 days restored spermatogenesis and fertility during test mating was not impaired. TF production, ABP accumulation and serum FSH levels returned to normal following orchidopexy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Temporal changes in rat Leydig cell function after the induction of bilateral cryptorchidism

Adult rats were made bilaterally cryptorchid and studied at intervals of 3, 7, 14 or 21 days to study temporal changes in Leydig cell function. Serum FSH and LH levels were measured and the cross-sectional area of the Leydig cells assessed by morphometry. The function of the Leydig cells was judged by the binding of 125I-labelled hCG to testicular tissue in vitro and the testosterone response of the testis to hCG stimulation in vitro. By 3 days after cryptorchidism, the binding of labelled hCG to testicular tissue was significantly decreased compared to that of controls, but the testes were able to respond to hCG stimulation in vitro. At 7, 14 and 21 days after cryptorchidism, an enhanced testosterone response was observed and the size of the Leydig cells was significantly greater than that of the controls, which indicated increased secretory activity by the cryptorchid testis. Although serum FSH levels were significantly elevated after 3 days of cryptorchidism, serum LH levels did not rise until 7 days, thereby suggesting that the loss of receptors is unlikely to result from down-regulation by LH. The reduced testosterone response of the cryptorchid testis in vivo to low doses of hCG and the enhanced response at high doses are probably related to the reduced blood flow to the cryptorchid testis and the decreased sensitivity of the Leydig cells induced by LH/hCG receptor loss.     

Changes in serum immunoreactive inhibin and follicle-stimulating hormone during gonadal development in male and female rats.

We have measured serum and ovarian immunoreactive inhibin alpha (irI alpha) and serum FSH in fetal and neonatal rats from 20 days of gestation until 40 days of age. For animals aged 10 days or older, serum measurements were made on intact and gonadectomized animals. Serum irI alpha was detectable in intact male and female rats at all ages studied. In females, irI alpha levels were low until Day 5 and then increased steadily to peak at Day 25. Thereafter they declined until Day 35 to reach levels typical of adult females. There was a significant decrease in irI alpha levels 24 h after ovariectomy at all ages. Serum FSH levels in females were low until Day 7, then increased rapidly to plateau from Days 10-15. The levels then declined until Day 25 and were generally unchanged after that time. There was a significant increase in FSH 24 h after ovariectomy in rats aged 20 days and older, and in younger rats by 48 h after ovariectomy. In male rats, serum irI alpha levels were significantly higher than females until Day 7. The levels increased at Day 7 and then remained relatively constant until Day 20, after which they declined to reach typical adult male levels. Serum irI alpha levels were significantly lower in males than females from Days 25-40. There was a significant decrease in serum irI alpha 24 h after castration at all ages studied. Serum FSH levels in males were low until Day 20, increased at Day 25, and thereafter remained relatively unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Testosterone selectively increases serum follicle-stimulating hormonal (FSH) but not luteinizing hormone (LH) in gonadotropin-releasing hormone antagonist-treated male rats: evidence for differential regulation of LH and FSH secretion

Both testosterone (T) and gonadotropin-releasing hormone (GnRH)-antagonist (GnRH-A) when given alone lower serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in intact and castrated rats. However, when graded doses of testosterone enanthate (T.E.) were given to GnRH-A-treated intact male rats, a paradoxical dose-dependent increase in serum FSH occurred; whereas serum LH remained suppressed. This surprising finding led us to ask whether the paradoxical increase in serum FSH in GnRH-A-suppressed animals was a direct stimulatory effect of T on the hypothalamic-pituitary axis or the result of a T effect on a testicular regulator of FSH. To test these hypotheses, we treated adult male castrated rats with GnRH-A and graded doses of T.E. In both intact and castrated rats, serum LH remained undetectable in GnRH-A-treated rats with or without T.E. However, addition of T.E. to GnRH-A led to a dose-dependent increase in serum FSH in castrated animals as well, thus pointing against mediation by a selective testicular regulator of FSH. These data provide evidence that pituitary LH and FSH responses may be differentially regulated under certain conditions. When the action of GnRH is blocked (such as in GnRH-A-treated animals), T directly and selectively increases pituitary FSH secretion.     

Fertility after unilateral cryptorchidism. Paternity, time to conception, pretreatment testicular location and size, hormone and sperm parameters.

OBJECTIVE: To further evaluate whether fertility is decreased among a cohort of men with previous unilateral cryptorchidism as compared with a control group of men. SUBJEcTS AND METHODS: Formerly unilateral cryptorchid men who had undergone orchiopexy between the years of 1955 and 1975 at the Children's Hospital of Pittsburgh and a control group of men who were matched for age of an unrelated surgery at the same institution were evaluated by review of medical records and by completion of a questionnaire. 359 previously cryptorchid men were identified as having attempted paternity. Of these men, 320 had information concerning preoperative testicular location and 163 for preoperative testicular size. 106 of these men had levels of testosterone, inhibin B, FSH, and LH measured, while 95 of the men had semen analyses. RESULTS: Among men who had attempted paternity, there was no statistical difference in success of paternity between the previously unilateral group (89.7%) and the control group (93.7%). There was no difference in the mean time to conception (7.1 +/- 0.7 months for the unilateral group vs. 6.9 +/- 2.3 for the control group). Within the unilateral group in regard to success at paternity, no difference was found compared with the age of orchiopexy, preoperative testicular location, or preoperative testicular size. Inhibin B levels were lower among the unilateral group. FSH, LH, testosterone, sperm density, motility and morphology were not different, but considerable variation was noted within the cryptorchid group. CONCLUSIONS: In this continued evaluation of a cohort of previously cryptorchid men who had undergone unilateral orchiopexy, paternity does not appear to be significantly compromised after unilateral cryptorchidism. Unilateral cryptorchidism appears to be one of several factors contributing to infertility, similar to those found in the general population. No correlation was found between success at paternity and the age of orchiopexy, preoperative testicular size or preoperative testicular location. Inhibin B levels were lower while FSH, LH, T and sperm parameters did not differ.     

Pituitary luteinizing hormone (LH) and follicle-stimulating hormone (FSH) responses to gonadotropin-releasing hormone during the rat estrous cycle: an increased ratio of FSH to LH is secreted during the secondary FSH surge

The hormonal interactions required for the generation of a secondary surge of FSH on the evening of proestrus have not been clearly defined. The role of GnRH in driving a surge of FSH has been questioned by findings in previous studies. In the current study, gonadotropin secretion was measured from pituitary fragments obtained from rats at 0900 and 2400 h on each day of the estrous cycle. Pituitary fragments were perifused in basal (unstimulated) conditions or in the presence of GnRH pulses to determine whether a selective increase in basal release of FSH and/or an increase in the responsiveness to GnRH occurs during the secondary FSH surge. Each anterior pituitary was cut into eighths and placed into a microchamber for perifusion. Seven pulses of GnRH (peak amplitude = 50 ng/ml; duration = approximately 2 min) were administered at a rate of one per hour starting at 30 min. Fractions of perfusate were collected every 5 min and frozen until RIA for LH and FSH. The mean total amount of LH or FSH secreted during the hour interval following each of the last six pulses of GnRH (or the corresponding basal hour) was calculated. Analysis of variance with repeated measures indicated that the evening secretion of LH on proestrus (2400 h) dropped significantly (p less than 0.05) from a maximum on the morning of proestrus (0900 h), whereas the FSH secretion remained elevated at this time. Therefore, the ratio of FSH to LH secreted in response to GnRH pulses was highest during the secondary FSH surge and lowest on the morning of proestrus.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of cadmium chloride on the serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH) and androgens in the adult male rat

Adult male rats injected with cadmium chloride were compared with controls with respect to serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), androgens and testicular histology. A single injection of cadmium chloride (9 mg/kg) was found to bring about no consistent short term changes in the plasma levels of FSH or LH, but after a long period the levels of both these hormones were elevated. In contrast, the levels of androgen showed a sharp increase at 6 h which declined by 12 h. In accordance with the elevated levels of gonadotropins found at 9–28 days after cadmium chloride injection, the androgen levels showed a drastic reduction. Histological aspect of the testis revealed acute necrotic changes of which the vacuolation of spermatid nuclei and fibrosis of Leydig cells are noteworthy.     

Study of testicular feedback in male rats using artificial cryptorchidism as a model.

Plasma LH, FSH and testosterone were measured in testosterone-treated and untreated cryptorchid and castrated male rats. Exogenous testosterone prevented the increase in basal LH but not FSH levels seen in the untreated cryptorchids. Increases in plasma LH and FSH in response to LH-RH were greater in the cryptorchid as compared to the control group and this could not be reversed by exogenous testosterone, suggesting that spermatogenesis-related feedback factors regulate LH as well as FSH at the pituitary level in the intact rat. The results were consistent with a reduced but nevertheless significant secretion of inhibin by the cryptorchid testis. Basal plasma testosterone levels and ventral prostate weights were not significantly different from intact animals.     

Fertility after bilateral cryptorchidism. Evaluation by paternity, hormone, and semen data.

PURPOSE: Evaluation of the fertility of a cohort of formerly bilaterally cryptorchid men in comparison with a group of formerly unilaterally cryptorchid men, and a group of control men. MATERIALS AND METHODS: Using a detailed questionnaire concerning paternity and factors related to paternity, a cohort of formerly bilateral cryptorchid men were studied and compared with men who had undergone orchiopexy for unilateral cryptorchidism, and a group of control men. All study subjects had had surgery at the Children's Hospital of Pittsburgh, Pittsburgh, Pa., between 1955 and 1975. A subset of the full cohort underwent clinical evaluation that included a physical examination, serum hormonal determination and semen analyses. RESULTS: Paternity rates are significantly lower among the formerly bilaterally cryptorchid men who have attempted to father a child (65.3%) as compared to the formerly unilaterally cryptorchid (89.7%; p < 0.001) and control men (93.2%; p < 0.001). Differences in the ability to father children are also apparent when semen and hormone levels are compared between the three groups. The bilateral group has significantly lower sperm density and inhibin B levels, and higher FSH and LH levels, than the unilateral and control groups. CONCLUSIONS: Men born with bilateral cryptorchidism have severely compromised fertility in adulthood. This reduction in fertility is clearly shown in comparisons of both paternity rates, and in semen and hormone analyses, between the formerly bilateral, formerly unilateral, and control groups.     

The effects of long-term administration of either a crude inhibin preparation or an antiserum to FSH on serum hormone levels, testicular function and fertility of adult male rats.

Adult male rats were given either daily injections of ram rete testis fluid for periods of up to 70 days or injections of an antiserum against FSH every 3 days for 90 days. Compared with the control groups, the rats injected with ram rete testis fluid had lowered serum FSH levels, but only at treatment periods of 30 days and less. The levels of LH and testosterone in serum, testicular fluid secretion, sperm counts, testis weights and fertility were not affected by rete testis fluid treatment. The rats injected with anti-FSH serum exhibited an impairment of fertility which was never complete and evident only after 49 days of treatment. After 90 days of anti-FSH treatment, testis weight and free serum FSH were reduced, but sperm counts, testicular fluid secretion and serum levels of LH and testosterone were not affected.     

A comparison of Leydig cell function after unilateral and bilateral cryptorchidism and efferent-duct-ligation

Surgical induction of cryptorchidism or ligation of the efferent ducts disrupts spermatogenesis. The response of Leydig cells to disrupted gametogenesis was studied in vitro in tissue and collagenase dispersed Leydig cells obtained from the testes of rats that were made unilaterally or bilaterally cryptorchid or had been efferent-duct-ligated. Four wks after surgery, androgen secretion per mg of tissue or per Leydig cell in response to maximal luteinizing hormone (LH) stimulation was greater in tissue from damaged than from sham-operated testes. It was concluded that disruption of spermatogenesis resulted in Leydig cells that were hyperresponsive to LH stimulation in vitro. Unilateral lesions produced different responsiveness of Leydig cells from the testes ipsilateral and contralateral to the lesion, supporting the hypothesis that intragonadal modulation of Leydig cells function occurs when the function of seminiferous tubules is impaired. Stimulated androgen production of Leydig cells from the contralateral nonligated testis did not differ from that of the sham-operated controls. With unilateral cryptorchidism, which is accompanied by an increase in the temperature of the operated testis, Leydig cells from the scrotal testis were also hyperresponsive compared to those from sham-operated controls. This suggests a possible intergonadal influence of aspermatogenesis caused by cryptorchidism.     

Interactions of follicle-stimulating hormone and luteinizing hormone in controlling estradiol synthesis by the testis of the infant rat

Experiments were conducted to assess the relative contribution of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) to the regulation of estradiol secretion by the testis of the 12-day-old rat. In an in vivo model system, stimulation of the whole testis with NIH-FSH-S13 (5% LH activity) caused an 8-fold increase in testosterone secretion within 1 h followed by a 5-fold increase in estradiol secretion. Qualitatively, similar findings were obtained from whole testes incubated in tissue culture medium 199. The in vitro system was used to further examine the response of the testes to LH and FSH. Testes exposed to a variety of doses of LH or 10 ng/ml of highly purified FSH (3 X 13, 1% LH activity) showed no change in estradiol secretion. However, a synergistic effect was observed when purified FSH and LH were combined, provided the LH concentration exceeded 25 pg/ml. It is suggested that FSH secretion in infant rats maintains the aromatizing capacity of the seminiferous tubule at a level such that availability of aromatizable substrate becomes a major factor in the rate of tubular estrogen formation.     

Testosterone restores testicular inhibin content in cryptorchid rats

The effects of testosterone administration on testicular inhibin content and histology were studied in bilaterally cryptorchid rats, in which a marked decrease in testicular inhibin content had been observed. Mature male Wistar rats weighing approximately 300 g were made bilaterally cryptorchid by placing the testes in the abdominal cavity. Testosterone in oil, 0.1, 1.0 or 10 mg, was given i.m. each week. Testicular inhibin and testosterone content, histology and plasma LH, FSH and testosterone were studied 2 weeks later. Abnormally decreased testicular inhibin in cryptorchidism was restored toward normal by testosterone in a dose dependent manner in 2 weeks after surgery. Sertoli cell structure also recovered toward normal with increasing amount of testosterone. Decreased testicular testosterone content and Leydig cell atrophy were observed with suppressed plasma LH and FSH after testosterone. These results showed that the increased plasma concentration of testosterone had a stimulatory effect on the Sertoli cell function in cryptorchidism, in which compensated Leydig cell failure was demonstrated.     

Circulating radioimmunoassayable inhibin during periods of transient follicle-stimulating hormone rise: secondary surge and unilateral ovariectomy

We have measured changes in circulating immunoreactive (ir-) inhibin in male and female rats using an RIA with an antiserum raised against porcine inhibin alpha (1-26)-Gly-Tyr. The same synthetic peptide was used for standards and for the preparation of tracer. Serum ir-inhibin levels were significantly higher in intact female than in intact male rats (p less than 0.001). Immunoreactive inhibin was significantly reduced in both sexes 24 h after bilateral gonadectomy (p less than 0.0001). Unilateral ovariectomy (ULO) of female rats on metestrus caused a transient decrease in serum inhibin 8 h after surgery, but levels were not significantly different from those of sham-operated controls at later times after surgery. Increases in serum FSH and LH were observed for 8-18 h after ULO. Serum ir-inhibin levels were also measured on the early morning of estrus during the secondary FSH surge. At this time, ir-inhibin levels were low, while FSH levels were high and LH levels were low. These results show that serum ir-inhibin levels in rats are decreased at times when serum FSH levels are high.     

Effects of cryptorchidism and orchidopexy on deoxyribonucleoside-activated nucleotidase (DAN) in the rat testis

1. Unilateral cryptorchidism was associated with an increase in specific DAN activity in the abdominal testis of adult rats. 2. In the scrotal, immature testis, there was an age-dependent decrease in specific DAN activity similar to that normally seen in rats. This decrease was less pronounced in the abdominal testis of unilaterally cryptorchid rats. 3. Total DAN activity in the abdominal testis showed a decrease in both immature and adult rats, when compared to that of the scrotal testis. 4. Orchidopexy following cryptorchidism in adult rats, resulted in complete restoration of DAN activity in spite of poor recovery of spermatogenesis.     

The effect of mating on the afternoon of proestrus on serum LH (and FSH) and ovulation in the rat

Possible relationships between coitus and serum gonadotrophin levels and ovulation in the rat were investigated. Female rats were mated betw een 1700 and 1730 or between 1800 and 1830 hours. 1.3 ml of blood was withdrawn by cardiac puncture 30 minutes postcoitus for luteinizing hormone (LH) analysis. After autopsy on the morning of estrus, counts were made of tubal ova, and LH and follicle-stimulating hormone (FSH) were measured in terminal blood from all animals. Those mated at 1700-1730 with no cardiac puncture showed significantly more ova than those with cardiac puncture (p less than .05) and those which were neither mated nor received cardiac puncture (p les than .05). No differences were found between those mated at 1800-1830 hours because of the large variance in each group. Coitus during the time of normal mating did not increase LH levels 30 minutes postmating or terminal LH and FSH levels. Terminal LH levels were significantly increased in the no cardiac puncture-no mate animals (p less than .05) in comparison with the cardiac puncture-no mate animals.     

Changes in rat testicular adenylate cyclase activities and gonadotrophin binding during unilateral experimental cryptorchidism

Unilaterally cryptorchid rats were examined at 3, 8, 15, 22 and 28 days after operation. There was a selective decrease in the adenylate cyclase (ATP pyrophosphate--lyase (cyclizing), EC 4.6.1.1) responses to gonadotrophin stimulation in the abdominal testis. This was associated with a parallel decrease in specific FSH and LH binding. There was no reduction in the response of testicular adenylate cyclases to prostaglandin (PG) E-1 or fluoride stimulation, indicating that both the GTP binding protein (N-component) and the catalytic subunit of the adenylate cyclase complexes were intact. The reduction in FSH-responsive adenylate cyclase activity in the abdominal testis was not due to a change in the Km for adenylate cyclase activation, but was due to a reduction in maximal velocities. Unilateral cryptorchidism was also associated with a rapid decline in soluble Mn2+-dependent adenylate cyclase activity in germ cells (spermatids). By 3 days after operation there was an 82% decrease in germ cell adenylate cyclase activity. The loss of soluble Mn2+-dependent adenylate cyclase activity was associated with a parallel decrease in Sertoli cell secretion of androgen binding protein, indicating that Sertoli cell factors may be important for the maintenance of germ cell adenylate cyclase activity. The desensitization of the gonadotrophin--responsive adenylate cyclases and the loss of gonadotrophin receptors in Leydig and Sertoli cells were not due to changes in plasma gonadotrophin values because LH concentrations were within normal limits and plasma FSH was only marginally elevated in the cryptorchid rats. No significant alterations of any of these parameters were seen in the scrotal testis of unilaterally cryptorchid rats when compared to values for intact controls.     

Seasonal levels of LH, FSH, testosterone and prolactin in adult male pudu (Pudu puda)

Seasonal levels of LH, FSH, testosterone (T) and prolactin (PRL) were determined in plasma of six captive adult male pudu (Pudu puda) kept in Concepcion, Chile. Average PRL levels exhibited one peak (28 ng/ml) in December (summer); minimal levels (3 to 6 ng/ml) were detected between April and July. FSH concentrations remained at peak levels (54–63 ng/ml) from December until March; minimal values (25–33 ng/ml) were detected from April until October. T levels exhibited two, almost equal peaks; the first peak (2.8 ng/ml) was detected in March (rut) and the second one (2.7 ng/ml) in October (spring). Both T peaks were preceded by an earlier elevation of LH in February and July (both around 1.3 ng/ml). During the fall, only the alpha male exhibited a sharp peak of T (8.4 ng/ml), whereas in the spring five out of six bucks demonstrated an increase of T levels. Two peaks of LH and T and the 4 months of elevated FSH may be related to a long period of spermatogenesis observed in this species.