Fluctuations in plasma testosterone levels in adult male rats and mice

Effects of lithium on the pituitary-gonadal axis in the rat: evidence for dose-dependent changes in plasma gonadotropin and testosterone levels

The purpose of the present study was to examine the effects of lithium, a drug which is now used rather widely in the treatment of acute mania and the prophylaxis of manic-depressive bipolar disorders, on the pituitary-gonadal function in the laboratory rat. Sexually adult male rats, maintained under standardized laboratory conditions (LD 14: 10; lights on at 06:00 h, CST), were injected (ip) with lithium chloride both acutely for 1 day and chronically for 5 days, and by utilizing a low and high dose. For the low dose, lithium was injected twice daily (at 10:00 and 15:00 h) at 2.5 meg/Kg for 1 and 5 days, whereas in the high dose groups, also receiving lithium twice daily and at the same hours, the dosages were 5 meq/Kg for 1 day and 3.5 meq/Kg for 5 days. Animals were sacrificed 4 hours after the last lithium (or saline) injections. Plasma and pituitary levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH), and plasma levels of testosterone (T) were measured by radioimmunoassay (RIA). The administration of the low dose led to a significantly higher (P less than 0.001) plasma FSH, but unaltered plasma LH, levels after 5 days. In contrast, the high dose lithium led to significant suppressions of plasma LH (P less than 0.02; on day 5) and FSH (P less than 0.001; on both day 1 and 5) levels. The levels of plasma T also showed a significant reduction following the low dose (P less than 0.02; on day 5), as well as the high dose lithium treatment, as evident after both 1 (P less than 0.02) and 5 (P less than 0.02) days. Regardless of the dosage, or the duration of treatment, pituitary gonadotropin levels remained unaltered following lithium. The results of our present experiments suggest that lithium administration, either acutely or on a chronic basis, might be associated with significant adverse effects on the pituitary-testicular axis. Furthermore, since some of the hormonal changes were evident when plasma lithium concentration was within the therapeutic range, our data may have potential clinical implications.

Effects in mice of testosterone and dihydrotestosterone on platelet aggregation in injured arterioles and ex vivo

Mice were implanted subcutaneously with placebo pellets, or with pellets containing either testosterone (T) or dihydrotestosterone (DHT). Eight to 19 days later platelet aggregation was produced in pial or mesenteric arterioles by injuring their endothelium with a noxious light/dye stimulus. The onset of platelet aggregation was significantly shortened in the mesenteric arterioles of male mice following implantation of 1.0 mg T or 0.1 mg DHT. However no effect was observed in females, nor did T or DHT alter aggregation in pial arterioles of either sex. Ex vivo studies showed that sodium arachidonate produced greater aggregation of platelets in plasma from testosterone treated males compared with controls. No effect of testosterone was observed ex vivo in platelets from females. These ex vivo results paralleled in vivo data from mesenteric vessels, but not from pial vessels. Moreover DHT failed to influence aggregation ex vivo in either sex. Thus enhanced aggregation observed in vivo in mesenteric arterioles of androgen treated males may not reflect direct action of androgen on the platelet. Rather enhanced aggregation may reflect hormonal action on endothelium or adjacent tissue. In addition to the preceding studies we tested the hypothesis that testosterone's action was due to its conversion to estradiol. This was considered because our data with T and mesenteric vessels resembled that previously reported by us with estradiol. However only minimal elevations in plasma estradiol levels resulted from testosterone treatment.

Transplantable human prostatic carcinoma (PC-82) in athymic nude mice: I. Hormone dependence and the concentration of androgens in plasma and tumor tissue

This paper is the first part of a series of three describing a number of observations made on the PC-82 human prostatic carcinoma, xenografted into nude mice. The previously described androgen-dependence, one of the main properties of this tumor, has been the subject of subsequent studies. The impact of hormonal manipulation on the growth of the tumor and on plasma and tissue concentrations of androgens is discussed in this first part of the series. The great variability of plasma testosterone (T) levels in intact male mice (range: 1-90 nmol/liter) has been levelled out by the use of T-containing Silastic implants, resulting in levels ranging from 18 to 35 nmol/liter. Moreover, this route of administration also facilitated hormonal manipulation of tumor bearing mice. Androgen withdrawal from male mice with growing PC-82 tumors caused 80% tumor regression at ten weeks after androgen deprivation; the decline of the tumor volume followed a biphasic course. Delayed androgen substitution in castrated male mice grafted with PC-82 30 days before resulted in growth of the tumor tissue. This indicates that cells do not die and keep the capability to respond to androgens. It was concluded that the growth of the PC-82 tumor is not compatible with plasma T levels lower than 1 nmol/liter. Variable concentrations of endogenous T and dihydrotestosterone (DHT) were detected in total homogenates of PC-82 tumor tissue. Androgen withdrawal from T-implanted, tumor-bearing female mice caused a rapid reduction (90% within one day) of the tissue-T and a slower decline (up to 90% within seven to ten days) of tissue-DHT concentrations.

Effectiveness of antiandrogens in the rat

In order to determine the relative effectiveness of several antiandrogens, megace (megestrol acetate), flutamide and RU23908 were administered in optimal doses (20 mg./kg., 10 mg./kg. and 20 mg./kg.) subcutaneously daily to adult male Sprague-Dawley rats for 14 and 28 days and their effects on ventral prostate, seminal vesicles, and serum testosterone were determined. To avoid the possibility that these agents might also work through inhibition of testosterone production, all the treated animals were castrated and then implanted with a testosterone-filled silastic pellet to maintain a constant exogenous source of the androgen. A castrate placebo-treated group, an implanted placebo-treated group, and an intact placebo-treated group served as controls. The mechanisms and sites of action of the antiandrogens were thus limited to the target organs. Serum testosterone levels were equivalent at all time periods for all groups except the castrate controls which were significantly lower. The ventral prostates of the flutamide and RU23908 groups were similar and reduced 75% and 85% at 14 and 28 days respectively; the group receiving megace experienced prostatic regression of 49% and 65% which was significantly less of a reduction than that of the flutamide or RU23908 group. Results for seminal vesicle weights indicated similar trends. The administration of both steroidal (megace) and nonsteroidal (flutamide and RU23908) antiandrogens yielded a significant reduction of androgen dependent tissue weights relative to the intact control group and the implanted placebo group but still not as great a reduction as the effect produced by castration. In the rat, castration remains the optimal means of inducing regression of androgen dependent tissues.

Evolution of oxidative metabolism of submandibular gland and testes in pancreatectomized rats

The purpose of this work was to study the effects of prolonged mild diabetes on the submandibular salivary glands and testes of male rats over a 22-month period. Diabetes was induced by means of a subtotal pancreatectomy in a group of male rats. Body weight was registered monthly as well as the blood glucose values after fasting the animals. These values were compared with those obtained in sham-operated animals. The weight of pancreatectomized animals was always slightly higher than that of the controls although the differences were not significant, whereas blood glucose values were slightly higher in experimental animals. Testis O2 uptake in pancreatectomized animals was significantly lower than in controls 8 months after the operation. From this time on, the values of experimental animals rose, reaching a maximum value 20 months after the operation. Submandibular glands in pancreatectomized animals showed an O2 uptake that was always higher in experimental animals and reached a maximum value at 20 months.

Dimethylnitrosamine metabolism: II. In vitro activation of dimethylnitrosamine by hepatic and renal tissues from crosses among BALB/c, DBA and C57BL mice

Crosses among BALB/c, C57BL and DBA mice were performed to investigate the genetic mechanisms involved in metabolism of DMN by renal and hepatic tissues. Liver S-9 fractions from parental strain DBA had the greatest potential to activate DMN and liver fractions from parental strain BALB/c had the lowest. No age or sex-related differences were observed within strain. Crossing of either C57BL or DBA to BALB/c mice resulted in F1 hybrids with liver microsomal enzymes that gave results similar to the BALB/c parental strain. There were no sex or age differences within crossbred strains in the potential of liver to activate DMN. In contrast male DBA and C57BL parental mice renal S-9 fractions did not differ significantly from each other but did differ significantly from male BALB/c renal fractions and from female and immature animals of all strains. Crossing of either DBA or C57BL mice with BALB/c mice resulted in male F1 hybrids whose renal S-9 fractions did not differ significantly from males of the parental BALB/c strain. In all instances, male renal S-9 fractions had a significantly greater potential to activate DMN than female or immature animals. F1 DBA X C57BL hybrids had renal S-9 fractions that did not differ significantly from the parental strains. These data suggest that the gene(s) for low DMN metabolism of BALB/c mice are apparently dominant over the genes from both DBA and C57BL. The exact genetic or physiological mechanism needs further elucidation.

The assessment of diminished testicular function in boys of pubertal age

Nine boys with anorchia and 9 individuals with diminished testicular function were followed between ages 10 and 18 with serial determinations of urine gonadotrophins and serum testosterone. Ten hCG stimulation tests were performed in eight of these patients. Adult levels of LH (greater than 500 mIU/h) and low measurements of serum testosterone (less than 54 ng/dl) confirmed the anorchic state. Boys with diminished testicular reserve exhibited urinary gonadotrophin changes similar to peripubertal anorchic patients but testosterone levels increased progressively with age (90-715 ng/dl). FSH attained adult castrate levels (greater than 1700 mIU/h) by age 13 in these boys and served to distinguish them from normal controls. The longitudinal assessment of basal hormone levels can separate anorchia from diminished testicular reserve in boys of pubertal age and testing with hCG is not required for evaluation.

Involvement of prostaglandin in the antifertility effects of gossypol

This study was undertaken to determine the effects of gossypol alone and gossypol in combination with prostaglandin and aspirin. Rats were administered gossypol (40 mg/kg/day), gossypol and prostaglandin (PGF2 alpha-2 mg/kg/day), gossypol and aspirin (300 mg/kg) for 4 weeks. A marked effect of the gossypol-prostaglandin combination was observed on sperm motility and spermatogenesis. The effect of the gossypol-aspirin combination was less pronounced. The ratio of body weight to testicular and epididymal weights between the different groups showed no marked difference. No effect of drug treatment on plasma testosterone, LH and FSH was observed. The data presented in this paper suggest that prostaglandin plays an important role in the antifertility effects of gossypol.

Testicular activity in mice selected for increased body weight

Parameters of testicular function were studied in mice selected for increased body weight and in contemporaneous unselected controls. Spermatogenesis occurred at the same time in the two lines. Body weight, testis weight, mean seminiferous tubular diameter and serum testosterone were increased significantly in the high growth mice. It is suggested that some genetically determined differences in body size are brought about by the differential secretion of testosterone.

Genetic analysis of the Y-chromosome of the mouse: evidence for two loci affecting androgen metabolism

Male mice from congenic lines carryY-chromosomes derived from two pairs of inbred strains (CBA/FaCamSt and C57BL/FaSt; PHL/St and PHL-YH/St) on various genetic backgrounds were compared. Serum testosterone levels, and the response of target organs in castrated animals to graded doses of exogenous testerone propionate were measured. These comparisons produced evidence for twoY-chromosomal loci influencing androgen metabolism. One of these affects serum testosterone levels, with variant alleles on theY-chromosomes derived from the PHL and PHL-YH strains. The other locus influences the response to testosterone of target organs, most significantly seminal vesicle, and variant alleles are found in the CBA and C57 strains. The effects of both loci are modulated by the genetic background. The relationship of these loci to otherY-chromosomal loci in the mouse is briefly discussed.

Acute changes in plasma steroids and agonistic behavior in male Japanese quail

A systematic analysis of the acute (minutes to hours) fluctuations of plasma steroids [androstenedione (A), 5 alpha-dihydrotestosterone (DHT), testosterone (T), corticosterone (B)] was investigated in relation to the fighting behavior displayed by experienced male Japanese quail (Coturnix coturnix) in short-term (2 min) dyadic encounters. Plasma levels of hormones measured in competitors either 1 hr before, during, or 3 min to 6 hr following a fight related poorly to either the attacking or nonattacking behavior displayed by opponents. However, transient fluctuations measured by the percentage change from prefight levels of plasma DHT, T, and B were identified in individuals following the onset of the fight. Winners demonstrated significantly greater percentage changes than did the losers at 3, 32, and 362 min for DHT and T and at 7 min for B. These differences in hormonal responses to the fight are attributed to the more aggressive behavior displayed by the victorious opponents (winners) over their defeated competitors (losers). Significance of these rapid changes is discussed in relation to the physiology and behavior of aggressive interactions.

Effects of age and luteinizing hormone antiserum on human chorionic gonadotropin-stimulated testosterone secretion in young male rats

The steroidogenic capacity of young male rats of different ages was studied. Two days prior to sacrifice at 5, 10, 15, 20, 25 and 30 days of age, the rats in treatment groups were given intramuscularly either human chorionic gonadotropin (HCG) at 20 I.U. twice daily/rat or luteinizing hormone (LH) antiserum (AS) at 0.25 ml twice daily/rat. Either saline or normal sheep serum (NSS) was given to control rats. The serum and testicular testosterone concentrations in the control rats averaged 0.85 +/- 0.03 ng/ml and 1.35 +/- 0.06 ng/mg testicular protein, respectively. At day-15 the serum and testicular testosterone concentrations in the HCG-treated rats had significantly increased to 9.30 +/- 0.85 ng/ml and 11.92 ng/mg of testicular protein, respectively. At the same age, the HCG-induced higher levels of serum and testicular testosterone concentrations were significantly reduced to 2.80 +/- 0.70 ng/ml and 6.02 +/- 1.00 ng/mg protein by concomitant administration of LH/AS and HCG. Our results suggest that the testosterone production in response to HCG stimulation is age-related. It was also determined that neutralization of circulating gonadotropin in LH/AS-treated rats decreased the sensitivity of Leydig cells to gonadotropin stimulation. This in vivo model should provide an excellent opportunity for the investigation of the testicular function in developing young males.

Seasonal changes in the testes and accessory reproductive organs and seasonal and circadian changes in plasma testosterone concentrations in the male grey squirrel (Sciurus carolinensis)

A 27-month study of cycles of regression and recrudescence of testis function in adult, grey squirrels in a natural environment in southern England has shown concomitant variation in mean testes weights, mean plasma testosterone concentrations, and mean weights of accessory sex organs, this variation being closely associated with months of the year. Testis regression occurred in the period June to August, the exact timing differing among individuals. In 1979-1980 the testes of all squirrels then remained regressed for 7 months, whereas in the autumn of 1980 testes were regressed in most squirrels for 4 months. There was also evidence of testis regression in some individuals in March 1979 and March 1981. Males born and housed in a small woodland enclosure in 1979-1980 and well fed with grain did not experience the long period of regressed testes. Plasma testosterone concentrations measured hourly over 24 hr in squirrels with large, active testes varied from 0.4 to 20 nmol/l, both within and between individuals, the higher concentrations being observed between midday and midnight. The range in the age of males at puberty, based on fusion of the epiphyses of the wrist, was 1.0 to 1.25 year. Juvenile males housed in a woodland enclosure together with adult males and females remained prepubertal up to 2 years of age.

Hyperprolactinemia and male sexual behavior: effects of steroid replacement with estrogen plus dihydrotestosterone

To determine if alterations in the availability of the active metabolites of testosterone (T) are involved in the inhibition of sexual activity in hyperprolactinemic animals, the effects of four ectopic pituitary grafts on copulatory behavior were examined in castrated male rats given subcutaneous implants of T or estradiol-17 beta (E2) plus 5 alpha-dihydrotestosterone (DHT). Two weeks after implantation of the steroid-filled capsules, half the animals of each group were given pituitary grafts and the remainder were sham-operated. Tests of copulatory behavior were performed prior to, and one, two, and three months following pituitary transplantation. Pituitary grafting caused significant inhibition of copulatory behavior in both T and E2 + DHT treated animals. PRL levels were significantly higher in E2 + DHT treated grafted males than in T treated grafted animals (2000 +/- 140 vs. 395 +/- 26 ng/ml), but did not differ between the corresponding control groups (61 +/- 8 vs. 73 +/- 6 ng/ml). The results of these experiments preclude the possible involvement of alterations in steroid secretion by the testes or modifications of the conversion of T to its active metabolites in the effects of hyperprolactinemia on copulatory behavior.

In vivo and in vitro inhibition of human chorionic gonadotropin-induced testosterone production in rat testis by bursa of fabricius extract

A bursa of Fabricius homogenate extract (BHE) was used to investigate the endocrine regulation function of this avian organ. In vivo and in vitro results indicated that BHE inhibited human chorionic gonadotropin (HCG)-induced testosterone production by rat testes. Leydig cells from collagenase-dispersed rat testes, when treated with BHE, showed a dose-response related depression of testosterone production under HCG stimulation. Young male rats, injected simultaneously with BHE and HCG, failed to show the marked testosterone production peak observed in rats injected with HCG only. However, in vivo treatments with BHE, in the absence of HCG stimulation, did not inhibit basal testosterone production. These results indicate that the bursa of Fabricius produces an endocrine regulation factor that inhibits HCG-induced testosterone production both in vivo and in vitro. Further investigation is necessary to isolate the active factor and determine its mechanism of action.

Taenia taeniaeformis: inhibition of rat testosterone production by excretory-secretory product of the cultured metacestode

In 3- to 5-month-old male Sprague-Dawley rats infected with the hepatic metacestode, Taenia taeniaeformis, the serum testosterone level was significantly lower than in comparable uninfected controls. By transmission electron microscopy, testicular Leydig cells of infected rats had less smooth endoplasmic reticulum than control Leydig cells. Cultured metacestodes isolated from the hepatic cysts secreted or excreted substances into the incubation medium. The effect of the excretory-secretory product on testosterone concentration in the sera and testes of 15-day-old rats was examined. Subcutaneous injection of 50-200 micrograms of excretory-secretory product/0.1 ml saline/rat for 2 days significantly reduced human chorionic gonadotropin-stimulated serum and testicular testosterone concentrations. Furthermore, the effect of the excretory-secretory product on isolated rat Leydig cell testosterone production was examined. Rat Leydig cells produced testosterone in vitro and, in the presence of 50 IU human chorionic gonadotropin/ml incubation medium, they responded with approximately 100% increase in testosterone production. Addition of 2-10 micrograms excretory-secretory product protein/ml of culture medium significantly reduced the testosterone production by rat Leydig cells in vitro. These results indicate that excretory-secretory product of cultured T. taeniaeformis metacestodes has a direct inhibitory effect on Leydig cell testosterone production under stimulation with human chorionic gonadotropin.

Increased serum prolactin levels mediate the suppressive effects of ectopic pituitary grafts on copulatory behavior in male rats

To determine if deficits in sexual activity observed in pituitary-grafted male rats are due to elevated serum prolactin (PRL) levels found in these animals, the effects of whole pituitary grafts, pars distalis grafts, and ovine (o) PRL treatment on male copulatory behavior were compared. Adult sexually experienced CDF male rats were given four whole pituitary grafts, four pars distalis grafts, or were sham operated. Both groups of grafted animals exhibited suppressed copulatory behavior patterns when tested 18 days after pituitary transplantation. Animals given whole pituitary grafts had significantly longer latencies to mount (P less than 0.05) and to intromit (P less than 0.01) than did the sham-operated controls, while the animals given anterior pituitary grafts differed from the sham-operated controls in latencies to mount (P less than 0.05) and to intromit (P less than 0.01), as well as in the number of intromissions (P less than 0.05). Prolactin-injected animals had significantly reduced intromission rates (P less than 0.01) and significantly increased latencies to mount (P less than 0.05) and to intromit (P less than 0.01) when compared to vehicle-injected controls. Furthermore, the time course of behavioral suppression was similar in oPRL-treated animals to that observed in pars distalis-grafted males, with both groups showing the onset of deficits in sexual activity within 8 to 9 days from the induction of the hyperprolactinemic state. The similarity in pattern and time to onset of behavioral suppression in pituitary-grafted and oPRL-treated animals suggests that behavioral deficits observed in animals with pituitary grafts result from chronic elevation of serum PRL levels.

Diurnal, premating, and postmating testosterone levels in roosters genetically selected for mating frequency

Circulating testosterone (T) levels were measured in roosters from lines genetically selected for high (HM) and low (LM) mating frequency and the randombred control (AC) base population. Lights were provided from 0600 through 2000 hr. A dirunal profile was determined by sampling at 0600, 1200, 1800, and 2400 hr. Plasma T levels prior to mating, immediately after mating, and 1 and 3 hr after mating were measured. By 1800 hr, AC males had higher T levels than both HM and LM males, which had levels that were similar to each other. Testosterone was at a minimum at 0600 hr and peaked at 2400 hr. Lines differed significantly both before and after mating with AC males highest, HM males intermediate, and LM males lowest. Control males had higher than baseline values prior to and after mating. Testosterone levels of AC males were correlated with their mating frequencies.

Suppression of male copulatory behavior by delta 9-THC is not dependent on changes in plasma testosterone or hypothalamic dopamine or serotonin content

Castrated B6D2 F1 male mice were tested for their sexual responses after being administered 0.5 mg/kg delta 9-tetrahydrocannabinol (THC) 50 mg/kg THC or oil. The animals that received 50 mg/kg, but not 0.5 mg/kg THC, showed deficits in copulatory behavior. Another group of B6D2 F1 castrates were given testosterone propionate (TP) replacement therapy plus 50 mg/kg THC or oil. Similarly, those mice which received 50 mg/kg THC showed behavioral deficits. Lastly, a group of intact B6D2 F1 males were treated with 0.5 mg/kg THC, 50 mg/kg THC or oil, were bled and decapitated, and their brains removed 10 min or 4 hr after treatment. Plasma testosterone (T) and hypothalamic dopamine (DA) levels were unaltered 4 hr after treatment with 50 mg/kg THC, but the concentration of serotonin (5-HT) in their hypothalami was elevated. This effect of THC on hypothalamic 5-HT concentration was not apparent in a larger group of randomly bred animals that were tested. These data strongly suggest that THC's behavioral effects are not mediated by variations in T levels, or by changes in hypothalamic 5-HT or DA concentrations.

Infanticide: accounting for genetic variation in mice

Infanticide, the killing of young, is one of a number of sexually-dimorphic traits in mice that is dependent upon androgen stimulation during perinatal life and during adulthood. Genotype also influences infanticide in that males of some strains of mice (C57BL/6J) exhibit high levels of this behavior while males of other strains (DBA/2J) seldom kill young. The experiments conducted here show that strain differences in pup killing behavior exhibited by males are not related to postweaning social factors nor are they due to differences in perinatal, pubertal, or adult levels of circulating hormones. These results, in combination with those previously reported, suggest that strain differences in the tendency of mice to kill young may instead depend upon the interaction of genotypic features such as prenatal hormone titers and/or sensitivity to these hormones, as well as on extra organismic factors such as intrauterine position. A model for understanding the manner in which genes and hormones may interact to influence infanticide and other hormone dependent sexually-dimorphic behaviors in mice is presented.

Neurotoxic esterase in rooster testis

Neurotoxic esterase (NTE) is the putative target protein in the nervous system for the initiation of organophosphorus-induced delayed neuropathy. Here it is reported that NTE activity is present in rooster testis. Complete titration of rooster testis phenyl valerate esterases with paraoxon shows that about 15% of the enzymic activity is resistant to paraoxon. NTE activity after complete mipafox titration accounts for 30% of paraoxon-resistant phenyl valerate esterases and corresponds to 7.93 +/- 0.39 nmol/min/mg of protein (mean +/- SD, n = 7). Testis NTE is inhibited in vitro similarly to brain NTE by several organophosphorus compounds. Subcellular fractionation studies of the testis indicate that most NTE activity is particle bound. Testis NTE is also inhibited in vivo by several organophosphorus esters but to a lesser extent than brain NTE. Birds doses with organophosphorus compounds, causing delayed neuropathy, became grossly ataxic, but no testicular pathology was noted by light microscopy in roosters killed 15 days after administration. Serum testosterone levels also measured 15 days after dosing were not different from those of a control group. Recovery of NTE activity was faster in testis than in brain (4 days vs 6 days to recover to 50% of initial activity) in animals that received a high dose of an organophosphorus ester which cause delayed neuropathy.

Hormonal control of carbonic anhydrase III

Using radioimmunoassay, the concentration of carbonic anhydrase III (CA III) in the livers of adult male rats was found to be approximately 30 times greater than that observed in mature females. Castration of male rats led to a marked reduction in liver CA III concentrations that could be partially restored to control levels by testosterone replacement. Administration of testosterone to ovariectomized female rats induced about a 5-fold increase in liver CA III concentration. Immunoprecipitational analysis of the products of liver mRNA translation in vitro with antiserum specific for CA III showed that hormonal control of the levels of CA III in rat liver is mediated by changes in the amount of translatable CA III mRNA. Marked changes in liver CA III concentrations were also observed in developing and aging male rats. Different control mechanisms appear to operate in mouse and man.

Biological effects of hormonal treatment regimens on a transplantable human prostatic tumor line (PC-82)

The effects of hormonal manipulation on the growth of a transplantable human prostatic carcinoma line (PC-82) were studied. The histological pattern of the PC-82 tumor, which still closely resembles the original tumor material, and the tumor growth rate did not change during the subsequent mouse passages. Growth of PC-82 tumor tissue on female and castrated male mice did not occur. Castration of tumor-bearing mice resulted in a cessation of tumor growth, after which the tumor volume decreased 50 +/- 27 per cent within 6 weeks after castration. Hormone-independent regrowth of the tumor tissue was not observed after long-term withdrawal of androgens. After a period of 10 weeks following tumor growth arrest, administration of testosterone almost directly resulted in regrowth of the tumor. Hormones, testosterone and estradiol, were administered by silastic implants. Intact male nude mice were shown to have highly fluctuating levels of testosterone. Implantation with testosterone resulted in constant levels of circulating testosterone, which could be maintained for at least 10 weeks, while the mean concentration of plasma testosterone was not different from that in control male mice. The doubling time of tumors grown on testosterone-substituted intact female and intact and castrated male mice was significantly shorter than that of tumors grown on intact male mice. Histologically the tumors grown on androgen-substituted mice were similar to those grown on untreated mice; the mitotic index, however, was much higher in the testosterone treated animals. Implantation of intact male mice with estradiol suppressed plasma testosterone to a mean level of 1 ng. per ml. and prevented the growth of PC-82 tumor tissue almost completely. Treatment of tumor-bearing mice with an estradiol implant following androgen withdrawal did not result in a further decrease of the tumor volume compared to the mice without additional estradiol implantation.

Growth and reproductive adaptation in male rats with chronic protein deficiency

In previous studies, male rats fed a low-protein diet beginning at weaning were found to have impaired sexual development through age 11 weeks when compared to food-restricted, weight-matched controls fed a diet with normal protein content. To determine whether male rats show long-term adaptation of the reproductive axis to low-protein feeding, we assessed sexual maturation and growth in rats fed a low protein (9%) diet from weaning until sacrifice at various points in time between ages 79 and 185 days. After age 80 days, there was no difference in reproductive organ weights (prostate, seminal vesicles, testis) or serum hormone levels (luteinizing hormone, follicle stimulating hormone, testosterone) between protein-deficient animals and food-restricted weight-matched controls given a normal diet. In addition, there was no difference between protein-deficient animals and controls in indices of linear growth (naso-anal and tail length) or fatness (Lee index). We conclude that both growth and reproductive function of male rats show adaptation to long term feeding of a low-protein diet.

The use of steroid-containing Silastic implants in male nude mice: plasma hormone levels and the effect of implantation on the weights of the ventral prostate and seminal vesicles

The effects of implantation of steroid-containing capsules into male nude mice on steroid concentrations in plasma and weight of accessory sex organs were studied. Intact male nude mice had plasma levels of testosterone (T) of 8.0 +/- 2.4 ng/ml, while T implantation (length 1.0 cm) of a group with castrated male mice resulted in a mean level of 8.1 +/- 0.3 ng/ml. This level was reached within 2 days after implantation and lasted for at least 40 days. After longer periods of application (up to 75 days) physiological levels could still be attained. Treatment of intact male nude mice with estradiol (E2)-containing implants (length 0.5 cm) resulted in constant levels of plasma-E2 (250 pg/ml) also lasting for at least 32 days. This treatment resulted in a mean plasma-T level of 1.0 +/- 0.2 ng/ml, which was still significantly higher than that obtained after castration (0.14 +/- 0.03 ng/ml). Up to 16 days after implantation E2 did not cause a decrease of the weights of the accessory sex glands in intact male mice, while after 32 days a significant reduction (50% of the control animals) of the organ weights was observed. The present data obtained with T and E2 implantation show that this route of administration of hormones is also very applicable in the nude mouse model.

Skeletal muscle cytosol [3H]methyltrienolone receptor binding and serum androgens: effects of hypertrophy and hormonal state

Normal, castrated, and hypophysectomized male rats underwent compensatory hypertrophy of plantaris muscles following surgical removal of their synergistic gastrocnemius muscles. The increases in muscle wet weights above control values, determined when the muscles were in stable-state hypertrophy, were as follows: normal 50%, castrated 50%, and hypophysectomized 32%. There were marked differences in concentration of serum androgens between surgical groups, yet no increases in testosterone or 5 alpha-dihydrotestosterone were observed as a result of hypertrophy. The amount of testosterone binding to serum proteins (approx 94%) was reduced only in hypophysectomized animals that underwent muscle growth. Cytosol androgen receptor specific binding (fmol/mg protein), measured using saturating concentrations of [3H]methyltrienolone (R1881) at 4 degrees C for 20 h for exchange with endogenous steroid, was significantly increased in hypertrophied muscles of normal, (1.77 +/- 0.17 vs 1.16 +/- 0.21), castrated (2.27 +/- 0.20 vs 1.46 +/- 0.03) and hypophysectomized (6.23 +/- 0.56 vs 3.64 +/- 0.30) animals. Receptor dissociation constants (Kd) were approx 10(-10) M in all groups and were not altered by the hypertrophy. These findings show that a major adaptation to skeletal muscle enlargement is an augmentation of cytosol [3H]methyltrienolone receptor binding capacity. This effect occurs in a normal or androgen deficient state.

Intermale aggression and infanticide in aged C57BL/6J male mice: behavioral deficits are not related to serum testosterone (T) levels and are not recovered by supplemental T

Healthy aged adult (24-26 months of age) and young adult (2-4 months of age) c57BL/6J male mice were assessed for intermale aggression, pup-killing behavior (infanticide), and circulating levels of testosterone (T). When compared to young adult male mice, aged adult males were highly variable in the exhibition of both androgen-dependent behaviors. Significant numbers of aged males exhibited deficits in aggression and pup-killing while other animals were as behaviorally active as their young male counterparts. Assessment of serum T showed that aging did not produce a reduction in levels of the steroid and individual variability in androgen-dependent behavior of aged males was not related to plasma levels of the hormone. When aged non-aggressive and non-killer males were exposed to supplemental T by way of subcutaneously implanted silastic capsules, circulating levels of the steroid were elevated but T-dependent behavior was not recovered. These findings, in combination with those previously reported for copulatory behavior, indicate that the deficits observed in the androgen-dependent behavior of aged male mice cannot be attributed to a breakdown in the production of testicular androgens. While neural refractoriness to T may account in part for deficits in androgen-dependent behavior of aged males, the variability that is observed in the reproductive behaviors of aged male rodents ultimately may be related to other sources of variation such as the perinatal environment.

Effect of gossypol on testicular testosterone production in vitro

Testicular minces were utilized to study the effect of gossypol on testosterone production. Testosterone production was assessed in both control nd gossypol treated groups after 0 to 4 hours incubation in the presence of hCG. Media testosterone was measured by radioimmunoassay. Gossypol did not alter testosterone production when present in incubates at the concentrations of 3.5 x 10(-5) M, 7 x 10(-5) M and 3.5 x 10(-4) M. Preincubation of testis mince with gossypol (7 x 10(-6) M, 7 x 10(-5) M, 3.5 x 10(-4) M) for 1 to 4 hours did not alter subsequent hCG induced testosterone production in mature rats. Testosterone production however, was inhibited in immature rat testis when the whole testis was incubated for 4 hours with different concentrations of gossypol (7 x 10(-6) M, 7 x 10(-5) M, 3.5 x 10(-4) M). In vivo testosterone production was not inhibited in the immature rat testis 24 hours after oral administration of gossypol (100 mg/kg).

Effect of intratesticular administration of BCG on testicular function (preliminary report)

Four patients suffering from carcinoma of the prostate (2 in stage C and 2 in stage D) in whom orchidectomy was indicated clinically, were enrolled in the study. Two patients were given a single injection of 25 units of BCG per testis and the other two received 50 units intratesticularly. Testicular biopsy at 0, 4 and 16 weeks showed the effects of the procedure in the tubular and interstitial compartment. The tubules were partially or completely atrophied, Sertoli cells were vacuolated. In the interstitium, mononuclear infiltration was evident. The reaction was more intense in patients receiving 50 units. The plasma testosterone after a slight drop in the first month returned to normal and pretreatment levels, respectively, and remained so during the eight months of observation. There was no significant change either in plasma oestradiol and prolactin or in T3, T1 and cortisol levels. FSH and LH, however, increased beyond the basal levels after an initial drop. The general condition of the patients remained good. All four patients gained weight. No side effects other than scrotal swelling during the first few weeks were either seen or reported by the patients. The swelling subsided after four weeks. This preliminary study indicates that there is a partial or total destruction of geminal elements. As the plasma testosterone levels remained undiminished in these four cases over a period of 8 months, it is apparent that testosterone production is not affected by intratesticularly administered BCG.

Androgen influence on lateral hypothalamus in the male rat: possible behavioral significance

The lateral hypothalamus and other structures in the forebrain were explored with microelectrodes in the male rat under urethane anesthesia before and after IV injections of testosterone. In the lateral hypothalamus, significant proportion of neurons responded after a few minutes to the hormonal increases by changes in firing rate. These responses could be attributed neither to a solvent effect nor to generalized changes in cerebral activity as indicated by EEG monitoring. The rapid onset implies that the steroid molecule exerted a non-genomic effect on target cells. The brain cells detected here were either such testosterone target cells or other neurons transsynaptically connected to them. All units tested with estradiol and testosterone reacted in the same way to both steroids, suggesting that testosterone acts after being aromatized into estradiol. This supports a possible role of these neurons in the regulation of male sexual behavior. Their involvement in the modulation of motivation during the appetitive component of sexual behavior, according to the hormonal state of the subject, is discussed.

Testicular dysfunction in untreated Hodgkin's disease

Gonadal function was examined in 19 young men with Hodgkin's disease before therapy and compared with that of 11 men with other malignancies, 13 men with primary testicular failure, and 19 normal men of similar age. Total (p less than 0.01) and free (p less than 0.05) testosterone levels were decreased in Hodgkin's disease. In those with advanced (stage III + IV) and symptomatic (B), Hodgkin's disease serum testosterone levels were indistinguishable from those in primary testicular failure, yet serum levels of luteinizing hormone were normal. Moreover, the acute response of serum testosterone to exogenous human chorionic gonadotropin (HCG) was significantly greater in Hodgkin's disease than in primary testicular failure (p less than 0.03). These data and the finding that basal serum follicle-stimulating hormone levels are significantly lower than normal in Hodgkin's disease (p less than 0.05) suggest that the cause of pretreatment hypogonadism in Hodgkin's disease is not simple primary testicular failure. Total sperm count was decreased in 40 percent of men with Hodgkin's disease but in none of the men with other malignancies (p less than 0.05), suggesting specific seminiferous tubular dysfunction in Hodgkin's disease. However, motility was abnormal in 69 percent of men with Hodgkin's disease and 60 percent of those with other malignancies, suggesting that this is a nonspecific effect of cancer. Serum prolactin levels were significantly higher than normal in Hodgkin's disease (p less than 0.05) but not in other malignancies. Our findings suggests that the cause of testicular dysfunction that is present before treatment of Hodgkin's disease is complex, perhaps involving both pituitary and gonadal abnormalities.

Testicular function after torsion

A group of 20 patients with torsion was investigated. The study indicated that immediate surgical intervention with a period of torsion of the testis of less than 6 h will prevent impairment of testicle function. The histology of testicular biopsies taken from such patients revealed only interstitial oedema and, at the most, partial necrosis. If torsion time exceeded 6 h testicular histology revealed severe alterations, and surgical correction could not prevent atrophy of the testis. Patients with pathological spermiograms showed FSH values over or at the upper limit of the normal range. As far as can be concluded from one single basal hormone determination, the testosterone secretion remained unaltered. Libido, potency and virilization remained normal.

Lithium: short-term and chronic effects on plasma testosterone and luteinizing hormone concentrations in mice

The effects of short-term and chronic lithium administration on the concentrations of plasma testosterone (T) and luteinizing hormone (LH) were evaluated in C57BL/6 mice, maintained on a fixed photoperiod of LD 14:10 (white lights on at 06:00 h, CST). Lithium chloride was injected intraperitoneally twice daily (at 09:00 and 16:00 h) in groups of adult male mice at a dosage of 2.5 meq/kg for 7 days, and 1.25 meg/kg for 21 days. Circulating levels of T and LH were measured by standard radioimmunoassay (RIA) methods. Plasma T levels showed a significant increase in mice treated with lithium for 7 days as compared to those in saline-injected control animals. However, there was no significant difference in the concentrations of plasma T between chronic (21 days) lithium-treated mice and the matched control. Plasma LH levels remained unchanged following both short-term and chronic lithium treatment.

Blood hormone profiles in prostate cancer patients in high-risk and low-risk populations

Epidemiologic data reveal that the incidence rate of prostate gland carcinoma among the black population in the United States (US) is several times higher than among Nigerians. A collaborative study between the two countries was undertaken, and blood hormone (testosterone [T], dihydrotestosterone [DHT], estrone [E1], estradiol [E2], and prolactin [P1]), total acid phosphatase (TP), and prostatic acid phosphatase (PAP) profiles in the two population groups were compared. In the US groups (patients and controls) there were significantly higher levels of T (P less than 0.01) and E1 (P less than 0.05) compared with the Nigerians. Also, the US patients had significantly higher levels of T (P less than 0.05) and E1 (P less than 0.01) compared with their matched controls. In the Nigerians T but not E1 levels were significantly lower (P less than 0.05) in patients compared with controls. DHT, E2, and P1 were not significantly different in patients and controls between and within the populations. Nigerian patients had higher levels (P less than 0.001) of TP and PAP compared with US patients. It is concluded that differences in blood hormone profiles in the two population groups are based on factors other than the genetic makeup of the populations.

The effect of growth hormone on the Leydig cell response to chorionic gonadotrophin in boys with hypopituitarism

Eleven boys with growth hormone (hGH) deficiency received human chorionic gonadotrophin (hCG) stimulation tests for the assessment of Leydig cell function before, during, and after 1 year of treatment with somatotrophin. Two patients entered puberty during the course of the study protocol. Analysis of the data in nine prepubertal boys revealed an augmentation of testosterone (T) responses to hCG in the presence of hGH. In six of these individuals in whom dihydrotestosterone (DHT) was determined, a similar augmentation in responsiveness of this steroid was found in the presence of hGH. Three prepubertal boys exhibited poor T responses to the basal hCG test with only partial improvement following hGH. In man growth hormone may be an important permissive factor in Leydig cell activity during periods of changing testicular function such as occur in utero or during puberty.

Hydrogenated soybean oil (HSO) as a vehicle for the chronic and controlled administration of testosterone in the orchidectomized rat

The use of a novel vehicle, hydrogenated soybean oil (HSO) for the chronic and controlled release of testosterone (T) in the orchidectomized rat is described. At 60 degrees C, HSO is a liquid in which T is readily soluble. When cooled at approximately 43 degrees C, HSO can be injected into experimental animals without the need of special equipment. At body temperature, the oil forms a solid depot from which T is released over prolonged periods of time. Our studies indicate that a single injection of 5 mg T in HSO in the orchidectomized rat, maintains sex accessory gland weights (AGW) above castrate levels, decreases serum concentrations of LH and maintains serum concentrations of T within the intact range for 10 days after injection. In contrast, these parameters of functional androgenicity are maintained for only three days when T is administered at the same dosage in a conventional oil vehicle. A dose of 15 mg T in HSO maintained serum T concentrations and AGW within intact range for 55 days after injection, but was unable to maintain LH suppression in these castrated animals beyond 14 days after injection.

A novel female influences delta 9-THC effects on plasma hormone levels in male mice

Exposure to delta 9-tetrahydrocannabinol (THC) (50 mg/kg) alters the endocrine responsivity of male mice to female-related exteroceptive stimuli. Exposure to a novel female prevents or delays the THC-induced decrease in plasma testosterone (T) and luteinizing hormone (LH) levels. These hormonal alterations are apparently not due to the LH-releasing effects of female-related pheromonal or tactile cues, since administration of luteinizing hormone releasing factor (LRF) did not mimic the effects of a novel female on plasma T levels in THC-treated males. Exposure to a much lower dose of THC (0.5 mg/kg) did augment the LRF-induced increases in plasma T levels suggesting a possible synergism between gonadotropins and THC on androgen production. The present findings suggest that THC-induced alterations in hormonal status may be influenced by complex social or environmental factors.

Hypothalamic neurons responsive to increased plasma level of testosterone in the male rat

Unitary activity was recorded from several forebrain structures. Out of 108 cells, 35 reacted to a testosterone i.v. injection by an increase (24 cells) or a decrease (11 cells) of firing rate. This response was early (latency: 5.0 +/- 0.6 min), lasted 25.7 +/- 1.9 min and was reproducible. Responsive neurons were found to be significantly more numerous in the lateral hypothalamic area than in other structures.

Epidermal growth factor in the submandibular glands of inbred mice

Epidermal growth factor (EGF), and androgen-dependent polypeptide, occurs in high concentration in male mouse submandibular gland. Glands of adult male and female mice of six inbred strains (129/J, C57BL/6J, C58/J, SWR/J, RF/J, A/J) were assayed for EGF by radioimmunoassay. In all strains, the glands of males contained 30 to 500-fold more EGF than those of females. Furthermore, significant differences in EGF content were found among the various strains in both sexes, the highest amount of EGF was present in RF/J and the lowest in C57BL/6J, with a ratio of three in the males and four in the females of the two strains, respectively. Factors that effect EGF levels were analyzed further, using these two strains. EGF was measurable in the glands of mice of both strains at 21 days of age and increased rapidly thereafter, up to 14 weeks of age. Throughout postnatal development, the level of EGF was greater in the glands of RF/J mice than in those of the C57BL/6J animals. Thirty days after castration, the EGF levels were reduced by about 98% in both strains, but the strain difference was not abolished. Testosterone implants (1 mg in Silastic tube) in castrated mice induced EGF levels six- to ten-fold compared to castrates. Even in induced animals, which had similar plasma testosterone levels, as measured by radioimmunoassays, the difference in EGF levels between the two strains was manifest. Such a difference, however, was not seen after the daily administration of 5-alpha-dihydrotestosterone for 3-14 days. Immunocytochemical straining for EGF also indicated a higher concentration of the polypeptide in the glands of RF/J mice than in those of C57BL/6J animals, and confirmed the exclusive localization of EGF in the cells of the granular convoluted tubules (GCT). According to our morphometric analysis, in the glands of male RF/J mice the GCT compartment occupied a greater portion (8% greater, P less than 0.001) of the gland volume than in C57BL/6J mice. The difference in the relative GCT volumes in the glands of female mice of the two strains was, however, statistically not significant. There was no direct correlation between the amount of EGF and the relative volume of the GCTs in the two strains. The evidence obtained implies that strain difference in submandibular-gland EGF levels are determined genetically.

Influence of exposure to moderate altitude on the plasma concentraton of cortisol, aldosterone, renin, testosterone, and gonadotropins

The influence of 11 days at moderate altitude (2,000 m) combined with exercise on plasma concentration of testosterone, FSH (follicle-stimulating hormone), LH (luteinizing hormone), cortisol, aldosterone, and renin activity was studied in ten healthy subjects. Within 48 h of arrival at moderate altitude a significant increase in testosterone was found whereas FSH had decreased significantly and LH showed a tendency to decrease. Cortisol increased significantly at the beginning and reached a maximum at the end of altitude exposure. The plasma aldosterone level rose continuously and on the last day of altitude was significantly elevated. Plasma renin activity showed a tendency to decrease. On return to low land all measured parameters returned to base line values within 2 days. The findings of increases in plasma levels of aldosterone and testosterone (and serum T3 and T4, as reported by others) are in contrast to the previously found decrease of urinary excretion of all these hormones. This appears to be a distinct dissociation of serum levels of adrenal (and thyroid) hormones from their urinary excretion. The observed increase in plasma aldosterone is probably mediated through ACTH and the rise in plasma potassium, since plasma renin activity showed an opposite trend. The rise in plasma testosterone is probably of adrenal origin since plasma gonadotropins declined simultaneously. The increase of plasma levels of glucocorticoids, mineralocorticoids, and androgens after an ascent from 600 m to 2,000 m above sea level is compatible with an ACTH-mediated stimulation of the entire adrenal cortex and/or a diminished elimination of adrenal steroids: The concomitant fall of FSH, LH, and plasma renin would then be a consequence of a direct negative feedback inhibition of these hormones.