Hypothalamic, pituitary, testicular, and secondary organ functions and interactions during the sexual maturation of the male rat

Pathophysiology of Pediatric Traumatic Brain Injury

The national incidence of traumatic brain injury (TBI) exceeds that of any other disease in the pediatric population. In the United States the Centers for Disease Control and Prevention (CDC) reports 697,347 annual TBIs in children ages 0–19 that result in emergency room visits, hospitalization or deaths. There is a bimodal distribution within the pediatric TBI population, with peaks in both toddlers and adolescents. Preclinical TBI research provides evidence for age differences in acute pathophysiology that likely contribute to long-term outcome differences between age groups. This review will examine the timecourse of acute pathophysiological processes during cerebral maturation, including calcium accumulation, glucose metabolism and cerebral blood flow. Consequences of pediatric TBI are complicated by the ongoing maturational changes allowing for substantial plasticity and windows of vulnerabilities. This review will also examine the timecourse of later outcomes after mild, repeat mild and more severe TBI to establish developmental windows of susceptibility and altered maturational trajectories. Research progress for pediatric TBI is critically important to reveal age-associated mechanisms and to determine knowledge gaps for future studies.

Effects of motor vehicle exhaust on male reproductive function and associated proteins

Air pollution is consistently associated with various diseases and subsequent death among children, adult, and elderly people worldwide. Motor vehicle exhaust contributes to a large proportion of the air pollution present. The motor vehicle exhaust systems emit a variety of toxic components, including carbon monoxide, nitrogen oxides, volatile organic compounds, ozone, particulate matter, and polycyclic aromatic hydrocarbons. Several epidemiological studies and laboratory studies have demonstrated that these components are potentially mutagenic, carcinogenic, and endocrine disrupting agents. However, their impact on male reproductive function and associated proteins is not very clear. Therefore, a comprehensive review on the effects of motor vehicle exhaust on male reproductive function and associated proteins is needed to better understand the risks of exhaust exposure for men. We found that motor vehicle exhaust can cause harmful effects on male reproductive functions by altering organ weights, reducing the spermatozoa qualities, and inducing oxidative stress. Remarkably, motor vehicle exhaust exposure causes significant changes in the expression patterns of proteins that are key components involved in spermatogenesis and testosterone synthesis. In conclusion, this review helps to describe the risks of vehicle exhaust exposure and its relationship to potential adverse effects on the male reproduction system.

Adolescent TBI-induced hypopituitarism causes sexual dysfunction in adult male rats

Adolescents are at greatest risk for traumatic brain injury (TBI) and repeat TBI (RTBI). TBI-induced hypopituitarism has been documented in both adults and juveniles and despite the necessity of pituitary function for normal physical and brain development, it is still unrecognized and untreated in adolescents following TBI. TBI induced hormonal dysfunction during a critical developmental window has the potential to cause long-term cognitive and behavioral deficits and the topic currently remains unaddressed. The purpose of this study was to determine if four mild TBIs delivered to adolescent male rats disrupts testosterone production and adult behavioral outcomes. Plasma testosterone was quantified from 72 hrs preinjury to 3 months postinjury and pubertal onset, reproductive organ growth, erectile function and reproductive behaviors were assessed at 1 and 2 months postinjury. RTBI resulted in both acute and chronic decreases in testosterone production and delayed onset of puberty. Significant deficits were observed in reproductive organ growth, erectile function and reproductive behaviors in adult rats at both 1 and 2 months postinjury. These data suggest adolescent RTBI-induced hypopituitarism underlies abnormal behavioral changes observed during adulthood. The impact of undiagnosed hypopituitarism following RTBI in adolescence has significance not only for growth and puberty, but also for brain development and neurobehavioral function as adults.

Harmful effects of carbamazepine on the postnatal development of the rat ventral prostate

BACKGROUND

Carbamazepine (CBZ) is a first-line antiepileptic drug (AED), although it is also used for the treatments of psychiatric disorders and neuropathic pain. The CBZ utilization has been associated with male reproductive damage, including hormonal alterations, sexual dysfunction and reduction of sperm quality. The wide and long-term use of the CBZ is a common schedule in children and adolescents and alters the testosterone level in adult rats and humans. The objective of this work was to evaluate the CBZ side effects on the ventral prostate of rats from pre-puberty to sexual maturation, since the prostate is an androgen-dependent organ.

METHODS

Twenty three day-old male albino Wistar rats received CBZ diluted in propylene glycol (20 mg/Kg/i.p via). The treatment lasted 20, 40 and 70 days, according to the different stages of the rat sexual maturation. At the end of each treatment period, ventral prostates were removed and histologically processed. The prostate sections were submitted to the histopathological, morphological and stereological analyses using image analysis system.

RESULTS

Reductions of the glandular epithelium, glandular lumen and fibromuscular stroma volume of the ventral prostate were observed in adult rats treated with CBZ since the weaning. Triggering and degranulation of mast cells were observed in the fibromuscular stroma of prepubertal and pubertal CBZ treated rats.

CONCLUSIONS

The results suggest a direct effect of the CBZ on rat ventral prostate, evidenced by increase of mast cell and macrophage populations during pre-puberty and puberty causing a ventral prostate accentuated damage in the adult phase.

Hirsutism, virilism, polycystic ovarian disease, and the steroid-gonadotropin-feedback system: a career retrospective

This career retrospective describes how the initial work on the mechanism of hormone action provided the tools for the study of hirsutism, virilism, and polycystic ovarian disease. After excessive ovarian and or adrenal androgen secretion in polycystic ovarian disease had been established, the question whether the disease was genetic or acquired, methods to manage hirsutism and methods for the induction of ovulation were addressed. Recognizing that steroid gonadotropin feedback was an important regulatory factor, initial studies were done on the secretion of LH and FSH in the ovulatory cycle. This was followed by the study of basic mechanisms of steroid-gonadotropin feedback system, using castration and steroid replacement and the events surrounding the natural onset of puberty. Studies in ovariectomized rats showed that progesterone was a pivotal enhancer of estrogen-induced gonadotropin release, thus accounting for the preovulatory gonadotropin surge. The effects of progesterone were manifested by depletion of the occupied estrogen receptors of the anterior pituitary, release of hypothalamic LHRH, and inhibition of enzymes that degrade LHRH. Progesterone also promoted the synthesis of FSH in the pituitary. The 3α,5α-reduced metabolite of progesterone brought about selective LH release and acted using the GABA(A) receptor system. The 5α-reduced metabolite of progesterone brought about selective FSH release; the ability of progesterone to bring about FSH release was dependent on its 5α-reduction. The GnRH neuron does not have steroid receptors; the steroid effect was shown to be mediated through the excitatory amino acid glutamate, which in turn stimulated nitric oxide. These observations led to the replacement of the long-accepted belief that ovarian steroids acted directly on the GnRH neuron by the novel concept that the steroid feedback effect was exerted at the glutamatergic neuron, which in turn regulated the GnRH neuron. The neuroprotective effects of estrogens on brain neurons are of considerable interest.

Effects of triclocarban on intact immature male rat: augmentation of androgen action

Triclocarban (TCC; 3,4,4'-trichlorocarbanilide) is an antimicrobial agent used widely in various personal hygiene products including soaps. Recently, TCC has been shown to enhance testosterone-induced effects in vitro and to enlarge accessory sex organs in castrated male rats. This study was designed to evaluate the effects of TCC on intact age-matched male rats and on human prostate LNCaP and C4-2B cells. Seven-week-old male Sprague-Dawley rats received either a normal diet or a diet supplemented with TCC (0.25% in diet) for 10 days. Triclocarban induced hyperplasia of accessory sex organs in the absence of significant qualitative histological changes. Serum luteinizing hormone (LH) and testosterone were not significantly altered by TCC treatment. In prostate cancer-derived LNCaP and C4-2B cells, TCC potentiated androgen actions via androgen receptor-dependent actions. In conclusion, TCC significantly affects intact male reproductive organs and potentiates androgen effects in prostate cancer cells.

OECD validation of phase-3 Hershberger assay using the stimulated weanling male rat in Korea

The OECD has proposed a new, validated test guideline with the stimulated weanling male Hershberger assay to avoid the surgical castration step. In the present study, we assessed the relevance and reliability of the stimulated weanling Hershberger assay in four stages. All chemicals except for testosterone propionate (TP) were orally administered to sexually immature male rats of 22 days old for 10 days. The weights of four mandatory accessory sex organs, two additional reproductive tissues and optional systemic organs were evaluated. At the first two stages, TP, as reference androgen, significantly increased the weights of epididymides and accessory sex organs (ASO) at 1.0 mg kg(-1) and flutamide (FLU), as a positive anti-androgen control, decreased the TP-stimulated organ weights at 3.0 mg kg(-1). At stage 3, trenbolone (40 mg kg(-1)), an anabolic steroid, significantly increased ASO weights, and weak anti-androgens (DDE and linuron) decreased the TP-stimulated ASO weights at each high dose. The above results were confirmed in a blind test with coded substances provided by OECD. Compared with results from our previous castrated male assay, the intact weanling version is less sensitive than the castrated male version, in terms of a smaller response at the reference dose of TP or FLU. However, this study suggests that the stimulated weanling Hershberger assay can detect the effects of both potent and weak anti-androgens on androgen-producing and androgen-dependent tissues.

Endocrine-disrupting chemicals: prepubertal exposures and effects on sexual maturation and thyroid function in the male rat. A focus on the EDSTAC recommendations. Endocrine Disrupter Screening and Testing Advisory Committee

Puberty in mammalian species is a period of rapid interactive endocrine and morphological changes. Therefore, it is not surprising that exposure to a variety of pharmaceutical and environmental compounds has been shown to dramatically alter pubertal development. This concern was recognized by the Endocrine Disrupter Screening and Testing Advisory Committee (EDSTAC) that acknowledged the need for the development and standardization of a protocol for the assessment of the impact of endocrine-disrupting compounds (EDC) in the pubertal male and recommended inclusion of an assay of this type as an alternative test in the EDSTAC tier one screen (EPA, 98). The pubertal male protocol was designed to detect alterations of pubertal development, thyroid function, and hypothalamic-pituitary-gonadal (HPG) system peripubertal maturation. In this protocol, intact 23-day-old weanling male rats are exposed to the test substance for 30 days during which pubertal indices are measured. After necropsy, reproductive and thyroid tissues are weighed and evaluated histologically and serum taken for hormone analysis. The purpose of this review was to examine the available literature on pubertal development in the male rat and evaluate the efficacy of the proposed protocol for identifying endocrine-disrupting chemicals. The existing data indicate that this assessment of puberty in the male rat is a simple and effective method to detect the EDC activity of pesticides and toxic substances.

Termination of the peripubertal FSH increase in male rats

To determine if the pubertal testosterone rise plays a role in the termination of the peripubertal follicle-stimulating hormone (FSH) increase, male rats were injected with ethylene dimethanesulfonate (EDS) at 40 days of age to eradicate the Leydig cells just before the onset of the testosterone rise. Rats were decapitated at weekly intervals from age 26 to 96 days. Compared with vehicle-injected controls, EDS treatment resulted in a delay in the peripubertal increase in the relative weights of prostates and seminal vesicles of approximately 2 wk. Serum testosterone remained at pretreatment levels for 1 wk postinjection. Testicular interstitial fluid testosterone remained at pretreatment concentrations for considerably longer and was significantly lower than controls for 2 wk postinjection. EDS treatment resulted in serum FSH levels that were elevated by 1 wk postinjection. They remained significantly higher than controls until 96 days of age. Compared with controls, serum alpha-inhibin was elevated after EDS as was serum luteinizing hormone. These results suggest that the pubertal testosterone increase plays an important role in terminating the peripubertal FSH rise.

Chronic ethanol ingestion during puberty alters the transient increase in testicular 5 alpha-reductase in the Swiss-Webster mouse

Previous experiments with inbred mice showed that chronic ethanol treatment delays male pubertal development. An initial event in sexual maturation in the rat is a transient increase in 5 alpha-reductase. The present study was conducted to determine whether similar ethanol effects occur in outbred mice (Swiss-Webster), to determine the ontological profile of testicular 5 alpha-reductase in the mouse, and to evaluate the effect of ethanol treatment on this enzyme. After 29 days of treatment with a liquid diet (beginning at age 20 days), reductions in the ethanol-treated mice as compared with the controls were noted in testicular weight (55.0 +/- 2.0 vs. 63.0 +/- 2.4 mg; P less than 0.01), epididymal sperm content (6.8 X 10(5) vs. 14.4 X 10(5); P less than 0.05), and sperm motility (45% vs. 57%; P less than 0.05). After 43 days, differences no longer existed. In chow-fed mice, a substantial rise in 5 alpha-reductase (1 unit = 1 pmole DHT formed/45 min/mg testis) began at age 24 days. Activity peaked at approximately 65 units at 25 to 30 days and gradually declined to 6.4 +/- 0.8 units at 63 days. After 29 days treatment, 5 alpha-reductase of the pair-fed control group was 26.8 +/- 4.9 units, which decreased to a baseline value of 7.0 +/- 2.1 units after 43 days treatment. In contrast, 5 alpha-reductase of the ethanol-treated group remained at baseline levels after 29 days (7.7 +/- 2.3 units) and 43 days of treatment (7.6 +/- 2.3 units).(ABSTRACT TRUNCATED AT 250 WORDS)

Ethanol-induced delayed male puberty in mice is not due to impaired Leydig cell function

The present study was performed to evaluate the involvement of reduced testosterone in ethanol-induced impairment of male reproductive tract development. In vivo and in vitro gonadotropin (hCG)-stimulated steroidogenesis were examined in CFW mice as a function of chronic ethanol treatment during pubertal development. Chronic ethanol treatment from ages 20 to 49 days impaired testicular growth from ages 35 days (29 +/- 2 mg vs 37 +/- 2 mg for pair-fed controls) to 50 days (42 +/- 2 mg vs 63 +/- 2 mg for pair-fed controls). Consistent with a reduction in testicular weight, testicular content of androstenedione, testosterone, and dihydrotestosterone (DHT) was depressed in ethanol-treated mice. At age 50 days, the content (expressed as pg/testis) of androstenedione, testosterone, and DHT was reduced in ethanol-treated animals by 49%, 31%, and 38%, respectively, as compared to that of their respective controls. However, no difference in plasma (ng/mL) or testicular (pg/mg protein) concentrations of steroids was observed. Except for the DHT response at ages 35 to 40 days, neither in vivo nor in vitro steroidogenesis was impaired by chronic ethanol treatment at ages 26 to 50 days; similarly, the acute ethanol effect on steroidogenesis was unaffected. However, an adaptive increase (54%-173%) in the in vivo testosterone response to hCG was seen at ages 26 to 40 days. The data indicate that 1) chronic ethanol treatment does not impair gonadotropin-stimulated steroidogenesis or result in tolerance to acute ethanol effects on steroidogenesis in older animals; and 2) ethanol-induced reduction in testosterone is not a likely mechanism for delayed sexual maturation.

Testosterone production by the prepubertal mouse testis is not depressed by ethanol

The purpose of the present study was to evaluate the sensitivity of testicular steroidogenesis during pubertal development to inhibition by ethanol. In vivo and in vitro human chorionic gonadotropin (hCG)-stimulated steroidogenesis were examined in CFW mice as a function of age. Plasma androstenedione, testosterone, and dihydrotestosterone (DHT) increased from ages 23 to 60 days in control mice. Acute ethanol treatment (3 g/kg) yielded static levels of androstenedione (0.45 +/- 0.03 ng/mL), testosterone (6.4 +/- 0.56 ng/mL), and DHT (2.3 +/- 0.18 ng/mL) from ages 23 to 60 days, 30 to 60 days, and 35 to 60 days, respectively, resulting in reduction of plasma androstenedione, testosterone, and DHT (P less than 0.05) relative to control values, but not until ages 35, 50, and 45 days, respectively. A similar insensitivity of the prepubertal testis to ethanol was seen in vitro. Inhibition of in vitro androstenedione and testosterone accumulation was seen only after ages 26 and 45 days, respectively. The data indicate that testosterone production by the pubertal testis is relatively insensitive to direct inhibition by ethanol. Previous studies have shown that chronic ethanol treatment of adolescent mice delays testicular maturation. The present study suggests that if chronic ethanol-induced delayed testicular development were due to impaired steroidogenesis, such impairment would be secondary to reduced gonadotropin stimulation and/or due to a chronic, rather than an acute, effect of ethanol.

Prolactin and Leydig cell steroidogenic enzymes in the bonnet monkey (Macaca radiata)

The effect of treatment with prolactin or bromocryptine on testicular steroidogenesis and serum hormone levels were studied in immature and mature bonnet monkeys. Leydig cells alone showed the presence of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) in normal immature and mature monkeys. Administration of prolactin increased the activity of 3 beta-HSD and 17 beta-HSD in Leydig cells from mature monkeys, and also increased the serum levels of testosterone. Bromocryptine treatment induced exactly the opposite effect. These changes occurred in the absence of any change in serum gonadotrophin levels. In immature monkeys, prolactin and bromocryptine had no significant effect. These results suggest a direct stimulatory effect of prolactin on testicular steroidogenesis in mature monkeys.

Delayed pubertal development of the male reproductive tract associated with chronic ethanol ingestion

Little is known concerning the sensitivity of the reproductive tract to ethanol as a function of development. The present study was conducted to evaluate the action of chronic ethanol ingestion on sexual maturation of the male. Mice were given free access to liquid diets containing 5% (v/v) ethanol for either 29 or 43 days, starting at age 20 days. Controls were given liquid diets in which isocaloric sucrose replaced the ethanol. Daily diet consumption and peak blood ethanol levels were highest during the first 2 weeks of treatment, dropping thereafter to adult levels of approximately 680 ml/kg body weight and 160 mg/dl respectively. Plasma testosterone levels were depressed by ethanol throughout treatment, the reduction being somewhat greater when measured during week 6 of treatment (average = 74% inhibition) as compared to either week 2 (36%) or week 4 (25%). Average weights of testes, epididymides and seminal vesicles were depressed by 24% (P less than 0.002), 16% (P less than 0.005) and 13% (NS), respectively, after 29 days. Testicular development was also impaired in ethanol-treated animals after 29 days. Tunica albuginea thickness and seminiferous tubule diameter were decreased (by 31%, P less than 0.05; and 16%, P less than 0.01 respectively), whereas desquamation of immature germ cells and inactive tubules were increased (325 and 780% respectively; P less than 0.01). Quality of spermatogenesis was poorer in ethanol-treated animals (P less than 0.05). Also observed were decreased sperm motility (62% inhibition, P less than 0.01) and capacity to fertilize (decreased by 67%, P less than 0.01), and an increase in the incidence of morphologically abnormal spermatozoa (by 163%, P less than 0.001). Semen volume was lower (reduced by 57%, P = 0.05), as was the total number of motile ejaculated spermatozoa (reduced by 81%, P less than 0.05). After 43 days treatment, improvement was noted in all indices of fertility except for the number of motile ejaculated spermatozoa. Significant differences persisted only for dysmorphic spermatozoa and volume and sperm count of electroejaculated semen. These data suggest that ethanol ingestion during pubertal development can delay several aspects of sexual maturation in the male.

Concentrations of free testosterone, total testosterone, and androgen binding protein in the peripheral serum of male rats during sexual maturation

To investigate the relationship between free testosterone and sexual maturation in the male rat, animals were decapitated every 5 days from 25 through 75 days of life. Serum was assayed for androgen binding protein and total testosterone by radioimmunoassay. Free testosterone concentrations were calculated from the total testosterone concentration and the free testosterone fraction. The free testosterone fraction was determined by ultrafiltration. The pubertal increase in relative prostate and relative seminal vesicle weights began between 45 and 50 days and 40 and 45 days, respectively. Although the over-all trend in the free testosterone fraction was to increase with increasing age (r = 0.46, P less than 0.0001), there was a significant secondary peak at 50 days. The serum concentration of androgen binding protein was highest on day 25, fell rapidly until day 40, and declined slowly thereafter. Despite these variations in both androgen binding protein and the free testosterone fraction during sexual maturation, the calculated serum concentration of free testosterone was remarkably similar in pattern to that of total testosterone (r = 0.99, P less than 0.0001). These data indicate that the serum concentration of total testosterone is an accurate reflection of the serum concentration of free testosterone during the sexual maturation of the male rat.

Testicular testosterone concentrations in protein-calorie malnourished rats

The effects of protein-calorie malnutrition on testicular testosterone were studied at 5-day intervals in rats from 20 to 80 days of age. A significant increase in steroid hormone production did not occur in the malnourished rats before 60 days of age, whereas in well-fed controls, a marked rise was recorded between days 35 and 40. These changes correspond to a 5- to 10-day period which preceded the first appearance of mature sperm in both animal groups.

Administration of constant low doses of androgens to steers by silastic implant. Suppression of gonadotropins and peripheral conversion of androgens

Yearling Hereford calves approximately 300 kg in weight were castrated and assigned to one of six treatment groups receiving subcutaneous implants (3 implants, 0.5 cm diameter by 10 cm length, 10% steroid by weight) of either androstenedione (D); testosterone (T); 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol); dihydrotestosterone (DHT); androsterone (A); or control (no steroid). Blood samples were obtained at half-hour intervals for eight hours one day prior to, and one week after, castration. The castration-induced elevation in FSH secretion was suppressed or modified by the DHT, T, and 3 beta-diol implants. LH levels were not significantly suppressed. The T implants elevated serum T concentrations; DHT implants elevated serum 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol) and 3 beta-diol, but not DHT concentrations; 3 beta-diol implants elevated serum 3 beta-diol concentrations. The effects of D and A implants upon serum androgen concentrations were not statistically significant, although observations in vitro suggested an adequate release rate. These data imply that T and DHT, or metabolites of DHT, suppress FSH secretion and suggest that extensive peripheral androgen metabolism occurs.

Influence of hypothyroidism on epididymal enzymes involved in carbohydrate metabolism. Studies in pubertal and adult rats

The influence of thyroidectomy on key epididymal enzymes of the Embden-Meyerhof and pentose phosphate pathway have been studied in pubertal and adult animals in relation to the serum hormone profile. Age related differences in the response of epididymal segments were observed with respect to hexokinase activity, although the other 2 key enzymes of the Embden-Meyerhof pathway (6-PFK and PK) were suppressed in all regions of the epididymis in both pubertal and adult rats. The enzymes involved in the pentose phosphate pathway (G-6-PDH and 6-PGDH) remained unaltered. The serum hormone profile revealed that while FSH and testosterone titres were reduced, LH and Prl were unaltered. Replacement of T4 in thyroidectomized animals maintained serum hormone levels and the activities of the enzymes studied at control levels. It is inferred that thyroid hormones may be one part of a complex mechanism that controls carbohydrate metabolism in the epididymis.

Effect of adrenalectomy and corticosterone replacement on epididymal carbohydrate metabolism--studies on mature male rats

The effect of adrenalectomy and corticosterone replacement on epididymal enzymes involved in obligatory steps of glycolysis and pentose phosphate pathway were studied along with serum hormonal profiles. Adrenalectomy was found to elevate serum prolactin while the gonadotropins and testosterone were unaltered. In caput epididymal tissue enzymes of the pentose phosphate pathway. Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities were increased after adrenalectomy. However, in corpus epididymal tissue the key enzymes viz. hexokinase, 6-phosphofructokinase and pyruvatekinase of the glycolytic pathway were elevated leaving the pentose phosphate pathway unaffected. Adrenalectomy was also found to favour glycolysis of the epididymal spermatozoa. The possible direct effect of prolactin is discussed to explain the enzymatic changes in epididymis. Corticosterone replacement was found to maintain the enzyme activities along with serum prolactin and corticosterone at control levels. In conclusion, it is suggested that the adrenalectomy induced changes in enzyme activities could be due to the direct effect of prolactin.

Male reproductive tract sensitivity to ethanol: a critical overview

While endocrinological effects of acute and chronic ethanol ingestion have been extensively reviewed, a survey of ethanol induced functional and physical perturbations of the male reproductive tract remains lacking. A brief overview of recent literature concerned with ethanol sensitivity of various components of the reproductive tract is presented. Clinical findings are reviewed as they relate to the possible pathogenesis of alcohol-related testicular atrophy. Currently available animal models for the study of ethanol-induced male reproductive failure are discussed. Attempts have been made to separate the contribution of ethanol per se from secondary factors, such as hepatic dysfunction and nutritional deficiency, to manifestations of male infertility. Studies directed toward elucidating the mechanism(s) by which ethanol exerts its inhibitory effect on testicular steroidogenesis are discussed. Finally, evidence suggesting an effect of ethanol on the functional integrity of other components of the reproductive tract is reviewed. It is concluded that ethanol is a male reproductive tract toxin. Future clinical studies of alcoholics afflicted with testicular atrophy, but having normal liver histology, will be of great value in efforts to identify the mechanisms by which chronic ethanol ingestion results in reproductive impairment. Similar benefits will be realized in laboratory experimentation, in which models are employed that describe ethanol-induced infertility, while minimizing nutritional factors and hepatic involvement, and control for the reproductive maturity of the organism.

Epididymal carbohydrate metabolism in experimental hypercorticosteronism: studies on mature male rats

Corticosterone induced changes in serum hormonal profiles and the key enzymes involved in glycolytic and pentose phosphate pathways were studied in caput, corpus and cauda epididymides of mature male rate (200-250 g body weight). Corticosterone (3.5 mg/100 g body weight sc. for 20 days) treatment was found to depress serum testosterone and prolactin while the gonadotrophins were unaltered. Enzymes of both the glycolytic and pentose phosphate pathways were significantly decreased in caput epididymidis. But in corpus and cauda epididymides only the glycolytic enzymes were reduced. Withdrawal of treatment (for 20 days), resulted in restoration of the glycolytic enzymes to normalcy. Tge serum hormonal profiles were also found to be within the normal range. The pentose phosphate pathway in caput epididymidis showed a significant increase in enzyme activities following withdrawal of treatment. From the present investigation it is clear that hypercorticosteronism had a definite influence on epididymal enzymes involved in carbohydrate metabolism.

Specific effect of thyroid hormone on testicular enzymes involved in carbohydrate metabolism. II. Hyperthyroidism

The influence of thyroxine on some of the key enzymes involved in glycolytic and pentose phosphate pathways in the testes of pre-pubertal; pubertal and adult rats was studied. Thyroxine-induced (25 micrograms/100 g body weight) hyperthyroidism for 1 month resulted in no change in either hexokinase (EC 2.7.1.1) or 6-phosphofructokinase (EC 2.7.1.11) activity in the testes of rats in any age group studied. However, pyruvate kinase (EC 2.7.1.40) activity was reduced significantly in the pre-pubertal and pubertal rats. Both glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) activities were markedly increased after thyroxine treatment. Withdrawal of hormone treatment resulted in reversion of enzyme activities towards normal. The results suggest that thyroxine has an age-dependent, specific effect over testicular pyruvate kinase activity. Thyroid hormone may have a direct control over the pentose phosphate pathway in the testis.

Role of adrenal in control of gonadotropin secretion in the immature male rat

A study was made of adrenal control of gonadotropin secretion during the prepubertal period. Male rats were adrenalectomized (ADX) or sham operated on day 26. The sensitivity of the hypothalamus/pituitary to the negative feedback effects of testosterone (T) was examined by simultaneously castrating the animals and implanting various size Silastic capsules filled with crystalline T. These animals were decapitated on day 30. Another group of immature rats was examined to determine pituitary sensitivity to luteinizing hormone releasing hormone (LHRH). These rats were ADX on day 26 and injected intravenously with various doses of LHRH on day 30. ADX did not alter the negative feedback of T on luteinizing hormone (LH) secretion or the ability of the pituitary to release LH in response to LHRH. ADX appeared to lower the set point for follicle stimulating hormone (FSH) secretion but not the ability of T to reduce FSH. Pituitaries of ADX rats released less FSH in response to LHRH than did controls. These results show the role of the adrenal in the control of FSH secretion in the prepubertal male rat.

The influence of the parental environment on sexual maturation in male mice

Experiments were designed to examine the influence of either one or both parents on the sexual maturation of male mice. A pregnant female and an adult vasectomized male were housed together and, at delivery, the litter was reduced to 6 pups, 3 of each sex. After weaning, mother, foster-father or both, stayed in cohabitation with their pups until sacrifice. The results showed that: (1) the permanent presence of one or both parents did not affect either testicular growth or the age at first fertile matings. (2) in maturing males (30-40 days), seminal vesicle growth was accelerated by the presence of the mother, inhibited by the presence of the foster-father. (3) in maturing males, the presence of one or both parents lowered plasma testosterone levels. On the opposite, in 90-day-old males, the same conditions increased testosterone levels. These results indicate that only the endocrine function of the testis is affected by the parental environment. The effects are age-dependent.

LH-induced testicular steroid secretion after FSH treatment in immature and young adult hypophysectomized rats

Immature and young adult male rats were hypophysectomized on day 21 and 71 respectively. Beginning 2 days later, animals received five daily subcutaneous injections of 4 microgram/100 g body weight of NIAMDD-oFSH-13 or saline. On the sixth day the rats received either 15 microgram/100 g body weight of NIAMDD-oLH-21 or saline intraperitoneally and were decapitated 1 hr later. Serum levels of steroids were measured by radioimmunoassay. Serum steroid levels in animals receiving a saline injection on day 6 were low to undetectable and not affected by pretreatment. The serum steroid concentrations after LH challenge on day 6 were altered by FSH pretreatment. In immature rats, pretreatment with FSH resulted in a significant increase in 17 hydroxyprogesterone, androstenedione and testosterone. Progesterone and estradiol were unaffected, while 5 alpha dihydrotestosterone was elevated but not significantly. In young adults, FSH pretreatment resulted in increased levels of androstenedione, testosterone, and 5 alpha dihydrotestosterone, but not progesterone, 17 hydroxyprogesterone, or estradiol. These data suggest that FSH may play a role in stimulating cholesterol side chain cleavage activity, the 17 alpha hydroxylase, the C17-C20 lyase as well as the 17 beta hydroxysteroid dehydrogenase at puberty. Additionally, FSH may be involved in the maintenance of cholesterol side chain cleavage activity, the C17-C20 lyase and the 17 beta hydroxysteroid dehydrogenase in the adult rat.