Influence of estradiol on mammary tumor collagen solubility in DMBA-induced rat mammary tumors.

Estradiol plays a vital role in the growth and development of mammary glands. It is a potent stimulator of metabolic processes in normal and carcinoma breast. A critical factor in determining mammary glandular morphology is the stroma. Collagen is a predominant component of the extracellular matrix and cell-collagen interactions are essential carcinogenesis. The present investigation explored the influence of estradiol on collagen solubility and metabolism in mammary tumors during tumor progression and regression. A single injection of 20 mg of 9,10-dimethyl-1,2-benzanthracene was given to rats at 7 weeks of age. With the appearance of the first palpable mammary tumor, the rats were treated with 0.5 microg estradiol or 50 microg tamoxifen daily for 30 days. The rats were sacrificed 24 h after 30 days of treatment. Estradiol appears to stimulate the synthesis of new collagens and thus contributes to the enlargement of the mammary tumors. This might have created a potential microenvironment by increasing the synthesis of suitable matrix that sustains the growth of the mammary tumors. In short, the present findings emphasize a definite mediatory role for collagen in estradiol promoted mammary tumor growth.

Chronic chromium exposure-induced changes in testicular histoarchitecture are associated with oxidative stress: study in a non-human primate (Macaca radiata Geoffroy).

BACKGROUND: Reproductive toxicity of chromium is in dispute despite positive findings in rodents. Recently we reported epididymal toxicity of hexavalent chromium (CrVI) in bonnet monkeys and in this paper we report its testicular toxicity. METHODS: Adult monkeys (Macaca radiata) were given drinking water containing CrVI (100, 200, 400 p.p.m.) for 6 months and testes were removed for ultrastructural and biochemical analyses. RESULTS: CrVI treatment disrupted spermatogenesis, leading to accumulation of prematurely released spermatocytes, spermatids and uni- and multinucleate giant cells in the lumen of seminiferous tubules. Transmission electron microscopy revealed granulation of chromatin and vacuolation between acrosomal cap and manchette microtubules of elongated spermatids and in the Golgi area of round spermatids. Pachytene spermatocytes had fragmented chromatin and swollen mitochondria with collapsed cristae. Spermatocytes and spermatogonia in the basal compartment were unaffected. Macrophages containing phagocytosed sperm and dense inclusions in Sertoli cells were seen. Specific activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase and concentrations of the non-enzymatic antioxidants glutathione, vitamins A, C and E decreased, while concentrations of H(2)O(2) and hydroxyl radicals increased in the testis of chromium-treated monkeys. Withdrawal of chromium treatment for 6 months normalized spermatogenesis and the status of pro- and antioxidants in the testis. CONCLUSIONS: CrVI disrupts spermatogenesis by inducing free radical toxicity, and supplementation of antioxidant vitamins may be beneficial to the affected subjects.

Microcanalization in the epididymis to overcome ductal obstruction caused by chronic exposure to chromium - a study in the mature bonnet monkey (Macaca radiata Geoffroy).

In order to apprehend the toxic effects of chromium, an occupational/environmental pollutant, on the epididymis, adult bonnet monkeys were exposed to chromium (VI) in their drinking water at concentrations of 100, 200 and 400 p.p.m. for a chronic period of 180 days. At the end of the experimental period, testicles and segments of epididymis from control and treated monkeys were subjected to light microscopic (resin-embedded semi-thin sections) and transmission electron microscopic analyses. Among the various changes undergone by the epididymal epithelium, the present paper describes the origin of two different kinds of microcanals, probably caused by ductal obstruction. The first type of microcanal, which appears to provide passage for spermatozoa to bypass the obstructed main duct, is comparable with the one already reported in carbendazim-treated efferent ductules of the rat. The second type of microcanal, which is novel, consisted of a lumen in the epithelium enclosed by four to five cells, which are either modified basal cells, principal cells or a hitherto unknown cell type. This novel type of microcanal is suggested to be a device to entrap the spermatozoa which reach the core of the epithelium and may be a mechanism to prevent extravasation of sperm so as to avoid an autoimmune response of spermatic granuloma formation. Thus, the present study has shown that chronic exposure to chromium (VI) through drinking water can produce pathological manifestations in the epididymal epithelium but the epididymis, being a versatile organ, is capable of overcoming such adverse situations through novel devices.

Effects of estradiol and progesterone on vertebral collagen, glycosaminoglycans and phosphatases in ovariectomized adult rats.

Vertebral collagen, glycosaminoglycans (GAGs), tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP) were measured in ovariectomized (ovx) adult Wistar rats treated with estradiol (E 2 ) (10 micro g/kg BW for 35 days on alternate days, and progesterone (P 4 ) (140 micro g/kg BW for 35 days on alternate days) in E 2 + P 4 treated rats. P 4 given alone or in combination with E 2 significantly increased the levels of collagen in the vertebral bone. Neither ovx nor E 2 treatment altered the concentration of collagen in these rats. Administration of E 2 or P 4 significantly decreased the concentration of hyaluronic acid (HA), but remaining unaffected when a combination of these steroids was given. In contrast to their effect on HA, E 2 and P 4 each significantly increased the levels of chondroitin sulfate (CS) in the vertebral bone. The specific activity of ALP was decreased after ovx. E 2 and P 4 alone or in combination also registered a significant decrease in the activities of ALP and TRAP. The results suggest that E 2 and P 4 each exert definite effects on vertebral bone turnover in ovariectomized rats.

Modulatory effect of estradiol and testosterone on the development of N-nitrosodiisopropanolamine induced thyroid tumors in female rats.

Both experimental and clinical research support the conclusion that thyroid tumors are sex dependent. Also, several studies have pointed out that the use of oral contraceptives is associated with a higher risk of thyroid tumor. Most of the existing reports suggest indirect effects of sex steroids on thyroid tumor growth in women. In this work, we present data to support the direct promoting effect of estradiol and testosterone on carcinogen-induced thyroid tumorigenesis. Thyroid tumors were induced in rats by a combination of N-nitrosodiisopropanolamine (DHPN) and phenobarbital (PB) treatment. Serum thyroid hormones, thyroid stimulating hormone (TSH), steroid hormones, thyroidal steroid concentration, androgen and estrogen receptors were quantified. Serum thyroid hormones and TSH suggested euthyroid status of the all experimental animals. Ovariectomy decreased the incidence of DHPN + PB induced thyroid tumor when compared with ovary intact rats and estradiol/testosterone supplementation increased the same. Thyroidal estradiol level and its nuclear receptors increased in the tumor tissue specifically. Testosterone supplementation to DHPN-treated ovariectomized rats specifically induced the development of malignant thyroid tumors. Addition of estradiol in vitro to thyrocytes induced a higher proliferation rate. Our data proves a direct promoting role of estrogen on carcinogen-induced thyroid tumor development.

Testosterone and estradiol up-regulate androgen and estrogen receptors in immature and adult rat thyroid glands in vivo.

Thyroid gland is one of the non-classical target organs for sex steroids. Presence of androgen and estrogen receptors in the neoplastic and non-neoplastic thyroid glands of mammalian species is well documented. The aim of the present study is to elucidate the changes in serum and thyroidal sex steroids, and their receptors in the thyroid gland of rats from immature to adult age under gonadectomized (GDX) and sex steroids replaced conditions. Normal Wistar male and female rats from immature to adult age (day 21, 30, 45, 60 and 160 post-partum (pp)) were used in the present study. One group (I) of rats was GDX at an early age (day 10 pp) and the other group (II) at the adult age (day 120 pp). Group I rats were sacrificed at different experimental periods such as 21, 30, 45 and 60 days pp, and group II rats were sacrificed at day 160 pp. Another group of GDX rats from group I and II were replaced with physiological doses of testosterone or estradiol. Serum and thyroidal concentrations of sex steroids were estimated by RIA method and the concentrations of receptors by radioreceptor assay. Gonadectomy significantly decreased serum and thyroidal testosterone and estradiol and concentrations of androgen receptor (AR) and estrogen receptor (ER) in the thyroid. Replacement of sex steroids to GDX rats restored the normal level of sex steroids, AR and ER. Therefore, it is suggested from the present study that (i). sex steroids up-regulate their own receptors in the thyroid, (ii). sex steroids may influence thyroid growth and the proliferation of thyrocytes by modulating their receptor concentrations in the thyroid.

Impact of foetal-onset hypothyroidism on the epididymis of mature rats.

It is well established that congenital hypothyroidism leads to male infertility. However, there is a dearth of information on foetal-onset hypothyroidism-induced changes in the epididymis. With regard to transient hypothyroidism, the existing literature deals mainly with the testis. However, it is not known whether there is any corresponding alteration in epididymal morphology and physiology under such a condition. The present study is therefore aimed at understanding the impact of persistent and transient hypothyroidism on the concentration of epididymal sex steroids, as they play a vital role in maintaining the normal structure and function of the epididymis. Normal rats of 90 days of age served as controls (Group I). Hypothyroidism was induced by using pregnant/lactating mothers and post-weaning rats to 0.05% (w/v) methimazole (MMI) in the drinking water. Group II were subjected to persistent hypothyroidism from day 9 of post-coitum (pc) to 90 days. Group III rats were subjected to transient hypothyroidism from day 9 day pc to day 1 post-partum (pp), 21 pp or 35 pp (IIIa, b and c, respectively) and group IV rats were given simultaneous T3 supplementation (3 microg/100 g body wt./day i.m.) with MMI from day 9 pc to day 1 pp; 21 pp and 35 pp (Group IVa, b and c). Animals from all groups were killed on day 90 pp. Serum thyroid stimulating hormone (TSH) and thyroid hormones confirmed euthyroidism in group I, IIIa, b and c and IVa, b and c rats and hypothyroidism in group II rats. Caput and cauda epididymal concentration of testosterone, dihydrotestosterone (DHT), estradiol (E2) and androgen binding protein (ABP) markedly decreased in group II rats. While the concentration of testosterone, E2 and ABP increased in group III rats, that of DHT remained unaltered. However, group IV rats maintained normal concentration of the sex steroid and ABP. The activity of 5-alpha-reductase in the epididymis of all the groups followed the same trend as that of the concentration of epididymal DHT. From the present data it is evident that persistent hypothyroidism diminishes the bioavailability of androgens and oestrogens, while transient hypothyroidism enhances the same, indicating the importance of euthyroidism during foetal and neonatal period towards the maintenance of optimal hormonal status in the epididymis required for its maturation.

Testosterone and estradiol differentially regulate TSH-induced thyrocyte proliferation in immature and adult rats.

Though sex steroids are found to influence thyroid pathogenesis in human and in animals, their role in normal thyroid growth and thyrocyte proliferation is not yet understood fully. The present study is addressed to know the effect of testosterone and estradiol on the basal and TSH-induced thyrocyte proliferation in immature and adult rats in vitro. The male and female Wistar rats were gonadectomized (GDX) and one group of GDX rats were supplemented with either testosterone or estradiol. After the experimental period, the rats were sacrificed by decapitation and thyroid glands were removed, washed in Hank's Balanced Salt Solution (HBSS), pH 7.4 and digested with the enzyme mixture containing 0.08% collagenase and 0.12% dispase in HBSS. The isolated follicles were washed thrice with Dulbecco's modified Eagle's medium (DMEM) containing 0.5% fetal bovine serum (FBS), and were cultured in Falcon's tissue culture flasks containing 5 ml DMEM with FBS (5%) transferrin (5 microg/ml), hydrocortisone (10(-8) M), somatostatin (10 microg/ml), insulin (10 microg/ml) and glycyl-L-histidyl-L-lysine acetate (10 microg/ml). The cells (2.5 x 10(4)) were exposed to various exponential doses of TSH or testosterone (6.25-800 ng/ml) or estradiol (6.25-800 pg/ml). It is suggested from the present study that both TSH and sex steroids enhance thyrocyte proliferation. The mitogenic effect of TSH is greater than that of sex steroids. Sex steroids modulate TSH-induced cell proliferation in a gender-specific manner.

Developmental profiles of TSH, sex steroids, and their receptors in the thyroid and their relevance to thyroid growth in immature rats.

Sex steroids are reported to influence thyroid pathogenesis in human and experimental animals. However, there is no report on this phenomenon during the early developmental period. The mitotic activity of thyrocytes in rats reaches its peak by day 10 postpartum. Thyrocytes actively proliferate in immature rats during the first three postnatal weeks, during which the pre-pubertal rise in serum titers of testosterone and estradiol has been recorded. The aim of the present study was to analyze whether there is a physiological relevance between thyroid growth and sex steroids during the postnatal period. Serum and thyroid tissue hormones (TSH, testosterone, and estradiol) were assayed by liquid phase RIA, and receptors for these hormones were also quantified. The peak rate of thyrocyte proliferation was observed during the second postnatal week in rats. Since the concentrations of sex steroids and their receptors also reached a peak around this period, it is suggested that elevated sex steroids and their receptors in the thyroid might enhance thyrocyte proliferation. A positive correlation between thyroid growth indices and sex steroids and their receptors further strengthens this suggestion. This is a preliminary study, and further experimental study may strengthen this proposal. This is the first report to show the availability of sex steroids and their receptors in the thyroid glands of immature rats under normal conditions.

Testosterone and estradiol have specific differential modulatory effect on the proliferation of human thyroid papillary and follicular carcinoma cell lines independent of TSH action.

Differential effects of testosterone and estradiol on the proliferation of human thyroid papillary (NPA-87-1) and follicular (WRO-82-1) carcinoma cell lines were assessed by [(3)H]-thymidine incorporation and the cell number. Cells (2.5 x 10(5)) plated in 24-well culture plates in 400 microL RPMI-1640 medium/well, under 5% CO(2) and 95= air, at 37 degrees C were exposed to exponential concentrations of human thyroid-stimulating hormone (hTSH) (1.25-640 ng/mL), testosterone (1.25-640 ng/mL), or estradiol (1.25-640 pg/mL) for 24 h. Testosterone and estradiol increased the proliferation of NPA cell line in a dose-dependent manner; flutamide (an anti-androgen) and tamoxifen (an anti-estrogen) (10(-8), 10(-7), 10(-6), and 10(-5) mol/L) effectively inhibited the testosterone and estradiol-induced cell proliferation, respectively. While flutamide inhibited the stimulatory effect of testosterone on the WRO cell line, tamoxifen augmented the inhibitory effect of estradiol. TSH did not have any effect on the proliferation of NPA or WRO cell lines, and testosterone-estradiol had no impact on TSH binding to these cells. N-ethylmalemide (5alpha-reductase inhibitor) (10(-8)-10(-5) mol/L) did not modulate basal and testosterone-induced cell proliferation, indicating the direct effect of testosterone without getting converted into dihydrotestosterone (DHT). Both the cell lines tested positive for androgen and estrogen receptors and were up-regulated by the respective ligands. It is concluded that testosterone and estradiol modify the proliferation of thyroid cancer cells through homologous up-regulation of their own receptors, which is independent of TSH, and their effects may vary according to the cell type.

Testosterone and estradiol modulate TSH-binding in the thyrocytes of Wistar rats: influence of age and sex.

Age and sex are important factors that influence thyroid pathophysiology. Though sex steroids are known to enhance thyrotropin (TSH) mRNA expression and incidence of thyroid tumours, there is no report on their effects on TSH action under normal physiological conditions. In the present study, the effects of testosterone (T) and estradiol (E2) on thyroidal TSH-receptor (TSH-R) concentration, and TSH-binding to thyrocytes (in vitro) were elucidated in immature and mature Wistar rats. Immature (10 days old) and adult (120 days old) rats of either sex were gonadectomized (GDX) and one group of GDX rats was treated with physiological doses of T and another with E2. Immature GDX rats were supplemented with the steroids for 10 days and adults were supplemented with the steroids for 30 days. While supplementation of steroids to immature rats was begun immediately after surgery, for adult rats it was started 10 days after gonadectomy. The rats were killed at the end of the experimental period. Gonadectomy significantly decreased serum TSH, and TSH-R concentration under in vivo condition and [125I]-TSH binding to thyrocytes under in vitro conditions. Supplementation of T to male and E2 to female GDX rats restored normality of the parameters. Thyrocytes of immature male rats challenged with linearly increasing doses of TSH or T (6.25-800 ng/ml) showed a dose-dependent increase in TSH-binding. However, thyrocytes of immature female rats challenged with T showed a gender-specific response. While there was a linear increase in TSH-binding in thyrocytes of males, a biphasic response was evident in thyrocytes of females. In the case of thyrocytes from adult rats, T induced a dose-dependent change in TSH-binding in males, which reached the peak in response to 12.5 ng T, and diminished thereafter. In contrast, E2 was inhibitory to TSH-binding to thyrocytes of adult male rats. On the other hand, E2 showed a clear gender-specific stimulation of TSH-binding in thyrocytes of females and an inhibition of the same in males. TSH and sex steroids upregulated TSH receptors in immature rats, whereas the effect was biphasic in adult rat thyrocytes. It is concluded from the present study that sex steroids modulate TSH-binding in rat thyrocytes, which may vary according to the age and sex of the animals.

Progesterone induced modulations of serum hormonal profiles in adult male and female rats.

The impact of progesterone on serum hormonal profiles in the presence and absence of gonads was studied in adult male and female albino rats. Progesterone was administered intramuscularly for 30 days at a dose of 1 mg/100g body weight/day. Serum testosterone, estradiol and prolactin titres decreased in male and female rats with intact gonads given progesterone. While the levels of both luteinizing hormone (LH) and follicle stimulating hormone (FSH) decreased in male rats with intact gonads, only FSH decreased in female rats. The inhibitory effect of progesterone on serum estradiol, LH, FSH and prolactin persisted even after gonadectomy in male rats. This persistent inhibitory effect of progesterone was also seen on serum testosterone, FSH and prolactin levels of female rats. Ovariectomy modified progesterone action on LH, as is evident from the decreased levels of LH observed only in ovariectomized rats given progesterone. While progesterone had no effect on serum T3 and T4 in male rats, gonadectomy altered the levels of T3 and T4 in male and female rats. Progesterone increased the levels of T3 and decreased the levels of T4 in ovariectomized rats. Growth hormone (GH) and thyroid stimulating hormone (TSH) levels seem to be resistant to changes in progesterone titre, irrespective of the sex and gonadal status. The present data suggest the existence of a sex specific effect of progesterone on gonadotrophins. The data on T3, T4 and TSH reveals that progesterone has no effect on the pituitary thyroid axis in the presence of gonads.

Testosterone and estradiol differentially regulate thyroid growth in Wistar rats from immature to adult age.

Experimental and clinical data from cancerous thyroid tissue suggest gender as one of the major factors influencing thyroid growth. However, there is not much information on the effect of sex steroids on the normal development and growth of the thyroid. The aim of the present study was to examine the effect of sex steroids on thyroid growth, serum TSH and TSH receptors in the thyroid, at various stages of sexual maturation. Normal Wistar male and female rats from immature to adult age (day 21, 30, 45, 60 and 160 post partum (PP)) were used in the present study. One group of rats was gonadectomized (GDX) (Group II); another 2 groups of GDX rats (Groups III and IV) were treated with replacement doses (i.e. physiological amounts) of either testosterone or estradiol. Thyroid growth indices (thyroid weight, concentration of DNA, mitotic index and numerical density of thyrocytes), serum TSH and concentration of TSH receptors in the thyroid were assessed. It is concluded from the present study that (i) sex steroids influence thyroid growth by interfering with the secretion of TSH and regulating its receptor number in the thyroid (ii) while testosterone facilitates the mitogenic activity of the thyroid gland of rats irrespective of sex and age, estradiol plays a gender-specific stimulatory role on thyroid growth.

Altered corticosterone status impairs steroidogenesis in the granulosa and thecal cells of Wistar rats.

Hypo- and hyper-corticosteronisms have adverse effects on ovarian endocrine and exocrine functions. In the present study, the mechanism by which corticosterone in excess or insufficiency impairs steroidogenesis in granulosa and thecal cells was investigated in adult albino Wistar rats. In this regard, rats were administered with corticosterone-21-acetate (2 mg/100 g b.wt., s.c., twice daily) or metyrapone (11beta-hydroxylase blocker) (10 mg/100 g b.wt., s.c., twice daily) for 15 days and a group of corticosterone/metyrapone treated rats was withdrawn of treatment and maintained for another 15 days and killed during their diestrus phase. Administration of corticosterone-21-acetate while elevated the serum corticosterone levels, metyrapone diminished the same. Administration of metyrapone reduced the serum levels of LH and estradiol; corticosterone reduced the levels of FSH in addition to LH and estradiol. In vitro production of progesterone and estradiol by the granulosa and thecal cells was decreased due to altered corticosterone status. Whereas administration of corticosterone significantly reduced the activity of 3beta-hydroxysteroid dehydrogenases (3beta-HSD) in granulosa and thecal cells, it reduced the activity of 17beta-HSD only in granulosa cells. While metyrapone treatment reduced the activity of 17beta-HSD in granulosa as well as thecal cells, it reduced the activity of 3beta-HSD only in thecal cells. The findings of the present investigation clearly demonstrate that excess or insufficiency in corticosterone affects steroidogenic process in the ovary. This is achieved by decreasing the levels of gonadotropins probably by their diminished synthesis and secretion and by interfering at the signal transduction process of these gonadotropins.

Chronic corticosterone treatment impairs Leydig cell 11beta-hydroxysteroid dehydrogenase activity and LH-stimulated testosterone production.

The effects of excess corticosterone on luteinizing hormone (LH)-stimulated Leydig cell testosterone production and activity of 11beta-HSD was studied. Adult male rats (200-250 g body weight) were treated with corticosterone-21-acetate (2 mg/100 g body weight, i.m., twice daily) for 15 days. Another set of rats was treated with corticosterone (dose as above) plus LH (ovine LH 100 microg/kg body weight, s.c., daily) for 15 days. Corticosterone administration significantly increased serum and testicular interstitial fluid (TIF) corticosterone but decreased testosterone levels. Administration of LH with corticosterone partially prevented the decrease in serum and TIF testosterone. The oxidative activity of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) was significantly decreased in Leydig cells of rats treated with corticosterone alone and in combination with LH. The direct effect of corticosterone on Leydig cell steroidogenic potency was also studied in vitro. Addition of corticosterone to Leydig cell culture showed a dose dependent effect on LH-stimulated testosterone production. Corticosterone at 50 and 100 ng/ml did not alter LH-stimulated testosterone production, but at high doses (200-400 ng/ml), decreased basal and LH-stimulated testosterone production. Basal and LH-stimulated cAMP production was not altered by corticosterone in vitro. It is concluded from the present study that elevated levels of corticosterone decreased the oxidative activity of 11beta-HSD and thus resulting in impaired Leydig cell steroidogenesis and the inhibitory effects of corticosterone on testosterone production appear to be mediated through inhibition of LH signal transduction at post-cAMP level.

Chronic administration of corticosterone impairs LH signal transduction and steroidogenesis in rat Leydig cells.

The mechanism involved in the inhibitory actions of chronic corticosterone treatment on Leydig cell steroidogenesis was studied in adult Wistar rats. Rats were treated with corticosterone-21-acetate (2 mg/100 g body weight, i.m., twice daily) for 15 days and another set of rats was treated with corticosterone plus ovine luteinizing hormone (oLH) (100 microg/kg body weight, s.c., daily) for 15 days. Chronic treatment with corticosterone increased serum corticosterone but decreased serum LH, testosterone, estradiol and testicular interstitial fluid (TIF) testosterone and estradiol concentrations. Administration of LH with corticosterone partially prevented the decrease in serum and TIF testosterone and estradiol. Leydig cell LH receptor number, basal and LH-stimulated cAMP production were diminished by corticosterone treatment which remained at control level in the corticosterone plus LH treated rats. Activities of steroidogenic enzymes, 3beta- and 17beta-hydroxysteroid dehydrogenase (3beta-HSD and 17beta-HSD) were significantly decreased in corticosterone treated rats. LH plus corticosterone treatment did not affect 3beta-HSD activity but decreased 17beta-HSD activity, indicating a direct inhibitory effect of excess corticosterone on Leydig cell testosterone synthesis. The indirect effect of corticosterone, thus, assume to be mediated through lower LH which regulates the activity of 3beta-HSD. Basal, LH and cAMP-stimulated testosterone production by Leydig cells of corticosterone and corticosterone plus LH treated rats were decreased compared to control suggesting the deleterious effect of excess corticosterone on LH signal transduction and thus steroidogenesis.

Influence of streptozotocin-induced diabetes and insulin treatment on the pituitary-testicular axis during sexual maturation in rats.

Effects of streptozotocin (STZ)-diabetes and insulin treatment on the functioning of pituitary-testicular axis during sexual maturation was studied. Prepubertal (30 days old) and pubertal (50 days old) male Wistar rats were made diabetic by a single injection of STZ. A group of diabetic rats was given insulin (3U/100 g b.wt./day in 2 equally divided doses), 3 days after STZ treatment. Prepubertal and pubertal rats of all groups were killed on postnatal days 51 and 71, respectively. STZ-diabetes caused marked reduction in serum LH, FSH, prolactin, testosterone and testicular interstitial fluid testosterone as well as the activities of Leydig cellular steroidogenic enzymes (3beta-and 17beta-hydroxysteroid dehydrogenases). Insulin treatment to diabetic rats maintained these changes at control range except FSH and prolactin in prepubertal rats. The results indicate that (i) diabetes-induced steroidogenic lesions in Leydig cells represent a direct consequence of dysfunctioning of pituitary-testicular axis, (ii) the adverse effects of diabetes on pituitary-testicular functions are influenced by age of its induction and (iii) optimum insulin level is essential for the acquisition of Leydig cellular steroidogenic efficacy during sexual development.

Impact of oestradiol and progesterone on the glycosaminoglycans and their depolymerizing enzymes of the rat mammary gland.

The influence of oestradiol and progesterone either singly or in combination with each other on the levels of hyaluronic acid, heparan sulphate, chondroitin sulphate, and on the activity of hyaluronidase and chondroitinase were investigated in the mammary gland of ovary-intact and in ovariectomized rats, administered oestradiol and/or progesterone. Administration of oestradiol to ovary-intact rats elevated the levels of hyaluronic acid and decreased the levels of heparan sulphate while progesterone, when administered alone, could elevate only chondroitin sulphate when compared with controls. The steroids when administered in combination, however, increased the levels of all glycosaminoglycans studied. Ovariectomized animals showed a decrease in heparan sulphate alone as compared with controls while administration of oestradiol to these rats elevated the levels of both heparan sulphate and chondroitin sulphate as compared with ovariectomized rats. Also the administration of progesterone either singly or in combination increased the levels of heparan sulphate and also decreased the levels of hyaluronic acid with no impact on the levels of chondoritin sulphate. In ovary-intact animals administration of oestradiol alone had no effect on hyaluronidase activity. Progesterone either singly or in combination with oestradiol reduced the activity of hyaluronidase, whereas it had no influence on the activity of chondroitinase. The activities of both the enzymes were decreased in ovariectomized animals and administration of oestradiol and/or progesterone to the above groups resulted in an increase. This study demonstrates that oestradiol anzd progesterone play an important role in modulating glycosaminoglycans and their depolymerizing enzymes, thereby influencing the activities of the mammary epithelium.

Streptozotocin-diabetes impairs prolactin binding to Leydig cells in prepubertal and pubertal rats.

Prolactin (PRL) binding to Leydig cells in prepubertal and pubertal streptozotocin (STZ)-diabetic and insulin-treated rats was studied. Prepubertal (30-day-old) and pubertal (50-day-old) rats were made diabetic by single injection of STZ (120 and 100 mg/kg b.wt, respectively). After 3 days of STZ administration, a group of rats was given insulin injections subcutaneously (3 U/100 g b.wt/day in 2 equally divided doses). Animals of prepubertal and pubertal groups were killed on postnatal days 51 and 71, respectively. Age-dependent increase in serum testosterone, PRL levels and PRL receptors on Leydig cells were prevented by STZ-diabetes. Insulin administration partly or completely prevented these changes. These results suggest that steroidogenic defects in Leydig cells of prepubertal and pubertal diabetic rats may be associated with decrease in serum PRL levels and its receptors on Leydig cells. Insulin probably has a role in the maintenance of PRL receptor numbers on Leydig cells during pubertal maturation.

Differential response of rat skeletal muscle glycogen metabolism to testosterone and estradiol.

Although reports on sex steroids have implicated them as promoting protein synthesis and also providing extra strength to the skeletal muscle, it remains unclear whether sex steroids affect glycogen metabolism to provide energy for skeletal muscle functions, since glycogen metabolism is one of the pathways that provides energy for the skeletal muscle contraction and relaxation cycle. The purpose of the current study was to show that testosterone and estradiol act differentially on skeletal muscles from different regions, differentially with reference to glycogen metabolism. To study this hypothesis, healthy mature male Wistar rats (90-120 days of age, weighing about 180-200 g) were castrated (a bilateral orchidectomy was performed to test the significance of skeletal muscle glycogen metabolism in the absence of testosterone). One group of castrated rats was supplemented with testosterone (100 microg/100 g body weight, i.m., for 30 days from day 31 postcastration onwards). To test whether estradiol has any effect on male skeletal muscle glycogen metabolism 17beta-estradiol (5 microg/100 g body weight, i.m., for 30 days from day 31 postcastration onwards) was administered to orchidectomized rats. To test whether these sex steroids have any differential effect on skeletal muscles from different regions, skeletal muscles from the temporal region (temporalis), muscle of mastication (masseter), forearm muscle (triceps and biceps), thigh muscle (vastus lateralis and gracilis), and calf muscle (gastrocnemius and soleus) were considered. Castration enhanced blood glucose levels and decreased glycogen stores in skeletal muscle from head, jaw, forearm, thigh, and leg regions. This was accompanied by diminished activity of glycogen synthetase and enhanced activity of muscle phosphorylase. Following testosterone supplementation to castrated rats, a normal pattern of all these parameters was maintained. Estradiol administration to castrated rats did not bring about any significant alteration in any of the parameters. The data obtained suggest a stimulatory effect of testosterone on skeletal muscle glycogenesis and an inhibitory effect on glycogenolysis. Estradiol did not play any significant role in the skeletal muscle glycogen metabolism of male rats.