Regulation of estrogen sulfotransferase expression in Leydig cells by cyclic adenosine 3',5'-monophosphate and androgen

Estrogen sulfotransferase (EST) catalyzes the specific sulfonation and inactivation of estrogens. A common site for EST expression in mammalian species is the testicular Leydig cells. In previous in vivo studies, we have shown that testicular expression of EST is under the regulation of LH. Thus, EST expression in mouse Leydig cells was abolished by hypophysectomy, but could be restored by hCG injection. In this study, we have evaluated the downstream mechanisms by which LH exerts its regulatory effect on EST. Primary mouse Leydig cells were isolated and purified by collagenase digestion and Percoll density gradient centrifugation. They were cultured in serum-free medium at 32 C and treated with various agents for 24 or 48 h, and levels of EST messenger RNA and enzyme activity were determined. Consistent with the in vivo data suggesting an essential role of LH in regulating EST expression, treatment of primary mouse Leydig cells in vitro with 100 microM 8-bromo-dibutyryl cAMP [(Bu)2cAMP] increased EST expression 3- to 5-fold. The effect of (Bu)2cAMP was attenuated by the steroidogenesis inhibitor aminoglutethimide and was mimicked by the potent androgen 5alpha-dihydrotestosterone (5-DHT). The activity of 5-DHT in stimulating EST expression was blocked by the androgen receptor antagonist, hydroxyflutamide. These data suggested the involvement of androgen in (Bu)2cAMP-induced EST expression. Further evidence came from the study with interleukin-1beta, another agent known to suppress Leydig cell steroidogenesis by down-regulating P450c17 gene expression. Treatment of Leydig cells with 0.2 ng/ml interleukin-1beta inhibited (Bu)2cAMP-induced EST expression, which was overcome by the addition of 5-DHT. Finally, in the testis-feminized mouse (Tfm) in which the androgen receptor is nonfunctional due to a frameshift mutation, testicular EST expression is completely absent, whereas messenger RNAs of steroidogenic enzymes such as P450c17 and 3beta-hydroxysteroid dehydrogenase are relatively abundant. We conclude that, by acting as an autocrine or paracrine factor, androgen plays an essential role in the regulation of estrogen sulfotransferase expression in Leydig cell by LH and cAMP.     

Hepatic estrogen and androgen receptors and binding proteins in streptozotocin-diabetic male Wistar rats

Summary We have previously shown that there are decreases in the sex differences seen in certain hepatic drug and steroid metabolising enzymes in rats with early (4 day) streptozotocin-induced diabetes [31]. We postulated that hepatic sex hormone receptors or binding proteins might be involved in modulation of the sex differences noted in metabolism. In the present study, we measured the binding kinetics of the hepatic cytosolic estrogen receptor and androgen receptor, along with the high capacity-low affinity estrogen binding protein. At 4 or 10 days post-streptozotocin (60 mg/kg intravenously), there was no change in the maximum binding capacity of the estrogen receptor, nor in the hormone affinity of any of the three proteins. However, the binding capacity of the androgen receptor and estrogen binding protein in the diabetic animals was decreased to less than half of control levels. This effect could not be reversed by hormone replacement with any of the following regimens: protamine zinc insulin, 10 U/kg subcutaneously once a day; Toronto insulin, 15 U/kg subcutaneously twice a day; testosterone enanthate, 1 mg/kg s.c. once a day; triiodothyronine, 30 g/kg s.c. daily; ovine growth hormone: 0.02 U/h s.c., 30 g s.c. 7 times daily, 30 g i.v. 4 times daily; or various combinations of these hormones. Stress, such as 4 intravenous injections of saline per day, was noted to decrease the binding capacity of the estrogen binding protein. Therefore, we measured the basal serum corticosterone levels, which were not significantly different from control values in untreated or insulin-treated diabetic rats. In addition, the hepatic cytosolic glucocorticoid receptor capacity was not significantly changed in the diabetic animals. This provides evidence that at 4 days post-streptozotocin, the diabetic state is not so stressful as to result in major alterations in these two parameters.In summary, because insulin is known to restore the sex differences in hepatic drug and steroid metabolism to control levels but does not restore the capacity of the cytosolic androgen receptor or estrogen-binding protein, we conclude that they are not of primary importance in regulation of the metabolic enzymes.     

Differential expression of apolipoprotein E messenger RNA within the rat liver lobule determined by in situ hybridization

Apolipoprotein (Apo) E plays a key role in the metabolism of lipoproteins. It also modulates immunoregulation, cell growth and differentiation and the response to nerve injury. The liver is a major site of ApoE synthesis. Most of the circulating ApoE is thought to be of hepatic origin with most synthesized in hepatocytes. We showed that total liver ApoE messenger RNA (mRNA) levels were greater in normal adult female rats than in male and that gender-specific patterns of liver ApoE mRNA expression were present by in situ hybridization. In the male liver, the signal was strongest in the portal area, decreasing toward the central vein with the weakest signal in pericentral hepatocytes, resulting in a hepatic lobular gradient of expression. In female liver, a strong periportal signal also was observed that decreased in Zone 2, similar to that in males, but which then increased in pericentral hepatocytes resulting in a bowl-like distribution in marked contrast with that of the male. The results suggest that ApoE mRNA level is regulated differentially in hepatocytes within the liver plate and that the regulation is gender-dependent. Further, the results suggest that in males, hepatocytes in the portal area are the major contributors of ApoE to the plasma and/or sinusoidal pool, whereas in females, both portal and central area hepatocytes play an equal role.     

Impaired androgen 16 alpha-hydroxylation in hepatic microsomes from carbon tetrachloride-cirrhotic male rats

Hepatic cirrhosis produced by repeated inhalation of carbon tetrachloride is associated with reduced levels of microsomal cytochrome P450. In this study the C19-steroids androstenedione and testosterone were used as specific probes of the functional activity of several forms of cytochrome P450 in microsomal fractions from control and cirrhotic rat liver. The principal finding, that androstenedione 16 alpha-hydroxylation and testosterone 2 alpha-, 16 alpha-, and 17 alpha-hydroxylation were reduced to 14%-38% of control activity, strongly suggests that levels of the male sexually differentiated cytochrome P450 (P(450)16 alpha) are decreased in hepatic cirrhosis. The activity of other cytochrome P450-mediated C19-steroid hydroxylases, with the exception of androstenedione 6 beta-hydroxylase, appeared essentially unaltered in microsomes from cirrhotic rats. Cirrhosis induced by carbon tetrachloride was also associated with greatly decreased activity of the microsomal cytochrome P450-independent 17 beta-oxidoreductase, an enzyme that catalyzes the conversion of androstenedione to testosterone. Consequently, and in view of the impaired activity of cytochrome P450-mediated testosterone 17 alpha-hydroxylation, the capacity of cirrhotic microsomes to catalyze the interconversion of androstenedione and testosterone was much lower than that of control microsomes. The present data confirm and extend earlier observations that selective impairment of drug oxidation pathways occurs in hepatic cirrhosis. These changes are unrelated to the acute toxicity produced by carbon tetrachloride exposure. The available evidence supports the assertion that specific forms of cytochrome P450 are subject to altered regulation in cirrhosis.     

Polymorphisms in androgen and estrogen receptor genes: effects on male aging

Besides lifestyle and environmental factors, the life-long exposure to the endocrine milieu of gonadal steroids is a determining factor to gender specific features of aging. In contrast to women, men do not experience a sudden cessation of gonadal function comparable to menopause. However, cross-sectional and longitudinal population studies demonstrate that the hormones with anabolic actions (e.g. testosterone [T], growth hormone, insulin-like growth factor [IGF]-1, dehydroepiandrosterone) do decrease progressively with aging in healthy men, and chronic systemic illnesses accelerate this process. In addition, estrogen has recently been established to be essential for normal physiology of the male. The slow progressive decline of the hypothalamic-pituitary-gonadal (HPG) function is thought to be responsible for many common signs and symptoms of aging men, such as general weakness, sexual dysfunction, and increased fat mass. There is a large inter-individual variation in sex hormone levels cross-sectionally within given age groups as well as longitudinally with aging. A contributing factor to this variability are the numerous functionally significant polymorphisms that have been detected in the receptors for androgen and estrogen. In this review, we summarize the recent information on some common polymorphisms in androgen and estrogen receptor genes and their effect on gender specific and aging-related symptoms and diseases of men.     

雄激素对老龄大鼠血管平滑肌组织雄、雌激素受体基因表达的影响

目的　探讨不同剂量的庚酸睾酮 (TE)对老龄雄性大鼠血管平滑肌组织中雄激素受体 (AR)及雌激素受体 β(ER β)基因表达的影响。方法　 2 1月龄的老龄雄性Sprague Dawley纯系大鼠 4 0只随机分为A组 (老龄对照组 )、B组 (老龄低剂量组 ,肌注每次TE 2 .5mg/kg ,1次 /周× 16周 )、C组 (老龄中剂量组 ,肌注每次TE 5 .0mg/kg ,1次 /周× 16周 )、D组 (老龄高剂量组 ,肌注每次TE 10 .0mg/kg ,1次 /周× 16周 )。Western印迹法检测血管平滑肌组织中AR及ER β基因表达情况。结果　给予低、中、高 3种剂量的TE作用后血管平滑肌组织AR蛋白条带吸光度分别为 (99.5 0± 2 1.74 ) ,(12 5 .38± 2 8.6 8) ,(10 1.98± 15 .4 2 ) (对照组为 10 0 ) ;ER β蛋白条带吸光度分别为(92 .34± 18.6 8) ,(47.72± 18.12 ) ,(82 .13± 2 3.5 0 ) (对照组为 10 0 )。结论　中剂量的TE可促进AR基因的表达量 ,而中、高剂量的TE则抑制ER β基因的表达量。     

Gender-specific expression and mechanism of regulation of estrogen sulfotransferase in adipose tissues of the mouse

Although primarily regarded as a sex steroid, estrogen plays an important role in many other physiological processes including adipose development and disposition. Estrogen sulfotransferase (EST) regulates estrogen activity by catalyzing the sulfoconjugation and inactivation of estrogens. In the present study, we report the gender-specific expression of EST in adipose tissues of the mouse and describe contrasting mechanisms of EST regulation in the fat and liver. EST is expressed in the white adipose tissues of the male but not female mouse. Within the various fat depots of male mice, it is most abundantly expressed in the epididymal fat pad, with variable levels in other white fats and no expression in the brown fat. Fractionation of epididymal fat cells showed EST to be predominantly associated with stromal vascular cells (preadipocyte). EST expression in male mouse adipose tissues is dependent on testosterone as castration ablated, and administration of exogenous testosterone restored, EST expression. Furthermore, testosterone treatment induced abnormal EST expression in the parametrial fat of female mice. EST induction by testosterone in female mice is tissue specific because testosterone treatment had no effect on liver EST expression. Conversely, the liver X receptor agonist TO-901317 induced EST expression in female mouse liver but not in their adipose tissues. Finally, we demonstrate that male EST knockout mice developed increased epididymal fat accumulation with enlarged adipocyte size. We conclude that EST is expressed in adipose tissues in a sexually dimorphic manner, is regulated by testosterone, and plays a physiological role in regulating adipose tissue accumulation in male mice.     

Prolactin receptor in rat liver: sex difference in estrogenic stimulation and imprinting of the responsiveness to estrogen by neonatal androgen in male rats

Rat hepatic prolactin receptor is regulated by sex steroids. A high level of the receptor was found in female rats but the level was nearly undetectable in males. Gonadectomy reduced the receptor level in females but increased the level in males. Administration of estradiol benzoate (0.05 μmoles/kg on alternate days subcutaneously for 9 days) to adult gonadectomized females increased the receptor level by 473% whereas the same treatment in adult gonadectomized males produced a more modest 276% increase. This sexually dimorphic pattern in the responsiveness to estrogen stimulation in adult rats appeared to be determined neonatally. Neonatal gonadectomy of male rats changed the hepatic response system to a more female pattern in adulthood. Replacement of testosterone (1.45 μmoles at days 1 and 3 after birth) to these neonatally gonadectomized male rats restored the male pattern. Diethylstilbestrol replacement (1.45μmoles at days 1 and 3 after birth) to the neonatally gonadectomized male rats showed the same effect as neonatally administered testosterone. Scatchard analysis revealed that the observed changes in binding are related to changes in binding capacity but not affinity. Desaturation by 4 M MgCl₂ indicated that the amount of endogenously bound hormone was negligible in our membrane preparations.     

Behavioral action of estrogen in the male dove brain: area differences in codistribution of aromatase activity and estrogen receptors are steroid-dependent.

Brain aromatization of androgen to estrogen (E) and presence of estrogen-receptor (ER) containing cells (ERC) are required for the control of E-dependent neural events under-lying male sexual behavior. We examined whether (a) numbers of ERC and steroid-inducible aromatase activity are codistributed and directly correlated in the same brain areas of individual sexually active male doves and whether, (b) distribution of ERC is altered by a change in E formation in preoptic areas known to be involved in control of male behavior. To allow spatial correlation between ERC and aromatase activity, a new approach was used that combined in vitro measurement of aromatase activity (stereospecific formation of 3H2O from [1 beta-3H]-testosterone) in microdissected brain areas of one side of the brain and immunocytochemical localization of ERC (ER antibody H222Spy) in homologous contralateral areas of the same coronal brain section. The relationship between ERC and aromatase activity differs according to brain area in sexually active males: (a) large populations of ERC in preoptic areas, notably in nucleus preopticus medialis (6.5 +/- 0.8 ERC/5,000 microns2) and nucleus preopticus medialis, pars medianis (9.5 +/- 1 ERC/5,000 microns2) are codistributed with high steroid-dependent aromatase activity (greater than 100 fmol/mg tissue); (b) areas containing the nucleus interstitialis and ventromedial hypothalamic nuclei also have relatively high aromatase activity, but lower ERC density than POA; (c) the anterior hypothalamic nuclei have few ERC, but steroid-regulated aromatase activity; (d) the infundibular area contains elevated ERC and little steroid-inducible aromatase activity; (e) area basalis and neostriatum contain few or no ERC and no inducible aromatase activity. Castration of sexually active doves reduces aromatase activity in preoptic and posterior hypothalamic areas (by greater than 75%) to basal levels, but does not affect the distribution or number of ERC in brain areas containing steroid-regulated aromatase activity, notably in the preoptic area. The results show that steroid regulation of aromatase occurs in brain loci with high numbers of ERC. We suggest that steroid-inducible aromatase occurs in brain loci with high numbers of ERC. We suggest that steroid-inducible aromatase activity and ERC are codistributed in areas controlling male sexual behavior; thus the formation and action of E may occur in the same area. Regulation of the aromatase activity and supply of E, but not of number of cells containing ER, is one mechanism which accounts for changes in action of testosterone on estrogen target sites in the male brain.     

石蜡包埋子宫内膜样腺癌中雌激素硫酸转移酶和甾体硫酸酯酶基因的表达

目的 探讨石蜡包埋子宫内膜样腺癌组织中雌激素硫酸转移酶(estrogen sulfotransferase,EST)和甾体硫酸酯酶(steroid sulfatase,STS)的RNA表达. 方法 使用罗氏产品从30例石蜡包埋子宫内膜组织(对照组和患病组各15例)中提取EST、STS的RNA. 结果 对照组RNA的表达EST为0.25±0.03,STS为0.08±0.02,STS与EST比值为0.11±0.08;患病组RNA的表达:EST为0.06±0.02,STS为0.24±0.92,STS与EST比值4.40±0.64,患病组与对照组比较,差异有统计学意义(t分别为-8.223、7.345和11.591,均P<0.05). 结论 (1)石蜡包埋组织是子宫内膜样腺癌基础研究的材料来源;(2)在子宫内膜样腺癌中,EST下降,STS和STS与EST比值升高.     

Effects of estrogen and androgen deprivation on the progression of non-alcoholic steatohepatitis (NASH) in male Sprague–Dawley rats

Aim:  We studied the mechanisms of estrogen/androgen involvement in the induction of NASH by treating Sprague–Dawley (SD) rats fed with a normal or high fat (HF) diet by depriving them of endogenous estrogens/androgens.
Methods:  Male adult SD rats ( n  = 10/group) on normal or HF diets were treated for 75 days either with tamoxifen (Tam) or flutamide (Flu) or Tam + Flu in order to induce NASH. We analyzed histopathologically the liver samples from the treated groups for NASH, checked the serum biochemical and lipid profile markers and finally analyzed the signal pathways underlying the molecular mechanisms for the induction process of NASH.
Results:  Deprivation of endogenous estrogens and/or androgens (Tam or Flu or Tam + Flu) without the HF diet did not induce NASH. Tam or Tam + Flu induced NASH, compared to milder lesions without fibrosis in HF diet and Flu-treated liver. Serum alanine aminotransferase or lipid profile markers further proved the Tam, Flu or Tam + Flu effects on the induction of NASH in conjunction with a HF diet. Tam treatment predominantly downregulated the ERα and FAS and upregulated UCP2 and TNF-α.
Conclusions:  Deprivation of endogenous estrogen/androgens in conjunction with a HF diet may induce NASH where the downregulated ERα and FAS, and upregulated UCP2 and TNF-α could be involved in their molecular pathomechanism pathways. These results could suggest the potential negative roles of estrogenic/androgenic depriving compounds in the induction of NASH, along with obesity.     

Trans-seasonal action of androgen in the control of spring courtship behavior in male red-sided garter snakes.

Gonadal steroids have traditionally been found to have short-term effects on the mating behavior of adult vertebrates, such that increased steroid hormone levels influence behavior over the course of a few days. Long-term effects also have been observed in which embryonic exposure to steroid hormone influences the sexual behavior of adults. The generality of the paradigms that have resulted from this work must be viewed with caution as all of the species studied exhibit a particular reproductive pattern. Here it is shown that in the adult red-sided garter snake, the seasonal androgen peak in the summer has a delayed action (8 months) on the male's readiness to court the next spring following emergence from hibernation. This suggests that the interval between the exposure to and the effects of steroid hormones in adult vertebrates may range from short latencies to long latencies and that the present dichotomy of organizing (permanent) versus activating (transient) effects of steroid hormones may not apply in certain instances.     

Dietary genistein down-regulates androgen and estrogen receptor expression in the rat prostate

The incidence of clinically manifested prostate cancer is higher in the United States and Europe than in Asian countries. One of the major differences in lifestyle between these populations is the diet, with Asians consuming a greater amount of soy. Soy and genistein, the predominant isoflavone found in soy, inhibit prostate tumor development in animal models. The purpose of this study was to investigate the effect of dietary genistein on sex steroid receptor expression in the dorsolateral prostate, on circulating androgens, and the potential for toxicity in the male rat reproductive tract. Male Sprague-Dawley rats were fed 25 and 250 mg genistein/kg diet from conception until day 70 postpartum, or 250 and 1000 mg genistein/kg diet from day 56 to 70 postpartum. Exposure to genistein in the diet, starting at conception, resulted in down-regulated androgen receptor (AR), and estrogen receptors (ER)-alpha and -beta mRNA expression in the dorsolateral prostate in a dose-dependent manner. Also, genistein fed to adult rats for 2 weeks reduced mRNA expression of AR, ER-alpha and ER-beta in the dorsolateral prostate. ER-alpha protein levels were significantly reduced in animals fed 1000 mg genistein/kg diet compared to control animals. There were no significant alterations to male reproductive tract histomorphology or weights. We conclude that dietary genistein down-regulated expression of the AR and ER-alpha and -beta in the rat prostate at concentrations comparable to those found in humans on a soy diet. Down-regulated sex steroid receptor expression may be responsible for the lower incidence of prostate cancer in populations on a diet containing high levels of phytoestrogens.     

Microheterogeneity of pituitary follicle-stimulating hormone in male rats: differential effects of the chronic androgen deprivation induced by castration or androgen blockade.

Testicular androgens are known to influence not only the secretion but also the bioactivity and molecular composition of pituitary FSH. In the present study, we investigated the effects of chronic androgen blockade and castration on the molecular heterogeneity of the gonadotrophin. Groups of male adult rats (five animals per group) received one of the following treatments: vehicle, the non-steroidal anti-androgens casodex (20 mg/kg per day) or flutamide (20 mg/kg per day), or castration. After 8 weeks, the animals were killed and individual pituitary homogenates fractionated by isoelectric focusing (IEF) on sucrose density gradients in the pH range 2.5-8. FSH was measured by radioimmunoassay (RIA) in the individual fractions and by invitro bioassay (Sertoli cell aromatase bioassay) in pools of fractions which were combined according to pH intervals of 0.5 units. Bioactive and immunoreactive FSH were also measured in sera and unfractionated pituitary extracts. Testosterone and inhibin were assayed in sera by RIA. A significant increase in serum immunoreactive and bioactive FSH was demonstrated in flutamide-treated and castrated animals, whereas the pituitary content of bioactive FSH remained unchanged in the four groups. Serum testosterone and inhibin were undetectable in castrated animals and significantly increased in those treated with flutamide. By RIA, the IEF profiles of the flutamide-treated and castrated rats showed a significant reduction of the FSH isoforms with 3.5 < pI < 4, with a significant increase in the isoforms with pI > 4 only in the castrated group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neonatal estrogen exposure induces lobe-specific alterations in adult rat prostate androgen receptor expression.

Brief administration of estrogen to newborn rats results in permanent suppression of prostate growth and reduced prostatic responsiveness to testosterone in adulthood. To determine whether this imprinting may be a result of alterations in androgen receptor (AR) expression, the separate adult prostate lobes of neonatally estrogenized rats were examined for AR concentration and distribution. Sprague-Dawley rat pups were given 25 micrograms estradiol benzoate or oil alone on days 1, 3, and 5 and were killed on day 90. Half of the animals received 2-cm testosterone implants 10 days before death to assess the activational response to androgen. In a separate series, neonatally estrogenized rats were given prepubertal dihydrotestosterone pellets for 3 weeks as well as testosterone implants in adulthood to determine if the observed effects of neonatal estrogen on the adult prostate were an indirect result of androgen deprivation during developmentally critical periods. The ventral, dorsal, and lateral prostate lobes were processed for nuclear AR quantitation by [3H]dihydrotestosterone exchange binding assay and for indirect immunocytochemical localization of AR. Weights and DNA contents of the three prostate lobes were significantly reduced in neonatally estrogenized rats, and this decrease was only partially reversed by prepubertal and/or adult androgen replacement. Histologically, the hypoplastic ventral and dorsal lobes exhibited a relative increase in interacinar stromal tissue, disorganized acini with epithelial hyperplasia, luminal sloughing, and an apparent lack of differentiation. The hypoplastic lateral lobe also showed a relative increase in the stromal fraction; however, the acinar epithelium appeared differentiated, with normal basal/apical orientation and luminal secretions. The AR concentration was significantly reduced in the ventral and dorsal prostates of estrogenized rats, but was unaltered in the lateral lobe. Immunocytochemistry revealed a marked reduction or absence of epithelial AR in ventral and dorsal lobes from estrogenized rats, whereas the lateral lobe epithelial cells expressed AR similarly to controls. The incidence of AR-positive fibroblastic stromal cells increased in lateral prostates from 5% in controls to approximately 25% in estrogenized rats. Neonatally estrogenized rats given testosterone for 10 days in adulthood showed increased levels of AR in the ventral and dorsal lobes compared to nonstimulated rats; however, these levels remained well below control values. Lateral lobe epithelial histology and AR expression appeared relatively unchanged in estrogenized rats given testosterone during adulthood, whereas an increased proportion of stromal cells (approximately 35%) were AR positive. In summary, neonatal estrogen administration permanently altered prostatic growth and produced lobe-specific changes in AR expression in the adult gland.(ABSTRACT TRUNCATED AT 400 WORDS)     

Neonatal estrogen exposure induces lobe-specific alterations in adult rat prostate androgen receptor expression.

Brief administration of estrogen to newborn rats results in permanent suppression of prostate growth and reduced prostatic responsiveness to testosterone in adulthood. To determine whether this imprinting may be a result of alterations in androgen receptor (AR) expression, the separate adult prostate lobes of neonatally estrogenized rats were examined for AR concentration and distribution. Sprague-Dawley rat pups were given 25 micrograms estradiol benzoate or oil alone on days 1, 3, and 5 and were killed on day 90. Half of the animals received 2-cm testosterone implants 10 days before death to assess the activational response to androgen. In a separate series, neonatally estrogenized rats were given prepubertal dihydrotestosterone pellets for 3 weeks as well as testosterone implants in adulthood to determine if the observed effects of neonatal estrogen on the adult prostate were an indirect result of androgen deprivation during developmentally critical periods. The ventral, dorsal, and lateral prostate lobes were processed for nuclear AR quantitation by [3H]dihydrotestosterone exchange binding assay and for indirect immunocytochemical localization of AR. Weights and DNA contents of the three prostate lobes were significantly reduced in neonatally estrogenized rats, and this decrease was only partially reversed by prepubertal and/or adult androgen replacement. Histologically, the hypoplastic ventral and dorsal lobes exhibited a relative increase in interacinar stromal tissue, disorganized acini with epithelial hyperplasia, luminal sloughing, and an apparent lack of differentiation. The hypoplastic lateral lobe also showed a relative increase in the stromal fraction; however, the acinar epithelium appeared differentiated, with normal basal/apical orientation and luminal secretions. The AR concentration was significantly reduced in the ventral and dorsal prostates of estrogenized rats, but was unaltered in the lateral lobe. Immunocytochemistry revealed a marked reduction or absence of epithelial AR in ventral and dorsal lobes from estrogenized rats, whereas the lateral lobe epithelial cells expressed AR similarly to controls. The incidence of AR-positive fibroblastic stromal cells increased in lateral prostates from 5% in controls to approximately 25% in estrogenized rats. Neonatally estrogenized rats given testosterone for 10 days in adulthood showed increased levels of AR in the ventral and dorsal lobes compared to nonstimulated rats; however, these levels remained well below control values. Lateral lobe epithelial histology and AR expression appeared relatively unchanged in estrogenized rats given testosterone during adulthood, whereas an increased proportion of stromal cells (approximately 35%) were AR positive. In summary, neonatal estrogen administration permanently altered prostatic growth and produced lobe-specific changes in AR expression in the adult gland.(ABSTRACT TRUNCATED AT 400 WORDS)     

Targeted disruption of the mouse estrogen sulfotransferase gene reveals a role of estrogen metabolism in intracrine and paracrine estrogen regulation.

Elicitation of biological responses by estrogen in target tissues requires the presence of ER as well as receptor-active ligand in the local microenvironment. Though much attention has been devoted to the study of the receptor in estrogen target tissues, the concept is emerging that tissue estrogen sensitivity may also be regulated by ligand availability through metabolic transformation in situ. Here, we show that targeted disruption, in the mouse, of an estrogen metabolic enzyme, estrogen sulfotransferase (EST), causes structural and functional lesions in the male reproductive system. EST catalyzes the sulfoconjugation and inactivation of estrogen and is expressed abundantly in testicular Leydig cells. Although knockout males were fertile and phenotypically normal initially, they developed age-dependent Leydig cell hypertrophy/hyperplasia and seminiferous tubule damage. Development of these lesions in the testis could be recapitulated by exogenous E2 administration in younger knockout mice, suggesting that they arose in older knockout mice from chronic estrogen stimulation. Older knockout mice were also found to have reduced testis and epididymis weights but increased seminal vesicle/coagulating gland weight because of tissue swelling. Furthermore, total and forward sperm motility of older knockout mice was reduced by 60% and 80%, respectively, and these mice produced smaller litters compared with age-matched wild-type males. These findings establish a role for EST in the male reproductive system and indicate that intracrine and paracrine estrogen activity can be modulated by a ligand transformation enzyme under a physiological setting. Thus, inhibition of estrogen metabolic enzymes by environmental chemicals, as has been demonstrated recently for the human EST, may constitute a novel mechanism of endocrine disruption in vivo.     

Immunofluorescence of phenobarbital inducible cytochrome P-450 in the hepatic lobule of normal and phenobarbital-treated rats

The localization of the form of cytochrome P-450 that is induced by phenobarbital was studied by direct immunofluorescence in the hepatocytes of rats pretreated with phenobarbital in comparison with saline-treated rats. Specific fluorescence was seen in the hepatocyte cytoplasm in saline- and phenobarbital-treated rats; a more concentrated halo of fluorescence was detected surrounding the nuclei in the centrilobular zones after phenobarbital treatment. In the saline-treated rats, fluorescence was barely discernible but slightly more intense in the centrilobular than perilobular zones. In phenobarbital-treated rats, fluorescence was much more intense, with a similar but much greater difference between the centrilobular and perilobular zones. The tissue distribution and induction site of this component of the cytochrome P-450-dependent microsomal system may be relevant to the site of drug toxicity and the development of chemical carcinogenesis.