Interaction of the anti-oestrogen, nafoxidine hydrochloride, with the soluble nuclear oestradiol-binding protein in chick liver

Nafoxidine hydrochloride (Upjohn, 11100A)injected with oestradiol into immature chicks inhibits the hormone-induced increase in [3H]oestradiol-binding activity in salt extracts of liver nuclei as well as the subsequent production by liver of egg-yolk phosphoprotein. Substantial inhibition of both oestradiol-induced responses is seen when nafoxidine is given in a dose approximately equimolar with that of oestradiol. In vitro nafoxidine competitively inhibits binding of [3H]oestradiol in nuclear extracts. The Ki for the inhibition is 43 nM, which indicates an affinity of nafoxidine for the binding protein about 4% of that of oestradiol. The inhibitory action of nafoxidine in vivo thus is more potent than the relative binding affinity determined in vitro might indicate. One possible explanation is that the primary site of nafoxidine action is at a point proximal to nuclear receptor interaction. Nafoxidine injected alone into the chick does not induce phosphoprotein synthesis, but it does increase [3H]oestradiol-binding activity in extracts of liver nuclei to a limited extent. No differences in the properties of the oestradiol-binding activity in extracts from nafoxidine-treated chicks or from oestradiol-treated chicks were detected. Chick liver cytosol does not contain detectable high-affinity oestradiol-binding activity. A low-affinity oestradiol-binding component with a sedimentation coefficient of 3.5S was found, but it was unaffected by treatment of chicks with earlier nafoxidine or oestradiol. The results suggest a difference in the mechanism of oestradiol action in the chick liver and in the widely studied rat uterus, on which the usual model for oestradiol action is largely based.     

Competitive protein binding assay of oestradiol-17 beta and oestrone using uterine cytosol prepared from HCG-treated rabbits

Uterine cytosol was prepared from rabbits after treatment with human chorionic gonadotrophin (HCG) and used for the determination of oestradiol-17 beta and oestrone by competitive protein binding (CPB) assay. The so obtained uterine cytosol gave higher percentage of binding and proved to be more stable when stored at --20 degrees C than cytosol obtained from the pregnant uterus.     

Metabolism and excretion of oestradiol-17beta and progesterone in the Sumatran rhinoceros (Dicerorhinus sumatrensis)

3H-labelled oestradiol-17beta and 14C-progesterone were injected i.v. into an adult female Sumatran rhinoceros (Dicerorhinus sumatrensis) and all urine and faeces collected over 4 days. Of the injected steroid, 68% of 3H-oestradiol and 89% of 14C-progesterone were recovered. Peak excretion in urine occurred on day 1 for both steroids, and for faeces on day 2 for 14C-progesterone, and between days 2 and 3 for 3H-oestradiol. Oestradiol metabolites were predominantly (nearly 70%) excreted into the urine, while progesterone metabolites were almost exclusively (> 99%) excreted into the faeces. The majority (> 70%) of urinary excreted oestrogens consisted of water-soluble (i.e., conjugated) forms, with > 90% of these being glucuronides. In contrast, > 75% of faecal oestrogen and progesterone metabolites were excreted as ether-soluble (i.e., unconjugated) forms. HPLC co-chromatography of oestrogens in hydrolysed urine indicated only one peak of radioactivity, co-eluting with authentic oestradiol-17beta, whereas two peaks of radioactivity were found after HPLC of faecal oestrogens, the major one co-eluting with oestrone and the less prominent one with oestradiol-17beta. Progesterone was excreted as numerous metabolites into the faeces. The three most abundant of these were identified using HPLC and gas chromatography mass spectrometry (GCMS) as 5beta-pregnane-3alpha,20alpha-diol, 5beta-pregnane-3alpha-ol-20-one, and a second pregnanediol, the exact structure of which could not be deduced. Measurement of urinary oestradiol-17beta and faecal immunoreactive pregnanediol and 5alpha-pregnane-3alpha-ol-20-one in daily samples enabled the first endocrine characterization of the ovarian cycle and indicated a cycle length of approximately 25 days.     

Growth hormone, insulin, prolactin and total thyroxine in the plasma of sheep implanted with the anabolic steroid trenbolone acetate alone or with oestradiol

The mode of action of the anabolic steroid trenbolone acetate (19-norandrost-4,9,11-trien-3-one-17-acetate) was studied through the endogenous hormonal response of castrated male sheep to subcutaneous implantation of 140 mg of trenbolone acetate and 20 mg of oestradiol both separately and in combination. Radioimmunoassay of delta-4,9,11-trienic steroids and oestradiol-17 beta in plasma confirmed that simultaneous administration of trenbolone acetate with oestradiol led to a significantly greater persistence of oestradiol-17 beta residues in plasma (P less than 0.05) than with implantation of oestradiol alone. Oestradiol treatment increased concentrations of growth hormone and insulin (P less than 0.05; P less than 0.001 respectively) in plasma samples collected weekly. Trenbolone acetate by itself had no significant effect and the oestrogenic response was blocked on the simultaneous implantation of trenbolone acetate and oestradiol (despite higher plasma levels of oestradiol-17 beta with this treatment). Plasma total thyroxine was markedly depressed to 45 per cent of its basal level by trenbolone acetate, alone or with oestradiol (P less than 0.001) and depressed to 80 per cent of basal by oestradiol treatment alone (P less than 0.001). Plasma prolactin was unaltered by the above treatments.     

Luteinizing hormone releasing factor in pituitary stalk plasma from long-term ovariectomized rats: effects of steroids

The concentration of LH releasing factor (LH-RF) was measured by radioimmunoassay in blood collected from the cut pituitary stalk of long-term ovariectomized rats anaesthetized with Althesin. Stalk plasma LH-RF concentrations were increased immediately after ovariectomy (carried out at oestrus) and low at 2 and 4 days after operation. The concentrations then began to increase to reach a level at 24-28 days which was significantly higher than the concentrations during the oestrous cycle except for the time of the ovulatory surge at pro-oestrus. This pattern was similar to that of the concentrations of LH in jugular venous plasma taken from the same animals before exposure of the pituitary stalk. Like peripheral plasma LH concentrations, the concentrations of LH-RF in stalk plasma fluctuated and fell significantly and rapidly after the intravenous injection of 1 microgram oestradiol-17 beta. The release of LH-RF in long-term ovariectomized rats, into which had been implanted an oestradiol-containing Silastic capsule, was similar to the diurnal pattern of LH release; the afternoon increase in stalk plasma LH-RF concentration could be blocked by sodium pentobarbitone administered at 13.00 h and augmented by administering this anaesthetic at 13.00 h of the preceding day. The stalk plasma LH-RF concentrations in animals injected with oestradiol benzoate (OB) followed 72 h later with either OB or progesterone were lower than the concentrations in animals injected only with oil. These data show that in the rat (1) ovarian steroids could moderate LH release ('negative feedback') by inhibiting LH-RF release, and that in long-term ovariectomized animals (2) the oestradiol-induced circadian pattern of LH release is due to a circadian pattern of LH-RF release, and (3) the surge of LH produced by administering OB followed by either OB or progesterone is probably due mainly to a massive increase in the responsiveness of the anterior pituitary gland to LH-RF.     

Oestrogen in human pregnancy faeces

The oestrogen content of two 24 h pools of pregnancy faeces, obtained from 2 normal women in the 33rd-37th week og gestation, was studied. The qualitative analyses were made by gas chromatography - mass spectrometry and the quantitative analyses by mass fragmentography. The presence of the following oestrogens in pregnancy faeces was established: Oestriol, oestrone, oestradiol-17 beta, 16-epioestriol, 17-epioestriol, 16 alpha-hydroxyoestrone, 16-oxo-oestradiol-17 beta, 15 alpha-hydroxyoestrone and 15 alpha-hydroxyoestradiol-17 beta. In addition, mass fragmentographic evidence was obtained for the presence of 16 beta-hydroxyoestrone, 2-methoxyoestrone and oestradiol-17 alpha. The total oestrogen excretion determined in the two pools was 786 and 1300 mug per 24 h. Unconjugated oestrogens accounted for 97.8 and 98.6% of these amounts, respectively. Oestriol, oestradiol-17 beta, 15 alpha-hydroxyoestradiol-17 beta, 16-epioestriol and oestrone, in that order, were quantitatively the most significant of the oestrogens determined. The remarkably high levels of oestradiol-17 beta fround in faeces show, that in pregnancy, this mode of excretion is as important as urine for the elimination of this biologically active steroid. It is suggested that some of the oestradiol may have b-en formed through bacterial enzyme action from other oestrogens or neutral steroids. Only trace amounts of ring D alpha-ketolic oestrogens were found in faeces. This is in marked contrast to the considerable amounts of these steroids found in pregnancy bile and urine.     

Steroid glucuronyltransferases of rat liver. Properties of oestrone and testosterone glucuronyltransferases and the effect of ovariectomy, castration and administration of steroids on the enzymes

1. Microsomal preparations from rat liver, kidney and intestine were tested for UDP-glucuronyltransferase activity by using oestrone, oestradiol-17 beta, oestriol, testosterone, cortisol, cortisone, corticosterone, aldosterone, tetrahydrocortisol and tetrahydrocortisone as substrates. The microsomal preparation from the liver glucuronidated oestrone, oestradiol-17 beta and testosterone. 2. The specific activity of the enzyme was significantly higher in livers from female rats than in those from male rats. 3. Testosterone was actively glucuronidated by both sexes. Cortisol, cortisone, corticosterone, aldosterone, tetrahydrocortisol and tetrahydrocortisone were not glucuronidated by any of the three tissues. 4. The non-ionic detergent Lubrol WX activates liver microsomal UDP-glucuronyltransferase 2-3-fold with oestrone and testosterone as substrates. 5. Oestrone glucuronyltransferase was inhibited by oestradiol-17 beta, predominantly competitively and by testosterone non-competitively. Bilirubin was a non-competitive inhibitor of oestrone glucuronidation. p-Nitrophenol had no effect. 6. Oestrone glucuronyltransferase could not be stimulated by either acute or prolonged treatment of animals with phenobarbital, whereas a single dose of 3-methylcholanthrene led to a moderate stimulation. 7. Ovariectomy leads to a 56% decrease in oestrone glucuronyltransferase activity; administration of oestradiol-17 beta induces the enzyme to normal activity after 12 days, and after 15 days the activity is twice the control value. Actinomycin D and cycloheximide block the oestradiol-17 beta-induced increase in enzyme activity. 8. Castration has no effect on the activity of testosterone glucuronyltransferase, nor does administration of testosterone influence enzyme activity. The results provide strong evidence for the existence of multiple steroid glucuronyltransferases in the liver of the rat.     

The acute effect of oestrogen injection on plasma LH in freemartin heifers

The acute effects on plasma LH concentrations of an injection of oestradiol-17beta were studied in 7 non-cyclic heifers and 19 freemartins. One freemartin showed a normal LH surge due to the positive feedback effect of oestrogen on the hypothalamus. Of the other 18 freemartins, 4 showed positive increases in plasma LH and 6 were unclassified. There was no correlation between the degree of chimaerism and responsiveness to oestrogen. The results also showed that injected oestradiol suppressed the spontaneous fluctuations of plasma LH.     

Identification and regulation of testicular interferon-gamma (IFNgamma) receptor subunits: IFNgamma enhances interferon regulatory factor-1 and interleukin-1beta converting enzyme expression

Interferon-gamma (IFNgamma) transmits its signal through a specific cell surface receptor (IFNgammaR), which consists of a primary ligand binding alpha-chain (IFNgammaR alpha) and a signaling beta-chain (IFNgammaR beta). Recent studies identified the cytokines IFNgamma, interleukin-6 (IL-6), IL-1alpha, and tumor necrosis factor-alpha in testicular cells. Therefore, we: 1) examined the expression of IFNgammaR alpha and IFNgammaR beta subunits in freshly isolated and purified rat testicular cells; 2) examined the differential regulation of receptor components by cytokines using primary cultures of Sertoli cells; 3) identified the cell signaling pathway components of testicular IFNgammaR; and 4) characterized the functional role of testicular IFNgamma using primary Sertoli cells. We demonstrated the messenger RNAs for both chains of IFNgammaR in rat testicular cells using Northern hybridization analysis. Western blot analysis and immunocytochemistry showed that both specific IFNgammaR protein subunits were present in cultured primary Leydig and Sertoli cells prepared from the testes of immature rats. The expression of both IFNgammaR component messenger RNAs in cultured Sertoli cells was increased by its specific ligand (IFNgamma), as well as IL-1alpha and tumor necrosis factor-alpha, in both a time- and dose-dependent manner. IFNgamma-activation of the Janus (JAK) tyrosine kinases, JAK1 and JAK2 proteins, indicate that IFNgammaR, expressed in the Sertoli cell, is functional. Moreover, IFNgamma modulates the expression of interferon regulatory factor (IRF)-1 and IL-1beta converting enzyme genes in Sertoli cells. Thus, our data are suggestive of a role(s) for IFN-gamma in the regulation of distinct gene expression and cell-specific sensitivity to apoptosis in the testis.     

Induction of a differentiated ciliated cell phenotype in primary cultures of Fallopian tube epithelium

Human Fallopian tubal epithelial cells in culture lose morphological features associated with the epithelium in situ and the extent to which they retain their in-vivo phenotype or function is unknown. In order to address this question, immunocytochemical markers were identified which distinguish secretory (HMFG2+, LhS28-) from ciliated (HMFG2-, LhS28+) epithelial cells in tissue sections of Fallopian tube. These markers were used to analyse the phenotype of tubal cells in vitro. Primary cultures of human tubal epithelial cells were seeded onto glass and grown to confluence before addition of oestradiol-17beta. In the absence of hormone, tubal epithelial cells expressed cytokeratins and nuclear receptors for oestrogen and progesterone and adopted a homogeneous (HMFG2+, LhS28-) secretory cell phenotype. Following the addition of oestradiol-17beta, a proportion of cells became positive for LhS28. The induction of a ciliated epithelial cell phenotype was confirmed by scanning electron microscopy, where on permeable collagen membranes, approximately one-third of tubal epithelial cells became ciliated in the presence of oestradiol-17beta. We suggest that in vitro, tubal epithelial cells adopt an immature secretory-like phenotype and that oestrogen can induce differentiation to a ciliated epithelial cell phenotype.     

Expression of oestrogen receptor beta (ER beta) occurs in multiple cell types, including some germ cells, in the rat testis

The identification of a second oestrogen receptor (beta) has prompted a re-evaluation of the potential sites of action of oestrogens. The aim of the present study was to characterize immunoexpression of ER beta expression in the testis to complement earlier data which had demonstrated that expression of ER alpha is confined to testicular interstitial Leydig cells. In all testes studied, including those from both fetal (day 20.5 p.c.) and adult rats, ER beta was found to be expressed in multiple cell types. Sertoli cell nuclei were immunopositive at all ages. In adult testes expression in Sertoli cells was not stage dependent and was unaffected by ablation of Leydig cells. In fetal testes ER beta was also expressed in peritubular cells, fetal Leydig cells and gonocytes. In the pubertal and adult testis ER beta was detected in the nuclei of spermatogonia and most pachytene spermatocytes. Weak immunopositive staining was present in the cytoplasm of spermatocytes undergoing the second meiotic division. In conclusion the widespread expression of ER beta in the testis is consistent with a role for oestrogens in modulating spermatogenesis, and hence fertility, in the male.     

The effect of human chorionic gonadotropin on methotrexate concentration in the rat testes

PURPOSE: We analyzed the effect of human chorionic gonadotropin (hCG) on drug concentrations in testicular interstitial fluid and whole testis tissue samples in rats receiving hCG prior to methotrexate (MTX) administration and in animals that did not receive hCG. MATERIALS AND METHODS: Adult male Sprague-Dawley rats were injected subcutaneously with 200 i.u. hCG (Goldline Laboratories, Ft. Lauderdale, FL.). Controls were injected subcutaneously with normal saline (0.2 cc). Sixteen hours after injection, each rat was given methotrexate (Methotrexate LPF, Immunex Corp. Seattle WA.) via a carotid artery cannula in a dose of 30 mg./kg. Methotrexate (MTX) levels were collected 60 minutes post infusion time in 27 rats and 90 minutes post infusion in 27 rats. MTX levels were measured in serum, testicular interstitial fluid and testicular tissue. MTX levels were measured using high performance liquid chromatography (HPLC). RESULTS: A significantly higher concentration of MTX was found in testicular interstitial fluid (TIF) in rats injected with hCG when specimens were collected 60 minutes post infusion. MTX levels in TIF had reversed 90 minutes post infusion with higher levels found in control rats. Tissue levels of MTX demonstrated no significant difference at either 60 or 90 minutes in the hCG treated animals or controls. CONCLUSION: Our results suggest that hCG effects the tissue distribution of MTX within the testis. Human chorionic gonadotropin may have this effect on the testicular microvasculature by 1) selectively increasing capillary permeability, 2) increasing lymphatic flow within the testes or 3) increasing testicular blood flow.     

Desensitization of beta3-adrenergic receptor-stimulated adenylyl cyclase activity and lipolysis in rats

The beta3-adrenergic receptor is an integral membrane protein consisting of seven transmembrane domains. Unlike the beta1 and beta2 receptors, this subtype lacks the consensus phosphorylation sites required for desensitization by serine kinases. Using the rodent specific beta3 agonist BRL 35135, our initial data indicated that beta3 receptor-mediated glycerol levels progressively decreased following daily oral doses of 5 mg/kg. Therefore, we initiated studies designed to delineate the possible mechanism(s) for this decreased response. Within 3 hours following a single oral dose of BRL 35135, serum glycerol levels and UCP (uncoupling protein) RNA levels were significantly increased whereas beta3 RNA levels were significantly decreased. Rats were dosed daily for 5 days with either vehicle or BRL 35135 (5 mg/kg, p.o.) and blood samples were collected for glycerol analysis. Adipose tissue was excised for lipolysis and adenyl cyclase measurements. In addition, UCP and beta3 receptor RNA levels were assessed. No effect on adipocyte BRL 37344-stimulated adenylyl cyclase activity was observed 3 hours following the initial dose of BRL 35135. Although a slight decrease (approximately 25%) in adenylyl cyclase activity could be observed 24 hours following the initial dose, it wasn't until day 4 of dosing that a significant decrease (50%) was observed. In contrast, beta3- stimulated lipolysis in adipocytes from BRL 35135-treated rats was decreased 85% within 24 hours and this decrease persisted through four days of treatment. These data indicate that the lipolytic response to beta3 receptor activation is decreased after only a single oral dose of BRL 35135, whereas receptor-mediated adenylyl cyclase activation, although initially unaffected, also desensitizes by day four of treatment.     

Effect of estradiol-17 beta on preprolactin messenger ribonucleic acid activity in the rat pituitary gland

Rat pituitary RNA was translated in the wheat germ system. Preprolactin messenger RNA activity was estimated by adsorption of cell-free products to solid phase antiprolactin. When male rats were injected for 4 days with estradiol-17beta, pituitary preprolactin mRNA activity was increased 2.5- to 3.0-fold over controls. This increase was evident when either total RNA, poly(adenylic acid) RNA, or polysomal RNA was translated in the cell-free system. In male rats receiving daily injections of estradiol-17beta, preprolactin mRNA activity was increased to an apparent maximum of 300% of controls after 7 days of treatment. Our data also indicate that estradiol increases preprolactin mRNA activity per microgram of RNA as well as the pituitary content of RNA. After estradiol treatment was discontinued, preprolactin mRNA activity declined to 50% of the maximum stimulation after approximately 2 days. In ovariectomized retired breeder female rats, a 5-fold increase in preprolactin activity over ovariectomized controls was obtained. In other studies, a 2-fold increase in preprolactin mRNA activity was obtained in male rats 24 h after a single injection of pimozide, a dopamine blocking drug.     

A dose-ranging study of the use of cyclical dydrogesterone with continuous 17 beta oestradiol

OBJECTIVE: To establish the lowest dose of cyclical dydrogesterone that protects against endometrial hyperplasia induced by continuous 2 mg 17 beta oestradiol, and to study the dose effect on vaginal bleeding and side effects. DESIGN: Double-blind, prospectively randomised dose-ranging study. SETTING: Menopause clinics in the UK and The Netherlands. SUBJECTS: Three hundred and seventy-one postmenopausal women with intact uteri, aged 40 to 60. INTERVENTIONS: Administration of six 28-day treatment cycles of continuous daily micronised 17 beta oestradiol with a randomly allocated dose of 5 to 20 mg of dydrogesterone added for the last 14 days of each. MAIN OUTCOME MEASURES: Histological assessment of adequate progestational endometrial response, bleeding patterns and adverse effects. RESULTS: The study was completed by 320 subjects (86%). Endometrial transformation occurred in over 94% of those taking 5 mg of dydrogesterone, and in over 97% of those on higher doses, without significant differences between the 10, 15 and 20 mg groups. Acceptable bleeding patterns were found at all doses, with the incidence of withdrawal bleeding rising with increasing dose. The day of onset of bleeding was predictable from cycle to cycle, and occurred later in the 20 mg group than in the others. The incidence of noncyclic bleeding was about 6% at all doses. Withdrawal occurred in 3.3% due to unacceptable bleeding and in 5.4% due to side effects. There was no relation with dose. CONCLUSIONS: A dydrogesterone-17 beta oestradiol combination hormone replacement therapy confers endometrial protection with an acceptable bleeding pattern and few side effects At least 10 mg of dydrogesterone for 14 days is required for acceptable endometrial protection.     

Gonadotrope responsiveness in orchidectomized sheep: effect of duration of a simulated follicular phase

The effect of duration of a simulated follicular phase on gonadotrope responsiveness was assessed in orchidectomized sheep (wethers). The oestrogenic and hypothalamic inputs characteristic of the ovine follicular phase were simulated by continuous infusion of oestradiol (5 micrograms h-1 in 10% (v/v) ethanol saline) and circhoral delivery of GnRH (200 ng per hourly pulse) for 0, 6, 12, 24, 48 or 96 h (n = 6 wethers per group). Responsiveness increased (P < 0.05) with increasing duration of simulated follicular phase. In a second experiment, responsiveness was assessed 96 h after initiation of infusion of oestradiol in wethers receiving hourly pulses of GnRH or saline. Concurrent administration of GnRH reduced (P < 0.05) the magnitude of the oestradiol-induced increase in gonadotrope responsiveness. In a companion study, anterior pituitary tissue was collected 96 h after the start of infusion of oestradiol and circhoral delivery of GnRH or saline. Pituitary stores of LH and tissue concentrations of GnRH receptor and mRNA encoding the GnRH receptor were increased (P < 0.05) by oestradiol infusion. The magnitude of these oestradiol-induced responses was not affected (P > 0.05) by concurrent GnRH treatment. Tissue concentrations of FSH and mRNA encoding the FSH beta subunit were decreased (P < 0.05) by oestradiol infusion. This suppressive effect of oestradiol was not reversed by GnRH. These results indicate that oestradiol stimulation, but not concurrent delivery of GnRH, is essential for full expression of surge-like secretion of LH. In addition, the oestradiol-induced increase in gonadotrope responsiveness during the simulated follicular phase is sustained throughout the period of oestradiol delivery.     

Plasma levels of oestriol-17 beta, oestriol and human placental lactogen during bed rest

Plasma unconjugated oestradiol-17 beta, total oestriol and human placental lactogen levels were measured in twelve healthy volunteers admitted for bed rest in the last trimester of pregnancy. No significant alteration in levels was observed.     

Transforming growth factor beta as a predictor of liver and lung fibrosis after autologous bone marrow transplantation for advanced breast cancer

BACKGROUND: Hepatic veno-occlusive disease and idiopathic interstitial pneumonitis are major causes of morbidity and mortality after bone marrow transplantation. Fibrosis is a characteristic of both conditions, and transforming growth factor beta (TGF beta) has been implicated in the pathogenesis of fibrosis. METHODS: Using acid-ethanol extraction to remove TGF beta from human plasma and a mink-lung epithelial-cell growth-inhibition assay to measure TGF beta activity, we quantified plasma TGF beta in 10 normal subjects and 41 patients before and after they underwent high-dose chemotherapy and autologous bone marrow transplantation for advanced breast cancer. RESULTS: There was no difference in pretransplantation TGF beta levels between the controls and the patients who did not have hepatic veno-occlusive disease or idiopathic interstitial pneumonitis after transplantation. In contrast, pretransplantation TGF beta levels were significantly higher in patients in whom hepatic veno-occlusive disease or idiopathic interstitial pneumonitis developed than in the controls or the patients without these conditions. The predictive value for the development of either condition was 90 percent or more when pretransplantation plasma TGF beta levels were more than 2 SD above the mean established in the controls. CONCLUSIONS: The plasma TGF beta concentration measured after induction chemotherapy but before high-dose chemotherapy and autologous bone marrow transplantation strongly correlates with the risk of hepatic veno-occlusive disease and idiopathic interstitial pneumonitis after these treatments.     

The inhibitory effect of intracerebroventricularly injected interleukin 1beta on testosterone secretion in the rat: role of steroidogenic acute regulatory protein

Exposure to disease or injury often results in impaired reproductive activity accompanied by decreased testosterone levels. After immune activation, the cytokine interleukin 1-beta (IL-1beta) circulates in high concentrations, and its exogenous administration evokes many of the sequelae of immune activation. Previously, we have shown that the administration of this cytokine into the cerebral ventricles blunts hCG-stimulated testosterone secretion. This effect, though time-dependent, occurs before significant elevation of interleukin 6 in the peripheral bloodstream, does not depend on adrenal activation, and/or changes in LH concentrations, leading us to hypothesize a direct connection between the brain and testis. To explore this mechanism further, we isolated testicular tissue from rats treated intracerebroventricularly (icv) with vehicle or IL-1beta 30 or 90 min before they were killed. We found that in vivo cytokine treatment blunted ex vivo testosterone secretion in response to hCG, showing that the mechanism is independent of circulating cytokines. Though hCG binding was moderately reduced by icv IL-1beta in these preparations, the extent of this inhibition did not explain our observations. As the first acutely and hormonally regulated step in the biosynthesis of testosterone is the transfer of cholesterol into the inner mitochondrial membrane, which is mediated by steroidogenic acute regulatory (StAR) protein, we hypothesized that the rapid effects of icv IL-1beta on testicular responsiveness to hCG might be due to reduced levels of StAR. We report here that StAR protein was indeed reduced in Leydig cells isolated from rats treated in vivo with IL-1beta. Furthermore, treatment with a water-permeable form of cholesterol that bypasses the requirement for StAR partially restored hCG-stimulated testosterone secretion from testes isolated from rats treated icv with IL-1beta. Taken together, our data indicate that StAR plays a role in the suppression of testicular function evoked by central administration of IL-1beta.