Influence of sex hormonal status on alcohol-induced oxidative injury in male and female rat liver.

BACKGROUND: Oxidative stress contributes to the development of liver injury after chronic alcohol intake. Women exhibit greater sensitivity to alcohol-induced liver disease than do men. The aim of the study was to determine the relationship between the sex hormone status of male and female rats and the degree of alcohol-induced oxidative stress in the liver. METHODS: Male and female rats were pair-fed a liquid diet that contained 36% of their total daily calories as ethanol (EtOH group) or maltose (control group). Blood and liver samples were collected at the end of 8 weeks of diet. RESULTS: Male EtOH rats experienced a reduction in plasma testosterone (T) and an increase in estradiol (E2) levels, with an increase in their calculated E2/T ratio with respect to their controls. Malonaldehyde (MDA) levels, an index of lipid peroxidation, and protein carbonyl content, an index of protein oxidation, in the liver were greater among the EtOH groups in females than in males. In males, an inverse correlation was found between hepatic MDA and circulating T levels, and a direct correlation was disclosed between MDA and estradiol levels. In addition, the hepatic histopathological score correlated inversely with the plasma T levels and directly with the calculated E2/T ratio, an index of feminization. CONCLUSIONS: Alcohol-induced oxidative injury, which contributes to hepatic injury in both male and female rats, is enhanced in females compared with males. A role for plasma T levels in protecting male rat liver from ethanol-induced oxidative injury can be hypothesized.

The effect of castration on steady state levels of luteinizing hormone-releasing hormone (LHRH) mRNA and proLHRH processing: time course study utilizing semi-quantitative reverse transcription/polymerase chain reaction.

Many studies have consistently shown that castration induces a prompt increase in serum levels and pituitary content of the gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), as well as a concomitant rise in steady state levels of the messenger RNAs directing their synthesis. The reports of effects of castration on the overall physiology of hypothalamic luteinizing hormone-releasing hormone (LHRH)--steady state levels of LHRH mRNA, post-translational processing and secretion--have, however, not been consistent. The goal of the studies reported here was to provide the first analysis of the effect of castration, at multiple postoperative time points, on steady state levels of LHRH mRNA and on the levels of hypothalamic proLHRH. All these data are correlated with hypothalamic levels of the mature LHRH decapeptide and with serum and pituitary levels of immunoreactive LH and FSH. Adult male rats were either castrated or sham-castrated (controls) and then sacrificed at 1, 3, 5, 7, 14, 21 or 28 days postoperatively. As expected, there was a prompt and sustained rise in serum immunoreactive LH and FSH in castrates compared with sham-operated animals. Intra-pituitary LH levels rose above levels in the sham-operated animals by 14 days post castration. Intra-pituitary FSH showed a biphasic response, first falling significantly below control levels, then rising above control levels at 21 days. Steady state levels of LHRH mRNA in castrates, measured by reverse transcription/polymerase chain reaction, were increased about 2-fold above control levels by 1 day postoperatively, but were virtually identical to control levels at each of the other time points despite marked changes in the gonadotropins. ProLHRH content in castrates was 1.8-times that seen in controls at 1 day post castration (P<0.05), concomitant with the rise in steady state levels of LHRH mRNA at that time point. However, proLHRH content in castrates was no different from that seen in controls at each of the later time points examined. LHRH content was unchanged through 7 days after castration, but then fell significantly to 57% of control levels in hypothalami from animals gonadectomized 14 to 21 days previously (P<0.001 vs control), and to 54% of sham-operated levels at 28 days postoperatively (P<0.001). We conclude that: (1) changes in steady state levels of LHRH mRNA after castration are small and transient and (2) increased proLHRH coupled with unchanged LHRH levels at 1 day post castration, and castrate animal proLHRH at control levels coupled with falling LHRH at later post-castration time points indicate that the effect of gonadectomy on post-translational processing of proLHRH to LHRH is, likewise, small and transient. In aggregate our data suggest that most of the increase in serum LH and FSH seen in male rats after castration is not mediated at the hypothalamic level.

Signal requirements for production of luteinizing hormone releasing-hormone by human T cells.

We have previously demonstrated that both human CD4+ and CD8+ T lymphocytes produce enhanced levels of luteinizing hormone-releasing hormone (LHRH) mRNA and peptide upon stimulation with monoclonal antibody directed at the CD3 component of the T cell receptor for antigen (TCR) or mitogenic lectin. In the current study, we define the signaling pathways that control TCR-mediated LHRH production by using agents known to affect distinct signals, and compare the messenger systems required for LHRH response to other T-cell-associated activation responses, such as expression of CD69 and interleukin-2 receptor (IL-2R) molecules and production of interleukin-2 (IL-2). Results indicate that the activation of protein kinase C (PKC) is essential for LHRH production by previously nonstimulated T cells, not increased concentration of cytosolic-free calcium ([Ca2+]i). Phorbol ester (PMA), a direct activator of PKC, provoked LHRH production and cell surface expression of CD69 and IL-2R molecules by T cells, but not IL-2 synthesis. The synthesis of IL-2 by T cells required costimulation with PMA and ionomycin, a Ca2+ ionophore. Consistent with these observations, H7, an inhibitor of PKC, prevented T cells from producing LHRH upon activation with mitogen. However, LHRH production was not suppressed by HA1004, which inhibits all cyclic nucleotide-dependent protein kinases except for PKC. Genistein, a selective inhibitor of protein tyrosine kinase, blocked PMA-induced increase in LHRH production, but not CD69 and IL-2R expression, suggesting that protein tyrosine phosphorylation events distal from PKC activation may play a role in regulating LHRH response.

Luteinizing hormone-releasing hormone (LHRH) in rat prostate: characterization of LHRH peptide, messenger ribonucleic acid expression, and molecular processing of LHRH in intact and castrated male rats.

Continuous administration of LHRH agonist suppresses the pituitary-gonadal axis, achieving chemical castration. Thus, LHRH agonist has been used as an alternative (to surgical castration) for the treatment of steroid-dependent prostate cancer. However, recent reports have demonstrated that LHRH agonist had a direct inhibiting effect on prostate cancer cell proliferation and that cancerous prostate tissue contained a LHRH-like peptide. In this paper we are reporting for the first time that the normal rat ventral prostate contained immunoactive and bioactive LHRH as well as its precursor molecule, pro-LHRH. Our investigation showed that the LHRH concentration in prostate increased 2 weeks after castration from 1.68 +/- 0.09 to 3 +/- 0.2 pg/mg tissue (P < 0.001). At the same time, the concentration of pro-LHRH decreased from 149 +/- 6.5 to 68 +/- 6.8 pg/mg tissue (P < 0.001). Furthermore, intact rat prostate expressed LHRH mRNA, which increased 13-fold 2 weeks after castration. In summary, the prostate of intact Sprague-Dawley rats has the capacity to produce the LHRH precursor and process it to the mature decapeptide, and this production/processing increases significantly after castration.

Immunoactivation enhances the concentration of luteinizing hormone-releasing hormone peptide and its gene expression in human peripheral T-lymphocytes.

An immunomodulatory role for LHRH was suggested when we reported the presence of immunoactive and bioactive LHRH and its mRNA in rat splenic and thymic lymphocytes. In this paper we report that human peripheral T-cells as well as its subsets CD4+ and CD8+ contained immunoactive and bioactive LHRH. Furthermore, analysis of phytohemagglutinin (PHA)-activated T-cell lysates for LHRH by RIA demonstrated that the mean concentration of LHRH in PHA-activated T-cells increased from 45 +/- 4.5 to 64 +/- 7 pg/10(6) cells after 24 h of culture and from 47 +/- 3.6 to 117 +/- 11.8 pg/10(6) cells (P < 0.01) after 48 h. While the LHRH concentration in PHA-activated cells increased over the last 24 h of culture h from 64 +/- 7 to 117 +/- 11.8 pg/10(6) cells (P < 0.001), there was no change in mean concentration of LHRH in T-cells kept in medium alone. In a preliminary study we found that fresh T-cells contain 20 +/- 1.4 pg pro-LHRH/10(6) cells, and PHA stimulation increased the pro-LHRH content similar to the increase in LHRH. As with unfractionated T-cells, a significant PHA-induced time-dependent enhancement of intracellular LHRH was noted in CD4+ and CD8+ T-cells. RNA extracted from lymphocytes was subjected to reverse transcription-polymerase chain reaction analysis using LHRH and histone-3.3, primers, the latter as an internal control. The polymerase chain reaction-generated data demonstrated that the relative amount of LHRH mRNA in cultured, but non-PHA-stimulated (resting), cells diminished dramatically between 5-24 h, but recovered by 48 h of culture. The relative amount of LHRH mRNA in PHA-stimulated cells revealed a markedly different pattern. LHRH message expression in PHA-activated cells increased slightly at 5 h of culture and was maximally stimulated by 24 h, but declined by 48 h of culture. The PHA activation-induced time-dependent enhancement of intracellular accumulation of LHRH peptide at 5 and 24 h was accompanied by increased LHRH message. However, the increased concentration of LHRH peptide at 48 h coincided with decreased LHRH message expression. The data from total protein synthesis in PHA-activated cells showed a progressive increase in protein synthesis, a pattern entirely similar to the changes in the cell content of LHRH.(ABSTRACT TRUNCATED AT 400 WORDS)