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M A Emanuele

Publications and source records attributed to M A Emanuele.

At least 19 recordsLinked to original sources
PubMed1999

Reversal of chronic ethanol-induced testosterone suppression in peripubertal male rats by opiate blockade.

Teenage drinking continues to be a significant problem in the U.S., as well as abroad. We have previously demonstrated that opiate blockade with naltrexone, a drug currently used in patients to diminish alcohol craving, prevented the fall in serum testosterone seen after acute ethanol (EtOH) exposure in young, peripubertal male rats. To follow-up on this reversal, a series of experiments was performed to determine if naltrexone would also prevent the testosterone suppression caused by chronic EtOH exposure. Peripubertal rats either 45 days old (mid-pubertal) or 55 days old (late pubertal) were fed an EtOH-containing liquid diet or pair-fed control diet for 14 days. Each animal was implanted with either a naltrexone containing or placebo pellet before starting the liquid diet. In each age group, EtOH alone significantly suppressed testosterone, whereas naltrexone prevented this fall, although it had no effect alone. Serum luteinizing hormone was also suppressed by EtOH; however, naltrexone did not abrogate this fall. In the 45-day-old animals, beta-luteinizing hormone mRNA levels rose significantly in the EtOH group, but not when naltrexone was coadministered with EtOH. There was no change in hypothalamic luteinizing hormone releasing hormone (LHRH) mRNA, pro-LHRH, or LHRH in any group at either age. Thus, naltrexone is able to partially prevent the EtOH-induced suppression of gonadal testosterone of young, adolescent male rats. This effect appears to be mediated directly at gonadal level, because hypothalamic and pituitary hormone changes were minor and nonsignificant.

Age Factors↗
PubMed1998

Castration differentially regulates nitric oxide synthase in the hypothalamus and pituitary.

Mammalian reproductive function is under control of the integrated hypothalamic-pituitary-gonadal (HPG) axis. Castration in male rats has been utilized as an effective tool to investigate hormonal interactions in the mammalian HPG axis. Recently, nitric oxide (NO) has been suggested to play a role in HPG hormonal regulation. In order to gain further insight into the function of the NO-NOS system in reproductive neuroendocrine control, particularly in the gonadal feedback regulation of the hypothalamic-pituitary unit, we examined steady state levels of nNOS mRNA, nNOS protein, and the important physiological index, NOS enzyme activity, of the intrinsic NOergic system in both hypothalamus and pituitary in castrated male rats and their sham-operated counterparts one week after surgery. In the pituitary, we found a significant four-fold increase in nNOS mRNA, p < 0.0003 compared to sham. Castration also resulted in a four-fold rise in pituitary nNOS protein, p < 0.02 compared to sham. Pituitary NOS enzyme activity was stimulated 2 fold, p < 0.003 after castration. In the hypothalamus, conversely, we observed no significant castration-modulated difference in either nNOS mRNA, nNOS protein or NOS enzyme activity. Thus, it appears that the hypothalamic NO-NOS system is either not required for hypothalamic adaptations to castration, although important in the release of LHRH under normal physiological conditions, or alternatively, the hypothalamus may become more sensitive to the effects of NO in the castrated state. In the pituitary, NO may attenuate the gonadotropin response to castration as a local balancing mediator.

Animals↗
PubMed1998

Reversal of ethanol-induced testosterone suppression in peripubertal male rats by opiate blockade.

Teenage drinking is a major problem in the United States, as well as abroad. Besides psychosocial implications, ethanol (EtOH) has detrimental effects on the reproductive system. Clinical problems associated with reduced reproductive hormones include osteoporosis, decreased muscle function, anemia, altered immune function, prostate involution, and decreased reproductive abilities. Education coupled with strategies aimed at preventing these deleterious consequences even in the face of continued EtOH intake is extremely important. We have tested the possibility that naltrexone, a drug currently used in patients to decrease alcohol craving, might also prevent the fall in the male hormone, testosterone, caused by EtOH exposure. Rats aged 35 days old (prepubertal), 45 days old (midpubertal), and 55 days old (late pubertal) were injected (intraperitoneally) with either saline, EtOH, naltrexone, or EtOH plus naltrexone. In the two older age groups, EtOH significantly suppressed testosterone, which was prevented by administration of naltrexone. In the youngest animals, there was no treatment effect presumably due to low basal levels of testosterone. EtOH similarly reduced luteinizing hormone (LH), but this suppression was not prevented by naltrexone. There was no consistent effect of any treatment on hypothalamic concentration of pro-LH releasing hormone (RH) (LHRH), LHRH, or on steady-state levels of LHRH mRNA. We conclude that, as animals progress through puberty, EtOH suppresses LH and testosterone. The testosterone decline can be prevented by opiate blockade with naltrexone, an effect primarily seen at gonadal level. Thus, naltrexone, a drug already used clinically to reduce EtOH intake, also has protective physiological effects on the endocrine system.

Animals↗
PubMed1998

Interaction of ethanol and nitric oxide in the hypothalamic-pituitary-gonadal axis in the male rat.

Ethanol (EtOH) exerts deleterious actions on reproductive function at all three levels: the hypothalamus, pituitary, and gonad (HPG). Nitric oxide (NO), a newly identified messenger molecular in a variety of biological systems, has been suggested as playing a role in HPG hormone regulation. NO stimulates luteinizing hormone releasing hormone secretion from the hypothalamus and has variable effects on luteinizing hormone release from the pituitary. NO is inhibitory to testosterone production, and it may also directly inhibit some steroidogenic enzymes. Related studies in the accompanying paper have demonstrated that inhibiting NO synthase (NOS) using various NOS inhibitors can prevent the EtOH-induced suppression of testosterone on the male HPG axis, and this action is mainly, although not entirely, due to a direct gonadal effect. To further investigate the role of NO in the HPG axis, we assessed the HPG NO-NOS system by determining NOS mRNA levels, protein levels, and enzyme activity in the presence and absence of EtOH. At the testicular level, EtOH's action did not appear to be mediated by increasing NO content. However, EtOH was able to potentiate NO's suppressive effect on the testicular synthesis system. One locus where EtOH and NO interacted was at the steroidogenic enzyme level. N(G)-nitro-L-arginine methyl ester, a NOS inhibitor, was found to antagonize the EtOH-induced fall on P-450 17alpha-hydroxylase/C17-20 lyase mRNA levels when administered along with EtOH. EtOH had no apparent effect on the pituitary NO-NOS system and its effects on the hypothalamic NO-NOS system do not explain its ability to reduce luteinizing hormone releasing hormone secretion.

Animals↗
PubMed1998

Effect of nitric oxide synthase inhibitors on preventing ethanol-induced suppression of the hypothalamic-pituitary-gonadal axis in the male rat.

Ethanol (EtOH) suppression of the hypothalamic-pituitary-gonadal (HPG) axis results in broad reproductive malfunction. In the HPG axis, the suppressive effects of EtOH are manifested by decreased serum testosterone, reduced testicular luteinizing hormone (LH) receptor numbers, lowered serum LH and pituitary beta-LH mRNA levels (in castrated animals), and impaired luteinizing hormone releasing hormone (LHRH) release from the hypothalamus. Increasing evidence has suggested that nitric oxide (NO) plays a role in regulation of the HPG axis. NO was shown to stimulate LHRH secretion from the hypothalamus and to have variable effects on LH release from the pituitary. At the gonadal level, NO is inhibitory to testosterone production. NO may directly inhibit some testicular steroidogenic enzymes. To investigate the effect of EtOH, NO, and their interaction on the male HPG axis, three NO synthase (NOS) inhibitors, N(G)-nitro-L-arginine methyl ester, N(G)-nitro-L-arginine, and 7-nitro indazole were used to study overall HPG function in the presence and absence of EtOH. Animals were given intraperitoneal injections of saline, EtOH, various NOS inhibitors, or EtOH, along with NOS inhibitors 2 hr before sacrifice. Serum testosterone and LH concentrations, pituitary beta-LH mRNA levels, hypothalamic LHRH mRNA levels, and LHRH content were determined. It was found that blocking NOS by these NOS inhibitors prevented EtOH-induced suppression of testosterone and, in some cases, serum LH. However, this was not accompanied by concurrent changes with NOS blockade on LHRH mRNA, hypothalamic pro-LHRH or LHRH content or pituitary LH beta mRNA levels. It appears that the protective effect of NOS blockade was largely, although not completely, due to a direct effect at the gonadal level.

Animals↗
PubMed1997

Ethanol, growth hormone and testosterone in peripubertal rats.

The deleterious effects of ethanol on the hypothalamic pituitary growth hormone axis in adult male humans and animals have been well documented. It is also well established that ethanol has toxic effects on testicular function in adult humans and animals. Much less is known, however, about the effects of ethanol on the growth hormone (GH) axis and testicular function in adolescence. Recent studies have established that adolescent problem drinking is a widespread and growing threat to the health of young people in the United States. In the present study, therefore, we investigated if acute ethanol exposure in peripubertal male Sprague-Dawley rats altered normal pituitary and testicular function. Serum levels of GH and testosterone were measured at 1.5, 3, 6, and 24 h after a single i.p. injection of either saline or 3 g/kg body weight ethanol. Histologic analysis as well as serum testosterone levels allowed us to assign animals to either early puberty (35-day-old animals), mid-puberty (41-day-old animals), or young adult (51- and 66-day-old animals) status. Ethanol produced significant decrements in serum testosterone in the 51- and 66-day-old animals, with a trend toward suppression in the 41-day-old group. Furthermore acute ethanol administration significantly decreased serum GH (P < 0.0001 by 3 way ANOVA) demonstrating a significant effect of ethanol on serum GH in all age groups and at all time points studied when compared with saline injected controls (P < 0.01 by Turkey's studentized range test). Despite this significant fall in peripheral GH levels, there was no decrease in either GH mRNA or growth hormone-releasing factor (GRF) mRNA levels nor in hypothalamic concentration of GRF peptide. We conclude that, as in adult animals, acute exposure to ethanol causes a prolonged and severe decrement in serum GH which is possibly mediated at the level of secretion. In addition, there is attenuation in testosterone secretion. These data are all the more important since GH and testosterone play critical roles in organ maturation during this stage of development.

Analysis of Variance↗
PubMed1997

Effect of chronic ethanol on reproductive and growth hormones in the peripubertal male rat.

Ethanol (EtOH) has previously been shown to have profound effects on various endocrine systems. The present study further investigates the action of EtOH on testosterone and on the GH-IGF-I axis. Since these hormones are particularly important in male rats progressing through puberty, we examined the effect of 10 days of EtOH treatment at three different ages (35, 50 and 65 days old) as male rats progressed through puberty into adulthood. After 10 days of feeding a 6% EtOH liquid diet, serum testosterone levels were markedly decreased in all three ages (P < 0.02 at 35 days, P < 0.01 at 50 days and P < 0.03 at 65 days). IGF-I was assessed and was differentially affected at each age. At 35 days IGF-I levels were suppressed by EtOH (P < 0.0002), at 50 days no change was apparent, and at 65 days levels were significantly higher in EtOH-treated (P < 0.01) compared with liquid-fed controls. The levels of IGF-I in the EtOH-treated animals paralleled pituitary GH mRNA levels with a significant fall in the expression of GH mRNA levels noted at 35 days (P < 0.04), no change at 50 days and a significant rise observed at 65 days (P < 0.03). At the hypothalamic level, GH-releasing hormone (GRF) mRNA was significantly reduced in the two younger EtOH-treated age groups compared with controls (P < 0.04 at 35 days; P < 0.02 at 50 days). At 65 days of age, EtOH did not alter GRF mRNA levels. No EtOH-induced changes were seen in GRF content at any age. These observations indicate definite age-related alterations in hormonal gene expression and circulating serum hormone levels and emphasize the importance of studying these critical peripubertal ages after chronic EtOH exposure.

Animals↗
PubMed1997

Diabetic neuropathy: therapies for peripheral and autonomic symptoms.

Painful peripheral diabetic neuropathy is a major cause of morbidity in diabetes mellitus. In addition to good glycemic control, therapeutic options include simple analgesics, the occasional use of narcotic analgesics, tricyclic antidepressants, or topically applied capsaicin cream. Other options such as carbamazepine and lidocaine have clinical drawbacks, but some investigational compounds may hold promise in the future. Diabetic autonomic neuropathy is often undiagnosed because of its diffuse organ involvement and gradual onset. Affected organ systems may include the ocular pupil, sweat glands, gastrointestinal tract, bladder, sex organs, cardiovascular system, and adrenal medullary system. Diagnosis requires the exclusion of other causes for the patient's symptoms.

Autonomic Nervous System Diseases↗
PubMed1997

The impact of acute ethanol on reproductive hormone synthesis, processing, and secretion in female rats at proestrous.

It is the purpose of this study to investigate the effects of acute ethanol (EtOH) on the female rat hypothalamic-pituitary-gonadal (HPG) axis. The molecular and cellular mechanistic details of such effects have been studied intensively in the male rat. However, there has been relatively little in-depth study of EtOH's effects on the adult, postpubertal female rat. Adult female rats with confirmed 4- or 5-day estrous cycles were given a single injection of EtOH or saline between noon and 1:00 PM on proestrous and were killed at 4:00 PM. EtOH caused a sharp 97% reduction in luteinizing hormone (LH) serum levels (p < 0.001), compared with controls with no concomitant change in LH mRNA. EtOH also significantly reduced hypothalamic LH releasing hormone (LHRH) by 49% (p < 0.01), with no change in content of the precursor pro-LHRH compared with saline-injected controls. The ratio of LHRH to pro-LHRH was also significantly reduced by EtOH (p < 0.05), compared with control. There was no EtOH-induced change in LHRH mRNA. Compared with saline, EtOH reduced both serum estradiol by 37% (p < 0.02) and progesterone by 47% (p < 0.001). These results show that EtOH has profound disruptive effects on the female HPG axis. Our data suggests that EtOH decreases the releasable LHRH pool either by decreasing conversion of pro-LHRH to LHRH and/or by increasing local LHRH degradation. This acutely restricts the release of LH and subsequent estradiol and progesterone secretion.

Animals↗
PubMed1996

Ethanol-induced alterations in the posttranslational processing, but not secretion of luteinizing hormone-releasing hormone in vitro.

The effects of ethanol (EtOH) on the male hypothalamic pituitary reproductive axis are multiple and varied. Although direct gonadal toxicity has been reported, hypothalamic-pituitary perturbations have also been noted. The difficulty of sampling the hypothalamus has made direct investigation of EtOH-induced alterations on luteinizing hormone-releasing hormone (LHRH) fraught with interpretation problems. To circumvent this, we have conducted a series of experiments exploring the effect of 200 mg% EtOH in vitro on GT1-7 cells, a newly developed LHRH secreting neural cell line. Cell lines were treated with EtOH-containing or EtOH-free media for 2, 6, 24, or 48 hr. EtOH caused no significant change in LHRH secretion at any time point, although there was a trend to increased secretion after 2 hr EtOH exposure when compared with control. Significantly increased total (i.e., cellular plus secreted) pro-LHRH coupled with significantly reduced cellular LHRH after 6 hr only of EtOH exposure suggested that EtOH caused a transient decrease in processing from bioinactive pro-LHRH to bioactive LHRH. However, even at this time point, LHRH secretion from these EtOH-exposed cells was no different than from control cells. Steady-state LHRH mRNA levels were not changed by EtOH at any time point. These findings are concordant with previous in vitro data using hypothalamic tissue that has similarly demonstrated no effect of EtOH on LHRH secretion. Taken together with the in vivo demonstration that EtOH reduces hypothalamic-pituitary portal blood levels of LHRH, these data indicate that EtOH exerts its effect either at an extrahypothalamic locus and/or on non-LHRH-producing cells within the hypothalamus.

Animals↗
PubMed1996

Sustained effects of a single injection of ethanol on the hypothalamic-pituitary-gonadal axis in the male rat.

The hormones responsible for regulating the hypothalamic-pituitary-gonadal axis are essential for proper reproductive function. Ethanol (EtOH) has been shown to exert its effect at all three levels of this axis. The present study defines striking differences in the time course of recovery of luteinizing hormone (LH) in gonadally intact, compared with, castrated male rats after acute EtOH administration. Serum levels of LH and testosterone were measured at various time points up to 2 weeks (1.5, 3, 24, 48, 72, 96, 168, and 336 hr) after a single intraperitoneal injection of either saline or 3 g/kg of EtOH in intact adult male rats. One EtOH injection significantly suppressed testosterone levels as low as 20% (p < 0.01) of saline-injected intact rats. This occurred as early as 1.5 hr after EtOH administration (the first measured time point), and statistically significant suppression was sustained for 96 hr. Similarly, LH levels showed a significant decrease. However, this significant fall in LH did not begin until 3 hr (p < 0.05) and continued up to 96 hr (p < 0.01), with a gradual return to control levels at 168 and 336 hr after treatment. Despite the significant and prolonged fall in testosterone levels in the EtOH-treated intact rats, beta-LH mRNA levels were inappropriately not elevated, as would be expected in the context of low circulating testosterone. However, at 168 and 336 hr, steady-state levels of beta-LH mRNA were significantly higher than seen in saline-injected controls (p < 0.05 and p < 0.01, respectively), temporally correlating with the return of serum LH to control. LH levels in the castrated animals were significantly suppressed at 1.5 hr (p < 0.05) and 3 hr (p < 0.01) after EtOH treatment, compared with controls, yet they returned much more quickly by 24 hr after treatment. beta-LH mRNA levels of castrated animals also showed a significant depression at 1.5 and 3 hr, and returned to control levels by 24 hr. In these rats, the hypothalamic LH-releasing hormone mRNA levels were not altered by a single EtOH injection at any time point. However, in the intact animals, there was a transient increase in LH-releasing hormone mRNA at 72 and 96 hr (p < 0.01 and p < 0.05, respectively) that may lead to the upregulation of beta-LH mRNA expression. These studies indicate that EtOH causes prolonged decreases in important serum hormones that are essential to the reproductive axis of the adult male rat.

Animals↗
PubMed1995

Failure of ethanol metabolites to alter gonadotropin secretion or luteinizing hormone synthesis in vitro.

The impact of ethanol on the male reproductive axis are multiple and varied, with both gonadal and control hypothalamic-pituitary pertubations being reported. There appears to be a discrepancy, however, between the in vivo and in vitro effects of ethanol on hypothalamic luteinizing hormones releasing hormone (LHRH) and the pituitary gonadotropins luteinizing hormone (LH) and follicle stimulating hormone (FSH). While in vivo data suggests a decrease in LHRH release after EtOH, in vitro studies find no effect on secretion. Similarly, in vivo acute EtOH profoundly diminishes LH synthesis and secretion, while in vitro impaired release with no alteration in the transcription of beta LH has been found. A potential exploration for these discrept results could be the in vivo metabolism of EtOH into acetaldehyde and acetate, or the subsequent formation of salsolinol, a product of acetate combining with dopamine. To test this possibility, a series of in vitro experiments were conducted exposing dispensed anterior pituitary cells from male rats to different doses of acetaldehyde, acetate or salsolinol for varying amounts of time for which gonadotropin secretion and beta LH mRNA levels were assessed. The results demonstrated no effect of either acetaldehyde or acetate on basal or LHRH stimulated LH release, FSH release or steady-state beta LH mRNA levels. These data suggest that the metabolites of EtOH, which occur in vivo but not in vitro, are not responsible for the discrepant gonadotropin changes reported between the in vivo and in vitro setting. Other potential mechanisms to explain this phenomenon include differences in the molarity of EtOH, hyperprolactinemia and suprapituitary influences including hypothalamic LHRH, catecholamines, excitatory amino acids, substance P and beta endorphin.

Acetaldehyde↗
PubMed1994

The effect of in vitro ethanol exposure on luteinizing hormone and follicle stimulating hormone mRNA levels, content, and secretion.

It has been previously shown that acute ethanol (EtOH) exposure in vivo resulted in suppression of serum LH and pituitary beta-LH subunit mRNA levels in castrated male rats. While serum FSH levels also were noted to fall after in vivo, the mRNA for beta-FSH was not altered. The aim of the present studies was to determine whether these effects could be accounted for by a direct EtOH effect at pituitary level. To this end we examined the direct effect of EtOH on LH and FSH synthesis and secretion utilizing dispersed anterior pituitary cells from gonadectomized adult male rats. After a 72 hour post dissociation healing period, the cells were exposed to media containing 0 or 200 mg% EtOH for one hour. The media was removed and the cells incubated with EtOH-free media for an additional 1, 3 or 6 hrs. In the EtOH exposed cells, secretion of both LH and FSH increased to > 300% (p < 0.001) of control. At 6 hrs after withdrawal of EtOH a significant reduction in both LH and FSH secretion was seen. Intracellular content of LH and FSH was unchanged before and after withdrawal of EtOH. Steady state levels of beta LH and beta FSH mRNA were unchanged at all time points. In a separate series of experiments, pituitary cells from gonadectomized adult male rats were continuously exposed to different concentrations of EtOH ranging from 0-400 mg% for 3 hrs. LH secretion was stimulated by 400 mgm% EtOH only, while the intracellular content of LH was significantly reduced with the 400 mg% dose. The secretion of FSH was stimulated by 200 mg% and 400 mg% high dose EtOH after 3 hours, with concomitant reduction in FSH pituitary content at both these EtOh dose levels. The mRNA for both beta-LH and beta FSH was not different with any dose of EtOH compared to levels of control, non-EtOH exposed cells. We conclude that though there were similarities between in vivo and in vitro LH and FSH responses to EtOH, the differences reported here indicate that the in vivo responses are not totally explained by a direct EtOH effect at pituitary level. Rather, they must, in addition, reflect action at suprapituitary site(s), pituitary effects of EtOH metabolites or condensation products, and/or alterations in LH and FSH clearance.

Animals↗
PubMed1993

Failure of ethanol to induce changes in gonadotropin gene expression in selectively bred ethanol-sensitive rats.

The recent availability of genetically altered rat lines differing in sensitivity to ethanol (EtOH) has allowed deeper investigation into the mechanisms of EtOH-induced cellular toxicity in several systems. Since the male central reproductive axis has been demonstrated to be exquisitely sensitive to EtOH, studies were undertaken to determine if the gonadotropin suppression reported earlier could be duplicated in one of these selected rat lines. Castrated high alcohol sensitivity (HAS), low alcohol sensitivity (LAS) and control alcohol sensitivity (CAS) rats were given EtOH or saline acutely. Castrated non-selectively bred Sprague Dawley rats were treated similarly and used as an additional control. At sacrifice, serum and pituitary luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels were obtained and the mRNA levels for both gonadotropins assessed. In the selectivity bred animal there was essentially no change in serum or pituitary LH or FSH levels between EtOH and saline treated animals. The mRNA levels for both LH and FSH similarly were unaffected by EtOH, in striking contrast to the non-selectively bred Sprague Dawley rats where serum LH, FSH and beta-LH mRNA levels are markedly suppressed after EtOH exposure. The selectively bred lines of rats genetically manipulated for high or low EtOH sensitivity, as well as their non-selected controls, appeared to have a hypothalamic-pituitary reproductive unit that is resistant to EtOH. This is in contrast to Sprague-Dawley rats, where suppression of this axis previously has been consistently demonstrated.

Animals↗
PubMed1992

The effect of acute in vivo ethanol exposure on follicle stimulating hormone transcription and translation.

The impact of ethanol (EtOH) on male rodent reproduction has been well characterized for luteinizing hormone (LH) with suppression of LH release from the pituitary being reported. We have previously reported that acute ethanol (EtOH) exposure in vivo results in rapid and marked suppression of beta-LH gene expression and protein release from the pituitary. This suppression of beta-LH gene expression was unaccompanied by a change in the common alpha-subunit mRNA. To further explore the impact of ethanol on male rodent reproduction, we have expanded our studies to follicle stimulating hormone (FSH) and hypothalamic luteinizing hormone releasing hormone (LHRH) as well as of pituitary protein kinase C (PKC). Previously castrated male rats were acutely exposed to EtOH and a dramatic reduction in both serum FSH and LH levels was noted at 1.5 and 3 hr after treatment. These levels returned to saline injected control values at 6 and 24 hr. Despite the fall in serum FSH, there was no change in intrapituitary FSH content at any time point; this lack of pituitary FSH depletion in the face of a fall in serum levels is suggestive of impaired FSH release. In contrast to the fall in beta-LH steady-state mRNA levels seen previously and confirmed in the present studies, there was no change in beta-FSH steady-state mRNA at any time point suggesting that EtOH has dichotomous effects on the expression of these two gonadotropins. Pituitary PKC levels were also assessed and found to be unaffected by EtOH at any time point.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholic Intoxication↗