Fetal alcohol exposure and effects of LHRH and PMA on LH beta-mRNA expression in the female rat

Prenatal ethanol exposure and changes in fetal neuroendocrine metabolic programming

Prenatal ethanol exposure (PEE) (mainly through maternal alcohol consumption) has become widespread. However, studies suggest that it can cause intrauterine growth retardation (IUGR) and multi-organ developmental toxicity in offspring, and susceptibility to various chronic diseases (such as neuropsychiatric diseases, metabolic syndrome, and related diseases) in adults. Through ethanol's direct effects and its indirect effects mediated by maternal-derived glucocorticoids, PEE alters epigenetic modifications and organ developmental programming during fetal development, which damages the offspring health and increases susceptibility to various chronic diseases after birth. Ethanol directly leads to the developmental toxicity of multiple tissues and organs in many ways. Regarding maternal-derived glucocorticoid-mediated IUGR, developmental programming, and susceptibility to multiple conditions after birth, ethanol induces programmed changes in the neuroendocrine axes of offspring, such as the hypothalamus-pituitary-adrenal (HPA) and glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axes. In addition, the differences in ethanol metabolic enzymes, placental glucocorticoid barrier function, and the sensitivity to glucocorticoids in various tissues and organs mediate the severity and sex differences in the developmental toxicity of ethanol exposure during pregnancy. Offspring exposed to ethanol during pregnancy have a "thrifty phenotype" in the fetal period, and show "catch-up growth" in the case of abundant nutrition after birth; when encountering adverse environments, these offspring are more likely to develop diseases. Here, we review the developmental toxicity, functional alterations in multiple organs, and neuroendocrine metabolic programming mechanisms induced by PEE based on our research and that of other investigators. This should provide new perspectives for the effective prevention and treatment of ethanol developmental toxicity and the early prevention of related fetal-originated diseases.

The effects of alcohol on testosterone synthesis in men: a review

INTRODUCTION

Testosterone concentrations in men decline with advancing age, with low testosterone concentrations being associated with multiple morbidities, an increased risk of early mortality, and a reduced quality of life. The purpose of this study was to examine the effects of alcohol on testosterone synthesis in men by investigating its effects on each level of the hypothalamic-pituitary-gonadal axis.

AREAS COVERED

Acute consumption of a low-to-moderate amount of alcohol increases testosterone concentrations in men, while consumption of a large volume of alcohol is associated with a reduction in serum testosterone concentrations. Elevated testosterone concentrations result from the increased activity of detoxification enzymes in the liver. Conversely, the primary mechanisms of action involved in the reduction of testosterone are increased hypothalamic-pituitary-adrenal axis activity, inflammation, and oxidative stress. When alcohol is consumed in excess, particularly chronically, it negatively affects testosterone production in men.

EXPERT OPINION

Since testosterone is an important component of men's health and wellbeing, current levels of alcohol consumption in many countries of the world require urgent attention. Elucidating the relationship between alcohol consumption and testosterone may be useful in identifying strategies to attenuate the testosterone-reducing effects of excessive or chronic alcohol consumption.

Effects of prenatal ethanol exposure on hypothalamic-pituitary-adrenal function across the estrous cycle

BACKGROUND

Rats prenatally exposed to ethanol (E) typically show increased hypothalamic-pituitary-adrenal (HPA) responses to stressors in adulthood. Importantly, prenatal ethanol may differentially alter stress responsiveness in male and female offspring, suggesting a role for the gonadal hormones in mediating the effects of ethanol on HPA activity. We investigated the role of ethanol-induced changes in hypothalamic-pituitary-gonadal (HPG) activity in the differential HPA regulation observed in E compared to control females across the estrous cycle.

METHODS

Peripheral hormones and changes in central neuropeptide mRNA levels were measured across the estrous cycle in adult female offspring from E, pair-fed (PF) and ad libitum-fed control (C) dams.

RESULTS

Ethanol females showed normal estrous cyclicity (vaginal smears) but delayed sexual maturation (vaginal opening). Both HPG and HPA activity were differentially altered in E (and in some cases, PF) compared to control females as a function of estrous cycle stage. In relation to HPG activity, E and PF females had higher basal and stress estradiol (E(2)) levels in proestrus compared to other phases of the cycle, and decreased GnRH mRNA levels compared to C females in diestrus. Further, E females had greater variation in LH than PF and C females across the cycle, and in proestrus, only E females showed a significant LH increase following stress. In relation to HPA activity, both basal and stress CORT levels and overall ACTH levels were greater in E than in C females in proestrus. Furthermore, AVP mRNA levels were increased overall in E compared to PF and C females.

CONCLUSIONS

These data demonstrate ethanol-induced changes in both HPG and HPA activity that are estrous phase-specific, and support the possibility that changes in HPA activity in E females may reflect differential sensitivity to ovarian steroids. E females appear to have an increased HPA sensitivity to E(2), and a possible shift toward AVP regulation of HPA activity. That PF were similar to E females on some measures suggests that nutritional effects of diet or food restriction played a role in mediating at least some of the changes observed.

Prenatal alcohol exposure increases vulnerability to stress and anxiety-like disorders in adulthood

Children and adults with fetal alcohol spectrum disorder (FASD) have elevated rates of depression and anxiety disorders compared to control populations. The effects of prenatal alcohol exposure (PAE) on anxiety, locomotor activity, and hormonal reactivity in male and female rats tested on the elevated plus maze (EPM), a task commonly used to assess anxiety-like behaviors in rodents, were examined. Pregnant dams were assigned to PAE, pair-fed (PF), or ad libitum-fed control (C) groups. At adulthood, half of all male (N= 60) and female (N= 60) PAE, PF, and C offspring were exposed to 10 days of chronic mild stress (CMS); the other half remained undisturbed. Animals were then tested on the EPM, and blood collected 30 min posttest for analysis of corticosterone (CORT), testosterone, estradiol, and progesterone. Overall, CMS exposure produced a significant anxiogenic profile. Moreover, CMS increased anxiety-like behavior in PAE males and females compared to controls and eliminated the locomotor hyperactivity observed in nonstressed PAE females. CMS also increased post-EPM CORT, testosterone, and progesterone levels in all groups, with CORT and progesterone levels significantly higher in PAE than in C females. By contrast, CMS selectively lowered estradiol levels in PAE and PF, but not C, females. CMS exposure reveals sexually dimorphic behavioral and endocrine alterations in PAE compared to C animals. Together, these data suggest the possibility that fetal reprogramming of hypothalamic-pituitary-adrenal (HPA) and -gonadal (HPG) systems by alcohol may underlie, at least partly, an enhanced susceptibility of fetal alcohol-exposed offspring to depression/anxiety-like disorders in adulthood.

Prenatal alcohol exposure: foetal programming, the hypothalamic-pituitary-adrenal axis and sex differences in outcome

Prenatal exposure to alcohol has adverse effects on offspring neuroendocrine and behavioural functions. Alcohol readily crosses the placenta, thus directly affecting developing foetal endocrine organs. In addition, alcohol-induced changes in maternal endocrine function can disrupt the normal hormonal interactions between the pregnant female and foetal systems, altering the normal hormone balance and, indirectly, affecting the development of foetal metabolic, physiological and endocrine functions. The present review focuses on the adverse effects of prenatal alcohol exposure on offspring neuroendocrine function, with particular emphasis on the hypothalamic-pituitary-adrenal (HPA) axis, a key player in the stress response. The HPA axis is highly susceptible to programming during foetal and neonatal development. Here, we review data demonstrating that alcohol exposure in utero programmes the foetal HPA axis such that HPA tone is increased throughout life. Importantly, we show that, although alterations in HPA responsiveness and regulation are robust phenomena, occurring in both male and female offspring, sexually dimorphic effects of alcohol are frequently observed. We present updated findings on possible mechanisms underlying differential effects of alcohol on male and female offspring, with special emphasis on effects at different levels of the HPA axis, and on modulatory influences of the hypothalamic-pituitary-gonadal hormones and serotonin. Finally, possible mechanisms underlying foetal programming of the HPA axis, and the long-term implications of increased exposure to endogenous glucocorticoids for offspring vulnerability to illnesses or disorders later in life are discussed.

Mechanisms involved in central nervous system dysfunctions induced by prenatal ethanol exposure

Clinical and experimental evidence has demonstrated that ethanol is a teratogen, and that its consumption during pregnancy induces harmful effects on the developing foetus that leads to foetal alcohol syndrome (FAS). Central nervous system dysfunctions are the most severe and permanent consequence of maternal alcohol intake and can occur in absence of gross morphological defects associated with FAS. Mental retardation and long-term cognitive and behavioural deficits are some of the problems commonly found in children of women who were moderate or heavy drinkers during pregnancy. Experimental evidence demonstrates that alcohol interferes with many molecular, neurochemical and cellular events occurring during the normal development of the brain. Some brain areas are more affected than others and, even within a given region, some cell populations are more vulnerable than others. The neocortex, hippocampus and cerebellum are especially susceptible to alcohol and have been associated with the behavioural deficits. For example, alcohol exposure during the development of neocortex increases natural apoptosis and induces cell necrosis. These effects may be associated with ethanol-induced alterations in both neurotrophic support, and the expression of cell adhesion molecules, which may affect cell-cell interactions and cell survival. Experimental evidence also shows that alcohol disrupts radial glial and astroglial development which may lead to alterations in cell migration and neuronal survival and differentiation. Impairment of several neurotransmitter systems and/or their receptors, as well as changes in the endocrine environment during brain development, are also important factors involved in the neurodevelopmental liabilities observed after in utero alcohol exposure.

Gonadotropin-releasing hormone mRNA and gonadotropin beta-subunit mRNA expression in the adult female rat exposed to ethanol in utero

Previous studies have demonstrated that exposure of female rats to ethanol in utero results in long-term deficits in reproductive function, including a delayed onset of puberty and an early onset of acyclicity. In the present studies, we determined if changes in reproduction are correlated with changes in gonadotropin-releasing hormone (GnRH) mRNA expression in the brain or gonadotropin subunit mRNA expression in the anterior pituitary gland. We used in situ hybridization histochemical techniques to examine the density of GnRH mRNA and the distribution of GnRH mRNA-containing cells in the basal forebrain, and reverse transcription-polymerase chain reaction (RT-PCR) to quantitate the beta-subunit mRNA of luteinizing hormone (LH beta) and follicle-stimulating hormone (FSH beta) in the anterior pituitary gland of adult (3 months of age) fetal alcohol-exposed (FAE) female rats. For GnRH mRNA measurements, animals were gonadectomized 4 days before use. Three groups of animals were examined. FAE females were derived from pregnant dams fed a liquid diet containing 35% ethanol-derived calories from gestational day 14 until parturition. Dams of control animals were either pair-fed (PF) an isocaloric diet with sucrose substituted for ethanol or maintained on normal laboratory rat chow [chow-fed (CF)]. Serial blood samples taken by indwelling right atrial cannulae demonstrated significantly smaller pulses of LH (p < 0.05) and FSH (p < 0.05) in ovariectomized FAE females at 3 months of age, compared with PF and CF controls. Distribution of GnRH mRNA-containing cells was mapped throughout the forebrain, and the number of autoradiographic silver grains/cell was determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Loss of reproductive competence at an earlier age in female rats exposed prenatally to ethanol

Previous studies have shown that prenatal ethanol exposure can partially masculinize or defeminize neurobehavioral development of female rats. An early age of onset of anovulation is one of the primary characteristics of partial defeminization. Consequently, we examined the occurrence of anovulation in fetal alcohol-exposed (FAE) female rats at 2, 6, and 12 months of age using both vaginal cytology as well as wheel-running behavior. We assessed the ability of estrogen and progesterone to elicit proprioceptive behaviors and lordosis at 2 and 17 months of age. Female subjects were derived from Sprague-Dawley dams administered an ethanol liquid diet (35% ethanol-derived calories), a pair-fed isocaloric liquid diet, or fed lab chow from days 14 to 22 of gestation. Litter representatives were placed in a computer-monitored wheel-running apparatus under a 12-hr lighting schedule from 49 to 60 days of age. Vaginal smears were taken from littermates during this same period. This same procedure was conducted again from 180 to 196 and from 380 to 396 days of age, except that vaginal cytology was examined in the same animals immediately after wheel-running behavior was studied. At approximately 2 months of age, a normal cyclical pattern of wheel-running, characteristic of 4- to 5-day estrus cycles, was observed in all animals. No differences were detected in mean activity levels during the wheel-running period. This was accompanied by normal cyclic vaginal cytology and normal proprioceptive behaviors and lordosis. At 6 months of age, FAE females exhibited significantly reduced wheel-running.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in the reproductive system following acute prenatal exposure to ethanol or methylazoxymethanol in the rat: I. Effects on immunoreactive LHRH cell number

It has long been recognized that ethanol (EtOH) interferes with the hypothalamo-pituitary-gonad axis in adults of many species, and recent studies have provided evidence for similar effects after prenatal EtOH exposure. Since EtOH is capable of injuring dividing cells, we investigated the possibility that a single acute in utero EtOH exposure during the period of LHRH neuron formation might change the number of immunoreactive LHRH cells in the hypothalamus. Final LHRH cell division in Long-Evans rats was determined by [3H]thymidine autoradiography to take place over a short period between gestation days 12 and 13. Subsequently, pregnant rats were treated acutely with either EtOH or methylazoxymethanol (MAM), a known neuroteratogen, and the numbers of immunoreactive LHRH cells were counted. On gestation day 22, LHRH-positive cell numbers were significantly fewer than control numbers in both EtOH- and MAM-exposed offspring. On postnatal day 60, cell numbers in EtOH-exposed offspring did not differ from control numbers, whereas cells in MAM-exposed offspring remained significantly reduced. In controls, there were 40% fewer LHRH-positive cells on postnatal day 4 than in late gestation or at maturity. We conclude that 1) acute exposure to a high dose of EtOH at a critical time in early gestation can alter the expression of LHRH in late gestation; 2) exposure to MAM in the same period alters LHRH expression before birth and in the adult; and 3) in the early postnatal period, LHRH expression decreases profoundly.

Comparison of two weeks versus one week of prenatal ethanol exposure in the rat on gonadal organ weights, sperm count, and onset of puberty

Sprague-Dawley dams from Harlan Ind. (Indianapolis, IN) were administered a fortified ethanol liquid diet containing 35% ethanol derived calories for two weeks (E-2) beginning on day 7 or one week (E-1) beginning on day 13 of gestation and continuing through parturition. Control dams were pair-fed an isocaloric liquid diet containing no ethanol during these periods or remained on lab chow and water. E-2 dams consumed an average of 13.52 g ethanol/kg bwt during the first week of exposure (days 8-14) and 12.50 g ethanol/kg bwt the second week (days 14-20). E-1 dams consumed significantly less than E-2 dams during the second week (9.75 g/kg; p < 0.0001). Although the lower consumption in E-1 dams led to a significant decrease in maternal weight gained during the few days of pregnancy compared to E-2 dams, birthweights of E-1 offspring were significantly heavier than those of E-2 offspring (p < 0.05). No effect of ethanol was detected on anogenital distance at birth in either sex. Puberty was delayed in female offspring of both E-1 and E-2 dams (p < 0.01) as measured by age of vaginal opening. These data suggest that the primary teratogenic actions of ethanol in the rat on fetal growth, as well as delayed puberty in females, occur in the last week of gestation. In adult E-2 males, testis weight was significantly heavier than all other groups when indexed to body weight. No effect of prenatal ethanol exposure was observed on the indexed weights of prostate, epididymis, or seminal vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)