Prenatal exposure to ethanol alters the ontogeny of the beta-endorphin response to stress

Role of corticosterone in anxiety- and depressive-like behavior and HPA regulation following prenatal alcohol exposure

Prenatal alcohol exposure (PAE) is known to cause dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, including hyperresponsivity to stressors. Dysregulation of the HPA axis plays a role in vulnerability to stress-related disorders, such as anxiety and depression. Thus, the effects of PAE on HPA function may result in increased vulnerability to the effects of stress and, in turn, lead to the development of stress-related disorders. Indeed, individuals prenatally exposed to alcohol have an increased risk of developing anxiety and depression. However, it is unclear whether hypersecretion of corticosterone (CORT) in response to stress per se is involved with mediating differential effects of stress in PAE and control animals. To investigate the role of CORT in mediating effects of stress in both adult females and males following PAE, adrenalectomy with CORT replacement (ADXR) was utilized to produce similar CORT levels among prenatal treatment groups before exposure to chronic unpredictable stress (CUS). Anxiety-like behavior was evaluated using the open field and elevated plus maze, and depressive-like behavior was examined in the forced swim test. Mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) mRNA expression was assessed in the medial prefrontal cortex (mPFC), amygdala, and hippocampal formation. Under the non-CUS condition, PAE alone differentially altered anxiety-like behavior in sham but not ADXR females and males, with females showing decreased anxiety-like behavior but males exhibiting increased anxiety-like behavior compared to their control counterparts. There were no effects of PAE alone on depressive-like in females or males. PAE also decreased GR mRNA expression in the hippocampal formation in females but had no effects on MR or GR mRNA expression in any brain region in males. CUS had differential effects on anxiety- and depressive-like behavior in PAE and control animals, and these effects were sex dependent. Importantly, ADXR unmasked differences between PAE and control animals, demonstrating that CORT may play a differential role in modulating behavior and HPA activity/regulation in PAE and control animals, and may do so in a sex-dependent manner.

Consumption of Substances of Abuse during Pregnancy Increases Consumption in Offspring: Possible Underlying Mechanisms

Correlative human observational studies on substances of abuse have been highly dependent on the use of rodent models to determine the neuronal and molecular mechanisms that control behavioral outcomes. This is particularly true for gestational exposure to non-illicit substances of abuse, such as excessive dietary fat, ethanol, and nicotine, which are commonly consumed in our society. Exposure to these substances during the prenatal period has been shown in offspring to increase their intake of these substances, induce other behavioral changes, and affect neurochemical systems in several brain areas that are known to control behavior. More importantly, emerging studies are linking the function of the immune system to these neurochemicals and ingestion of these abused substances. This review article will summarize the prenatal rodent models used to study developmental changes in offspring caused by prenatal exposure to dietary fat, ethanol, or nicotine. We will discuss the various techniques used for the administration of these substances into rodents and summarize the published outcomes induced by prenatal exposure to these substances. Finally, this review will cover some of the recent evidence for the role of immune factors in causing these behavioral and neuronal changes.

Sustained action of developmental ethanol exposure on the cortisol response to stress in zebrafish larvae and adults

Background

Ethanol exposure during pregnancy is one of the leading causes of preventable birth defects, leading to a range of symptoms collectively known as fetal alcohol spectrum disorder. More moderate levels of prenatal ethanol exposure lead to a range of behavioural deficits including aggression, poor social interaction, poor cognitive performance and increased likelihood of addiction in later life. Current theories suggest that adaptation in the hypothalamo-pituitary-adrenal (HPA) axis and neuroendocrine systems contributes to mood alterations underlying behavioural deficits and vulnerability to addiction. In using zebrafish (Danio rerio), the aim is to determine whether developmental ethanol exposure provokes changes in the hypothalamo-pituitary-interrenal (HPI) axis (the teleost equivalent of the HPA), as it does in mammalian models, therefore opening the possibilities of using zebrafish to elucidate the mechanisms involved, and to test novel therapeutics to alleviate deleterious symptoms.

Results and Conclusions

The results showed that developmental exposure to ambient ethanol, 20mM-50mM 1-9 days post fertilisation, had immediate effects on the HPI, markedly reducing the cortisol response to air exposure stress, as measured by whole body cortisol content. This effect was sustained in adults 6 months later. Morphology, growth and locomotor activity of the animals were unaffected, suggesting a specific action of ethanol on the HPI. In this respect the data are consistent with mammalian results, although they contrast with the higher corticosteroid stress response reported in rats after developmental ethanol exposure. The mechanisms that underlie the specific sensitivity of the HPI to ethanol require elucidation.

Involvement of the beta-endorphin neurons of the hypothalamic arcuate nucleus in ethanol-induced place preference conditioning in mice

BACKGROUND

Increasing evidence indicates that mu- and delta-opioid receptors are decisively involved in the retrieval of memories underlying conditioned effects of ethanol. The precise mechanism by which these receptors participate in such effects remains unclear. Given the important role of the proopiomelanocortin (POMc)-derived opioid peptide beta-endorphin, an endogenous mu- and delta-opioid receptor agonist, in some of the behavioral effects of ethanol, we hypothesized that beta-endorphin would also be involved in ethanol conditioning.

METHODS

In this study, we treated female Swiss mice with estradiol valerate (EV), which induces a neurotoxic lesion of the beta-endorphin neurons of the hypothalamic arcuate nucleus (ArcN). These mice were compared to saline-treated controls to investigate the role of beta-endorphin in the acquisition, extinction, and reinstatement of ethanol (0 or 2 g/kg; intraperitoneally)-induced conditioned place preference (CPP).

RESULTS

Immunohistochemical analyses confirmed a decreased number of POMc-containing neurons of the ArcN with EV treatment. EV did not affect the acquisition or reinstatement of ethanol-induced CPP, but facilitated its extinction. Behavioral sensitization to ethanol, seen during the conditioning days, was not present in EV-treated animals.

CONCLUSIONS

The present data suggest that ArcN beta-endorphins are involved in the retrieval of conditioned memories of ethanol and are implicated in the processes that underlie extinction of ethanol-cue associations. Results also reveal a dissociated neurobiology supporting behavioral sensitization to ethanol and its conditioning properties, as a beta-endorphin deficit affected sensitization to ethanol, while leaving acquisition and reinstatement of ethanol-induced CPP unaffected.

Prenatal alcohol exposure alters biobehavioral reactivity to pain in newborns

OBJECTIVES

To examine biobehavioral responses to an acute pain event in a Cape Town, South Africa, cohort consisting of 28 Cape Colored (mixed ancestry) newborns (n = 14) heavily exposed to alcohol during pregnancy (exposed), and born to abstainers (n = 14) or light (< or = 0.5 oz absolute alcohol/d) drinkers (controls).

METHODS

Mothers were recruited during the third trimester of pregnancy. Newborn data were collected on postpartum day 3 in the maternity obstetrical unit where the infant had been delivered. Heavy prenatal alcohol exposure was defined as maternal consumption of at least 14 drinks/wk or at least 1 incident of binge drinking/mo. Acute stress-related biobehavioral markers [salivary cortisol, heart rate (HR), respiratory sinus arrhythmia (RSA), spectral measures of heart rate variability (HRV), and videotaped facial actions] were collected thrice during a heel lance blood collection (baseline, lance, and recovery). After a feeding and nap, newborns were administered an abbreviated Brazelton Neonatal Behavioral Assessment Scale.

RESULTS

There were no between-group differences in maternal age, marital status, parity, gravidity, depression, anxiety, pregnancy smoking, maternal education, or infant gestational age at birth (all ps > 0.15). In both groups, HR increased with the heel lance and decreased during the postlance period. The alcohol-exposed group had lower mean HR than controls throughout, and showed no change in RSA over time. Cortisol levels showed no change over time in controls but decreased over time in exposed infants. Although facial action analyses revealed no group differences in response to the heel lance, behavioral responses assessed on the Brazelton Neonatal Scale showed less arousal in the exposed group.

CONCLUSIONS

Both cardiac autonomic and hypothalamic-pituitary-adrenal stress reactivity measures suggest a blunted response to an acute noxious event in alcohol-exposed newborns. This is supported by results on the Brazelton Neonatal Scale indicating reduced behavioral arousal in the exposed group. To our knowledge, these data provide the first biobehavioral examination of early pain reactivity in alcohol-exposed newborns and have important implications for understanding neuro-/biobehavioral effects of prenatal alcohol exposure in the newborn period.

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.

Novel role of adrenergic neurons in the brain stem in mediating the hypothalamic-pituitary axis hyperactivity caused by prenatal alcohol exposure

Exposure to alcohol during embryonic development leads to changes in the hypothalamic-pituitary-adrenal (HPA) axis such that adult offspring release more adrenocorticotrophic hormone (ACTH) than controls when exposed to stress. In the present work, we tested the hypothesis that changes in the activity of the catecholaminergic system modulate, at least in part, this upregulation of the HPA axis. Pregnant Sprague-Dawley rats were exposed to alcohol 6 h daily during gestation days 7-18 using the vapor chamber model, which generated mean blood alcohol levels of 188.6+/-10 mg/dl. All experiments were performed on 2 to 3-month-old offspring. We first measured the ACTH response to i.c.v. injection of adrenergic receptor agonists. In rats exposed to footshocks, we then investigated the activity of corticotrophin-releasing factor (CRF) as well as indexes of catecholamine ir, namely tyrosine hydroxylase (TH) immunopositive neurons in the paraventricular nucleus (PVN), TH immunopositive neurons in the locus coeruleus, and phenylethanolamine N-methyltransferase (PNMT) immunopositive neurons in the brain stem. While adult females exposed to alcohol during fetal development (FAE) displayed the expected enhanced ACTH response to stress, there were no significant differences in response to adrenergic receptor agonists or in shock-induced CRF/TH ir and neuronal activity, as determined by c-fos colocalization. In contrast, FAE female offspring exposed to footshocks showed a significant increase in the activity of adrenergic neurons in the C1 region of the brain stem, a population of cells that project to the PVN. Collectively, these results suggest that while FAE-induced hyperactivity of the HPA axis is not accompanied by significant changes in PVN CRF or TH-ir neurons, it is characterized by an upregulation of C1 adrenergic neurons of the brain stem. This novel finding should lead to the functional characterization of this brain region in the FAE model.

Age and gender differences in response to neonatal ethanol withdrawal and polyamine challenge in organotypic hippocampal cultures

BACKGROUND

Polyamines are synthesized and released in high concentrations during CNS development. These agents can potentiate N-methyl-D-aspartate receptor (NMDAR) function and appear to play an important role in CNS development. Previous work has shown that polyamine release is increased during ethanol withdrawal (EWD). This likely promotes NMDAR overactivity and contributes to neurotoxicity during EWD, however, little is known regarding such effects in early neonatal brain. The present study compared the effects of EWD and polyamine exposure on toxicity in hippocampal slice cultures derived from postnatal day 2 (PND 2) or postnatal day 8 (PND 8) day-old rats. Due to changes in NMDAR subtypes and response to polyamines, we predicted that slices taken from PND 2 pups would be more sensitive to EWD and polyamine challenge.

METHODS

Organotypic hippocampal slice cultures were obtained from neonatal rats either 2 or 8 days of age (PND 2 or PND 8). Five days after explantation, cultures were exposed to ETOH (50 mM- typically subthreshold for EWD induced cell death) for 10 days and then withdrawn from ETOH for 24-hour in the presence of 100 microM of the polyamine spermidine and/or 100 microM ifenprodil, an NMDAR antagonist that blocks the NMDAR that is the most sensitive to polyamine modulation. Cytotoxicity was measured after 24-hour by visualization of propidium iodide (PI) fluorescence.

RESULTS

There were clear age and gender-dependent differences in response to EWD and to polyamines. EWD produced significant increases in PI uptake in all subregions (CA1, CA3 and DG) of cultures derived from PND 2 pups, but not PND 8 pups. Exposure of cultures to spermidine for 24-hour also produced significant increases in cytotoxicity in all 3 regions of PND 2 cultures with no gender differences. In contrast, there were both gender and region-specific differences in response to spermidine in cultures from PND 8. While the CA1 region of both sexes displayed increased cytotoxicity following spermidine exposure, only females showed increased cytotoxicity in the CA3 region while the DG appeared relatively insensitive to spermidine. Exposure to spermidine during EWD produced enhanced toxicity in all 3 hippocampal subregions in tissue from both PND 2 and PND 8 rats and this was reduced or prevented by co-exposure to ifenprodil. Of interest, the PND 2 hippocampus was significantly more sensitive than the PND 8 hippocampus to the toxic effects of EWD and to spermidine during EWD in the DG and CA3 regions.

CONCLUSIONS

Hippocampal slice cultures derived from PND 2 rats were more sensitive to the toxic effects of both EWD and EWD + spermidine exposure than were those derived from PND 8 rats. These findings are similar to recent behavioral data collected from our lab showing greater sensitivity to ETOH's behavioral teratogenic effects when ETOH exposure in vivo occurred during the first postnatal week relative to the second postnatal week. Ifenprodil's ability to block the toxic effects of spermidine during EWD suggests that excess activity of NR2B subunits of the NMDAR contributed to the excitatory and cytotoxic effects of EWD plus spermidine. While no sex differences in toxicity were observed in cultures taken from pups during the first postnatal week, these data do suggest that later in neonatal life (i.e., the second postnatal week), the female hippocampus may be more sensitive to polyamine-induced neurotoxicity than males.

Effects of Prenatal Ethanol Exposure on Basal Limbic?Hypothalamic?Pituitary?Adrenal Regulation: Role of Corticosterone

BACKGROUND

Rats prenatally exposed to ethanol (E) exhibit hypothalamic-pituitary-adrenal (HPA) hyperresponsiveness and changes in central HPA regulation following exposure to stressors. Whether ethanol-induced alterations in basal HPA regulation play a role in mediating HPA hyperresponsiveness remains unclear. We utilized adrenalectomy (ADX), with or without corticosterone (CORT) replacement, to investigate basal HPA function and the role of CORT in mediating ethanol-induced alterations.

METHODS

Adult males and females from prenatal E, pair-fed (PF), and ad lib-fed control (C) groups were terminated at the circadian peak, 7 days following sham surgery or ADX, with or without CORT replacement. Plasma levels of CORT and adrenocorticotropin (ACTH), and mRNA levels of corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) in the paraventricular nucleus, CRH Type 1 receptor (CRH-R1) and pro-opiomelanocortin (POMC) in the anterior pituitary, and mineralocorticoid (MR) and glucocorticoid (GR) receptors in the dorsal hippocampus were determined.

RESULTS

Adrenalectomy resulted in significantly greater plasma ACTH elevations in E and PF males, and parallel CRH mRNA elevations in both E and PF males and females compared with their C counterparts. In contrast, pituitary CRH-R1 mRNA levels were lower in E compared with C males, with no differences in POMC. In addition, in response to ADX, E females showed a greater MR mRNA response, and E males showed a greater GR mRNA response compared with their C counterparts, and CORT replacement was ineffective in normalizing ADX-induced alterations in ACTH levels in E and PF females, hippocampal MR mRNA levels in E males, and AVP mRNA levels in PF males and females.

CONCLUSIONS

Together, these data indicate that the prenatal ethanol exposure induces HPA dysregulation under basal conditions at multiple levels of the axis, resulting in alterations in both HPA drive and feedback regulation and/or in the balance between drive and feedback. While some effects may be nutritionally mediated, it appears that the mechanisms underlying basal HPA dysregulation may differ between E and PF animals rather than occurring along a continuum of effects on the same pathway. Altered basal HPA tone may play a role in mediating the HPA hyperresponsiveness to stressors observed in E offspring.

Hypothalamic?Pituitary?Adrenal Responses to 5-HT1Aand 5-HT2A/CAgonists Are Differentially Altered in Female and Male Rats Prenatally Exposed to Ethanol

BACKGROUND

Prenatal ethanol exposure alters the development of the hypothalamic-pituitary-adrenal (HPA) axis, resulting in HPA hyper-responsiveness to stressors in adulthood. Prenatal ethanol exposure also alters the development and activity of the serotoninergic (5-HT) system. We have previously shown that 5-HT(1A) and 5-HT(2A/C) receptor-mediated behavioral and physiological function are altered in fetal ethanol-exposed offspring. As there are extensive interactions between the HPA axis and the 5-HT system, the present study tested the hypothesis that prenatal ethanol exposure would alter 5-HT(1A) and 5-HT(2A/C) receptor-mediated HPA function.

METHODS

The 5-HT(1A) agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 0.2 mg/kg), and the 5-HT(2A/C) agonist, (+)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI; 0.3 mg/kg), or vehicle (1 mL/kg) were administered to adult female and male offspring from prenatal ethanol-exposed (E), pair-fed control (PF), and ad libitum-fed control (C) dams. The plasma concentration of adrenocorticotropin (ACTH) and corticosterone (CORT) were determined at 0, 15, 30, 60, and 120 minutes postinjection. In addition, corticotropin releasing hormone (CRH) mRNA expression in the paraventricular nucleus of the hypothalamus, and 5-HT(1A) and 5-HT(2A/C) receptor mRNA expression in the hippocampus and prefrontal cortex, respectively, were determined by in situ hybridization.

RESULTS

Ethanol-exposed females showed a blunted ACTH response to 8-OH-DPAT at 15 and 30 minutes, and conversely, an increased ACTH response to DOI at all time points postinjection, compared with PF and C females. Differences among E, PF, and C males failed to reach significance. Centrally, however, DOI resulted in a trend toward lower CRH mRNA levels in E and PF compared with C females, but higher CRH mRNA levels in E compared with control males. There were no differences among prenatal groups in 5-HT(2A) receptor expression in the prefrontal cortex following either 8-OH-DPAT or DOI treatment. However, following 8-OH-DPAT, hippocampal 5-HT(1A) receptor expression was higher in E than in PF females in CA1, with a trend toward higher expression in E than in C females in CA2, whereas following DOI, a prenatal group by subfield interaction suggests lower 5-HT(1A) mRNA levels in E and PF compared with C females in CA1 and the dentate gyrus.

CONCLUSIONS

These data are the first to demonstrate that prenatal ethanol exposure has differential long-term effects on 5-HT(1A)-mediated and 5-HT(2A)-mediated neuroendocrine function in females and males, and suggest a sex-specific ethanol-induced alteration in the interaction between the HPA axis and the serotonin system.

Effects of mineralocorticoid and glucocorticoid receptor blockade on hypothalamic-pituitary-adrenal function in female rats prenatally exposed to ethanol

BACKGROUND

Rats prenatally exposed to ethanol (E) exhibit hypothalamic-pituitary-adrenal (HPA) hyperresponsiveness, demonstrated by increased and/or prolonged elevations of adrenocorticotropic hormone (ACTH) and/or corticosterone (CORT) in response to stressors. The present study examined the possible role of CORT feedback deficits in mediating this hyperresponsiveness by examining HPA function following mineralocorticoid (MR) and glucocorticoid (GR) receptor blockade.

METHODS

Adult female Sprague-Dawley offspring from E, pair-fed (PF), and control (C) groups were injected subcutaneously with the MR antagonist spironolactone (SPIRO; 30 mg/kg bw), the GR antagonist RU38486 (120 mg/kg bw), or vehicle. One hour postinjection, blood samples (0 minutes) were taken via jugular cannulae to obtain a measure of prestress ACTH and CORT levels. Rats were then loosely restrained for 1 hour, and samples were taken during (15, 30, and 60 minutes) and then 1 hour following stress, for determination of plasma ACTH and CORT levels.

RESULTS

Both SPIRO and RU38486 significantly increased prestress ACTH levels in E compared with both PF and C females. In contrast, RU38486 significantly increased ACTH levels in C compared with PF females during stress and in C compared with E females during recovery. CORT levels were increased during stress in E females in response to SPIRO, and RU38486 increased the CORT response during stress in PF and during recovery in E and PF females compared with vehicle.

CONCLUSIONS

E females showed enhanced HPA responses to both MR and GR blockade compared with PF and C before restraint as well as a different pattern of responsivity during and following restraint. While receptor blockade had some effect on CORT responses in PF females, changes in ACTH appear specific to ethanol. These findings suggest that the balance between HPA drive and feedback may be altered in E compared with C females.

Increased ethanol intake after prenatal ethanol exposure: studies with animals

This review analyses the most relevant studies in which ethanol intake was measured after prenatal exposure to the drug. Despite the variety in methodology, in most such studies this prenatal experience induced a higher consumption of ethanol. Several variables that may affect the expression of this phenomenon are discussed, such as gender, age at testing, period of ethanol exposure, ethanol dose and conditions during the test. The mechanisms proposed in all these studies to explain the increased ethanol intake effect are also discussed. Some of these mechanisms are related to the teratological effects of the drug on the neurochemical systems involved in the reinforcing effects of abuse drugs, as well as on the regulatory systems of stress response. Another explanation of this phenomenon is also proposed in terms of associative learning. Specifically, the increased ethanol intake effect may be the result of a conditioned preference for ethanol acquired by the fetus when exposed to the drug during the last days of gestation.

Differences in the Peripheral Levels of ??-endorphin in Response to Alcohol and Stress as a Function of Alcohol Dependence and Family History of Alcoholism

BACKGROUND

Evidence indicates that both genetic and environmental factors, such as stress, may play an important role for the development of alcoholism, while beta-endorphin may be implicated in the control of alcohol consumption. The objective of the present studies was to test the hypothesis that there are differences in the response of the pituitary beta-endorphin system to stress as a function of family history of alcoholism and alcohol dependence.

METHODS

The response of the pituitary beta-endorphin to a placebo or an alcohol (0.50 g ethanol/kg) drink and to a stress task performed 30 min following ingestion of either the placebo or the alcohol drink was measured in social and heavy drinkers with [high risk (HR)] and without [low risk (LR)] a family history of alcoholism. Thus, each subject participated in 4 experimental sessions given on different days in a randomized order. Four groups of subjects were investigated: 1) low risk nonalcoholics (LRNA); 2) high risk nonalcoholics (HRNA), 3) low risk alcoholics (LRA); and 4) high risk alcoholics (HRA). Plasma beta-endorphin was estimated prior to and for 3.5 hr post-stress. Changes in the concentration of plasma beta-endorphin following ingestion of either the placebo or alcohol drink without performance of the stress task served as controls to compare the stress-induced changes.

RESULTS

Basal plasma beta-endorphin levels were higher in LRNA than LRA, HRNA and HRA participants, while basal plasma beta-endorphin levels were higher in LRA than those in HRNA and HRA participants. Furthermore, there was no significant difference in the plasma beta-endorphin levels between HRNA and HRA participants. Stress, induced a significant increase in plasma beta-endorphin concentration in all four groups of participants. However, the stress-induced increase in plasma beta-endorphin levels was more pronounced in LRNA than HRNA, LRA and HRA participants. Thus, alcohol dependence decreased the basal plasma beta-endorphin levels in LR only, as well as the stress induced increase in plasma beta-endorphin levels of participants without, but not of those with, a family history of alcoholism. Alcohol prior to stress attenuated the stress-induced increase in plasma beta-endorphin levels of all four groups of participants.

CONCLUSIONS

The present data indicates that there are differences in both, the basal plasma beta-endorphin levels as well as the response of the pituitary beta-endorphin to stress as a function of family history of alcoholism and alcohol dependence. Thus, in HR individuals a dysfunction in the activity of the pituitary beta-endorphin system predates the development of alcoholism, while in LR individuals it develops following alcohol dependence. Furthermore, alcohol dependence did not alter the alcohol-induced attenuation of beta-endorphin response to stress.

Prenatal alcohol exposure and fetal programming: effects on neuroendocrine and immune function

Alcohol abuse is known to result in clinical abnormalities of endocrine function and neuroendocrine regulation. However, most studies have been conducted on males. Only recently have studies begun to investigate the influence of alcohol on endocrine function in females and, more specifically, endocrine function during pregnancy. Alcohol-induced endocrine imbalances may contribute to the etiology of fetal alcohol syndrome. Alcohol crosses the placenta and can directly affect developing fetal cells and tissues. Alcohol-induced changes in maternal endocrine function can disrupt maternal-fetal hormonal interactions and affect the female's ability to maintain a successful pregnancy, thus indirectly affecting the fetus. In this review, we focus on the adverse effects of prenatal alcohol exposure on neuroendocrine and immune function, with particular emphasis on the hypothalamic-pituitary-adrenal (HPA) axis and the concept of fetal programming. The HPA axis is highly susceptible to programming during fetal development. Early environmental experiences, including exposure to alcohol, can reprogram the HPA axis such that HPA tone is increased throughout life. We present data that demonstrate that maternal alcohol consumption increases HPA activity in both the maternal female and the offspring. Increased exposure to endogenous glucocorticoids throughout the lifespan can alter behavioral and physiologic responsiveness and increase vulnerability to illnesses or disorders later in life. Alterations in immune function may be one of the long-term consequences of fetal HPA programming. We discuss studies that demonstrate the adverse effects of alcohol on immune competence and the increased vulnerability of ethanol-exposed offspring to the immunosuppressive effects of stress. Fetal programming of HPA activity may underlie some of the long-term behavioral, cognitive, and immune deficits that are observed following prenatal alcohol exposure.

Postnatal handling does not normalize hypothalamic corticotropin-releasing factor mRNA levels in animals prenatally exposed to ethanol

Postnatal handling has been shown to attenuate some of the deficits in developmental outcome observed following prenatal ethanol exposure (E) although it appears to be ineffective at ameliorating the hypothalamic-pituitary-adrenal (HPA) hyperresponsiveness to stressors that has been observed in adult E animals. However, the effects of postnatal handling on central regulation of HPA activity in E animals, particularly with regard to alterations in steady-state hypothalamic corticotropin-releasing factor (CRF) activity, have not been examined. In the present study, offspring from E, pair-fed (PF), and ad-libitum-fed control (C) groups were exposed to daily handling during the first 2 weeks of life (H) or were left entirely undisturbed until weaning (NH). Basal CRF and arginine vasopressin (AVP) mRNA in the parvocellular portion of the paraventricular nucleus (pPVN) of the hypothalamus were assessed at 90-110 days of age. Prenatal ethanol exposure resulted in elevated basal pPVN CRF mRNA levels compared to those in ad-libitum-fed controls. Handling altered CRF mRNA levels in a sex-specific and prenatal treatment-specific manner. Females showed no significant effects of handling. In contrast, handling decreased CRF mRNA levels in PF and C but not E males compared to their NH counterparts. There were no effects of prenatal ethanol or postnatal handling on AVP mRNA levels. These findings indicate that prenatal ethanol exposure results in elevated basal CRF mRNA levels in adulthood and that handling appears to be ineffective in normalizing those elevations, supporting the suggestion that altered basal HPA regulation in E animals may, at least in part, underlie their HPA hyperresponsiveness to stressors.

Prenatal ethanol preferentially enhances reactivity of the dopamine D1 but not D2 or D3 receptors in offspring

Reports of prenatal ethanol (ETOH) effects on the dopamine system are inconsistent. In an attempt to clarify this issue, dams were given 35% ethanol-derived calories as the sole nutrient source in a liquid diet from the 10th through the 20th day of gestation (ETOH). Controls were pair-fed (PF) an isocaloric liquid diet or given ad libitum access to laboratory chow (LC). Prenatal exposure to both liquid diets reduced body weight of offspring relative to LC controls, more so for ETOH than for PF exposure. Prenatal ETOH also decreased litter size and viability, relative to both LC and PF control groups. On postnatal days 21-23, male and female offspring were given an injection of saline vehicle or one of eight specific dopamine receptor agonists or antagonists. Immediately after injection subjects were placed in individual observation cages, and over the following 30 min, eight behaviors (square entries, grooming, rearing, circling, sniffing, yawning, head and oral movements) were observed and quantified. No prenatal treatment effects on drug-induced behaviors were observed for dopamine D2 (Apomorphine, DPAT or Quinpirole) or D3 (PD 152255, Nafadotride, Apo or Quin effects on yawning) receptor agonists or antagonists, or for the vehicle control. In contrast, prenatal treatment effects were seen with drugs affecting the dopamine D1 receptor. Both D1 agonists (SKF 38393) and antagonists (SCH 23390 and high doses of spiperone) altered behaviors, especially oral and sniffing behaviors, in a manner which suggested enhanced dopamine D1 drug sensitivity in both ETOH and PF offspring relative to LC controls. These results suggest that at this age, both sexes experience a prenatal undernutrition-linked increase in the behavioral response to dopamine D1 agonists and antagonists, which can be intensified by gestational exposure to alcohol.

Prenatal ethanol exposure and spatial navigation: effects of postnatal handling and aging

Prenatal ethanol exposure results in spatial navigation deficits in young and mid-aged animals. In contrast, postnatal handling attenuates spatial deficits that emerge with age in animals that are not handled. Therefore, we investigated the ability of handling to attenuate spatial deficits in animals prenatally exposed to ethanol (E). Sprague-Dawley male offspring from E, pair-fed (PF), and control (C) groups were handled (H) or nonhandled (NH) from 1 to 15 days of age and tested on the Morris water maze at 2 or 13 to 14 months of age. In young animals, H-E males had longer latencies to locate the submerged platform, and E animals, across handling conditions, showed altered search patterns compared to their PF and C counterparts. Mid-aged animals had longer latencies than young animals, with no differences among E, PF, and C animals. However, corticosterone levels were higher in mid-aged E than in C males. Handling did not attenuate impairments associated with either prenatal ethanol exposure or aging.

Chronic intermittent stress does not differentially alter brain corticosteroid receptor densities in rats prenatally exposed to ethanol

Prenatal ethanol exposure produces hypothalamic-pituitary-adrenal (HPA) hyperresponsiveness to stressors. The present study tested the hypothesis that decreased corticosteroid receptor densities at HPA feedback sites may play a role in deficient feedback inhibition and the resultant HPA hyperresponsiveness that is observed following prenatal ethanol exposure. Brains of adult Sprague-Dawley rats from prenatal ethanol (E), pair-fed (PF) and ad libitum-fed control (C) treatment groups were examined for both mineralocorticoid receptor (MR; Type I) and glucocorticoid receptor (GR; Type II) densities using a cytosolic binding assay. Experiment 1 compared the effects of chronic intermittent stress (Stress Regimen I) and corticosterone (CORT) pellet implants on hippocampal corticosteroid receptor densities in control rats. Experiment 2 determined whether exposure to Stress Regimen I would differentially downregulate and whether adrenalectomy (ADX) would differentially upregulate hippocampal corticosteroid receptors in E compared with PF and C animals. Experiment 3 examined the effects of a modified chronic intermittent stress regimen (Stress Regimen II) on corticosteroid receptor densities at several HPA feedback sites (hippocampus, prefrontal cortex, hypothalamus, and anterior pituitary) in E compared with PF and C animals. CORT pellet implants significantly downregulated hippocampal GR and MR densities in control males and females. Exposure to Stress Regimen I produced downregulation of hippocampal GRs and MRs in males comparable with that produced with CORT pellet implants, and significant downregulation of hippocampal GRs in females across all prenatal treatment groups. This stress regimen also elevated basal plasma CORT levels without concurrent changes in plasma CBG levels, and increased relative adrenal weights in both males and females. In addition, upregulation of hippocampal GRs occurred at 7 days compared with 24 h following ADX in females that had previously been exposed to this stress regimen. Following exposure to Stress Regimen II, both the downregulation of hippocampal corticosteroid receptors and the increase in basal CORT levels in males and females appear to have been abolished by the changes in housing condition during the period of chronic stress. Importantly, prenatal ethanol exposure did not differentially alter GR or MR densities at any feedback site under non-stressed conditions. Exposure to Stress Regimen II, revealed subtle effects of prenatal treatments on hippocampal GRs however it is unlikely that these changes in corticosteroid receptor densities mediated the feedback inhibition deficits observed in E animals. Together, these data demonstrate that: (1) a relatively mild intermittent stress regimen can increase basal CORT levels and downregulate hippocampal corticosteroid receptor densities (2) a seemingly small change in housing conditions during stress appears to eliminate both receptor downregulation and increase in basal CORT levels and (3) decreased corticosteroid receptor densities at HPA feedback sites in the brain do not appear to underlie the HPA hyperresponsiveness observed in E animals.

Effects of maternal ethanol consumption and buspirone treatment on dopamine and norepinephrine reuptake sites and D1 receptors in offspring

Previously, it was shown that in utero ethanol exposure results in decreased serotonin (5-HT) and altered concentrations of 5-HT reuptake sites and 5-HT1A receptors in fetal and/or postnatal rats. Because fetal 5-HT is an essential trophic factor, this laboratory previously investigated the hypotheses that the early ethanol-associated 5-HT deficit contributed to subsequent development abnormalities in the serotonergic system and that the effects of the fetal 5-HT deficit could be prevented by maternal treatment with buspirone, a 5-HT1A receptor agonist. The present report determined the effects of maternal treatment with buspirone on two other neurotransmitter systems in the developing offspring of ethanol-fed dams: dopamine (DA) and norepinephrine reuptake sites and D1 receptors in postnatal day 19 offspring of control and ethanol-fed dams, that received daily injections of saline or 4.5 mg/kg buspirone. These investigations found that in utero ethanol exposure significantly decreased norepinephrine reuptake sites in the dorsomedial hypothalamic nucleus and anteroventral thalamic nucleus. There was also an ethanol effect in the dorsal raphe. D1 receptors were moderately increased (5-10% increase) in the striatum, and DA reuptake sites were unchanged in PN19 ethanol-exposed offspring. No other significant ethanol-related effects were noted. Maternal buspirone treatment did not adversely affect the concentration of DA reuptake sites or D1 receptors in control rats. Thus, whereas buspirone exerts protective effects on the developing 5-HT system of ethanol-exposed rats, it does not appear to damage the development of the DA system. Maternal buspirone produced only one significant abnormality in control offspring; it resulted in significant reduction of norepinephrine reuptake sites in the DR.

Alcohol stimulates ACTH secretion in the rat: mechanisms of action and interactions with other stimuli

This review discusses some of the mechanisms through which alcohol (EtOH) alters the activity of the hypothalamic-pituitary-adrenal (HPA) axis. In adult rats, acute EtOH treatment increases plasma ACTH and corticosteroids levels primarily by stimulating the release of corticotropin-releasing factor (CRF) and possibly vasopressin (VP) from nerve terminals in the median eminence. Increased CRF gene transcription in the hypothalamus may also be important. The HPA axis remains activated during chronic EtOH exposure, although habituation may take place. Changes in the responsiveness of hypothalamic neurons, a phenomenon itself dependent in part on a number of intermediate secretagogues, as well as decreased pituitary responsiveness to VP, all play a role. Finally, the activity of the HPA axis is influenced by exposure to EtOH during embryonic development, with mature offspring showing hyporesponsiveness to many stimuli. These altered responses appear to be caused in part by changes in the synthesis/release CRF, possibly under the influence of nitric oxide. CRF, VP, ACTH, and corticosteroids are important regulators of the immune system, behavior, metabolic pathways, and reproductive parameters. Alcohol therefore may influence such functions through the pathological secretion of these hormones. A better understanding of the mechanisms through which the drug alters their release thus may permit the development of therapies designed to alleviate some of the consequences of alcoholism.

Fetal ethanol exposure alters pituitary-adrenal sensitivity to dexamethasone suppression

The present study investigated the hypothesis that a deficit in feedback inhibition of the hypothalamic-pituitary-adrenal (HPA) axis may underlie the hormonal hyperresponsiveness seen in fetal ethanol-exposed rats. Male and female Sprague-Dawley rats from prenatal ethanol (E), pair-fed (PF) and ad lib-fed control (C) treatment groups were tested in adulthood. The effects of dexamethasone (DEX) blockade on basal and stress corticosterone (CORT) levels and stress adrenocorticotropin (ACTH) levels were examined over a 36-h period. Stress CORT and ACTH levels after DEX administration at the trough (AM) and peak (PM) of the CORT circadian rhythm were compared. DEX administration significantly suppressed both resting and stress levels of CORT and ACTH in all animals, regardless of prenatal treatment. Importantly, E animals did not differ from PF and C animals in basal CORT. However, E males and females had significantly higher stress levels of CORT and/or ACTH than PF and C animals, and further, showed differential responsiveness following DEX administration depending on the time of day when testing occurred. At the trough of the CORT circadian rhythm. E males did not differ from PF and C males, whereas E females had increased stress levels of CORT compared to PF and C females. In contrast, at the peak of the circadian rhythm, E males showed increased stress levels of CORT but not ACTH, whereas E females showed increased stress levels of both CORT and ACTH compared to males and females in respective control groups. These data support the hypothesis that E animals may exhibit deficits in HPA feedback inhibition compared to controls and suggest a sex-specific difference in sensitivity of the mechanism underlying HPA hyperresponsiveness.

Fetal ethanol exposure: hypothalamic-pituitary-adrenal and beta-endorphin responses to repeated stress

Previous studies provide evidence that fetal ethanol exposure induces hypothalamic-pituitary-adrenal (HPA) and pituitary beta-endorphin (beta-EP) hyperresponsiveness to acute stressors. The present study demonstrates significant effects of in utero ethanol exposure on the parallel response patterns of the HPA axis and the pituitary beta-EP system to repeated exposures to a stressor, restraint stress, and indicates sex differences in response. Together, data from the two experiments indicate that, after repeated restraint exposures, fetal ethanol-exposed (E) males and females both show significantly increased plasma levels of adrenocorticotropin (ACTH), and E males also show significantly increased plasma levels of beta-endorphin-like immunoreactivity (beta-EPLIR), compared with their respective pair-fed and control counterparts. Marginal increases in the corticosterone response of E males and the beta-EPLIR response of E females, compared with their controls, were also observed. In addition, delayed or deficient habituation to restraint stress was observed in the beta-EPLIR response of E males and the ACTH response of E females. These data demonstrate that fetal E-exposed males and females both exhibit hormonal hyperresponsiveness and/or deficits in recovery after repeated exposures to restraint stress, but that the patterns of response may differ depending on the number and duration of restraint exposures, the time course measured, and whether the endpoint measured is corticosterone, ACTH, or beta-EPLIR. In addition, the finding that E and pair-fed animals both differed from their respective controls in certain developmental and hormonal measures suggests that prenatal nutritional factors may play a role in mediating some of the changes that are observed.

Gender differences in the effect of prenatal alcohol exposure on the hypothalamic-pituitary-adrenal axis response to immune signals

Immature (3 week old) rat offspring of alcohol (E)-fed dams show a blunted ACTH response to immune signals such as interleukin-1 beta (IL-1 beta) and endotoxin (LPS). In contrast, mature offspring respond to physical stresses with an exaggerated activation of their hypothalamic-pituitary-adrenal (HPA) axis. The present work was aimed at determining if there was a differential influence of prenatal E exposure on the HPA axis responses to various stressors or if, alternatively, sexual maturation modified these responses. When administered IL-1 beta at 5 weeks age, E-treated intact male offspring released less ACTH, compared to control (C) or pair-fed (PF) animals. However, they showed an augmented response to LPS and a local inflammatory process induced by turpentine injection. At this same age, intact E females secreted significantly more ACTH in response to IL-1 beta, LPS and turpentine, than C or PF offspring. By 9 weeks of age, both E males and E females exhibited larger (p < .05) ACTH responses to all three immune stimuli. In order to determine whether sex steroids modulate the influence of E in females, ovariectomy was done prior to puberty. This treatment decreased the difference in the ACTH released by E and C rats in response to IL-1 beta, LPS and turpentine. These results show that while immature rats exposed to E prenatally released less ACTH in response to cytokines than C or PF animals did, this response was qualitatively reversed after puberty. At that time, the larger amounts of ACTH secreted by E offspring, compared to the other groups, were reminiscent of the hyperactive response of the HPA axis when these offspring were exposed to physical stress. Interestingly, removal of circulating ovarian steroids prevented the influence of E from being exerted. This suggests the presence of a functional relationship between the pathways influenced by prenatal E and those influenced by female sex steroids, that are important in regulating the activity of the HPA axis.

Effects of prenatal ethanol exposure and stress in adulthood on lymphocyte populations in rats

The present study was undertaken to assess the possible interactive effects of prenatal ethanol exposure and stress in adulthood on lymphocyte populations in rat offspring, and to examine differential vulnerability of males and females to these challenges. Male and female offspring from prenatal ethanol-exposed (E), pair-fed, and ad libitum-fed control conditions were exposed to a 3-week chronic intermittent stress regimen in adulthood. Animals were exposed to two of six different stressors daily, one each at random times in the morning and afternoon, with the same pair of stressors being repeated every 4 days. Following the 3-week stress period, lymphocytes from four compartments (peripheral blood, spleen, thymus, and cervical lymph nodes) were analyzed for expression of differentiation antigens. Data demonstrate that, whereas a number of the effects of prenatal ethanol on lymphocyte populations appeared to be nutritionally mediated, the additional challenge of exposure to stressors differentially affected animals exposed to ethanol prenatally and appeared to have effects primarily in male offspring. Stressed E males had a greater reduction in the number of pan T-cells in the thymus and peripheral blood, compared with nonstressed E males, but showed an increased peripheral blood pan T-antigen expression. Stressed E males also had reduced numbers of peripheral blood CD4+ T cells compared to nonstressed E males [corrected].(ABSTRACT TRUNCATED AT 250 WORDS)

Early handling can attenuate adverse effects of fetal ethanol exposure

The effects of early handling on physiological and hormonal responses of rats exposed to ethanol prenatally were studied. Male and female Sprague-Dawley rats from prenatal ethanol (E), pair-fed (PF), and ad lib-fed control (C) prenatal treatment groups were either handled (H) or nonhandled (NH) during the preweaning period and tested in adulthood. Early handling eliminated the deficit in preweaning weight gain observed in E compared to PF and C offspring. In adulthood, early handling eliminated the increased hypothermia observed in E and PF compared to C males following an ethanol challenge (2.0 g/kg, IP). In addition, H males displayed marginally less hypothermia overall than NH males. In contrast, handling accelerated the return to preinjection temperature in PF and C females but had no effect on E females. There were no significant differences among E, PF, and C rats in corticosterone (CORT) responses to ethanol challenge (1.5 g/kg, IP), but both males (marginally) and females in the H condition displayed higher CORT levels overall than NH rats. Early handling also eliminated the increased peak CORT response to restraint stress in E compared to C females, but did not affect the more prolonged elevation of CORT in E compared to PF and C females. There were no differences among E, PF, and C females in hippocampal type I and type II glucocorticoid receptor density or affinity. However, binding affinity of type II receptors was slightly but significantly increased in H compared to NH females. Together, these data indicate that early handling may modulate or attenuate some, but not all, of the adverse effects of fetal ethanol exposure on offspring growth and physiological responsiveness.

Effect of prenatal ethanol and stress on levels of beta-endorphin in different brain regions of the rat

The combination of prenatal ethanol exposure and footshock stress was investigated for its effects on brain beta-endorphin levels. Subjects were offspring of rats that received 1 of 3 prenatal dietary treatments: an ethanol-containing liquid diet, a identical liquid diet with ethanol substituted isocalorically with maltose-dextrin (pair-fed group), and standard laboratory rat chow (chow-fed group). Two different stress paradigms were used: a short (30-sec) footshock stress paradigm and a prolonged (180-sec) footshock stress paradigm. Levels of beta-endorphin were measured with radioimmunoassay in eight brain regions of unstressed (baseline) rats, and of stressed rats at 3 and 30 min following termination of the stress. Seven brain regions containing high densities of beta-endorphin axons and terminals were chosen, as well as the arcuate region of the hypothalamus, the only brain region where both beta-endorphin perikarya and terminals are located. Following the short footshock stress paradigm, there were no changes in beta-endorphin levels, except for a trend toward increased levels in the pair-fed group. After the prolonged stress paradigm, levels of beta-endorphin in both the pair-fed and chow-fed groups tended to be decreased in several brain regions, including the arcuate region, at 3 min after termination of the stress. In contrast, for the prenatally ethanol-exposed group, beta-endorphin levels were increased significantly in the arcuate region, and moderately increased in the septal/preoptic region and medulla/pons at 3 min after the prolonged stress paradigm.(ABSTRACT TRUNCATED AT 250 WORDS)

The development of beta 1-adrenoceptors in brown adipose tissue following prenatal alcohol exposure

Prenatal alcohol exposure delays the development of thermoregulation in newborn rats. Newborns generate heat by the sympathetic nervous system's activation of nonshivering thermogenesis in brown adipose tissue (BAT). In this study, the effects of prenatal alcohol exposure on the development of the beta-adrenergic receptor system of BAT was investigated by assessing the number and pharmacological properties of beta-adrenergic receptors in BAT in 1-, 5-, 10-, and 20-day-old offspring. Pregnant dams were given either a liquid diet with 35% of the calories derived from alcohol, a liquid diet without alcohol for any effects of the liquid diet administration, or ad lib food and water. Offspring from the alcohol prenatal treatment group had a greater number of beta 1 adrenergic receptors compared to offspring from both from the pair-fed and lab chow control groups, which did not differ from each other. The greater number of receptor sites in 5-day-old subjects suggests that the number of binding sites in alcohol-exposed BAT cells continues to rise due to the absence of sufficient neurotransmitter, and perhaps reflects a delay in the arrival of sympathetic nervous system neurons. During the second and third postnatal weeks, when NE concentrations are rising and reaching asymptotic levels, the number of beta 1 adrenergic receptors in BAT of control subjects is decreasing. This expected compensatory "downregulation" response in receptor concentration was not seen in BAT from subjects exposed to alcohol prenatally. These findings may have important implications for understanding the effects of prenatal alcohol exposure on developing plasticity in the peripheral nervous system.

Prenatal alcohol exposure alters the hypothalamic-pituitary-adrenal axis response of immature offspring to interleukin-1: is nitric oxide involved?

We have previously shown that following prenatal alcohol exposure, immature offspring showed blunted ACTH released in response to the peripheral administration of interleukin-1 beta (IL-1 beta). The present studies were conducted to investigate the role of changes in corticosteroid feedback (measured by altered adrenal responses to ACTH), corticotropin-releasing factor (CRF) content of the median eminence (ME), and the influence of endogenous nitric oxide (NO). The injection of several doses of ACTH failed to indicate measurable differences between the corticosterone responses of offspring born to dams fed ad libitum [control (C)], pair-fed (PF), or fed alcohol [ethanol (EtOH) = E]. CRF content in the ME, taken as an index of the amount of releasable peptide, showed a small, but statistically significant, decrease following prenatal alcohol exposure. A comparable change, however, was also noted in PF rats. As expected, the subcutaneous injection of IL-1 beta (0.5 microgram/kg) induced smaller increases in plasma ACTH levels of E than C pups. The response of PF animals was intermediate between that of E and C rats. Finally, we observed that inhibition of NO formation by the administration of the arginine derivative L omega nitro-L-arginine-methylester significantly augmented ACTH secretion in all three experimental groups, and reversed the decreased corticotrophs' response to IL-1 beta caused by prenatal alcohol. Taken together, our results suggest that the ability of prenatal alcohol exposure to alter ACTH released by immature pups in response to blood-borne IL-1 beta is probably not mediated through changes in adrenal responsiveness.(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.

Adrenalectomy but not adrenal demedullation during pregnancy prevents the growth-retarding effects of fetal alcohol exposure

Growth retardation, both in the prenatal and the early neonatal period, is a consistent feature of fetal alcohol exposure, but the mechanism by which alcohol affects growth has not been elucidated. Because other stressors--such as maternal restraint and neonatal glucocorticoid treatment--can also affect growth, we examined the effect of ethanol on pup birthweight under two experimental conditions that altered maternal adrenal function. In the first study when dams were adrenalectomized and given low replacement doses of dexamethasone, the ethanol-exposed offspring of the adrenalectomized dams had birthweights similar to those of dams maintained on regular lab chow diets. In a second study, we found that maternal adrenal demedullation did not alter the reduction in birthweight produced by fetal ethanol exposure. The results suggest that the effects of ethanol on fetal growth may be mediated in part through ethanol-induced changes in the function of the maternal adrenal cortex.

Prenatal alcohol exposure blunts interleukin-1-induced ACTH and beta-endorphin secretion by immature rats

The functional relationship between the immune and the hypothalamic-pituitary-adrenal (HPA) axis [and in particular the release of pro-opiomelanocortin (POMC)-related peptides and corticosteroids induced by interleukins (ILs)] is essential for coordinating the appropriate immune responses to pathogens. Exposure of pregnant mammalian females to alcohol results in abnormal immune functions in the offspring, as well as in altered HPA axis activity. We therefore tested the hypothesis that prenatal alcohol exposure might modify the stimulatory action of ILs on the HPA axis of the pups, thus providing a mechanisms through which this treatment results in increased rate of infectious or inflammatory processes. Pregnant dams were fed a liquid alcohol diet throughout gestation. Dams with free access to food (ad libitum group), or dams fed an isocaloric diet in which sucrose replaced alcohol (pair-feeding), were also included. At 22-24 days of age, the pups were injected intraperitoneally with IL-1 beta, corticotropin-releasing factor (CRF), or the vehicle. Blood samples obtained 1-2 hr later indicated that the alcohol diet resulted in significantly blunted adrenocorticotropic hormone (ACTH) and beta-endorphin, but not corticosterone release, in response to IL-1 beta. Pair-fed pups also showed some decrease in their pituitary response, although to a lesser degree. In contrast, there was no measurable difference in the ability of CRF to increase plasma ACTH levels. These results suggest that prenatal exposure to alcohol interferes with the stimulatory action of IL-1 beta on the secretion of POMC-related peptides, a phenomenon probably not caused by decreased pituitary responsiveness to CRF.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal ethanol effects: sex differences in offspring stress responsiveness

Previous studies have shown that offspring prenatally exposed to ethanol are hyperresponsive to stressors in adulthood, and have suggested that females are typically more affected than males. The present study was undertaken to investigate further this apparent sex difference in prenatal ethanol effects on stress responsiveness. Male and female offspring from prenatal ethanol-exposed (E), pair-fed (PF), and ad lib-fed control (C) conditions were tested in adulthood to determine adrenocortical responses to a prolonged (4-h) restraint stress. There were no significant differences in corticoid responsiveness among females from the three treatment groups. All females showed a marked increase in plasma corticosterone at 30 min, and corticoid levels remained elevated through 150-min restraint. By 180 min, all females showed a significant corticoid decrease, although corticosterone remained elevated over basal levels throughout the 240-min stress period. For males, in contrast, there were significant differences among groups. All males showed a significant corticoid increase over basal levels at 30 min, and corticoids remained significantly elevated through 90-min restraint. By 120 min, PF and C males showed a significant corticoid decrease although corticoids never returned to basal levels during the 240-min restraint period. E males, however, showed no significant decrease from peak corticosterone levels throughout the 240-min restraint stress. These data indicate that pituitary-adrenal hyperresponsiveness is not limited to fetal ethanol-exposed females, but may be demonstrated in fetal ethanol-exposed males under appropriate conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of early postweaning ethanol exposure on oral self-administration behavior in the rat

The effects of three early ethanol home cage consumption procedures on the maintenance of operant lever responding reinforced by ethanol presentation were examined in the rat. Two groups of rats, 25 and 31 days of age, were exposed to 10% (v/v) ethanol as the only fluid in the home cage for 3 or 10 days. A third group, 31 days of age, were exposed to 10% ethanol or tap water for 24 h, with the fluid alternating daily for 18 days. All animals were subsequently trained to lever press using 10% ethanol reinforcement under a decreasing water restriction schedule. All three groups were found to have substantial ethanol consumption levels during the initial exposure in the home cage, ranging from 11.2 to 11.9 g/kg/day. The animals were all successfully trained to lever press in the operant chamber with ethanol as the reinforcer when limited to 15 ml/day of water in the home cage. The average number of reinforcements per day ranged from 29 to 43.5, yielding ethanol intakes from 1.06 to 1.97 g/kg in the 30-minute operant session. However, when 50 ml/day of water was available in the home cage, ethanol reinforcements were substantially reduced, with intakes which ranged from 0.14 to 0.18 g/kg/day. The data suggest that early exposure does not enhance ethanol's reinforcing properties later in the animal's life. These results were discussed in terms the effect of early ethanol exposure on later ethanol consumption and the role of ethanol initiation procedures in oral self-administration.

Endogenous opiates: 1989

This paper is the twelfth installment of our annual review of the research published during 1989 involving the behavioral, nonanalgesic, effects of the endogenous opiate peptides. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal and renal functions; mental illness; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; locomotor activity; sex, development, pregnancy, and aging; immunological responses; and other behavior.

Rats exposed prenatally to alcohol exhibit impairment in spatial navigation test

Prenatal exposure to ethanol causes learning disabilities and low I.Q. scores. The objective of the present studies was to investigate whether exposure of rats to ethanol in utero, would induce a deficit in spatial memory in adult life. Pregnant rats were fed with an ethanol diet from day 1 of pregnancy till parturition. Control rats were either pair-fed with an isocaloric sucrose diet or were fed with lab-chow ad libitum. On the first day of birth, offspring exposed to ethanol in utero were placed with a control mother fed with lab-chow, while offspring of the lab-chow fed dams were placed with ethanol-treated dams. At 40, 60 and 90 days postnatally, behavioral testing was performed using the Morris swim maze, a test of spatial memory. Results indicated that the offspring exposed to ethanol in utero presented deficits in spatial memory processes. Ethanol did not completely block the learning of the swim maze task but the alcohol-exposed offspring exhibited longer latencies to perform the task, swam longer distances prior to locating and climbing onto the platform, and when the platform was removed, searched for it in all 4 quadrants of the pool. Restricted caloric intake during gestation and maternal behavior in early postnatal life also induced deficits in the performance on the swim maze task. However, these deficits were mild and short-lasting being absent at 60 and 90 days of age. In contrast, the deficits induced by ethanol were more severe and longer-lasting, being present in adult life.