Actions of ethanol on hypothalamic and pituitary hormones in prepubertal female rats

How alcohol affects insulin-like growth factor-1's influences on the onset of puberty: A critical review

Alcohol (ALC) is capable of delaying signs associated with pubertal development in laboratory animals, as well as in humans. The normal onset of puberty results from a timely increase in gonadotropin‐releasing hormone (GnRH) secretion, which is associated with a gradual decline in prepubertal inhibitory influences, and the establishment of excitatory inputs that increase GnRH release, which together drive pubertal development. In recent years, insulin‐like growth factor‐1 (IGF‐1) has emerged as a pivotal contributor to prepubertal GnRH secretion and pubertal development, whose critical actions are interfered with by ALC abuse. Here we review the neuroendocrine research demonstrating the important role that IGF‐1 plays in pubertal development, and describe the detrimental effects and mechanisms of action of ALC on the onset and progression of pubertal maturation.

Addiction among women and sexual minority groups

Gender-related alcohol and drug abuse problems are related not only to biologic differences but also to social and environment factors, all of which can influence the clinical presentation, consequences of use, and treatment approaches. The number of women becoming addicted to alcohol or drugs of abuse has significantly increased with women becoming the fastest-growing group of substance abusers in the United States. Given that women experience a more rapid progression of their addiction than men, it is important that we understand and address the differences to help develop prevention and treatment programs that are tailored for women, incorporating trauma assessment and management, comorbidities, financial independence, pregnancy, and child care.

Women and Addiction: An Update

Gender-related alcohol and drug abuse problems are related not only to biological differences, but also to social and environmental factors, which can influence the clinical presentation, consequences of use, and treatment approaches. Women are becoming the fastest-growing population of substance abusers in the United States. Given that women experience a more rapid progression of their addiction than men, it is important that we understand and address the differences to help develop prevention and treatment programs that are tailored for women, incorporating trauma assessment and management, identification and intervention for medical and psychiatric comorbidities, financial independence, pregnancy, and child care.

Alcohol Delays the Onset of Puberty in the Female Rat by Altering Key Hypothalamic Events

BACKGROUND

Because alcohol (ALC) delays signs of pubertal development, we assessed the time course of events associated with the synthesis of critical hypothalamic peptides that regulate secretion of luteinizing hormone-releasing hormone (LHRH), the peptide that drives the pubertal process.

METHODS

Immature female rats were administered either laboratory chow or BioServe isocaloric control or ALC-liquid diets from 27 through 33 days of age. On days 28, 29, 31, and 33, animals were killed by decapitation and tissue blocks containing the medial basal hypothalamus (MBH) and the rostral hypothalamic area (RHA) were isolated and stored frozen until assessed by Western blot analysis.

RESULTS

Synthesis of dynorphin (DYN), a prepubertal inhibitor of LHRH secretion, was increased (p < 0.05) in the MBH of ALC-treated animals by day 29. DYN was further elevated (p < 0.01) on day 33 and was associated with an increase (p < 0.01) in DYN receptor expression. ALC did not affect synthesis of neurokinin B (NKB), a prepubertal stimulator of LHRH; however, it did suppress (p < 0.05) NKB receptor expression in the MBH by day 31. The most potent stimulator of prepubertal LHRH secretion, kisspeptin (Kp), was also decreased (p < 0.05) in the MBH as early as day 29, with continued suppression (p < 0.01) through day 33. Similar timely suppressions of mammalian target of rapamycin (mTOR), an immediate upstream regulator of Kp, were also noted. These decreases in mTOR and Kp were consistent with ALC stimulating (p < 0.05) the p-AMP-activated protein kinase/Raptor inhibitory pathway to mTOR on day 29, then later suppressing (p < 0.001) an Akt-mediated induction pathway to mTOR by day 31. In the RHA, ALC affected the pathways regulating Kp in a manner similar to that described in the MBH; however, these effects were not noted until day 33.

CONCLUSIONS

ALC acts within the MBH as early as 29 days to induce inhibitor and repressor inputs to LHRH, while depressing stimulatory inputs to the peptide. Collectively, these events lead to delayed signs of pubertal development.

Murine sperm capacitation, oocyte penetration and decondensation following moderate alcohol intake

Male chronic alcohol abuse causes testicular failure and infertility. We analyzed the effects of moderate sub-chronic alcohol intake on sperm morphology, capacitation, fertilization and sperm head decondensation. CF-1 male mice were administered 15% ethanol in drinking water for 15 days; control mice received ethanol-free water. Similar patterns of tyrosine phosphorylation were observed in capacitated spermatozoa of control and treated males. Percentage of hyperactivation (H) and spontaneous (SAR) and progesterone-induced (IAR) acrosome reaction significantly decreased at 120 and 150 min of capacitation in treated males compared to controls (H: 14.1 ± 2.5 vs 23.7 ± 2.6, P < 0.05; SAR-T120 min: 17.9 ± 2.5 vs 32.9 ± 4.1, P < 0.01; IAR-150 min: 43.3 ± 3.5 vs 73.1 ± 1.1, P < 0.001, n = 6). During in vitro fertilization (2.5, 3.5 and 4.5 h post-insemination), there was an increased percentage of fertilized oocytes (with a decondensed sperm head and one or two pronuclei) in treated males (P < 0.001, n = 7). After 60 min of in vitro decondensation with glutathione plus heparin, the percentage of decondensed sperm heads was significantly higher in treated males than in controls (mean ± s.d.: 57.1 ± 5.6 vs 48.3 ± 4.5, P < 0.05, n = 5). The percentage of morphologically normal sperm heads was significantly decreased in treated males with respect to controls (P < 0.001, n = 9). These results show that short-term moderate alcohol consumption in outbred mice affect sperm morphology, hyperactivation, acrosomal exocytosis, and the dynamics of in vitro fertilization and in vitro sperm nuclear decondensation.

Regulation of Kisspeptin Synthesis and Release in the Preoptic/Anterior Hypothalamic Region of Prepubertal Female Rats: Actions of IGF-1 and Alcohol

BACKGROUND

Alcohol (ALC) causes suppressed secretion of prepubertal luteinizing hormone-releasing hormone (LHRH). Insulin-like growth factor-1 (IGF-1) and kisspeptin (Kp) are major regulators of LHRH and are critical for puberty. IGF-1 may be an upstream mediator of Kp in the preoptic area and rostral hypothalamic area (POA/RHA) of the rat brain, a region containing both Kp and LHRH neurons. We investigated the ability of IGF-1 to stimulate prepubertal Kp synthesis and release in POA/RHA, and the potential inhibitory effects of ALC.

METHODS

Immature female rats were administered either ALC (3 g/kg) or water via gastric gavage at 0730 hours. At 0900 hours, both groups were subdivided where half received either saline or IGF-1 into the brain third ventricle. A second dose of ALC (2 g/kg) or water was administered at 1130 hours. Rats were killed 6 hours after injection and POA/RHA region collected.

RESULTS

IGF-1 stimulated Kp, an action blocked by ALC. Upstream to Kp, IGF-1 receptor (IGF-1R) activation, as demonstrated by the increase in insulin receptor substrate 1, resulted in activation of Akt, tuberous sclerosis 2, ras homologue enriched in brain, and mammalian target of rapamycin (mTOR). ALC blocked the central action of IGF-1 to induce their respective phosphorylation. IGF-1 specificity and ALC specificity for the Akt-activated mTOR pathway were demonstrated by the absence of effects on PRAS40. Furthermore, IGF-1 stimulated Kp release from POA/RHA incubated in vitro.

CONCLUSIONS

IGF-1 stimulates prepubertal Kp synthesis and release following activation of a mTOR signaling pathway, and ALC blocks this pathway at the level of IGF-1R.

Women and Addiction

Gender-related alcohol and drug abuse problems are related not only to biological differences, but also to social and environmental factors, which can influence the clinical presentation, consequences of use, and treatment approaches. Women are becoming the fastest-growing population of substance abusers in the United States. Given that women experience a more rapid progression of their addiction than men, it is important that we understand and address the differences to help develop prevention and treatment programs that are tailored for women, incorporating trauma assessment and management, identification and intervention for medical and psychiatric comorbidities, financial independence, pregnancy, and child care.

Manganese protects against the effects of alcohol on hypothalamic puberty-related hormones

AIMS

Since manganese (Mn) is capable of stimulating the hypothalamic-pituitary unit and advancing female puberty, we assessed the possibility that this element might overcome some of the detrimental effects of prepubertal alcohol (ALC) exposure on the hypothalamic control of pituitary function.

MAIN METHODS

Rats received either saline or Mn (10mg/kg) daily by gastric gavage from day 12 to day 31. After weaning, all rats were provided Lab Chow diet ad libitum until day 27 when they began receiving either the Bio Serv control or ALC diet regime. On day 31, the medial basal hypothalamus (MBH) was collected to assess luteinizing hormone-releasing hormone (LHRH) and cyclooxygenase 2 (COX2) protein levels. Release of prostaglandin-E2 (PGE2), LHRH and serum luteinizing hormone (LH) were also assessed. Other animals were not terminated on day 31, but remained in study to assess timing of puberty.

KEY FINDINGS

Short-term ALC exposure caused elevated hypothalamic LHRH content, suggesting an inhibition in peptide release, resulting in a decrease in LH. Both actions of ALC were reversed by Mn supplementation. COX2 synthesis, as well as PGE2 and LHRH release were suppressed by ALC exposure, but Mn supplementation caused an increase in COX2 synthesis and subsequent PGE2 and LHRH release in the presence of ALC. Mn supplementation also ameliorated the action of ALC to delay puberty.

SIGNIFICANCE

These results suggest that low level Mn supplementation acts to protect the hypothalamus from some of the detrimental effects of ALC on puberty-related hormones.

Differential Effects of Alcohol on Excitatory and Inhibitory Puberty-Related Peptides in the Basal Hypothalamus of the Female Rat

BACKGROUND

An increase in development of excitatory inputs along with a decline in inhibitory inputs ultimately govern the timely increased secretion of hypothalamic luteinizing hormone-releasing hormone (LHRH) at the time of puberty. As chronic alcohol (ALC) exposure acts at the hypothalamic level to suppress LHRH secretion and delay puberty, we assessed its ability to differentially affect the expression of key puberty-related proteins.

METHODS

ALC was administered to female rats from days 27 to 33, at which time animals were killed and tissues collected for protein expression. In the medial basal hypothalamus (MBH), we assessed kisspeptin (Kp) 10, an excitatory peptide critical for prepubertal LHRH secretion, and Lin28b, a peptide with an inhibitory influence on puberty. As a direct mechanism of action of Lin28b was not known, we determined whether its central administration could induce dynorphin (DYN), a peptide that is inhibitory on LHRH secretion. Also, ALC's effect on DYN protein expression was assessed, as well as its effect on DYN release in vitro.

RESULTS

ALC markedly suppressed (p < 0.01) the expression of the excitatory Kp protein, while at the same time increased (p < 0.001) the expression of inhibitory Lin28b protein. Subsequently, we showed for the first time that the central administration of Lin28b stimulated (p < 0.01) the synthesis of DYN. Finally, ALC also induced (p < 0.01) the protein expression and stimulated (p < 0.01) the in vitro release of DYN from the MBH.

CONCLUSIONS

These results indicate that ALC can simultaneously and differentially alter both excitatory and inhibitory influences governing pubertal development, show for the first time a mechanism of action by which Lin28b exerts its prepubertal inhibitory tone, and further demonstrate the negative influences of ALC on the pubertal process.

Alcohol abuse: critical pathophysiological processes and contribution to disease burden

Alcohol abuse; the most common and costly form of drug abuse, is a major contributing factor to many disease categories. The alcohol-attributable disease burden is closely related to the average volume of alcohol consumption, with dose-dependent relationships between amount and duration of alcohol consumption and the incidence of diabetes mellitus, hypertension, cardiovascular disease, stroke, and pneumonia. The frequent occurrence of alcohol use disorders in the adult population and the significant and widespread detrimental organ system effects highlight the importance of recognizing and further investigating the pathophysiological mechanisms underlying alcohol-induced tissue and organ injury.

Effects of red ginseng extract on the epididymal sperm motility of mice exposed to ethanol

The protective effects of red ginseng extract and ginseng wine against ethanol-induced male reproductive toxicity were evaluated in male mice using computer-assisted sperm analysis. Mice were divided into 4 groups of 10 and fed plain saline, 6 g/kg per d of ethanol in saline, red ginseng extract plus ethanol, or a fermented preparation of red ginseng extract daily for 5 weeks. We found that the average seminal vesicle weight was significantly lower in the ethanol-treated group compared to the control group, while those of the ginseng-treated groups tended to be higher than the ethanol-treated group. We found a significant decrease in sperm motility and progressiveness in mice treated with ethanol for 5 weeks, while administration of ethanol plus red ginseng extract appeared to minimize the negative effects of ethanol toxicity on male fertility. Serum testosterone, luteinizing hormone (LH), and follicle stimulating hormone (FSH) were insignificantly lower in the ethanol-treated group than in the control group.

Prepubertal ethanol exposure alters hypothalamic transforming growth factor-α and erbB1 receptor signaling in the female rat

Glial-derived transforming growth factor alpha (TGFα) activates the erbB1/erbB2 receptor complex on adjacent glial cells in the medial basal hypothalamus (MBH). This receptor activation stimulates the synthesis and release of prostaglandin-E(2) (PGE(2)) from the glial cells, which then induces the release of prepubertal luteinizing hormone-releasing hormone (LHRH) secretion from nearby nerve terminals; thus, showing the importance of glial-neuronal communications at the time of puberty. Ethanol (EtOH) is known to cause depressed prepubertal LHRH secretion and delayed pubertal development. In this study, we assessed whether short-term EtOH exposure could alter the hypothalamic glial to glial signaling components involved in prepubertal PGE(2) secretion. Immature female rats began receiving control or EtOH diets beginning when 27 days old. The animals were killed by decapitation after 4 and 6 days of treatment and confirmed to be in the late juvenile stage of development. Blood and brain tissues were collected for gene, protein, and hormonal assessments. Real-time polymerase chain reaction (PCR) analysis demonstrated that EtOH did not affect basal levels of erbB1 gene expression in the MBH. Expression of total erbB1 protein was also unaffected; however, the EtOH caused suppressed phosphorylation of erbB1 protein in the MBH at both 4 and 6 days (P<.01) as revealed by Western blotting. Phosphorylation and total protein levels of erbB2 receptor were not affected by EtOH exposure. Because this receptor is critical for PGE(2) synthesis/release, which mediates the secretion of LHRH, we assessed whether in vivo EtOH exposure could affect the release of PGE(2). EtOH exposure for 6 days suppressed (P<.01) basal levels of PGE(2) released into the medium. The effects of 4- and 6-day EtOH exposure on gene and protein expressions of TGFα, an upstream component in the activation of erbB1/erbB2, were also studied. The levels of TGFα mRNA were increased markedly at 4 days (P<.001), but declined to near basal levels by 6 days in the EtOH-treated animals. The EtOH caused increases in TGFα protein expression at both 4 (P<.001) and 6 (P<.01) days; hence, suggesting that the EtOH inhibited release of the peptide. We confirmed this inhibition by showing decreased (P<.01) TGFα released from MBHs incubated in vitro following 6 days of EtOH exposure in vivo. Thus, these results demonstrate that EtOH is capable of interfering with hypothalamic glial to glial signaling processes involved in prepubertal PGE(2) secretion.

Insulin-like growth factor-1 stimulation of hypothalamic KiSS-1 gene expression is mediated by Akt: effect of alcohol

Kisspeptin, as well as insulin-like growth factor-1 (IGF-1), act centrally to stimulate luteinizing hormone-releasing hormone (LHRH) secretion at puberty. IGF-1 can induce KiSS-1 gene expression as an early pubertal event; however, the signaling pathway mediating this effect is not known. Since alcohol (ALC) blocks IGF-1 induced LHRH release acutely, we assessed whether this drug could affect IGF-1 stimulated prepubertal KiSS-1 gene expression following a binge type of exposure. Immature female rats were administered either ALC (3 g/kg) or water via gastric gavage at 07.30 h. At 09.00 h the ALC and control groups were subdivided where half received either saline or IGF-1 (200 ng) into the third ventricle. A second dose of ALC (1.5, 2 and 3 g/kg) or water was administered at 11.30 h. These regimens produced moderate blood alcohol concentrations of 77, 89 and 117 mg/dl, respectively, over the time course of the experiment. Rats were sacrificed 6 h after the IGF-1 injection and tissues containing the anteroventral periventricular (AVPV) and arcuate (ARC) nuclei were collected. IGF-1 stimulated (P<0.01) KiSS-1 gene expression in the AVPV nucleus at 6 h, but did not affect expression of the kisspeptin receptor, GPR54. While ALC did not alter basal expression of either gene, its dose dependently blocked IGF-1-induced KiSS-1 gene expression in the AVPV nucleus. No changes were observed in the ARC nucleus. Assessment of IGF-1 signaling indicated that the acute administration of IGF-1, ALC, or both did not alter the basal expression of IGF-1 receptor protein. However, IGF-1 stimulated (P<0.05) phosphorylated Akt protein over basal levels, an action blocked by ALC. Our results indicate that the IGF-1 induction of KiSS-1 gene expression is mediated by Akt activation, and that ALC alters this important prepubertal action of IGF-1.

Actions and interactions of alcohol and insulin-like growth factor-1 on female pubertal development

Alcohol (ALC) is a drug that is capable of disrupting reproductive function in adolescent humans, as well as immature rhesus monkeys and rats. Critical to determining the mechanism(s) of the effects of ALC on the pubertal process is to have a better understanding of the important events involved in the initiation of puberty. For years it has been hypothesized that there may be metabolic signals capable of linking somatic growth to the activation of the reproductive system at the time of puberty. In recent years it has been shown that insulin-like growth factor-1 (IGF-1) is one such signal that plays an early role in the pubertal process. In this review, we will describe the actions and interactions of ALC and IGF-1 on molecular and physiological processes associated with pubertal development.

Transitions into underage and problem drinking: developmental processes and mechanisms between 10 and 15 years of age

Numerous developmental changes occur across levels of personal organization (eg, changes related to puberty, brain and cognitive-affective structures and functions, and family and peer relationships) in the age period of 10 to 15 years. Furthermore, the onset and escalation of alcohol use commonly occur during this period. This article uses both animal and human studies to characterize these multilevel developmental changes. The timing of and variations in developmental changes are related to individual differences in alcohol use. It is proposed that this integrated developmental perspective serve as the foundation for subsequent efforts to prevent and to treat the causes, problems, and consequences of alcohol consumption.

Alcohol alters luteinizing hormone secretion in immature female rhesus monkeys by a hypothalamic action

We determined whether the effect of alcohol (ALC) to suppress LH secretion in immature female monkeys is due to a hypothalamic or pituitary site of action. Beginning at 20 months of age, four monkeys received a single intragastric dose of ALC (2.4 g/kg), and four monkeys received an equal volume of a saline/sucrose solution daily until they were 36 months old. For the hypothalamic response test, two basal samples (3.5 ml) were collected at 15-min intervals via the saphenous vein, and then N-methyl-D-L-aspartic acid (NMA; 20 mg/kg) was given iv and four more blood samples collected. Three weeks later, this protocol was repeated except LH-releasing hormone (LHRH) (5 microg/kg) was used to test pituitary responsiveness. NMA or LHRH was administered 3 h after the ALC. After the pituitary challenge, each monkey was ovariectomized and 6 wk later, implanted with an indwelling subclavian vein catheter. Blood samples were drawn every 10 min for 8 h to assess effects of ALC on post-ovariectomy LH levels and the profile of LH pulsatile secretion. The hypothalamic challenge showed NMA stimulated LH release in control monkeys, an action that was blocked by ALC. The pituitary challenge revealed that LHRH stimulated LH release equally well in control and ALC-treated monkeys. A post-ovariectomy rise in LH was observed in both groups, but levels were 45% lower in ALC-treated monkeys. This reduction was attributed to an ALC-induced suppression of both baseline and amplitude of pulses. Results demonstrate that the ALC-induced suppression of LH in immature female rhesus monkeys is due to an inhibitory action of the drug at the hypothalamic level.

Suppression by ethanol of male reproductive activity

Ethanol has been known to suppress reproductive activity in laboratory animals and humans through the inhibition of luteinizing hormone (LH) release by reduction of gonadotropin-releasing hormone (GnRH) secretion from the hypothalamus. There are, however, little data is available regarding the effect of ethanol on GnRH gene expression. Thus, the present study was designed to evaluate the effect of ethanol on GnRH gene expression and reproductive activity at all levels of the hypothalamus-pituitary-gonad (HPG) axis simultaneously. To this end, ethanol (3 g/kg i.p., 15% v/v in saline) was administered to adult male rats for 10 days. Serum levels of LH and testosterone were significantly decreased by ethanol. Using Northern blot analysis and in situ hybridization, the present study showed the reduction in GnRH mRNA levels in the hypothalamus by prolonged ethanol administration. The content of LH in the anterior pituitary was also significantly reduced by ethanol. In addition, steroidogenic acute regulatory protein (StAR) mRNA levels were significantly decreased by ethanol, suggesting a cause for the reduced production of testosterone under this condition. These results indicate that ethanol affects the HPG axis at all the levels. Especially, suppressed GnRH mRNA levels in the hypothalamus of ethanol-treated rats strongly demonstrated that hypothalamus is the major action site of ethanol on the HPG axis. Decreased serum LH level may affect the steroidogenesis in the testis, at least in part, through the inhibition of StAR gene expression that induces part of dysfunctions of reproductive activity.

EtOH disrupts female mammalian puberty: age and opiate dependence

The major drug of abuse among teenagers in the United States continues to be ethanol (EtOH), but use is seen in children as young as nine. In the studies reported here, the impact of EtOH on biologic and hormonal parameters of puberty was assessed in female rats. Rats were fed a liquid diet containing EtOH, pair fed an identical liquid diet containing dextrimaltose instead of EtOH, or fed a liquid diet not containing EtOH ad libitum. Feeding was started at 21, 25, or 28 d of age. EtOH markedly delayed the age at vaginal opening (34.5 +/- 0.5 d in controls vs 48.5 +/- 2.4 d in EtOH animals; p < 0.001), delayed the age at first estrous (40.9 +/- 0.6 d in controls vs 61.2 +/- 2.6 d in EtOH animals; p < 0.001), increased the length of the estrous cycle, and decreased the number of proestrous days. EtOH, concomitant with reduced ovarian and uterine weight, decreased serum estradiol and progesterone. Associated with these changes in ovarian hormones there was a selective increase in follicle-stimulating hormone, but not luteinizing hormone. EtOH consistently reduced insulin-like growth factor-1. In general, EtOH-induced disruption was more severe the younger the animals were at the start of feeding. Opiate receptor blockade with naltrexone completely prevented the EtOH-induced delay in vaginal opening. The impact of EtOH on female puberty is dramatic, is an emerging public health problem, and deserves more study.

Alcohol before puberty produces an advance in the onset of sexual behavior in male rats

The effect of alcohol consumption before puberty on the development of genital-grooming (GG) and on the onset of sexual behavior was assessed. Wistar male rats were continuously exposed in a one-bottle access situation to either 6% ethanol (alcohol group, AG), an isocaloric sweetened solution (vehicle group, VG) or were maintained in standard laboratory conditions (control group, CG). Each solution was the only available liquid in each group from weaning (22 days) to 40 days of age. GG behavior was recorded from 25 to 47 days of age and sexual behavior was recorded from 42 to 74 days of age. The age at the maximum peak of both frequency and duration of GG showed an advance in the AG (33-35 days of age) compared with the CG (45 days) and the VG (47 days). An advance in the onset of sexual behavior was observed in the AG: at 46 days of age, seven of the nine males of this group showed ejaculatory behavior. In contrast, in the CG and VG, ejaculation occurred in at least 50% of subjects after 58 days of age. Regardless of the advance in the onset of sexual behavior, the characteristics of the different parameters of the copulatory sequence were not impaired by alcohol. The apparent advance in the onset of puberty is discussed in terms of the opioid hypothalamic activity as a mechanism that affects the LH secretion.

The adolescent brain and age-related behavioral manifestations

To successfully negotiate the developmental transition between youth and adulthood, adolescents must maneuver this often stressful period while acquiring skills necessary for independence. Certain behavioral features, including age-related increases in social behavior and risk-taking/novelty-seeking, are common among adolescents of diverse mammalian species and may aid in this process. Reduced positive incentive values from stimuli may lead adolescents to pursue new appetitive reinforcers through drug use and other risk-taking behaviors, with their relative insensitivity to drugs supporting comparatively greater per occasion use. Pubertal increases in gonadal hormones are a hallmark of adolescence, although there is little evidence for a simple association of these hormones with behavioral change during adolescence. Prominent developmental transformations are seen in prefrontal cortex and limbic brain regions of adolescents across a variety of species, alterations that include an apparent shift in the balance between mesocortical and mesolimbic dopamine systems. Developmental changes in these stressor-sensitive regions, which are critical for attributing incentive salience to drugs and other stimuli, likely contribute to the unique characteristics of adolescence.

Alcohol treatment during lactation produces an advance in the onset of puberty in female rats

It has been described that alcohol treatment after weaning produces a delay in the onset of puberty and a decrease in the body weight of female rats; however, during development, there are periods with different sensitivity to endogenous and exogenous substances. In this study, two daily doses of 2.5 g/kg of ethanol each administered to female pups during days 13-18 of postnatal age produced an advance in the age at vaginal opening but induced no effect on the body weight; however, the onset of sexual behavior was not advanced. Fertility and reproduction measures were not significantly impaired by this treatment. It is supported that, in this period, alcohol can produce different effects - even opposite to those described in other developmental stages - which seems to represent a critical period for alcohol action.

Alcohol ingestion inhibits the increased secretion of puberty-related hormones in the developing female rhesus monkey

Alcohol (ALC) use and abuse by adolescents has been rising at an alarming rate. Whether ALC consumption during prepubertal years affects specific hormones and the process of sexual maturation is not known. We used immature female rhesus macaques to assess the effects of ALC on circulating levels of hormones known to be critical for the pubertal process. Ten monkeys averaging 20.3 +/- 0.3 months of age were bled by saphenous vein puncture at 0830 and 2030 h each day for 5 consecutive days to determine baseline levels of GH, insulin-like growth factor I, FSH, LH, estradiol (E2), and leptin. For the next 12 months, each day at 1330 h five monkeys were administered ALC (2 g/kg), and five monkeys were administered an isocaloric sucrose solution via a nasogastric approach. Blood was again collected twice daily on 5 consecutive days at 24, 28, and 32 months for hormone analysis. Food consumption and weight gain were similar for ALC-treated and control animals. The expected night-related increase in serum GH occurred during late juvenile development (28-32 months of age) in control animals, but was suppressed (P < 0.05) in ALC-treated animals. This action was paralleled by a decrease (P < 0.01) in serum insulin-like growth factor I. Serum LH and E2 were also depressed by ALC, with their effects most pronounced at 32 months (LH, P < 0.01; E2, P < 0.001). Serum FSH and leptin were not altered. Although ALC did not affect age at menarche, the interval between subsequent menstruations was lengthened (P < 0.05), thereby showing that ALC affected the development of a regular monthly pattern of menstruation. These results demonstrate the detrimental effects of ALC on the activation of hormone secretion that accompanies puberty in female rhesus monkeys. They also suggest that the subsequent growth spurt and normal timing or progression of puberty may be at risk in human adolescents and teenagers consuming even relatively moderate amounts of ALC on a regular basis.

Ethanol blocks the central action of IGF-1 to induce luteinizing hormone secretion in the prepubertal female rat

Insulin-like growth factor-1 (IGF-1) is emerging as a signal of peripheral origin capable of acting centrally to induce luteinizing hormone (LH) secretion and accelerate the initiation of female puberty. Since we have shown previously that ethanol (ETOH) can suppress prepubertal LH release and delay female puberty, we hypothesized that these detrimental effects might be due, at least in part, to the drugs ability to alter the central actions of IGF-1. Thus, we have investigated the effects of ETOH on IGF-1 induced LH release in vivo, and on IGF-1 induced prostaglandin-E2 (PGE2) and LH-releasing hormone (LHRH) release in vitro from rats during the juvenile phase of development as well as from rats during the early stage of first proestrus. For the in vivo experiment three initial jugular blood samples were taken at 10-min. intervals from all rats, then the animals received either a 3g/Kg dose of ETOH or an equal volume of saline by gastric gavage. The rats were subsequently left undisturbed for 90 min. to allow time for ETOH absorption, then a single blood sample was drawn from each rat. Finally, IGF-1 (200 ng/3 microl) was microinjected into the third ventricle of all animals and five more blood samples were withdrawn at 10 min. intervals. We demonstrated that IGF-1 induced the release of LH (p<0.01) in the saline controls from rats in both phases of pubertal development. Conversely, this effect of IGF-1 was blocked by ETOH in both developmental groups. For the in vitro experiment, median eminences (MEs) were dissected, then incubated in the presence or absence of ETOH (50 mM). The amount of PGE2 and LHRH released was measured from the same samples following the addition of IGF-1 (100 ng/ml). As above, similar responses were observed from rats in both developmental phases. IGF-1 stimulated the release of PGE2 (p<0.001) and LHRH (p<0.01) from the incubated nerve terminals in the absence of ETOH; however, these effects were blocked by the presence of ETOH. Thus, these combined in vivo and in vitro results suggest that ETOH can acutely block IGF-1 induced LH release during the juvenile-peripubertal transition period, and that this is a centrally mediated action which is due to the diminished formation of PGE2 resulting in decreased LHRH release.

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.

Effect of ethanol on the synthesis of insulin-like growth factor 1 (IGF-1) and the IGF-1 receptor in late prepubertal female rats: a correlation with serum IGF-1

For several years, it has been well accepted that insulin-like growth factor 1 (IGF-1) plays a critical role in peripubertal growth. Recently, we have provided evidence to suggest that this peptide may also be involved in the sexual maturation process, via an action to stimulate hypothalamic luteinizing hormone releasing hormone release. Because ethanol (ETOH) delays puberty, an event that is associated with depressed growth rates and decreased growth hormone and luteinizing hormone (LH) secretion via actions at the hypothalamic level, we investigated whether this drug is capable of altering the expression of genes encoding IGF-1 in liver and brain, as well as the expression of the type 1 IGF receptor (IGF-1R) within the median eminence (ME). Also, we wanted to determine if any regional changes in the expression of these genes were associated with concomitant alterations in the serum levels of IGF-1 and LH. Rats were implanted with gastric cannulae on day 24 and began receiving specific control or ETOH diets on day 29. Rats were killed on day 34, determined to be in the late juvenile stage of development, and their tissues and blood were collected. Results indicate that the ETOH-fed rats showed a decrease (p < 0.01) in the expression of hepatic IGF-1 mRNA when compared with the controls, and this paralleled depressions in both serum IGF-1 (p < 0.01) and LH (p < 0.01). In contrast, no changes were detected in IGF-1 mRNA expression in the preoptic area and hypothalamus, as well as in IGF-1R mRNA expression within the ME. These results suggest that the well-known detrimental effects of ETOH on growth rates and the progression of the female pubertal process in the rat may be associated with the drug's ability to depress the hepatic synthesis of IGF-1 and the subsequent prepubertal circulating levels of the protein.

Effects of chronic alcohol consumption and of dehydration on the supraoptic nucleus of adult male and female rats

Ethanol ingestion affects the hypothalamo-neurohypophysial system resulting in increased diuresis, dehydration and hyperosmolality. We studied the supraoptic nucleus, of the hypothalamus, in ethanol-treated rats, to determine if ethanol alone and/or the associated disturbances of water metabolism lead to structural alterations in a nucleus known to play a central role in fluid homeostasis. Groups of male and female rats were ethanol-treated until 12 and 18 months of age and compared with age-matched pair-fed controls. Twelve and 18-month-old control groups and 12-month-old water control groups (rats submitted to chronic dehydration) were also included in this study in an attempt to differentiate between the effects of undernutrition and dehydration/hyperosmolality, and the specific neurotoxic effects of ethanol. We estimated the volume of the supraoptic nucleus and the numerical density of its neurons and calculated the total number of supraoptic neurons. The volume of both supraoptic neurons and neuropil were also estimated. In immunostained material the ratio of vasopressin to oxytocin neurons and the cross-sectional areas of the two neuronal types were evaluated. There was marked neuronal loss in alcohol-treated rats, but the volume of the supraoptic nucleus was increased. The increase in the volume of the supraoptic nucleus correlated with and was due to increases in the volume was particularly marked for vasopressin neurons. No significant differences were found between controls and pair-fed controls in any of the parameters investigated. In water control rats, the volume of the supraoptic nucleus and of the supraoptic neurons and neuropil was also greater than in pair-fed controls. However, the variations found were not as marked as in ethanol-treated rats and there was no cell loss. These findings reveal, for the first time, that chronic ethanol consumption affects the morphology of supraoptic neurons and neuropil and, consequently, the structure of the entire supraoptic nucleus. Moreover, this study supports the view that ethanol has direct neurotoxic effects on supraoptic neurons because the alterations that occur are not mimicked in animals in which water metabolism alone is disturbed.

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)

Effects of prepregnancy ethanol on neuromotor development, activity, and learning

This study examines the behavioral consequences of both long-term chronic and acute high-dose administration of ethanol before pregnancy. Female rats were assigned to one of five conditions: a self-administered liquid diet with 35% ethanol-derived calories, a pair-fed liquid diet with 0% ethanol-derived calories, a gavage intubation with 4 g/kg ethanol, a gavage intubation control, or a standard lab chow control. Offspring were weighed at various ages and tested for neuromotor development, activity, and learning a Morris maze water task. Offspring of mothers in the high-dose condition were hyperactive as juveniles but not as adults. Hyperactivity was not seen in the low-dose chronic ethanol condition, contrary to previous reports. Neither ethanol administration paradigm was associated with learning deficits. Prepregnancy stress effects were apparent from both the restricted liquid diet feeding and the gavage treatment on neuromotor development. A possible mechanism for the effects of prepregnancy ethanol treatment is linked to ethanol's potential to alter hormone levels. Since hormones are directly responsible for the maturation of the egg, hormonal imbalances as a result of ethanol exposure may result in developmental deficiencies in the offspring.

Effects of low-level lead exposure on hypothalamic hormones and serum progesterone levels in pregnant guinea pigs

Pregnant guinea pigs were given a daily oral dose of 0, 5.5, or 11 mg lead (as lead acetate) per kg body weight during days 22-52 or 22-62 of gestation. Maternal serum progesterone levels were measured at the end of treatment, as well as hypothalamic levels of gonadotropin-releasing hormone (GnRH) and somatostatin (SRIF) in both the mothers and fetuses. Lead-treated dams had lower serum concentrations of progesterone at the end of treatment than did vehicle-treated animals. This effect was statistically significant for the higher Pb dose only. Hypothalamic levels of GnRH and SRIF were reduced in a dose-dependent manner by lead treatment in both dams and fetuses. The reduction of SRIF levels in 52-day-old fetuses was particularly severe (92%) in the 11 mg group. However, neither litter size nor body and organ weights, including placental weight, of the dams and fetuses was significantly affected. The relevance of these hormonal decreases is unknown, but could include decreased reproductive capacity in both the dams and fetuses that does not become apparent until later in the life-cycle.

The influence of acute ethanol exposure on growth hormone release in female rats

This study investigates the site (hypothalamic or pituitary) at which ethanol (ETOH) alters GH release in female rats. Both the hypothalamic response to clonidine (CLON), an alpha 2-adrenergic agonist, and the pituitary response to growth-hormone releasing hormone (GRH) were tested. Jugular cannulae were inserted for drug administration and undisturbed blood sampling. ETOH was injected IP 24 and 1 h before experimentation. In animals receiving saline or ETOH (1, 2, or 3 g/kg), there was no response to CLON and no difference in GH levels between groups. On the other hand, there was a significant surge in GH release in response to a high dose of GRH (1000 ng/kg) in both saline controls and in ETOH (3 g/kg) animals. Although there was no difference in the height of the surge between groups, baseline GH levels were higher in animals that received ETOH. In response to a low dose of GRH (250 ng/kg) the GH surge was only significant in the ETOH animals. In animals receiving somatostatin antiserum (anti-SRIF; 0.5 ml) in combination with the low GRH dose, the surge in GH levels was significant in both saline and ETOH animals, however, the surge was higher in saline compared to ETOH animals. The results of this study suggest that: 1) ETOH alters the SRIF system (release of reception) in female rats and that this interaction is evident when GRH concentration is low, and 2) ETOH may also inhibit GH release by interfering with the GRH system, however, the site of this influence most likely does not involve an alpha 2-GRH component.