Alcohol alters hypothalamic glial-neuronal communications involved in the neuroendocrine control of puberty: In vivo and in vitro assessments

The association between alcohol abuse and neuroendocrine system dysregulation: Race differences in a National sample

Health outcomes, including chronic disease and mortality, attributed to or associated with alcohol abuse are discrepant between African Americans and Whites. To date, the topic is not fully understood and few studies conducted have used biomarker indicators of health. We investigated whether the association between alcohol abuse and biomarkers of the neuroendocrine system vary between black or African American and White respondents aged 34-84 from the Midlife in the United States Study (MIDUS) II (2004-2006) (n=1129). Alcohol abuse was assessed with a modified version of the Michigan Alcohol Screening Test. Ordinary least squared (OLS) regression was used to evaluate whether race moderated the associations between alcohol abuse and four biomarkers-urinary cortisol and serum dehydroepiandrosterone sulfate (DHEA-S), epinephrine and norepinephrine-and two composite summary scores, each consisting of two components that characterize the hypothalamic pituitary adrenal (HPA)-axis and sympathetic nervous systems (SNS), respectively. Covariates included age, sex, education, income, current drinking, smoking, exercise, fast food consumption, heart disease, blood pressure, diabetes, body mass index, medication use, anxiety/depression, sleep duration, and cholesterol markers. Race significantly moderated the associations between alcohol abuse and norepinephrine concentration (χ² [1]=4.48, p=0.034) and the SNS composite score (χ² [1]=5.83, p=0.016). Alcohol abuse was associated with higher mean norepinephrine levels (b=0.26, standard error (SE)=0.12, p=0.034) and SNS composite score (b=0.23, SE=0.11, p=0.016) for African Americans compared to Whites. Interestingly, for Whites a paradoxical association between alcohol abuse, norepinephrine and SNS levels was observed; those who abused alcohol had lower mean norepinephrine levels than non-abusers. Race differences in neuroendocrine response could be biological pathways that contribute the excess risk of chronic disease and mortality attributed to alcohol abuse among African Americans compared to Whites. Replication of these analyses in larger cohorts are warranted in addition to further studies of underlying mechanisms among Blacks and Whites separately.

Deviant Peers as a Mediator of Pubertal Timing-Substance Use Associations: The Moderating Role of Parental Knowledge

PURPOSE

Early perceived pubertal timing and faster maturation have been linked to increased risk of adolescent substance use (SU), particularly for girls, but the mechanisms underlying this association are not well understood. We sought to replicate and extend findings from Westling et al. (2008) showing that peer deviance mediates the link between early puberty and SU with stronger pathways in the context of low parental knowledge of adolescents' whereabouts and activities.

METHODS

Participants (n = 1,023; 52% female, 24% nonwhite, and 12% Hispanic) were recruited through middle schools. Pubertal timing and tempo were derived from repeated measures of perceived pubertal development. Specific sources of parental knowledge included child disclosure and parental solicitation. Two measures of peer deviance (problem behaviors and SU) were obtained. The use of any substances (alcohol, cigarettes, marijuana, and other illicit drugs) was coded from all assessments.

RESULTS

For girls, earlier pubertal timing was associated with higher likelihood of SU but only in girls who disclosed less. For boys, slower tempo predicted greater SU, equally across parental knowledge groups. Pubertal timing and tempo were generally not associated with peer deviance; however, we detected a significant indirect effect such that peer problem behavior mediated the association between girls' early pubertal timing and SU. Parental knowledge did not moderate this effect.

CONCLUSIONS

Peer deviance was not strongly supported as a mechanism underlying atypical pubertal risk for SU (supported in one of the eight models). Parental knowledge appears to serve as a contextual amplifier of pubertal risk, independent of peer influences.

Prenatal Alcohol Exposure and Pair Feeding Differentially Impact Puberty and Reproductive Development in Female Rats: Role of the Kisspeptin System

BACKGROUND

Reproductive maturation is initiated with the onset of puberty, which activates the hypothalamic-pituitary-gonadal axis and coincidences with increased expression of the hormone kisspeptin within the hypothalamus. Maturational events are sensitive to environmental factors, including alcohol, which is known to delay reproductive development. We hypothesized that, similar to alcohol's adverse effects during reproductive maturation, prenatal alcohol exposure (PAE) would alter pubertal markers, sex hormone profiles, and kisspeptin expression in the hypothalamus.

METHODS

Female offspring from control (C), pair-fed (PF), and PAE groups were sacrificed prior to puberty onset (postnatal day [PND] 30), during puberty [PND 35], or in adulthood [PND 65]. Estradiol (E₂ ), progesterone (P₄ ), prolactin, and luteinizing hormone levels, and Kiss1 mRNA expression were measured in the arcuate (ARC) and anteroventral periventricular (AVPV) nuclei of the hypothalamus. Pubertal markers (vaginal opening [VO], uterus/body wt ratio) were assessed.

RESULTS

Our findings indicate that (i) PAE inhibits the expected increases in E₂ levels with age and delays maturational increases of P₄ levels; (ii) PAE and pair feeding have similar adverse effects on VO and uterus/body wt ratio; (iii) differential relationships between PRL and P₄ suggest that different mechanisms may underlie delayed maturation in PAE and PF; that is, PF females have low PRL levels and no increase in P₄ with age, whereas PAE animals, despite low PRL, show the expected age-related increase in P₄ ; and (iv) there is higher mean density of Kiss1 mRNA in the ARC of adult PAE females and altered Kiss1 expression in the AVPV of both PAE and PF females.

CONCLUSIONS

PAE and pair feeding have some overlapping but important differential effects on hormonal profiles and Kiss1 mRNA expression during reproductive development. Preadolescent alterations in Kiss1 expression in the AVPV and ARC, which may change the balance of function in these 2 nuclei, may differentially contribute to delayed reproductive maturation in PAE and PF compared to C females.