Binge-pattern alcohol exposure during puberty induces sexually dimorphic changes in genes regulating the HPA axis

Abstract

Maternal alcohol consumption during critical periods of fetal brain development leads to devastating long-term consequences on adult reproductive physiology, cognitive function, and social behaviors. However, very little is known about the long-term consequences of alcohol consumption during puberty, which is perhaps an equally dynamic and critical period of brain development. Alcohol abuse during adulthood has been linked with an increase in clinically diagnosed anxiety disorders, yet the etiology and neurochemical mechanisms of alcohol-induced anxiety behavior is unknown. In this study, we determined the effects of binge ethanol exposure during puberty on two critical central regulators of stress and anxiety behavior: corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP). Our results showed that ethanol increased plasma corticosterone (CORT) levels in both sexes, yet binge-treated animals had significantly lower CORT levels than animals exposed to a single dose, suggesting that the hypothalamo-pituitary-adrenal (HPA) axis habituated to the repeated stressful stimuli of ethanol. Binge ethanol exposure also significantly increased CRH and AVP gene expression in the paraventricular nucleus of males, but not females. Overall, our results demonstrate that binge ethanol exposure during puberty changes the central expression of stress-related genes in a sex-specific manner, potentially leading to permanent dysregulation of the HPA axis and long-term behavioral consequences.

Fig. 1.

Effects of ethanol (EtOH) treatment on body weight during pubertal development. Mean body weights of male (A) and female (B) animals untreated or treated with daily ip inejections of saline, saline + 1 day EtOH (acute), or binge EtOH paradigm.

Fig. 2.

Effects of EtOH treatments on blood alcohol and corticosterone levels in male and female rats. A: blood alcohol concentrations (BAC) 1.0 h postinjection in males (A) and females (B) treated with saline, acute EtOH, or binge EtOH. Data expressed as mean alcohol mg/dl. *Statistically significant difference (P < 0.05).

Fig. 3.

Effects of EtOH treatment on gonadal steroid hormone levels. Plasma concentrations of testosterone (T) in male rats (A) and 17β-estradiol (E₂) in female rats (B) 1.0 h after ip injection of saline, acute EtOH, or binge EtOH treatments. Untreated animals received no injection. Data expressed as T or E₂ pg/ml. *Statistically significant difference (P < 0.05).

Fig. 4.

Effects of EtOH treatment on circulating corticosterone (CORT) levels. Plasma CORT levels in peripubertal male (A) and female (B) rats 1.0 h after ip injection of saline, acute, or binge EtOH treatments. Untreated animals received no injection. Data expressed as mean CORT pg/ml of blood. Different symbols indicate statistically significant difference among groups (P < 0.05)

Fig. 5.

Effects of EtOH treatments on corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) mRNA in the paraventricular nucleus (PVN). CRH and AVP mRNA expression in the PVN of peripubertal male (A and B) and female (C and D) rats treated with saline, acute, or binge EtOH. Data expressed as mRNA copies/μg total RNA. *Statistically significant difference (P < 0.05).

Fig. 6.

Effects of EtOH treatments on AVP gene expression in the supraoptic nucleus (SON) of male and female rats. AVP mRNA expression in SON of peripubertal male (A) and female (B) rats treated with saline, acute, or binge EtOH. Data expressed as AVP mRNA copies/μg total RNA.