The impact of gonadectomy and adrenalectomy on acute withdrawal severity in male and female C57BL/6J and DBA/2J mice following a single high dose of ethanol

Abstract

Background: Steroid hormones can influence neuronal excitability and subsequent seizure susceptibility through genomic and nongenomic mechanisms. For example, there are proconvulsant steroids such as estradiol and corticosterone and anticonvulsant steroids such as testosterone, progesterone, and their GABAergic metabolites. Recent findings indicated that a single, acute administration of ethanol increased levels of GABAergic steroids and that the source of this increase was peripheral organs such as the adrenals and gonads. Thus, the purpose of the present study was to determine the impact of removal of the adrenals and/or gonads on withdrawal severity following a single high dose of ethanol in 2 genotypes that differ in ethanol withdrawal severity.

Method: Male and female C57BL/6J (B6) and DBA/2J (D2) mice were either left intact (SHAM), adrenalectomized (ADX), gonadectomized (GDX), or underwent ADX/GDX surgery. Seven days following surgery, baseline handling-induced convulsions (HICs) were measured prior to administration of a 4 g/kg dose of ethanol. HICs were assessed following the ethanol injection, then hourly for 12 hours and at 24 hours. A separate group of mice were used to measure the impact of surgical status on ethanol metabolism at 30, 60, 120, and 240 minutes after a single 4 g/kg dose of ethanol.

Results: ADX and ADX/GDX treatments in male B6 and D2 mice increased ethanol withdrawal severity following a single dose of ethanol, measured by area under the withdrawal curve and peak HIC scores. Acute ethanol withdrawal also was increased in female D2 mice that had undergone ADX/GDX. In contrast, surgical status did not alter ethanol withdrawal severity in female B6 mice. Surgical status had only minor effects on ethanol metabolism.

Conclusions: Removal of peripherally derived steroids with anticonvulsant properties significantly increased HIC scores during acute ethanol withdrawal following a single dose of ethanol in male and female D2 mice and in male B6 mice. These increases were not due to changes in ethanol metabolism.

Fig. 1

The effect of surgical status on acute ethanol (EtOH) withdrawal severity in male and female C57BL/6J (B6) and DBA/2J (D2) mice, measured by hourly handling-induced convulsions (HICs). Overall, male B6 (panel A) and D2 (panel C) mice that had undergone adrenalectomy (ADX) or ADX and gonadectomy (GDX) had a more severe withdrawal response from a high dose of EtOH. In D2 females (panel D) only ADX/GDX mice had a more severe withdrawal from an acute EtOH exposure, while there was no effect in B6 female mice (panel B). Values represent the mean ± SEM for 10 to 15/group. Note differences in y-axis between D2 and B6 mice.

Fig. 2

Surgical status significantly alters acute ethanol (EtOH) withdrawal severity, measured by area under the curve (AUC). Tukey post hoc tests confirmed that AUC in the adrenalectomy (ADX) and the ADX/GDX groups were significantly higher than in the gonadectomy (GDX) and no surgery (SHAM) groups in the C57BL/6J (B6; panel A) and DBA/2J (D2; panel C) males. In the D2 females (panel D), AUC was significantly increased only in the ADX/GDX group, while in the B6 females (panel B), there were no group differences in AUC. Values represent the mean ± SEM for the animals depicted in Fig. 1. *Indicates significance of p ≤ 0.05 versus SHAM. Note differences in y-axis between D2 and B6 mice.

Fig. 3

Surgical status significantly affects peak withdrawal scores in male mice, but not in female mice. Peak withdrawal is defined as the peak handling-induced convulsion score averaged with the 2 surrounding scores for each animal. In C5BL/6J (B6) males (panel A), peak withdrawal was significantly increased in groups that had undergone adrenalectomy (ADX) and ADX/gonadectomy (GDX) surgeries. The same pattern was true for DBA/2J (D2) males (panel C). There was no difference in peak withdrawal scores in D2 (panel D) or B6 (panel B) female mice. Values represent the mean ± SEM for the animals depicted in Fig. 1. *Indicates significance of p ≤ 0.05 versus respective SHAM.

Fig. 4

Surgical status has no significant effect on EtOH metabolism. In C57BL/6J (B6) males (panel A), there was no significant effect of surgery on blood ethanol concentration (BEC) at 30, 60, 120, or 240 minutes after EtOH administration. The same pattern was true for B6 females (panel B) and DBA/2J (D2) male and female mice (Panels C and D, respectively). Values represent the mean ± SEM for 12 to 15/group.