Chronic ethanol differentially alters susceptibility to chemically induced convulsions in withdrawal seizure-prone and -resistant mice

Withdrawal seizure-prone (WSP) and withdrawal seizure-resistant (WSR) mice were selectively bred to have severe (WSP) or mild (WSR) handling- induced convulsions after chronic ethanol inhalation. The purpose of the present experiments was to determine whether seizure susceptibility differences between WSP and WSR mice during ethanol withdrawal were specific to agents acting at γ-aminobutyric acid(A) or excitatory amino acid (EAA) receptors. Male WSP and WSR mice were exposed to ethanol vapor or air for 24 or 72 h. During peak withdrawal (i.e., between 6.5 and 8 h after removal from the inhalation chambers), separate groups of animals were administered pentylenetetrazol, (+)bicuculline, N-methyl-D-aspartate, kainic acid, or strychnine via timed tail vein infusion. Withdrawal from ethanol significantly increased sensitivity to pentylenetetrazol and (+)bicuculline versus air-exposed WSP and WSR mice. In contrast, sensitivity to N-methyl-D- aspartate-induced convulsions was significantly decreased in the ethanol- exposed WSR and unchanged in the ethanol-exposed WSP mice. Sensitivity to kainic acid was significantly increased in both ethanol-exposed WSR and WSP mice, although the magnitude of change in sensitivity was greater in the ethanol-withdrawing WSP line. Interestingly, sensitivity to strychnine was decreased similarly in the ethanol-exposed WSP and WSR mice, compared with their respective air-exposed animals. These results suggest that chronic ethanol increased sensitivity to convulsants active at γ-aminobutyric acid(A) receptors similarly in WSP and WSR mice, but differentially changed sensitivity to convulsants active at EAA receptors in the lines. This supports a role for EAA systems in determining genetic susceptibility to alcohol withdrawal.