Sex differences in rats in the development of and recovery from ethanol dependence assessed by changes in seizure susceptibility.
BACKGROUND
Previous investigations have found sex differences in rats in response to chronic ethanol exposure. The most dramatic differences were observed with anticonvulsant treatment during ethanol withdrawal, when seizure susceptibility is significantly increased. Sex differences in this response were found for both GABAergic and glutamatergic compounds. This study was aimed at exploring whether sex also influences the timing for the development of and recovery from ethanol dependence.


METHODS
Ethanol was administered in a liquid diet, with pair-fed animals receiving dextrose, substituted isocalorically for the ethanol. Ethanol dependence and withdrawal were assessed by measurement of seizure thresholds after abrupt removal of the ethanol diet. Seizure thresholds were determined by slow, tail vein infusion of the gamma-aminobutyric acidA-receptor antagonist bicuculline.


RESULTS
Male and female rats displayed differences in timing for both onset and recovery from ethanol dependence, as determined by changes in ethanol withdrawal seizure susceptibility. Female rats were slower to develop dependence and quicker to recover compared with male rats. Furthermore, acute ethanol administration did not alter seizure susceptibility in pair-fed control animals, but it was anticonvulsant in ethanol-withdrawn rats. Ethanol-withdrawn female rats showed a greater response to acute ethanol administration than did male rats.


CONCLUSIONS
This set of experiments uncovered additional sex differences in one measure of ethanol dependence and withdrawal. Proposed mechanisms for the development of ethanol dependence involve alterations in subunit assembly of gamma-aminobutyric acidA and NMDA receptors or various posttranslational modifications. In consideration of these findings, whatever mechanisms underlie the development of ethanol dependence, there is a different sequence of events in male compared with female rats. Studies are ongoing to determine associations between behavioral measures of ethanol dependence/withdrawal and selective neuronal adaptations.