Estrogen modulation of the gamma-aminobutyric acid receptor complex in the central nervous system of rat

Administration of estradiol benzoate to ovariectomized rats results in an increased binding of [3H]muscimol, [3H]diazepam and 35S-t-butylbicyclophosphorothionate in various areas of the central nervous system of rats. The effect is dose-dependent and its onset can be observed as early as 12 hr after s.c. administration of the hormone. The various binding activities are differentially affected by the hormonal treatment: the maximal effect observed for [3H]diazepam binding is in the cerebellum (+42%), for [3H]muscimol binding in the frontal cortex (+84%) and for 35S-t-butylbicyclophosphorothionate binding in the striatum (+46%) indicating that the activities of the sites are not under the same cellular regulatory control. The estrogen-induced increase in [3H]diazepam binding sites does not result in an increased protection against chemoconvulsants such as pentylenetetrazole.