INTERACTION AMONG ALFAXALONE, PREGNENOLONE SULFATE, AND 2 GABA(A) AGONISTS ON HIPPOCAMPAL SLICES

GABA(A) agonists do not respond to the same degree to allosteric modul ators of the GABA(A) receptor complex such as benzodiazepines. We repo rt there the effects of two steroids (alfaxalone and pregnenolone sulf ate) on the inhibition induced by two GABAA agonists, 3-amino propane sulphonic acid (3-APS) and muscimol, on the extracellular evoked poten tials obtained in CA1 of mice hippocampi. Alfaxalone (1 mu M) potentia tes the effects of both agonists, although incubation times longer tha n 15 minutes are required to potentiate the inhibitory effect of musci mol, Lower doses of pregnenolone sulfate at shorter incubation periods are able to inhibit the effects produced by single doses of 3-APS as compared to muscimol (15 mu M during 5 min vs 30 mu M during 5 min). O ur results confirm the possibility that there might be differences in the interaction between GABA(A) agonists and modulatory steroids.