Effects of acute and chronic ethanol administration and withdrawal on adenosine 3':5'-monophosphate and guanosine 3':5'-monophosphate levels in the rat brain.

The effect of ethanol on cyclic nucleotide levels was investigated in male Sprague-Dawley rats. The rats were sacrificed by microwave irradiation, the brains were divided into four areas, and cyclic nucleotides were measured by radioimmunoassays. Administration of a single dose of ethanol per os produced a dose-dependent decrease of adenosine 3':5'-monophosphate (cyclic AMP) in cerebral cortex, cerebellum, pons and medulla oblongata while guanosine 3':5'-monophosphate (cyclic GMP) was decreased in all brain areas. Dependence on ethanol was induced by three daily administrations of ethanol p.o. for 7 days. The last dose of ethanol did not produce any decrease of cyclic AMP levels while the decrease of cyclic GMP levels was still present. During ethanol withdrawal cyclic AMP levels increased in cerebral cortex, pons and medulla oblongata and did not change in cerebellum. Changes of cyclic AMP in subcortex were more complex. Cyclic GMP levels increased during ethanol withdrawal in cerebellum, pons and medulla oblongata and did not change in cerebral cortex and subcortex. These results indicate that changes of cyclic nucleotides might participate in the mechanism of ethanol dependence and withdrawal.