NO ALTERATIONS IN THE 5-HT1A-MEDIATED INHIBITION OF FORSKOLIN-STIMULATED ADENYLATE-CYCLASE ACTIVITY IN THE HIPPOCAMPAL MEMBRANES FROM RATS CHRONICALLY TREATED WITH LITHIUM OR ANTIDEPRESSANTS

In order to determine the relevance of 5-HT1A-related signal transduction in the mode of action of lithium and antidepressants, the effects of long-term treatment with these drugs on the 5-HT1A -mediated inhibition of forskolin-stimulated adenylate cyclase activity were investigated in the rat hippocampal membranes. Chronic administration of antidepressants altered neither the [H-3]8-hydroxy-2-(di-n-propylamino)tetralin ([H-3]8-OH-DPAT) binding sites nor the inhibition of forskolin-stimulated adenylate cyclase activity by 5-HT. Long-term treatment with lithium did not affect the inhibitory effect of 5-HT on the forskolin-stimulated adenylate cyclase activity, either. Neither the stimulation by forskolin nor the inhibition by guanyl-5' -ylimidodiphosphate (Gpp(NH)p) of adenylate cyclase activity was not influenced by lithium treatment, suggesting that lithium has no effects on the components of adenylate cyclase system distal to the 5-HT1A receptors. These results indicate that the 5-HT1A -mediated neural transmissio has not such an important relevance in the mechanisms of action of lithium or antidepressants.