INHIBITORY EFFECTS OF CHOLECYSTOKININ ON RATS GENICULATE ACTIVITY CANBE BLOCKED BY GABA-ANTAGONISTS

Cholecystokinin applied iontophoretically as the sulfated octapeptide (CCK-8S) or as highly selective CCKA- and CCKB-agonists induced excita tory as well as inhibitory effects on dorsal lateral geniculate unit a ctivity. Inhibitory effects of CCK could be abolished by administratio n of GABAergic antagonists, especially bicuculline. Therefore, interne urons seem to be largely excited by CCK, and in this way, they appear to mediate the inhibition of the discharge rate in geniculate relay ce lls induced by CCK.