EFFECTS OF SIGMA-LIGANDS ON RAT CEREBELLAR PURKINJE NEURON FIRING - AN IONTOPHORETIC STUDY

The electrophysiological responses of rat cerebellar Purkinje neurons to selective a ligands applied iontophoretically was examined in ureth ane anesthetized male Sprague-Dawley rats. 1,3-Di-o-tolylguanidine (DT G), dextrallorphan (DEX), (+)-pentazocine((+)-PENT), (+)-3-(3-Hydroxyp henyl)-N-propylpiperidine ((+)-3-PPP), and the novel diamine BD1008, w ere ejected from multibarrel pipettes onto individual Purkinje cells. In some neurons, cell firing was inhibited following ejections of all compounds. These inhibitory effects were dose dependent and occurred w ithout changes in spike amplitude or duration, thus ruling out local a nesthetic effects as a mechanism. (+)-3-PPP and DEX increased firing r ate in 27% and 14% (n = 15, n = 14, respectively) of cells studied. Th e results of this study indicate that a ligands significantly alter th e spontaneous firing of Purkinje neurons, consistent with previous wor k suggesting motor effects of a ligands via the rubro-cerebellar circu itry.