Effects of sigma ligands on rat cerebellar Purkinje neuron firing: an iontophoretic study.
The electrophysiological responses of rat cerebellar Purkinje neurons to selective sigma ligands applied iontophoretically was examined in urethane anesthetized male Sprague-Dawley rats. 1,3-Di-o-tolylguanidine (DTG), dextrallorphan (DEX), (+)-pentazocine((+)-PENT), (+)-3-(3-Hydroxyphenyl)-N-propylpiperidine ((+)-3-PPP), and the novel diamine BD1008, were 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 without changes in spike amplitude or duration, thus ruling out local anesthetic effects as a mechanism. (+)-3-PPP and DEX increased firing rate in 27% and 14% (n = 15, n = 14, respectively) of cells studied. The results of this study indicate that sigma ligands significantly alter the spontaneous firing of Purkinje neurons, consistent with previous work suggesting motor effects of sigma ligands via the rubro-cerebellar circuitry.
Martin
W J
WJ
Schrier Research Laboratory, Department of Psychology, Brown University, Providence, RI 02912.
De Costa
B R
BR
Walker
J M
JM
D000818:Animals; D005021:Ethylamines / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology; D007478:Iontophoresis; D007977:Levallorphan / Q000494:pharmacology; D008297:Male; D010423:Pentazocine / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011689:Purkinje Cells / Q000187:drug effects* / Q000502:physiology; D011759:Pyrrolidines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017480:Receptors, sigma / Q000502:physiology*
D005021:Ethylamines; D006146:Guanidines; D010880:Piperidines; D011759:Pyrrolidines; D017480:Receptors, sigma; C085527:BD 1008; D007977:Levallorphan; C044130:dextrallorphan; C026539:preclamol; C050232:1,3-ditolylguanidine; D010423:Pentazocine