Pharmacology of ionotropic and metabotropic glutamate receptors on neurons involved in feeding behavior in the pond snail, Helisoma trivolvis.

Glutamate is a key regulatory neurotransmitter in the triphasic central pattern generator controlling feeding behavior in the pond snail, Helisoma trivolvis. It excites phase two motor neurons while inhibiting those in phases one and three. However, the receptors that mediate this regulation are only partially characterized.

NMDA receptor antagonists ameliorate the stepping deficits produced by unilateral medial forebrain bundle injections of 6-OHDA in rats.

Rationale And Objectives: To test the hypothesis that excess glutamatergic transmission at NMDA receptors may contribute to the pathogenesis of Parkinson's disease (PD), we examined the effects of various NMDA receptor antagonists on a recently developed rat model of PD.

Methods: Following unilateral injections of 12 microg 6-OHDA into the medial forebrain bundle of male Long Evans rats, stepping with both front paws was measured separately as the paws were dragged backwards and laterally. The effects of i.