Melanin-concentrating hormone (MCH) involvement in pentylenetetrazole (PTZ)-induced seizure in rat and guinea pig.

Intraperitoneal injection of 60 mg/kg of pentylenetetrazole (PTZ) induced seizure in rats, but was subthreshold and did not result in seizure in guinea pigs. Three days after intracerebroventricular (i.c.v.) injection of 75 micrograms 6-hydroxydopamine (6-OHDA) in guinea pigs, PTZ induced seizures similar to those seen in rats. In both rats and 6-OHDA-treated guinea pigs, i.c.v. injection of melanin-concentrating hormone (MCH) 15 min before PTZ prevented seizure activity. These results suggest that MCH-containing neurons may participate in the neural circuits involved in expression of PTZ-induced seizure.