Central administration of FMRFamide produces antipsychotic-like effects in rodents

Neuropeptide FMRFamide (Phe-Met-Arg-Phe-NH2) was evaluated in animal models of psychosis. FMRFamide (0.5-100 micrograms, i.c.v.) produced blockade of conditioned avoidance response in rats and antagonized apomorphine-induced climbing behaviour in mice. Similarly, FMRFamide at lower doses (0.1-10 micrograms, i.c.v.) inhibited 5-hydroxy-L-tryptophan (5-HTP)-induced head twitches in rats. These effects of the peptide were similar to haloperidol (1 mg/kg, i.p.). However, unlike haloperidol, FMRFamide per se did not induce any catalepsy in rats at the doses employed in the above paradigms. These results indicate antipsychotic-like activity for the neuropeptide FMRFamide with possible involvement of the dopaminergic/5-HT2 systems.