Behavioral effects of amylin injected intracerebroventricularly in the rat

Amylin is a peptide of pancreatic origin that has been reported to possess high-affinity binding sites in the brain and to affect central dopaminergic and serotonergic neurotransmission. Administered ICV the peptide induced a dose-dependent decrease of locomotor activity without affecting grooming and sniffing. At a dose of 5 micrograms/ rat, it antagonized the hypermotility and stereotypies induced by s.c. injection of amphetamine (2 mg/kg) or of the dopamine receptor agonist, apomorphine (250 mg/kg). Amylin did not change significantly the effect of haloperidol (0.5 mg/kg, s.c.) on locomotor activity, grooming, and sniffing. Moreover, the peptide did not modify the locomotor behavior of animals injected with the 5-HT2 antagonist, ritanserin (2 mg/kg, s.c.). These results suggest that amylin may exert motor effects, probably by interfering with central dopaminergic neurotransmission.