Structure-activity analysis of the motor effects of neuropeptide Y.

The purpose of the present study was to examine structure-activity relationships for three known motor effects of neuropeptide Y (NPY): decreased spontaneous activity, enhancement of muscle tone, and catalepsy. Various NPY fragments and structural analogues were synthesized and administered intracerebroventricularly in several doses (2.5-160 micrograms); their effects on these three motor variables were evaluated and compared. Globally, results indicate that the C-terminal portion of the peptide is responsible for the three motor effects of NPY. However, the distributions of potencies of the various fragments and analogues for each effect were clearly different, suggesting that the putative receptors mediating each motor effect are pharmacologically different. The findings of the present work are discussed in relation to those obtained in previous structure-activity studies.