Neuropharmacological properties of V-9-M, a putative neuropeptide derived from procholecystokinin, in the rat.

It has been suggested that a nonapeptide called V-9-M (Val-Pro-Val-Glu-Ala-Val-Asp-Pro-Met) is produced by the processing of procholecystokinin. However, its physiological and pharmacological activities are not known. In the present study, synthetic V-9-M amide was injected into the lateral ventricle of the rat and its effects on general activities were observed. V-9-M caused a marked sedation; it suppressed spontaneous activity and hypermotility induced by thyrotropin-releasing hormone, methamphetamine, and apomorphine. Hypomotility induced by small doses of apomorphine was also decreased further. V-9-M caused hypothermia and prolonged the duration of pentobarbital-induced sleep, and it decreased locomotion in an open-field situation. However, V-9-M did not affect appetite in fasted rats.