Suppressive effect of cholecystokinin and its related peptides on beta-endorphin-induced catalepsy in rats.

The effects of the C-terminal octapeptide of cholecystokinin (CCK-8) and its related peptides on the onset and duration of beta-endorphin-induced catalepsy on injection of the peptides into the lateral ventricle were investigated in male rats. The onset of catalepsy was delayed to some extent by nonsulfated CCK-8 and CCK-7 but CCK-8 and caerulein were ineffective. Naltrexone and caerulein significantly shortened the duration of catalepsy, but CCKs were less effective to shorten it. Pentagastrin had no effect on either parameter.