[Effects of systemically-administered beta-casomorphin-7 on nociception in rats].

The influence of food-derived heptapeptide beta-casomorphin-7 (beta-CM-7) on pain sensibility of white rats was studied by tail flick test. As shown for doses 10 and 20 mg/kg intraperitoneally, injected beta-CM-7 induced significant analgesia; lower peptide concentration (5 mg/kg) was ineffective. As a whole, there is a significant positive correlation between the intensity of analgesia and the quantity of administered exorphine. These changes of pain sensibility were observed for one hour after injection of heptapeptide; further measurements showed no significant difference of time reaction between control and experimental groups of rats. It was found out that animals with high native level of pain sensibility (4-8 sec) made the main contribution to manifestation of analgesia.