THE EFFECTS OF SHORT PEPTIDES ISOLATED FR OM THE BRAIN OF HIBERNATINGGROUND-SQUIRRELS ON BEHAVIOR AND EEG OF RATS

The intracerebroventricular injection of the peptides kyotorphin (KT), newkyotorphin (NKT), and Aps-Tyr (BS) changed rat behaviour. There wa s an increase in the rate of exploratory reactions, rearing, grooming, stereotypic scratching movements, yawning, stretching, hiccuping, sne ezing. Similar effects had been earlier observed in rats after adminis tration of the fraction (F, 1-10 kD) from the brain of hibernating gro und squirrels in which the studied peptides were found. The EEG effect s depended on a peptide dose. As in the case of F injection, KT in the dose of 4 meg suppressed the theta-and alpha-rhythms, KT injection in the dose of 8 meg produced similar effect within the first minutes. T hen it was substituted for an enhancement of the delta-, theta-, and a lpha-rhythms while the beta-activity was suppressed. The effects of BS (4 mcg) and KT (mcg) were similar, however, increase in the BS dose t o 8 meg resulted in an enhancement of the beta-activity as in the case of F injection. The NKT effects also consisted in delta-enhancement a nd beta-suppression, but, in contrast to KT, the theta- and alpha-supp ression was short-term, delayed and occurred only after the peptide in jection in the dose of 8 meg.