[Influence of acute and chronic administrations of beta-casomorphins on the maternal motivation in albino rats].

The influence of food-derived opioid peptides beta-casomorphines on the manifestation of nursing albino rats maternal behavior was investigated. It was shown that both acute and chronic (during the postnatal period) administration of beta-casomorphin-7 (Tyr-Pro-Phe-Pro-Gly-Pro), the typical representative of this group of peptides, decreases the level of the parental motivation. The effects of beta-casomorphin-7 were naloxone-dependent; N-terminal-reduced analogues had a significantly lesser activity. The obtained results testify in favor of the probable role of casein opioid fragments which were formed in mammary glands of a nursing female, in the development of maternal behavior abnormalities. At the same time, beta-casomorphins could be considered as the limiting factors to the excessive manifestation of the parental motivation.

[Behavioural effects of beta-casomorphin-7 in its intranasal administration]. / Povedenceskie éffekty beta-kazomorfina-7 pri intranazal'nom vvedenii.

Intranasally administrated natural opioid peptide beta-casomorphin-7 (doses 0.001, 0.005, 0.02, and 0.1 mg/kg) was shown to produce alterations in behavior of male albino rats. The anxiolytic effect of the peptide tested in two "open field" modifications was most pronounced. Besides, two higher doses of promoted learning under conditions of negative reinforcement. The beta-casomorphin-7 effects on pain sensitivity and locomotion were insignificant. The obtained results only in part coincide with the effects of intraperitoneal peptide injection described earlier. This suggests that the specific effects of beta-casomorphin-7 considerably depend on the way of its penetration into a body; in case of intranasal administration they are apparently determined by primarily influence of the peptide on hypothalamic structures.

[The neurotropic activity of food-derived opioid peptides beta-casomorphins]. / Neirotropnaia aktivnost' opioidnykh peptidov pishchevogo proiskhozhdeniia beta-kazomorfinov.

In the review the history of food-derived opioid peptides beta-casomorphins (beta-cas) discovery is given. The beta-cas formation in gastrointestinal tract during the beta-casein degradation and the following penetration into the blood are described, in the first place in newborn mammals. The attention is focused on neurotropic activity of beta-cas: their influence on the pain sensitivity, locomotion, anxiety and learning of experimental animals. The beta-cas ability to change the characteristics of mother-infant interaction is specially analysed. The necessity to take into consideration of beta-cas physiological effects on nursing dams and newborns behaviour is noted.

[Changes in beta-casomorphine-7 effect on behavior of albino rat pups in postnatal development]. / Izmeneniie povedencheskikh éffektov beta-kazomorfina-7 v khode postnatal'nogo razvitiia detenyshei belykh krys.

The analgetic effect of heptapeptide beta-casomorphine-7 in newborn albino rats (20 mg/kg, i.p.) was recorded already 14 days after birth in the "hot plate" test. The first signs of a possible influence of the peptide on motor activity were observed only at the age of 28 days. They are expressed in impairment of motor coordination and change in locomotion level ("Opto-Varimex" test). The obtained evidence probably reflect the processes of discrete maturation of different components of the opioid system of the rat brain.