[Effect of enkephalins on training the white rat in a T-maze].

It is shown that met-enkephalin and morphine injected intraperitoneally to rats in a dose of 0.15 mg/kg do not significantly affect the elaboration of conditioned reaction to place in a T-maze with food reinforcement. D-Ala-met-enkephalin amid in the same dose increases the number of unaccomplished reactions on the 2-nd day of learning without eliciting significant changes of other parameters. Leu-enkephalin and D-Ala-D-Leu-enkephalin (intraperitoneally, 0.15 mg/kg) increase the number of unaccomplished reactions and the time of maze-run when injected before the learning seances. D-Ala-D-enkephalin increases the time of run at its injection "immediately after" the learning seances as well. In this case the Leu-enkephalin is not effective. The obtained data show that enkephalin effects in this experimental test to a certain extent correlate with peptides' ability of binding tightly with delta-opiate brain receptors. Different effects of met- and leu-enkephalins confirm the hypothesis on diversity of peptides' functions in the central nervous system.