The estimation of interactions between arginine-vasopressin (AVP) and NMDA receptors in memory and learning processes.

Arginine-vasopressin (AVP) is a neuropeptide which facilitates learning and memory processes. We examinated the participation of NMDA receptors in beneficial effects of peptide. The results of our study show that noncompetitive antagonist of NMDA receptor-MK-801 impairs the effect of AVP on the consolidation of conditioned avoidance responses and antagonist of polyamines site-arcaine reduced advantageous effect of AVP on the retrieval of memory in passive avoidance situation.

The role of NMDA receptors in central action of angiotensin II.

The influence of noncompetitive (MK-801), competitive (AP-7) and the antagonist of polyamines site of NMDA receptor (arcaine) on the central activity of angiotensin II (A II) was studied. The open field test, conditioning of active avoidance responses (CARs) and passive avoidance situation was used to investigate learning and memory in rats. All used antagonists decreased beneficial action of A II on these processes.

Estimation of central activity of hydroxyproline--the amino acid characteristic for collagen degradation products.

The central activity of hydroxyproline - the amino acid characteristic for collagen degradation products was studied. The levels of urinary and serum hydroxyproline are elevated in many disturbances, among them is a mental deficiency connected with hydroxyprolinemia. Previous studies showed that the mixture of collagen degradation products is biologically active and exerts and effect on central nervous system.

Central activity of peptide Gly-Pro-Hyp--the main component of collagen degradation products mixture.

The effect of tripeptide Gly-Pro-Hyp on the central nervous system was studied. The peptide Gly-Pro-Hyp is a main component of the mixture of collagen type I degradation products obtained by 6-h digestion with bacterial collagenase. The investigated peptide in the doses 1 microgram, 2 micrograms, and 5 micrograms significantly reduces the psychomotor activity of animals, intensifies haloperidol-induced catalepsy and enhances stereotypy behaviour after apomorphine administration.

A search for new active amino acids responsible for pharmacological activity of collagen degradation products.

The pharmacological activity of glycine (Gly), proline (Pro) and hydroxyproline (Hyp)--the main amino acids in collagen degradation products--was studied in comparison to the activity of all mixture of DPTC (degradation products of trihelical collagen). The investigated amino acids decreased psychomotor activity of rats, enhanced apomorphine- and amphetamine-induced stereotypy. Pro and Hyp enhanced also catalepsy, but Gly decreased the haloperidol action.