[The Qualitative Analysis of the Amide Derivative of HLDF-6 Peptide and Its Metabolites with the Use of Tritium- and Deuterium-Labeled Derivatives].

The goal of the study was to elaborate the pharmacokinetics methods of the amide derivative of peptide HLDF-6 (TGENHR-NH2) and its range of nootropic and neuroprotective activity is wide. The hexapeptide 41TGENHR46 is a fragment of the HDLF differentiation factor. It forms the basis for the development of preventive and therapeutic preparations for treating cerebrovascular and neurodegenerative conditions. Pharmacokinetic and molecular mechanisms of the action of the HLDF-6 peptide were studied using tritium- and deuterium-labeled derivatives of this peptide, produced with the use of the high-temperature solid-state catalytic isotope exchange reaction (HSCIE). This reaction was employed to produce the tritium-labeled peptide [3H]TGENHR-NH2 with a molar radioactivity of 230 Ci/mmol and the deuterium-labeled peptide [2H]TGENHR-NH2 with an average deuterium incorporation equal to 10.5 atoms. It was shown by the NMR spectroscopy that the isotope label distribution over the labeled peptide's molecule was uniform, which allowed qualitative analysis ofboth the peptide itself and its fragments in the organism's tissues to be conducted. The newly developed pharmacokinetics method makes it possible to avoid almost completely losses of the peptides under study due to biodegradation during the analysis of tissues. These labeled peptides were used in mice, rats and rabbits to study the pharmacokinetics of the peptide and to calculate the values of its principal pharmacokinetic parameters. Characteristics of its pharmacokinetic profile in the blood were obtained, the hypothesis of pharmacokinetics linearity tested, its metabolism analyzed and its bioavailability value, 34%, calculated. It has been shown that the studied TGENHR-NH2 peptide shows high resistance to hydrolysis in the blood plasma, with dipeptidyl aminopeptidases making the largest contribution to its hydrolysis.

Neurotensin-like peptides as potential antipsychotics: modulation of the serotonin system.

Neurotensin-like peptides acting as functional antagonists of serotonin receptors were revealed in the head-shaking test on mice. The neurotensin-like peptides block the serotonin-induced platelet aggregation in humans. Radioligand binding assay showed that neurotensin-like peptides modulate specifi c binding of 5НТ2 serotonin receptor antagonist ketanserin, but have no effect on binding of ligands of 5HT2c receptor mesulergine and 5HT1а receptors NAN-190. Similar effects of neurotensin-like peptides in the experiments in vivo and in vitro suggest that the mechanisms of the detected antipsychotic effect of the peptides can be mediated by serotonin receptors.