Involvement of the vanilloid receptor 1 in the mechanisms of analgesic effect of amizonum

Abstract

SUMMARY The study of features of pharmacodynamics of a new analgesic is an important and urgent task of modern pharmacology. These data allow us to clarify the nosology for application of an analgesic and to create a theoretical background to optimize its use. An effect mediated by the transient receptor potential cation channel, subfamily V, member 1 (TRPV1) activation can also be an effective mechanism of the analgesic action. We evaluated the possibility of TRPV1 participation in implementation of the analgesic effect with the antiviral action of amizonum during the experiment. It is known that amino acids Tyr511 and Ser512 are the main components of the active site of TRPV1. In this connection, dipeptide Tyr-Ser has been completely synthesized as a model of the active site of TRPV1. In the experiment model this was shown, using the spectrophotometric method, with the formation of the “capsaicin - Tyr- Ser” intermolecular complex at the level of the stability constant Kkor=0.998 and Kr=0.3•10-4 L/mol and the “amizonum - Tyr-Ser” weak intermolecular complex Kr=0.05•104 L/mol; Kkor= 0.995, respectively. The data verification was carried out in experiments in vitro (isolated ratportal vein) and in vivo (Tail-flick model), with the TRPV1 agonist. It was shown that the amplitude of smooth muscle (SM) contraction of the portal vein at a capsaicin concentration 0.1 μmol/L, 0.5 μmol/L capsazepine, and 1.0 μmol/L amizonum was +30.3±5.3%, -3.2± 2.7% and +7.1±3.2% from initial level, respectivelly. In a combined application of amizonum with capsaicin or capsazepine, the amplitude of contraction of the SM portal vein was 20.1± 1.3% and -3.0±1.4%, respectively. This indicates the absence of action of amizonum under combined use of capsaicinoids. The Tail-flick model showed atypical potentiation of the amizonum antinociception with the use of capsaicin. The obtained data suggest the low probability of the participation of TRPV1 in the implementation of the antinociceptive action of amizonum.