Peculiarities of influence of NO-synthase inhibitors on behavioral parameters of rats

Aim. A comparative study of the influence of nitric oxide synthase (NO-synthase) inhibitors on the parameters of anxiety, motor activity and pain sensitivity of rats.

Materials and Methods. The work was conducted on male rats of Wistar line. The anxiety level and locomotor activity of rats were studied in the «elevated plus maze» (EPM) test. Pain sensitivity of the animals was tested on the «hotplate» apparatus. In the work, selective inhibitor of inducible isoform of NO-synthase – aminoguanidine – at a dose of 50 mg/kg, and non-selective inhibitor of this enzyme – N-nitro-L-arginine – at a dose of 50 mg/kg, were used. Rats of the control group were introduced the equivalent quantity of normal saline.

NO-synthase inducible inhibitor – aminoguadinine did not produce any influence on the anxiety level, but led to reduction of the horizontal motor activity of rats. Introduction of non-selective NO-synthase inhibitor – N-nitro-L-arginine – was accompanied by reduction of the anxiety and of the locomotor activity of animals in the EPM test. Both investigated NO-synthase inhibitors induced alteration of pain sensitivity of rats in the form of hypoalgesia. Here, the most pronounced nociceptive effect was observed with introduction of non-selective NO-synthase inhibitor.

Conclusion. In the work the evidence of participation of inducible isoform of NO-synthase in realization of the motor activity and pain sensitivity processes in rats is shown. In result of the conducted experiments it was found that introduction of non-selective NO-synthase inhibitor N-nitro-L-arginine was accompanied by evident alterations of anxious behavior, locomotor activity and nociceptive sensitivity of rats. The results obtained confirm the important role of the system of regulation of nitric oxide synthesis in neurochemical mechanisms of behavioral reactions in rats.