5-HT1A AGONIST OF BUSPIRONE RECEPTORS NORMALIZES THE CONSEQUENCE OF NEONATAL HYPOXIA IN ADULT RATS

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Purpose of the study was to examine a possibility of disturbances correction in adult rats provoked by normobaric hypoxia, which animals were exposed to in a newborn state by means of 5-HT1A agonist of buspirone receptors. Materials and methods of the study: two-month infant rats were divided into two groups. Experimental infant rats (injection of 5-HT1A agonist of buspirone receptors or physiological solution) with the further effect of hypoxia (8% of oxygen in respiratory nitrogen-oxygen gas blend) in a vacuum chamber with 60 minutes, and control infant rats (injection of buspirone or physiological solution) without further effect of hypoxia. Daily injections of buspirone or physiological solution were done during 14 days, beginning from the second day of life. Runs were conducted using adult animals. We examined adult rats about the effect of hypoxia on the indices of a prolonged pain response with the infection evoked by the injection with 2.5% of formalin solution into the foot of hind limb. In 24 hours after the formalin test all animals were exposed to the forced swimming test (Porsolt’s test). All animals were examined on a possibility of correction of hypoxia consequences in a nociceptive system and in psychoemotional behavior by means of buspirone use. Results: we have discovered that the influence of hypoxia was manifested as an intensification of the second tonic phase of the response, as the multiplication of patterns of creasing+succusion (p=0.046 and p=0.025), as well as in duration of licking pattern (p=0.03 in male rats and p=0.002 in female rats). Hypoxia effect in the course of the forces swimming test was manifested as a time increase of immobility in male rats (p=0.018) as well as in female rats (p=0.001). Chronic injections of buspirone decreased the effect of hypoxia at the second tonic phase, which was manifested in the decrease of creasing+succusion (p=0.001 in male and female rats), and a duration of licking patterns (p=0.03 in male and p=0.002 in female rats) in comparison with this index in rats exposed to the hypoxia effect or effect of physiological solution. In the forced swimming test chronic injections of buspirone for rats, which were exposed to hypoxia, provoked the decrease of immobility time in comparison with these indices of the rats exposed to the action of hypoxia and physiological solution (p≤0.05 in rats of both genders). Thus, chronic injections of buspirone allowed coordination the disturbances in tonic nociceptive and psychoemotional systems of rats which were exposed to hypoxia in their newborn state. Conclusions: the data obtained after runs on adult male and female rats show the participation of 5-HT1A receptors in correction of disturbances in tonic nociceptive system and psychoemotional behavior, evoked by normobaric hypoxia in a infant period.