[Neurotensin influence on painful stress afteractions in rats with neurotoxic damages of serotoninergic structures of brain substantia nigra].

The purpose of the research was to reveal the features of neurotensin influence on behavior of rats with damages of 5-HT structures of substantia nigra. Changes of recall of passive avoidance conditioned reactions, and also painful stimulation aftereffects on locomotor activity of rats in "open field" were studied. It was shown that neurotoxin 5,7-DOT administration into substantia nigra impaired recall of passive avoidance reactions and as well weakened oppressive aftereffects of painful stimulation. Administration of serotonin 5-HT1A receptors antagonist p-MPPF insert similar influence on aftereffects of painful stimulation. Neurotensin microinjections into caudate nucleus just before painful stimulation prevented disturbances of defensive behavior and its aftereffects evoked by neurotoxin. Neurotensin administration into substantia nigra in 24 h after painful stimulation didn't exert any significant influence on passive avoidance reactions but increased motor activity against a background of its recall. Effects of neurotoxin administrations into substantia nigra connected with weakened of painful stress influence on motor activity in rats. The prevention of this effect development after neurotensin administrations into caudate nucleus may be specified by recovery of recall passive avoidance reactions destroyed by neurotoxin action and is explained by normalization of relationships balance of 5-HT and dopaminergic brain systems.