Peculiarities of somatovisceral reactions in early postnata ontogenesis

To reveal possible ways of the somatovisceral interaction, in the 0–5-day, 11–13-day and one-month-old rats, reactions of the spontaneous contractile activity of the gastric antrum were studied to a rhythmic stimulation of the tibial nerve for 30 s with frequency 30 imp/s and strength equal to 3–4 thresholds of the gastrocnemial muscle motor response. Only the stimulations of the central, but not of peripheral, nerve segments were effective, which indicates the reflex nature of the reactions. It has been established that in the process of development, a shift occurs of the predominantly inhibitory reactions to predominantly activating the gastric wall reactions. Similar data were obtained by skin pain stimulation in the region of the tail base. Thus, the age-dependent change of direction of the observed somatoautonomous reactions can be produced by stimulation of different high-threshold somatic afferents. The efferent pathway both of inhibitory and of stimulatory reactions is mediated mainly, but not exclusively, by the gastric branches of the vagus nerve, which is confirmed by consequences of vagotomy and of section of the splanchnic nerve. As a whole, the results of the study can suggest that one of possible pathways of effects of the skeletal muscle contraction on rhythmic activity of the gastrointenstinal tract can be activation of muscle receptors.