Laboratory of physiology of digestion

Head - d.m.s., professor Vladimir I.Ovsyannikov

Main trend of research of the lab.of physiology of digestion: finding out mechanisms of integration of enteric neuromediators and gastrointestinal hormones during realization of neurogenic and humoral influences on the gastrointestinal motility.

For evaluation of the gastric contractile activity and the activity of various parts of the small intestine and colon in conscious animals (rabbits) myoelectric activity is registrated via bipolar electrodes implantated on smooth muscle layer. Frequency and amplitude of action potential bursts are quantitatively evaluated.
Participation of adrenergic mechanisms, excitatory cholinergic and inhibitory nonadrenergic neurons in realization of motor responses of gastroduodenal and ileocaecal zones to serotonin and immobilization stress is investigated. Excitatory and inhibitory components of specified reactions in conditions of food deprivation and in digestion are evaluated. The analysis of receptor mechanisms of the reactions is carried out with application of agonists and antagonists of alpha- and beta-adrenoceptors, muscarinic and nicotinic cholinoreceptors.

We investigate the character and mechanism of serotonin and peptidergic hormones ( gastrin, enkephalines) action on coupling of the gastric and duodenal contractile activity. A role of gastroduodenal motor discoordination as a pathogenic factor of gastric mucosal ulceration is studied.
Investigation of the colonic evacuatory function chronophysiology in healthy people has been started in the laboratory.

In the laboratory of physiology of digestion investigations of the mechanisms of integration of neuromediatory and hormonal factors in the regulation of digestive functions have revealed previously unknown exciting beta-adrenoreceptors on the cholinergic neurons of the enteral nervous system. The idea of double adrenergic control of these neurons is substantiated that widened the present-day consideration of the sympathoadrenal system as a central modulator of the motor activity of the gastrointestinal tract. It was shown that effects of serotonine, histamine, bradikinine, gastrine and met-enkefaline are realized in the gastro-intestinal tract with the involvement of the cholinergic neural contour and non-adrenergic inhibitory neurons of the enteral nervous system.

It was found that effects of stress on organism caused a discrepancy in the motor activity of the stomach and duodenum, that resulted in regurgitation of the duodenal content into the stomach and was followed by an erosive lesion of its mucosa. This functional asymmetry in the gastroduodenal area may become a pathogenetic factor in the development of ulcer disease of the stomach.

It was shown that the phase of the optimum of a diurnal rhythm of the evacuatory function of the in testine determined the minimum and the phase of pessimum - maximum risk of intestinal bradyarrhythmia. The main mechanism of stress inhibition of motor activity of the ileocecal zone of the gastro-intestinal tract is the centrogenic excitation of non-adrenergic inhibitory neurons of the enteral nervous system, while stress activation of motor activity of the duodenum is of non-cholinergic nature.