[Evidences of Existence of Serotoninergic Nerves, Enhancing Duodenal Motility].

The review is devoted to the mechanism of duodenal motility activation caused by sympathetic nerves. The authors havefound that stimulation of the sympathetic trunk in the thoracic cavity in dogs in most cases provide not inhibitory but excitatory motor responses of the duodenum. Excitatory effects were eliminated during 5HT-receptors blockade by promedol and lysergol. Analysis ofpublications showed that sympathetic trunk contains serotoninergic fibers, providing excitatory motor responses of the duodenum to electrical nerve stimulation. According to histochemical and physiological studies, amount of serotonergic fibers in the sympathetic trunk is several times more than the adrenergic. This means that the body has sertoninergic nerves. Serotoninergic nerve as well as the sympathetic is a collective notion. There are: sympathetic trunks, their ramifications and branches that innervate the internal organs. Since promedol blocks serotonergic nerves, this is plausible cause of constipation in patients after surgical treatment along with the application of this drug.

[The significance of different 5-HT-receptors in regulation of gastrointestinal motility].

Serotonergic mechanisms are involved in many, if not all digestive functions of the gastrointestinal tract. A special role is played by serotoninergic structures in the neuronal control of motor activity. The study of these structures is of particular interest due to the widespread occurrence of irritable bowel syndrome, covering up to 20% of the adult population, which makes the research in this area up to date and in demand. Acute experiments were performed on 102 Wistar rats in 6 series. Experiments were carried out under general anesthesia (Nembutal, 60 mg/kg) and mechanical lung ventilation. Motor responses of the stomach, duodenum and ascending colon were studied to i.a. Serotonin adipate infusion (1 mg/kg) during joint blockade of sympathetic and parasympathetic chains of ANS, as well as on the background of the blockade of various 5-HT-receptors. Infusions of 5-HT-blockers reduce the magnitude of motor responses in stomach, duodenum and colon in varying degrees. Based on these data found 5-HT(1b)-receptors are mainly located in enteric neurons. The distribution of 5-HT(2b-4)-receptor is heterogeneous: 5-HT(2b)-receptors are located in enteric neurons of the stomach and intestinal myocytes; 5-HT3-receptors localized in the ganglia supplying the stomach and colon and 5-HT4-receptors are mainly located in the smooth muscle of the stomach, duodenal and ascendent colon enteric neurons.

Study of the nature of sympathetic trunk nerve fibers enhancing gastric motility.

Stimulation of the sympathetic nerve in the thoracic cavity often does not inhibit, but increases stomach contractions in dogs. Blockade of α- and ß-adrenoceptors potentiates this stimulatory effect, while blockade of S(1,2)-receptors localized mainly in smooth muscle cells eliminates it. It is concluded that sympathetic nerve includes serotonergic fibers stimulating gastric motility.

Catecholamines, α-, and ß-adrenoceptors are not responsible for activation of duodenum motility induced by sympathetic nerve stimulation.

Stimulation of sympathetic nerve in anesthetized dogs not treated with adrenergic blockers more frequently exerted stimulating rather than inhibitory effect on duodenal motility. Blockade of α- and ß-adrenoceptors with phentolamine and propranolol, respectively, did not prevent the excitatory action of the sympathetic nerve stimulation, but even potentiated this effect. The data showed that catecholamines as well as α- and ß-adrenoceptors are not involved in the excitatory effect of sympathetic origin.