NERVE AND HUMORAL PATHWAYS OF INTESTINAL ENDOTOXINS INFLUENCE ON INTEROCEPTIVE REFLEX REACTIONS

In acute experiments on rats, an increase and decrease in afferent activity in the mesenteric nerves of the intestine as well as vagus under the diaphragm, depending on the site of lipopolysaccharide (LPS, 10 μg) injection into the intestinal lumen, has been established. In addition, the effect of endotoxin on the gastrointestinal tract (GIT) is manifested in a reflex change in the efferent nerve impulses. The reactions of the cervical sympathetic, splenic, cranial and caudal mesenteric nerves as well as vagus under the diaphragm are represented by an increase or decrease in the spontaneous activity of efferent fibers and depend on the zone of LPS infusion in the GIT. In general, inhibitory responses to endotoxin predominate, especially in the mesenteric nerves. According to experiments, the reflex responses of sympathetic efferent fibers caused by balloon distension of the colon are regularly weakened or completely suppressed after the infusion of LPS into the lumen of this organ. Under conditions of complete external decentralization of the GIT by transection of the vagus, all mesenteric nerves and the colon at the border with the rectum, the effects of modulation of the activity of both peripheral and central nervous structures under the influence of LPS are preserved due to the humoral pathway included in the complex neurotransmitter mechanism for controlling autonomic functions.