[An experimental study of the effect of Zofran on the manifestations of a primary reaction to irradiation].

Zofran is a selective antagonist of 5-HT3 receptors which effectively prevents postradiation dyspeptic and behavioral disorders in dogs and rats. Administration of the drug normalizes intestinal absorption and propulsion activity in irradiated animals.

[The role of the endogenous opioid system in the mechanisms of the development of early postradiation autonomic and behavioral disorders].

In the experiments with rats and dogs it was shown that irradiation within the dose range of 50-100 Gy is accompanied by the increasing of enkephaline content in various brain structures and beta-endorphine level in blood plasma. The blocking of the opiate receptors naloxone promotes the decrease of post-radiation vomiting in dogs, gastrostasis and hypokinesia in rats. That supports the participation of endogenous opioid system in the primary clinical reaction response to irradiation.

[Prostaglandins--their role in the mechanisms of the development of the primary reaction to radiation syndrome].

In experiments with dogs and rats it has been shown that early after high doses of irradiation, the content of prostaglandins in the blood plasma increases, whereas in the intestinal tissues it decreases. The inhibitors of prostaglandins synthesis indomethacin and voltaren hinder the development of early digestive disturbances, normalize the intestine absorptive and propulsive functions and make post-irradiation hypokinesia less pronounced. Possible mechanisms of the prostaglandins involvement in the genesis of prodromal radiation syndrome are discussed.

[The role of serotonin and histamine in the neurohumoral mechanisms of postirradiation diarrhea in rats].

In experiments with rats exposed to 200 Gy radiation it was shown that the diarrhea effect of serotonin under the effect of radiation is implemented via D- and M-type receptors, and that of histamine via H1 and H2 receptors. Serotonin and histamine, that were released under the effect of radiation from endocrine and mast cells of the digestive tract, stimulated the propulsion activity of the intestine whereas histamine, in addition, inhibited the absorption process. It is suggested that serotonin and histamine antagonists should be used as means of preventing of radiation-induced diarrhea.

[The role of biogenic amines in the neurohumoral mechanisms of postradiation gastrostasis in rats].

In experiments with rats it was shown that pharmacological substances that deplete the biogenic amine pool or selectively arrest dopamine and serotonin receptors prevent or considerably reduce the postirradiation gastrostasis. It is suggested that activation of dopamine- and serotonergic inhibiting mechanisms of regulation of motor-evacuative function of the stomach is responsible for the postirradiation delay in gastric evacuation.