Effect of Antihistamines, Disodium Cromoglycate (DSCG) or Methysergide on Post-irradiation Cerebral Blood Flowand Mean Systemic Arterial Blood Pressure in Primates after 25 Gy, Whole-body, Gamma Irradiation.

Abstract

Exposure to ionizing radiation causes hypotension, cerebral ischemia and release of histamine (HA) and serotonin (5-HT). To investigate the relationship among these responses, rhesus monkeys (Macaca mulatta) received physiological saline (i.v.), disodium cromoglycate (DSCG), antihistamines (AH, mepyramine and cimetidine), or methysergide (METH), then were given 25 Gy whole-body irradiation. Monkeys receiving DSCG, AH or METH had higher post-irradiation mean arterial blood pressure (MBP) than saline-treated controls. Compared to levels in controls, post-irradiation hippocampal blood flow (rCBF) levels were higher in monkeys receiving DSCG, AH or METH. Treatment with the 5-HT2 receptor antagonist methysergide was the most effective in maintaining both rCBF and MBP after irradiation. Results support the hypothesis that the irradiation-induced cerebral ischemia and, to some extent, the hypotension is mediated by serotonin through 5-HT2 receptor sites.

Implication of mast cell degranulation in ischemic preconditioning‐induced prevention of cerebral injury

“…On the other hand, sodium cromoglycate per se was observed to decrease markedly ischemia-and reperfusion-induced cerebral injury, quantitated in terms of cerebral infarct size, memory impairment and motor incoordination. These results are in line with an earlier report [29]. Excessive degranulation of mast cells elicited by a severe ischemic insult has shown to cause release of certain biochemical mediators to an extent that is cytotoxic to the neurons and thus mediate the ischemic cell death as well as the accompanying secondary inflammatory processes [30].…”

Effects of Electron Radiation on Serotonin Signaling and Reactivity of Rat Gastric Smooth Muscle

“…Even though most electron energy is absorbed superficially, electron beams can treat tumors at a 5 cm depth [ 14 ] and even up to a depth of 4 inches [ 15 ]. Entering the body, accelerated electrons provoke ionizing-induced effects on target tissues, and these effects could cause functional and/or structural changes in the 5-HT receptor [ 16 , 17 ]. However, the effect of electron radiation on serotonin signaling and the resulting effects have not been studied well enough.…”