Possible involvement of insulin, endogenous opioids and calcitonin gene related peptide in remote ischaemic preconditioning of brain

The present study has been designed to investigate the role of insulin, endogenous opioids and calcitonin gene related peptide (CGRP) on remote mesenteric ischaemic preconditioning induced reversal of global cerebral ischaemia-reperfusion injury in mice. Bilateral carotid artery occlusion of 10 min followed by reperfusion for 24 hour was employed in present study to produce ischaemia and reperfusion induced cerebral injury in mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Short-term memory was evaluated using elevated plus maze. Inclined beam walking and resistance to lateral push response, tests were employed to assess motor incoordination. Bilateral carotid artery occlusion followed by reperfusion produced cerebral infarction and impaired short-term memory, motor co-ordination and lateral push response. A preceding episode of mesenteric artery occlusion for 15 min and reperfusion of 15 min (remote mesenteric ischaemic preconditioning) prevented markedly, ischaemia-reperfusion-induced cerebral injury measured in terms of infarct size, loss of short-term memory, motor coordination and lateral push response. Anti-insulin serum, naloxone (an opioid receptor antagonist) and alpha-CGRP (8-37) (a selective CGRP receptor blocker) attenuated the neuroprotective effect of remote mesenteric ischaemic preconditioning. It may be concluded that neuroprotective effect of remote mesenteric ischaemic preconditioning probably is mediated through insulin, endogenous opioids and CGRP released as a consequence of mesenteric ischaemia and reperfusion in mice.