Hypoxic stress-induced convulsion and death: protective effect of alpha 2-adrenoceptor and benzodiazepine receptor agonists and Ro 5-4864.

Various alpha 2-agonists such as clonidine, guanfacine, B-HT 920 and ICI 106270 were investigated for their effect in hypoxic stress in rats and mice. Pretreatment with alpha 2-adrenoceptor agonists exhibited a yohimbine sensitive antistress effect as they prolonged the latencies for convulsion and death due to hypoxia. Intracerebroventricular administration of clonidine and ICI 106270 also shared the protective effect, indicating the involvement of central alpha 2-adrenoceptors. However, their protective effect, though comparable to diazepam and CL 218872, was more pronounced. The peripheral benzodiazepine receptor agonist, Ro 5-4864, also had a marked antihypoxic stress effect.