Acute stress stimulates 3H-inositol phosphates accumulation in rat cerebral cortex. An in vivo determination

Using an in vivo method, we examined the effects of acute stress on rat brain inositol phosphates (IPs) levels. Cerebral phosphoinositides were prelabeled with 3H-myoinositol injected i.c.v. 24 h prior to a 15 min forced swimming stress. The stressful condition resulted in a 35% increase in whole brain 3H-IPs content, mainly due to an enhancement in cerebral cortical 3H-IPs accumulation. Cerebellar and brain minus cortex levels of 3H-IPs showed no alteration in stressed animals. Among the IPs, stress induced a 102% and 92% increase in the cerebral cortical content of 3H-IP and 3H-IP2 respectively. Pretreatment of animals with diazepam (2 mg/kg, i.p.) prevented the stress-induced 3H-IPs increase, in both the whole brain and the cerebral cortex. Diazepam administration alone did not produce changes in 3H-IPs. These results suggest that an acute stress condition stimulates in vivo the brain IPs turnover, probably because of an enhanced receptor-linked hydrolysis of phosphoinositides.