Effect of Convulsive and Anti-Convulsive Agents on Brain Free Fatty Acids and Diacylglycerols
Brain free fatty acids (FFA) and diacylglycerols (DG) are maintained in a dynamic equilibrium with the membrane phospholipids. Many factors, including ischemia and drug induced convulsion, are known to disturb the equilibrium resulting in alteration of the FFA and DG level. The biochemical mechanism responsible for the disturbances is not yet fully understood. In this study, the FFA and DG in brain due to carbamylcholine and pentylenetetrazol induced convulsion and the suppressive action by scopolamine and diazepam was investigated. Carbamylcholine injected into rat brain intracerebrally gave rise to clonic and tonic seizures as well as exhibited some of the cholinergic symptoms. An increase in FFA and DG level was observed. The increase in FFA (but not DG) was blocked by pretreatment of scopolamine. Scopolamine injection (i. p.) alone could reduce the FFA level in brain but not DG. In all cases, subjecting the brain to 2 min post-decapitative ischemia resulted in a large increase in FFA and DG. Carbamylcholine stimulation potentiated the ischemia-induced increase in FFA and DG. Under this type of stimulation, arachidonic and stearic acids were preferentially released during stimulation and ischemia. Seizure was observed within two min after pentylenetetrazol administration (i. p.) to young rats. This drug also induced an increase in brain FFA but apparently was not effective in modulating the DG level. Pretreatment of rats with diazepam could effectively reduce the pentylenetetrazol-induced convulsion and FFA increase. A decrease in both FFA and DG was observed when rats were treated with diazepam (i. p.) alone. In general, FFA level in brain is increased during stimulation and decreased during depression. The differences in the FFA and DG changes as shown by convulsive and anti-convulsive agents further suggest that multiple biochemical mechanisms are present in mediating these changes.