Endogenous asymmetry of rat brain lipids and dominance of the right cerebral hemisphere in free fatty acid response to electroconvulsive shock.

An asymmetric distribution of free fatty acids (FFA) is shown to occur between right and left cerebral hemispheres (RCH, LCH) of the rat. The RCH contains 35% less FFA than the LCH, the difference being mainly accounted for by saturated and monoenoic fatty acids. Acute and chronic electroconvulsive shock (ECS) affects the distribution and apparent rate of fatty acid production differently in each hemisphere. Taking into consideration the basal content of each hemisphere, RCH produces significantly higher amounts of FFA during the acute tonic phase of the convulsion evoked by a single ECS. The largest increases correspond to arachidonic and stearic acids (1800% and 420% in RCH, 1200% and 330% in LCH, respectively). The hemispheric sidedness is evened out after successive ECSs. The removal of the released fatty acids is also faster in the RCH, as suggested by its lower FFA levels 5 min after a single shock (the acute condition) or after the last of a series of 5 daily shocks (the chronic condition). The endogenous FFA content and composition is altered by chronic ECSs. Thus, 24 h after the last of a series of 4 daily ECSs, total FFAs remain about 40% higher than in the controls for both hemispheres. Arachidonic acid increase amounts to 150%, doubling its percentage contribution to the FFA pool. The lower endogenous FFA content in RCH, its higher responsiveness to ECS, and its ability to more rapidly recover the pre-convulsive levels, suggest that the deacylation and reacylation of complex lipids are more active in this hemisphere.(ABSTRACT TRUNCATED AT 250 WORDS)