Cerebral asymmetry and behavioral lateralization in rats chronically lacking n-3 polyunsaturated fatty acids

Background: Anatomic and functional brain lateralization underlies hemisphere specialization for cognitive and motor control, and deviations from the normal patterns of asymmetry appear to be related to behavioral deficits. Studies on n-3 polyunsaturated fatty acid (PUFA) deficiency and behavioral impairments led us to postulate that a chronic lack of n-3 PUFA can lead to changes in lateralized behavior by affecting structural or neurochemical patterns of asymmetry in motor-releated brain structures. Methods: We compared the effects of a chronic n-3 PUFA deficient diet with a balanced diet on membrane phospholipid fatty acids composition and immunolabeling of choline acetyltransferase (ChAt), as a marker of cholinergic neurons, in left and right striatum of rats. Lateral motor behavior was assessed by rotation and paw preference. Results: Control rats had an asymmetric PUFA distribution with a right behavioral preference, whereas ChAt density was symmetrical. In deificient rats, the cholingeric neuron density was 30% lower on the right side, associated with a loss of PUFA asymmetry and behavior laterality. They present higher rotation behavior, and significantly more of them failed the bandedness test. Conclusion: These results indicate that a lack of n-3 PUFA is linked with a lateral behavior deficit, possibly leading to cognitive disturbances.