Differential behavioral and biochemical effects of right and left hemispheric cerebral infarction in the rat

Following ligation of the right middle cerebral artery, rats were hyperactive for 2 to 3 weeks whether activity was measured by running wheel revolutions or open field observations. Assays of brain catecholamines revealed 30 percent reductions of norepinephrine in the injured and uninjured cortex and locus coeruleus and a 20 percent reduction of dopamine in the substantia nigra. In contrast, rats with left middle cerebral artery ligations did not become hyperactive and did not show any significant change in catecholamines in any of the brain areas studied. Right and left hemispheric infarctions were comparable in their locations and extent of tissue damage. This lateralization of behavioral and biochemical response to cerebral infarction may be the consequence of anatomical or physiological asymmetries in the brain.