Endogenous dopaminergic asymmetry affects development of seizures kindled in the rat amygdala

Cerebral dominance in 56 rats was determined by observing the direction of their turning behavior in response to injection of d-amphetamine (1.5 mg/kg, i.p.). Rats subsequently subjected to kindling of the amygdala developed full epileptic seizures after significantly fewer kindling sessions if the kindling electrodes were in the amygdala of the nondominant, rather than the dominant hemisphere. Kindling rate also showed a significant negative correlation with the total amount of turning after amphetamine. Rats kindled through electrodes in the ventral mesencephalon generally failed to develop full convulsive seizures, and did not show interhemispheric differences in the rate at which they developed preictal behaviors. As the dominant hemisphere of the rat, identified by rotational preference, contains a higher concentration of dopamine, we conclude that even small differences in dopaminergic activity, within the normal physiologic range, can affect the relative susceptibility of the two hemispheres to the development of kindled epilepsy.