Amphetamine sensitization and amygdala kindling: pharmacological evaluation of catecholaminergic and cholinergic...

Chronic pharmacological experiments were conducted to evaluate the relationship between sensitization induced by repeated administration of amphetamine (AMPH) and electrical stimulation of the amygdala. While AMPH withdrawal did not influence the kindling process, AMPH administered during the kindling procedure increased the rate at which seizures evolved, and under these conditions withdrawal from chronic AMPH further facilitated the propensity to kindle. Haloperidol (HAL) treatment failed to block the stimulant-induced increase in kindling acquisition indicating that changes in dopamine (DA) are not necessary for the AMPH/kindling synergism to develop. Scopolamine dose-dependently retarded kindling evolution irrespective of prior AMPH pretreatment also ruling out a cholinergic mechanism in the kindling sensitization. Subsequent experiments assessed the interactive effects of AMPH and desipramine (DMI) on the kindling process. Animals chronically exposed to AMPH and switched to DMI treatment during the kindling procedure kindled faster than control subjects. In addition, withdrawal from DMI preexposure advanced the AMPH-induced increase in kindling rate. These results were discussed in terms of the role of norepinephrine-mediated inhibition of the kindling process, and were related to drug-elicited alterations in beta-adrenergic receptor functioning. Taken together, these findings implicate the amygdala as an important structure in the development of non-DA forms of AMPH sensitization.