Changes in monoamine metabolism in the brain during unilateral cortical spreading depression in BALB/c mice

Abstract

BACKGROUND: BALB/c mice can be adequate models for elucidating the actions of neurotropic drugs in conditions of abnormal interhemispheric interactions. AIM: To examine the effect of unilateral cortical spreading depression on monoamine metabolism in BALB/c mice. MATERIALS AND METHODS: Twenty-four adult male BALB/c mice were analyzed. Unilateral cortical spreading depression (functional inactivation of one of the cerebral hemisphere cortex) was induced by applying a 1 × 1 mm filter paper moistened with a 25% KCl solution. Fifteen minutes after exposure, the animals were decapitated. By using high-performance liquid chromatography with an electrochemical detector in the cerebral cortex, hippocampus, olfactory tubercle, and striatum, the levels of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and their metabolites (dioxyphenylacetic [DOPAC], homovanilinic [HVA] and 5-hydroxyindolacetic acids) were measured. RESULTS: Unilateral cortical spreading depression was accompanied by a decrease in NE levels in the hippocampus and an increase in the DA extracellular metabolism (HVA and/or HVA/DA) in the olfactory tubercle and striatum on the side of the inactivated cortex. In addition to the listed effects, only functional inactivation of the right hemisphere caused a bilateral decrease in the NE level in the cortex and a decrease in the NE level and the DOPAC/DA ratio in the left (contralateral) hippocampus. No regular changes were noted in the posture of animals after the unilateral inactivation of the cerebral cortex. CONCLUSION:The results suggest that in BALB/c mice, the right hemisphere cortex plays a dominant role in regulating the activity of the noradrenergic system in the brain.