EFFECT OF METHAMPHETAMINE ON GLUTAMATE-POSITIVE NEURONS IN THE ADULT AND DEVELOPING RAT SOMATOSENSORY CORTEX

The neurotoxic effects of methamphetamine (MA) on dopaminergic and ser otonergic terminals have been well-documented. Another neurotoxic effe ct of MA is neuronal degeneration in the somatosensory cortex, as seen by silver staining. The neurochemical characteristics of these degene rating neurons are unknown. Using glutamate and glial fibrillary acid protein (GFAP) immunohistochemistry, it was found that MA exposure in adult rats (10 mg/kg given 4 times intraperotoneally (i.p.) at 2-h int ervals) causes localized depletion of glutamate-positive neurons and a strogliosis in the somato-sensory cortex 3 days following treatment. T he affected region covered the middle one-third portion from the longi tudinal fissure to the rhinal sulcus and was predominately seen in lay ers II-III of the cortex. This pattern of depletion is consistent with that demonstrated previously with silver staining following MA, d-amp hetamine, and 3,4-methylenedioxymethamphetmine (MDMA) exposures. Compa rable effects were not found in developing animals at ages previously shown to also be resistant to MA-induced effects on dopaminergic termi nals (age 20 and 40 days). Results suggest that MA exposure induces de generation of glutamatergic neurons in the somatosensory cortex of adu lt rats. (C) 1996 WiIey-Liss, Inc.