PREOPERATIVE REGIMENS OF MAGNESIUM FACILITATE RECOVERY OF FUNCTION AND PREVENT SUBCORTICAL ATROPHY FOLLOWING LESIONS OF THE RAT SENSORIMOTOR CORTEX

Following brain injury, there is a reduction of intra- and extracellul ar levels of magnesium (Mg++), which may contribute to the severity of the lesion-induced behavioral impairments. Injections of magnesium pr ior to or after brain injury attenuate these behavioral impairments. T he present study extends these findings by manipulating the number of injections and the time period between the injections and the time of injury, Rats were given either two or five daily preoperative injectio ns of MgCl2 (1 mmol/kg, ip), or saline (1 ml/kg, ip) with the final in jection given 24 h prior to electrolytic lesions of the somatic sensor imotor cortex (SMC). Following SMC lesions the rats exhibited contrala teral deficits in forelimb placing and locomotor placing. Rats treated with either two or five preoperative injections of MgCl2 showed a red uction in the initial magnitude of the contralateral deficits and an a ccelerated rate of recovery compared to saline-treated rats. In additi on, analysis of striatal atrophy revealed that MgCl2 treatment prevent ed atrophy in the ipsilateral posterior striatum compared to rats trea ted with saline. These data suggest that preoperative injections of Mg Cl2 produce facilitation of sensorimotor recovery and reduce subcortic al atrophy. Moreover, to observe the beneficial effects of MgCl2, the timing of injections need not be tied to the period immediately around the brain injury. The present data may indicate that daily supplement s of magnesium may partially protect against some of the deleterious e ffects of brain injury. (C) 1998 Elsevier Science Inc.