Upregulation of GABAA-receptor α1- and α2-subunit mRNAs following ischemic cortical lesions in rats

Focal cortical lesions are associated with a functional downregulation of the GABAergic system in perilesional tissue lasting (at least) several weeks. The molecular mechanisms underlying this phenomenon are still poorly understood. Here we used RT-PCR to investigate whether mRNA-levels of two alpha-subunits of the GABA(A)-receptor (alpha 1- and alpha 2-subunits) change following ischemic cortical lesioning. The results show that 7 days after lesion induction mRNA-levels for both the alpha 1- and alpha 2-subunits are increased threefold in perilesional tissue ipsilateral, but not contralateral to the lesion. Taken together with the results of a previous immunohistochemical study in which a moderate decrease of the alpha 1-subunit-protein and no change for the alpha 2-subunit [T. Neumann-Haefelin, J.F. Staiger, C. Redecker, K. Zilles, J.M. Fritschy, H. Mohler, O.W. Witte, Immunohistochemical evidence for dysregulation of the GABAergic system ipsilateral to photochemically induced cortical infarcts in rats. Neuroscience (Oxford) 87 (4) (1998) 871-879] was observed, this is interpreted as a partial block of translation in the perilesional tissue surrounding cortical ischemic lesions. (C) 1999 Elsevier Science B.V. All rights reserved.