Adrenergic receptors mediate tissue responses to catecholamines. Multiple subtypes of adrenergic receptors are expressed in the CNS, each with a unique pattern of distribution. Little is known of the functional significance of these multiple subtypes. Pharmacologic studies after brain injury have suggested that alpha-1 adrenergic receptors may be involved in improved recovery of function. In order to evaluate the subtype of adrenergic receptors that may be involved, alpha-1D and alpha-1B mRNA expression was evaluated by in situ hybridization after CNS focal ischemia in the adult rat.

Right-sided ischemia was produced by permanent middle cerebral artery intravascular occlusion via insertion of an intravascular suture. The animals were sacrificed 24 hours after injury and receptor mRNA expression was examined by in situ hybridization using oligonucleotide probes specific for each subtype. A significant increase in alpha-1B receptor mRNA expression was observed in the rim of healthy tissue medially bordering the ischemic lesion. A similar increase in receptor expression was not observed for the alpha-1D subtype.

These results suggest that the alpha-1B adrenergic receptor subtype may be involved in functional recovery after ischemic lesions. Thus, the routine catecholamine surge at birth may be important in protecting against potential perinatal ischemic injury.