MAXIMAL DENSITIES OF MU-RECEPTORS, DELTA-RECEPTORS, AND KAPPA-RECEPTORS ARE DIFFERENTIALLY ALTERED BY FOCAL CEREBRAL-ISCHEMIA IN THE MOUSE

Though opioids are known to have neuroprotective properties, little in formation is available on the functional state of opioidergic receptor s following focal cerebral ischaemia. The present study investigated t he evolution of the B-max and K-d for [H-3]DAMGO, [H-3]DADLE, and [H-3 ]U69,593, respectively, for the mu, delta, and kappa opioidergic recep tors after permanent focal cerebral ischaemia in mice. While the vario us K-d were unchanged, mu and delta B-max values were precociously dec reased in frontoparietal cortices, earlier than kappa receptors, refle cting infarct extension with time. The B-max values for mu and delta r eceptors were also altered in non-infarcted tissues, such as tissues a t risk (e.g., temporal auditory cortex) and exofocal (e.g., contralate ral and non-infarcted) cortices. These results suggest that, in non-in farcted areas, the observed changes reflect functional modifications t o focal ischaemia. (C) 1998 Elsevier Science B.V.