Opiate receptor avidity is increased in rhesus monkeys following unilateral optic tract lesion combined with transections of corpus callosum and hippocampal and anterior commissures

Opiate receptor avidity (B-max'/K-D) was measured in four rhesus monkeys following unilateral lesioning of the optic tract combined with transection of the corpus callosum and the hippocampal and anterior commissures depriving one hemisphere of visual input (Tract and Split), two animals with transection of commissures only (Split), and nine healthy monkeys with positron emission tomography (PET) and 6-deoxy-6-beta-[F-18]fluoronaltrexone (cyclofoxy, CF), a mu- and kappa -opiate receptor antagonist. Opiate receptor avidity was found to be significantly higher in the Tract and Split animals, only, bilaterally, throughout the lateral cortex and in the cingulate and posterior putamen (41-117%). Ipsilateral changes were consistently greater than those contralateral, but this asymmetry was of statistical significance only in the parietal and occipital cortices. Cyclofoxy avidity was decreased in the medial cortex of both the Tract and Split and Split animals (similar to 25%), The results suggest that opiate pathways undergo extensive alteration in response to changes in brain functional activities brought about through hemispheric visual deprivation. (C) 2000 Elsevier Science B.V. All rights reserved.