EVOLUTION OF DOPAMINE-RECEPTORS IN THE RAT AFTER NEONATAL HYPOXIA-ISCHEMIA - AUTORADIOGRAPHIC STUDIES

The aim of this work was to follow the evolution of striatal dopamine D1 and D2 receptors after hypoxic-ischemic (H/I) insult in immature ra ts. SPET imaging of these receptors could be used as an index to asses s brain dysfunctions after perinatal H/I without change in cerebral bl ood flow or neuronal loss. We submitted 1-week-old rat pups to unilate ral ligation of the left carotid artery plus 2h exposure to 8% O2. Aft er recovery periods of 1, 2 or 9 weeks, ex vivo and in vitro autoradio graphic studies of dopamine receptors were performed on normal appeari ng brains using specific ligands usable in human SPET imaging. Striata l dopamine D2 receptors tended to decrease bilaterally after one week' s recovery. The decrease then reached 40% at 3 weeks of age and at 10 weeks of age the level of receptors had returned to normal values. By contrast, no change in dopamine D1 receptors was seen, whatever the ag e studied. In conclusion, changes in dopamine D2 receptors could be a valuable index for SPET imaging to evaluate H/I brain damage in the ab sence of anatomical lesions.