MRNA D-2 dopaminergic receptor expression after hypoxia-ischemia in rat immature brain

Previous studies have shown a reduction of dopaminergic D-2 receptors (D2R) in the striatum after hypoxia-ischemia in newborn rats. We show here an ea rly and transient reduction of mRNA D2R in nonatrophic brains following hyp oxia-ischemia. The left carotid artery of P7 rats was ligated followed by h ypoxia for 2 h. The rats were sacrificed after 24 h, 48 h and 14 days. D2R mRNA was studied by in situ hybridization, the cell number by conventional histology, and neuronal and astrocyte differentiation by immunohistochemist ry. A 20% reduction of striatal mRNA D2R occurred 24 h after hypoxia-ischem ia, whereas no reduction was observed after 48 h and 14 days. There were no differences in total cell number and in the expression of neuronal (MAP-1, MAP-2) and astrocyte (GFAP) markers between both brain hemispheres nor bet ween control and hypoxia-ischemia animals. The early decrease in mRNA D2R c ould explain the delayed reduced D2R after neonatal hypoxia-ischemia. Copyr ight (C) 2001 S.Karger AG, Basel.