Regional Expression of Dopamine D 1 and D 2 Receptor Proteins in the Cerebral Cortex of Asphyxic Newborn Infants

Abstract

Dopamine D₁ and D₂ receptor protein expression was examined by Western blotting in newborn infants dying from cerebral asphyxia between 31 and 42 weeks' gestation, and matched controls. Frontal, occipital, temporal, and motor cortex tissue samples were obtained at autopsy (median postmortem interval 35 hours) and frozen for storage at —80^°C. A total of 2 immunoreactive bands were detected with each primary antibody in infant brain, whereas a single band was present in adult human and rat tissue. Immunoreactivity varied between cortical areas for both receptors, but their regional patterns differed significantly. D₁ protein levels were higher in motor and temporal cortex than in frontal or occipital cortex. D₂ protein showed graded expression frontal > motor > occipital > temporal cortex. Asphyxia cases showed lower expression of the upper D₂ immunoreactive band, but no difference in regional pattern. Lower D₂ receptor expression may attenuate stress responses and underlie increased vulnerability to hypoxia at birth.