Reduced cortical neurotransmitter receptor complex levels in fetal Down syndrome brain

In this study, cortical receptor complex levels were determined in fetal Down syndrome (DS, trisomy 21) brain. Frontal cortices were obtained from individuals with DS (19th-22nd week of gestation) and controls. Membrane proteins were extracted, assayed on blue native gels and immunoblotted with brain receptor antibodies. Levels of a D1R-containing complex were markedly decreased in male and female cortices of DS individuals. Females with DS had significant reductions of nicotinic acetylcholine receptors alpha 4 and alpha 7, NMDA receptor GluN1 and AMPA receptor GluA1- and GluA3-containing receptor complexes. Levels of other brain receptor complexes (5-hydroxytryptamine 1A, GluA2 and GluR4 receptor-containing complexes) were comparable between the groups of females. Levels of GluA2- and GluA3-containing complexes were significantly increased in males. Decreased levels of D1R complexes in both sexes, along with the significant reduction of alpha 4, alpha 7-containing receptor complexes observed in females, may explain the brain deficits and impaired cognition observed in DS.