Autoradiographic studies of neurotransmitter receptors in the brain of newborn infants with Down syndrome

The autoradiographic pattern of cholinergic muscarinic receptors in the brain of two newborn infants with Down syndrome (DS) (stillbirths, 31 and 39 gestational weeks), were compared with that of age-matched control fetuses. Densities and distribution patterns of muscarinic receptors in the forebrain were similar in both groups. However, a marked receptor reduction was found in the midbrain (superior colliculus, substantia nigra) of DS brains compared to control brians. The results indicate the existence of deficient prenatal development of cholinergic transmission in DS that may be responsible for the occurrence of specific difficulties in early postnatal life.