Muscarinic binding sites in newborn brain from intrauterine growth-retarded rabbits.

Intrauterine growth retardation (IUGR) was induced in rabbits by means of vascular ligation in utero 4-6 days prior to birth. The vascular-restricted living newborns and controls from the unligated uterine horns were killed at birth and the level of the muscarinic cholinergic receptors in cerebral and cerebellar homogenates measured using the potent antagonist 3H-QNB. No significant difference in the binding sites of the cerebellum and the cerebral cortex was found between restricted and control animals. It is speculated that the ineffectiveness of the vascular insult to affect specifically muscarinic binding sites could partially be explained by the specificity of the receptors and the timing of the ischemic insult in relation to the stage of the developing brain. Other cholinergic markers should also be assessed.