Decreased cholinergic function in the cerebral cortex of hypoxic neonatal rats: Role of glucose, oxygen and epinephrine resuscitation

Molecular processes regulating cholinergic functions play an important role in the control of respiration under hypoxia. Cholinergic alterations and its further complications in learning and memory due to hypoxic insult in neonatal rats and the effect of glucose, oxygen and epinephrine resuscitation was evaluated in the present study. Receptor binding and gene expression studies were done in the cerebral cortex to analyze the changes in total muscarinic receptors, muscarinic M1, M2, M3 receptors and the enzymes involved in acetylcholine metabolism – choline acetyltransferase and acetylcholine esterase. Neonatal hypoxia decreased total muscarinic receptors with reduced muscarinic M1, M2 and M3 receptor genes. The reduction in acetylcholine metabolism is indicated by the down regulated choline acetyltransferase and up regulated acetylcholine esterase expression. These cholinergic disturbances were reversed to near control in glucose resuscitated hypoxic neonates. The adverse effects of immediate oxygenation and epinephrine administration are also reported. This has immense clinical significance in establishing a proper resuscitation for the management of neonatal hypoxia.

► Neonatal hypoxia caused decreased muscarinic M1/2/3 receptor expression in cerebral cortex.
► Acetylcholine metabolism was also disturbed – contributing to ventilatory decline.
► Glucose resuscitation, alone and with oxygen, reversed the cholinergic alterations.
► Common clinical practice of 100% oxygen or epinephrine upset the cholinergic system.
► This highlights the importance of glucose supplementation in neonatal care to hypoxia.