Altered ontogenesis of muscarinic cholinergic receptor in mouse brain: effect of L-thyroxine and betamethasone.

The effects of L-T4 and betamethasone treatment of newborn mice on the development of the cholinergic muscarinic receptor in certain brain regions was studied using the potent labeled muscarinic antagonist [3H]4-N-methyl-piperidyl benzilate. Treatment with both L-T4 and betamethasone caused an accelerated accumulation of muscarinic receptors in the cortex 16 days post partum, with a subsequent reduction in level at 30 days. In the cerebellum and caudate putamen, only betamethasone caused a similar early accumulation of muscarinic receptors, while the later effect, namely a reduction in the level at 30 days, was seen with both hormones in these two regions as well as in the hippocampus. The results can explain some behavioral effects observed in other studies after treatment with these hormones.