Tyrosine hydroxylase and tryptophan hydroxylase activities and its cofactor biopterin level in brain regions of the rolling mouse: The influence of thyrotropin releasing hormone

Biopterin, the cofactor for tyrosine hydroxylase and tryptophan hydroxylase, was decreased in caudate nucleus, hypothalamus and cerebellum of the rolling mouse. Though there were not significant differences of tyrosine hydroxylase and tryptophan hydroxylase activities between the rolling and normal control mouse in the hypothalamus, the rolling showed significant increase of biopterin concentration and tyrosine hydroxylase activity after administration of thyrotropin releasing hormone (TRH). These results suggest that ataxic gait of the rolling mouse may be partly due to some abnormalities of catecholaminergic neurons, especially noradrenergic neurons, and that TRH may improve the abnormalities of catecholaminergic neurons. The changes of biopterin concentration by TRH administration indicate that biopterin may be a regulatory factor in catecholamine biosynthesis.