AN INHERITED DEFICIENCY IN NORADRENALINE BIOSYNTHESIS IN THE BRINDLED MOUSE

—A reduction in central and peripheral synthesis of noradrenaline has been demonstrated in mice hemizygous for the X-linked brindled (Mo^br) mutant in the mouse. The results are consistent with defective hydroxylation of dopamine to NA, arising either as a result of a primary genetic defect in the enzyme dopamine-β-hydroxylase or from the presence of a highly specific inhibitor of this enzyme in mutant mice. Associated with this deficiency of noradrenaline are an increase in the activity of tyrosine hydroxylase in the central nervous system and an increase in the active uptake of tyrosine (and other amino acids sharing a common uptake mechanism with tyrosine) across the blood-brain barrier.