Neurochemical and immunocytochemical studies of catecholamine system in the brindled mouse

The distribution of immunoreactivecatecholamine neurons and fibers was investigated in brindled mottled mouse, a murine model of Kinky hair syndrome (KHS), using antisera against tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (DBH). In all mice, including normal littermate controls, a transient increase of TH-immunoreactive neurons (TH-IN) was observed in the cerebral cortex during the second postnatal week. The numbers of TH-IN were more pronounced in hemizygous brindled males (MO^br/y). In addition, TH-IN appeared and rapidly increased in number in the striatum of MO^br/y after postnatal day 11 (PI 1). Striatal TH-IN were rarely detected in controls. After cupric chloride (CuCl₂) treatment, TH-IN in the striatum of some of the MO^br/y mice became less conspicuous. In the substantianigra and ventral tegmental area where TH-IN are normally present, no differences either in the immunostaining of TH-IN or the pattern of TH immunoreactive fibers were detected between MO^br/y and controls. In MO^br/y, a superficial plexus of DBH immunoreactive fibers was more pronounced than in controls but there were no DBH immunoreactive neurons in the cerebral cortex or striatum in any of the mice examined. Neurochemical analysis revealed a marked decrease in norepinephrine levels and increase of serotonin and its metabolites in the brain in MO^br/y. Together, these data suggest that the unusual expression of TH-IN in MO^br/y represents perturbations of normal development of catecholamine neurons in this copper deficient mutant mouse.