EVIDENCE FOR TRANSIENT EXPRESSION OF TYROSINE-HYDROXYLASE IMMUNOREACTIVITY IN THE MOUSE STRIATUM AND THE EFFECT OF COLCHICINE

Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the catecholamine (CA) biosynthesis. The transient existence of TH-immunoreactive (IR) cells in the caudoputamen (CP) of postnatal mice was proved for the first time by means of the peroxidase-antiperoxidase method, using a specific antibody to TH. TH-IR cells appeared from postnatal day 5 (P5) and the number of their cells reached maximum from P6 to P7, and slowly decreased until P20. At P30, only a few TH-IR cells were detected in the CP. Most number of the TH-IR cells were seen at the central part of the CP. They had round or oval cell bodies and short processes. TH-IR cells lacked other CA-synthesizing enzymes, such as aromatic L-amino acid decarboxylase, dopamine-beta-hydroxylase, phenylethanolamine-N-methyltransferase, and dopamine.