Tyrosine hydroxylase (TH) gene encodes the rate-limiting enzyme in catecholamine biosynthesis, responsible for converting tyrosine to L-dopa, a critical step in the synthesis of dopamine, norepinephrine, and epinephrine. This gene is predominantly expressed in dopaminergic neurons of the substantia nigra and ventral tegmental area, as well as in adrenal chromaffin cells and sympathetic neurons. The Th-IRES-iCre mice are constructed by integrating an IRES-iCre expression cassette into the endogenous mouse Th gene via gene editing technology, enabling expression of the iCre recombinase (a codon-optimized Cre recombinase) under the control of the Th gene regulatory elements. The expression pattern of iCre recombinase is similar to that of the endogenous Th gene. When Th-IRES-iCre mice are crossed with mice containing loxP sites, sequence recombination between loxP sites mediated by Cre recombinase is predicted to occur in dopaminergic neurons in the nervous system of the offspring mice.