Mongolian gerbil (Meriones unguiculatus) has been as an model animal for studing the neurologic disease because of the long-term survival in the condition of water-deprived desert condition. In order to accomplish the this research, first of all another divided the laboratory animals 10groups. In this study of the long term water deprived condition investigated catecholamine synthetic enzymes, tyrosine hydroxylase(TH), dopamine-beta-hydroxylase (DBH), and phenylethanolamine-N- methyltransferase(PNMT) in the brain by using immunohistochemical stain. The results obtained in this study were summarized as following. 1. It were observed TH-IR cells in substantia nigra pars compacta, ventral tegmental area and substantia nigra pars reticular of Midbrian. Most of them were presented in pars compacta and ventral tegmental area, but a few in pars reticular. TH-IR cell decreased until the 5th water-deprived day, increased from the 10th water-deprived day to the 15th water-deprived day and redecreased in the 20th water-deprived day 2. In locus ceruleus and rubrospinal tract were observed TH-IR cells and a few DBH-IR cell. Therefore there was composed of dopaminergic neuron and noradrenergic neuron. 3. The quantity of dopamin in serum were decreased until the 4th water-deprived day, increased from the 5th water-deprived day, redecreased on the 15th water-deprived day and reincreased from the 20th water-deprived day.