Abstract: Preliminary research in our laboratory found that compound YZG-330 can reduce mouse body temperature, which could be blocked by adenosine A₁ receptor (A₁R) antagonist DPCPX. Based on the downstream signaling pathway of the A₁R, the mechanism by which YZG-330 lowers body temperature was further studied. The pharmacodynamics of YZG-330 was evaluated by measuring the rectal temperature; expression of the transient receptor potential (TRP) ion channel, the P38 protein and its phosphorylated form in mouse hypothalamic homogenate were detected by Western blotting. A Ca²⁺ fluorescent probe, Fluo-3AM, was added to cells to detect the effect of YZG-330 on the Ca²⁺ content of mouse hypothalamic cells. YZG-330 dose-dependently reduced the body temperature in mice, and the selective P38 inhibitor SB-203580 (20 mg·kg^-1, i.p.) significantly inhibited the hypothermic effect of YZG-330. A TRPM8 antagonist 2 (0.1 μg per mouse, i.c.v.) markedly attenuated the hypothermic effect of YZG-330 (0.25 or 1 mg·kg^-1, i.p.). YZG-330 (2 mg·kg^-1, i.p.) significantly increased the phosphorylation of P38, an effect that could be attenuated by the A₁R antagonist DPCPX (5 mg·kg^-1, i.g.) in mouse hypothalamus. In addition, YZG-330 also prominently enhanced the expression of TRPM8, which could be blocked by SB-203580; YZG-330 (0.1-10 μmol·L^-1) increased intracellular Ca²⁺ concetration in mouse hypothalamic cells in a dose-dependent manner, and was inhibited by the A₁R inhibitor DPCPX (0.5 and 1 μmol·L^-1) and TRPM8 antagonist 2 (1 μmol·L^-1). In conclusion, YZG-330 exerts its hypothermic effect by activating the A₁R to promote the phosphorylation of P38 protein and thereby up-regulating the expression and activity of the TRPM8 ion channel, resulting in increased intracellular Ca²⁺ concentration to stimulate mouse hypothalamus cells to down-regulate body temperature. All animal experiments were approved by the Ethics Committee of the Institute of Materia Medica, Chinese Academy of Medical Sciences.