Ming-Tsuen Hsieh (1), Fu-Yu Chueh (1), Shui-Mu Lin (1), Fu-Shin Chueh
(1), Chieh-Fu Chen (2) and Mao-Tsun Lin (3)
(1) Institute of Chinese Pharmaceutical Sciences, China Medical College, No. 91, Hsueh-Shih Rd., Taichung 40421, Taiwan
(2) National and Research Institute of Chinese Medicine, Taipei, Taiwan
(3) Department of Physiology, National Yang-Ming University, Taipei, Taiwan
Abstract: Intraperitoneal administration of magnolol (25 - 100 mg/kg) produced a dose-related fall in rats' colonic temperature. The magnolol-induced hypothermia was attenuated by pretreatment with intracerebroventricular 6-hydroxydopamine (200 microg/rat). The L-DOPA (200 mg/kg, i.p.) plus benserazide (50 mg/kg, i.p.)-induced hyperthermia was attenuated by magnolol. On the other hand, the alpha-methyltyrosine (100 mg/kg, i.p.)-induced hypothermia was potentiated by magnolol. Furthermore, magnolol (50 mg/kg, i.p.) decreased the dopamine and norepinephrine release in the hypothalamus, but did not change the concentrations for their metabolites (3,4-dihydroxyphenylacetic acid and homovanillic acid). The data suggest that magnolol decreases colonic temperature by reducing catecholaminergic activity in rat hypothalamus.
Keywords: Magnolol, Hypothermia, Catecholamine