Injection of muscimol in the posterior hypothalamus reduces the pge,-hyperthermia in the rat

The firing rate of the nerves innervating interscapular brown adipose tissue PBAT), MAT and colonic temperatures (T_IBAT and T_c, heart rate, and oxygen (O₂) consumption were monitored in urethane-anesthetized male Sprague-Dawley rats. These variables were measured for 40 min before (baseline values) and 40 min after a 56 ng muscimol injection in the posterior hypothalamus and an intracerebroventricular administration of 500 ng prostaglandin E, (PGE₁). The same variables were monitored in other rats with muscimol injection or PEE₁ administration alone. No drug was Injected in control rats. The results show that muscirnol injection reduces the increases in firing rate, T_IBAT, T_c, heart rate, 02 consumption induced by PGE₁. These findings suggest that GABAergic tone in the posterior hypothalamus is important in the control of thermogenic changes induced by PGE₁.