Procaine or tetrodotoxin microinjected into the midbrain increased temperatures of the interscapular brown adipose tissue (BAT) and rectum. L-Glutamate microinjected into the same area decreased these temperatures. Neurons in the inferior olive (IO) expressed c-fos following body temperature increase with midbrain procaine. Electrical stimulation of and glutamate injection into the IO increased body temperature, and IO lesions blocked the midbrain procaine-induced body temperature increase. Since decerebration of the hypothalamus had no effect on the temperature increase, it was concluded that neurons in the midbrain tonically inhibit BAT thermogenesis via IO neurons independently of the hypothalamus.
Shibata, M., Uno, T., & Hashimoto, M. (1999). Neurons in the lower midbrain tonically inhibit non-shivering thermogenesis through their influence on inferior olivary neurons in anesthetized rats. In Journal of Thermal Biology (Vol. 24, pp. 365–368). https://doi.org/10.1016/S0306-4565(99)00081-9