Inhibitory control of shivering and nonshivering thermogenesis by preopticwarm-sensitive neurons

To investigate the characteristics of efferent projections fi-om the preopt ic area for the control of shivering and nonshivering thermogenesis, we tes ted the effects of thermal stimulation and injecting excitatory substances into the preoptic area on shivering and nonshivering thermogenesis in anest hetized rats. Preoptic warming and injection of glutamate suppressed shiver ing at ambient temperatures of 15-21 degrees C. Likewise, preoptic warming and D,L-homocysteic acid injection suppressed nonshivering thermogenesis el icited by electrical stimulation of the ventromedial hypothalamic nucleus. Inhibitory signals from warm-sensitive neurons, thus, contribute a larger e fferent signal for heat production than do signals from cold-sensitive neur ons. (C) 2000 Elsevier Science Ltd. All rights reserved.