Hypothalamic region facilitating shivering in rats

Although the posterior part of the hypothalamus has long, been considered i mportant for thermoregulatory shivering, it is unknown whether the neurons there or the passing fibers are implicated in the response. Exposure of ure thane-anesthetized rats to cold (15-21 degreesC) elicits shivering. An inje ction of muscimol (0.5 mm), a GABA(A) receptor agonist, into the medial par t of the hypothalamus, including the dorsomedial and posterior nuclei, supp ressed the cold-induced shivering. This result suggests that neurons having an excitatory effect on shivering are in this region of the hypothalamus.