Thermosensitivity of medulla oblongata in control of body temperature.

LIPTON, J. R/I. Thermosensitiuity of medulla oblongata in control of body temperature. Am. J. Physiol. 224(4): 890-897. 1973.-When the temperature of the medulla oblongata (T,) of conscious rats was altered, changes occurred in rectal temperature (T,) and in thermoregulatory behavior that were generally similar to those produced by altering the temperature of the preoptic/anterior hypothalamic (PO/AH) “thermoregulator.” In the majority of rats with thermodes implanted in the lower brainstem, manipulating T, for 20-min periods caused changes in T, that were proportional to brain temperature. In other animals AT, was proportional to T, except at high (41-43 C) or low (34-37 C) T, levels. Shivering occurred when T, was lowered to 34-37 C. The T, and shivering responses were unchanged after destruction of the PO/AH region. In behavioral experiments the time spent pressing a pedal to lower ambient temperature was proportional to T,. The influence of T, on this behavior was enhanced by PO/AH destruction. Similarities between effects of altering T, and Tpo/ah together with the lack of dependence of the AT, response on PO/AH mediation, enhancement of T, control over behavioral thermoregulation after PO/AH destruction, and differences in precision of control exerted by the two brain temperatures, suggest that medullary thermosensitivity can mediate a separate secondary control of physiological and behavioral thermoregulatory activities.