Abstract
Ducks were chronically implanted with thermodes in the POAH region, the lower brainstem or the vertebral canal. At thermoneutral conditions, lowering the temperature of the spinal cord (Tvc) or the lower brainstem (Tmb) stimulated metabolic heat production (M) with a subsequent rise of core temperature (Tc). Lowering the temperature of the POAH region (Thy) induced a fall of Tc due to paradoxical activation of heat defence and, thus, induced slight to moderate general hypothermia depending on the cooling intensity. When Thy was normalized, the hypothermia temporarily stimulated metabolic heat production until Tc was normalized. Cold sensitivity of the entire body, as revealed by the metabolic response to the hypothermia induced by preceding POAH cooling, and cold sensitivity of the spinal cord and the lower brainstem, as revealed by the metabolic response to local cooling, were quantified by calculating the quotient δM/δT from the maximum metabolic response and the experimentally induced drop of Tc, Tmb and Tvc. With lower brainstem cooling δM/δTmbdid not exceed −0.4 W/(kg · ‡C). With spinal cord cooling, δM/δTvc did not exceed −0.6 W/(kg · ‡C). The mean value of δM/δTc after hypothermia induced by POAH cooling was −4.02 W/(kg · ‡C). The results indicate that the cold sensitivity residing in the CNS of ducks represents only a small fraction of the entire cold sensitivity of the body.
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Simon, E., Martin, R. & Simon-Oppermann, C. Central nervous versus total body thermosensitivity of the duck. Int J Biometeorol 25, 249–256 (1981). https://doi.org/10.1007/BF02184526
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DOI: https://doi.org/10.1007/BF02184526