Beziehung zwischen Thermogenese im „braunen“ Fettgewebe, Temperatur im cervicalen Anteil des Vertebralkanals und Kältezittern

Summary

Multilocular (“brown”) adipose tissue, which is found in the newborn and cold-acclimatized adult mammal, has been previously shown to be a significant site of non-shivering heat production; its interscapular and cervical portions possess a venous vascular connection to the inner vertebral sinus. As shown by the present study, the temperatures both in the cervical vertebral canal and in the interscapular adipose tissue are maintained above 39°C in the newborn guinea-pig exposed to a cold environment (16°C), whereas the temperatures drop in the hypothalamus, in the lumbar vertebral canal, and beneath the skin. Electrical activity of the sceletal musculature remained at zero level under these conditions, but oxygen uptake rose by a factor of 3.5 (non-shivering thermogenesis). After pharmacologically induced blockade of the nonshivering thermogenesis all the temperatures measured fell, and this was accompanied by onset of shivering. The same occurred in animals, 3–4 weeks of age, which had been reared in a warm environment (30°C), what has been formerly shown to lead to replacement of the brown fat by white fat. In the latter group shivering could be suppressed by moderate local rewarming of the cervical vertebral canal. Local heating of the lumbar vertebral canal and of the hypothalamus was less effective. It is concluded that shivering is suppressed in the newborn (and cold-acclimatized adult) mammal in that the temperature of thermosensitive structures in the area of the cervical vertebral canal is maintained above shivering threshold by the heat supplied from the interscapular and cervical brown adipose tissue.