364 



B. ANDERSSON AND OTHERS 



periods of seven days, indicating an increased metabolism of non-shivering 

 origin (Andersson, Gale and Sundsten, 1962a) (Fig. 4). Studies of 

 thyroid function in these animals have revealed that local cooling of the 

 " heat loss centre " leads to a conspicuous release of protein bound iodine 



EAR 



Fig. 2. Shivering induced by the intravenous infusion of adrenaline and nor- 

 adrenaline during coohng of the preoptic area at an environmental temperature 

 of 40°C. In the third period of shivering, the pupillary constriction and the 

 persistent peripheral vasoconstriction indicate that " endopyrogen " was 

 released in this experiment. The brain temperature was measured 4 mm 

 lateral to the surface of the thermode. A, adrenaline ; N-a, nor-adrenaline 

 (Infusion rate = 1.3//g/kg b.w./min). (From Andersen, Andersson, and 



Gale, 1962.) 



^pgji3i^ from the thyroid. The thyroid activation is comparable to, or 

 even greater, than that observed when the same animals are subjected to 

 rather severe general cold stress (Andersson, Ekman, Gale and Sundsten, 

 1962a and b) (Fig. 5). If the hypothalamic control of anterior pituitary 

 function is disturbed by lesioning the median eminence, this thyroid res- 

 ponse to anterior hypothalamic cooling is ehminated. 



Moderate local warming of the " heat loss centre " has the opposite 

 effect to cooling (Andersson, Ekman, Gale and Sundsten, 1962c). It blocks 

 the thyroidal response to a general cold stress (Fig. 6) and also seems to 

 inhibit the normal release of hormone from the thyroid (Fig. 7). It may 



