Effects of hypothalamic injections of 5,6-dihydroxytryptamine on thermoregulation in rats.

5,6-Dihydroxytryptamine, a serotonin depletor, infused directly into the anterior hypothalamus of rat's brain, produced an increase in both heat production and heat loss (as indicated by changes in peripheral circulation) at temperatures of 8, 15 and 22 degrees C. The rectal temperature of these treated rats remained constant.     

Effects of hypothalamic injections of 5,6-dihydroxytryptamine on thermoregulation in rats

Summary 5,6-Dihydroxytryptamine, a serotonin depletor, infused directly into the anterior hypothalamus of rat's brain, produced an increase in both heat production and heat loss (as indicated by changes in peripheral circulation) at temperatures of 8, 15 and 22°C. The rectal temperature of these treated rats remained constant.This work was supported by grants from National Science Council of Taiwan and J. Aron Charitable Foundation (USA). The author is grateful to Dr C. Y. Chai and Mr C. C. Wei for their support.     

Effects of thyrotrophic-releasing hormone (TRH) on thermoregulation in the rat

Summary At ambient temperatures (T_a) of both 8 and 22°C, intraventricular administration of TRH (10–80 g) produced a dose-dependent hypothermia in rats. The hypothermia was due to both decreased metabolic heat production and cutaneous vasodilatation. In contrast, at 30°C T_a, TRH increased metabolic heat production (due to behavioral excitation) and led to hyperthermia.This work was supported by the grants from the National Science Council of Republic of China and the Pjing-Ling Neurological Foundation (VGH, Taipei, Taiwan).     

Effects of thyrotrophic-releasing hormone (TRH) on thermoregulation in the rat

At ambient temperatures (Ta) of both 8 and 22 degrees C, intraventricular administration of TRH (10-80 microgram) produced a dose-dependent hypothermia in rats. The hypothermia was due to both decreased metabolic heat production and cutaneous vasodilatation. In contrast, at 30 degrees C Ta, TRH increased metabolic heat production (due to behavioral excitation) and led to hyperthermia.     

Restraint stress induced changes in rat liver and serum metallothionein and in Zn metabolism

24 h of a psychogenic stress (restraint) caused a strong increase of liver metallothionein (MT) levels. 3 h of stress were sufficient to induce an increase in liver MT, measured 21 h later, but the increase was much lower than in continuously restrained rats. Stress induction of liver MT was not due to food deprivation, since rats deprived for 24 h showed lower MT levels than stressed ones. Zn on MT presented the same qualitative but not quantitative pattern of response as MT protein. Liver cytosolic Zn was increased by restraint in spite of their being no decrease in serum Zn. Any treatment altered serum MT. Liver and serum MT were not correlated. The present results demonstrate that basically psychogenic stresses increased liver but not serum MT levels. No positive evidence for a relationship between corticosterone secretion and MT induction was found.     

Restraint stress induced changes in rat liver and serum metallothionein and in Zn metabolism

Summary 24 h of a psychogenic stress (restraint) caused a strong increase of liver metallothionein (MT) levels. 3 h of stress were sufficient to induce an increase in liver MT, measured 21 h later, but the increase was much lower than in continuously restrained rats. Stress induction of liver MT was not due to food deprivation, since rats deprived for 24 h showed lower MT levels than stressed ones. Zn on MT presented the same qualitative but not quantitative pattern of response as MT protein. Liver cytosolic Zn was increased by restraint in spite of their being no decrease in serum Zn. Any treatment altered serum MT. Liver and serum MT were not correlated. The present results demonstrate that basically psychogenic stresses increased liver but not serum MT levels. No positive evidence for a relationship between corticosterone secretion and MT induction was found.     

Acute changes in dopamine metabolism in the medio-basal hypothalamus following adrenalectomy

Summary During the first hour following adrenalectomy the -MPT-induced disappearance of dopamine was increased in the arcuate nucleus compared to that in sham-operated rats. In a number of other brain regions of both adrenalectomized and sham-adrenalectomized rats only stress-induced changes were observed in catecholamine utilization. These data suggest that corticosterone selectively modulates dopamine utilization in the medio-basal hypothalamus.Acknowledgment. The skilful technical assistance of Ms Joke Van Put, Ms Henny De Vos Burchart-Lodewijks and Mr Henk Spierenburg is gratefully acknowledged.     

Acute changes in dopamine metabolism in the medio-basal hypothalamus following adrenalectomy

During the first hour following adrenalectomy the alpha-MPT-induced disappearance of dopamine was increased in the arcuate nucleus compared to that in sham-operated rats. In a number of other brain regions of both adrenalectomized and sham-adrenalectomized rats only stress-induced changes were observed in catecholamine utilization. These data suggest that corticosterone selectively modulates dopamine utilization in the medio-basal hypothalamus.     

The effects on thermoregulation of intracerebroventricular injections of L-aspartic acid in the sheep

Summary L-Aspartic acid was injected into a lateral cerebral ventricle of the sheep at ambient temperatures between 0° and 40°C. Doses of 100 or 500 nmoles·kg^–1 caused a rise in heat production and/or a decrease in heat loss; rectal temperature rose. Atropine sulphate attenuated or prevented these effects.     

Role of catecholamines in thyroxine-induced changes in metabolism and body temperature during exercise in dogs

Summary Blockade of beta receptors inhibited thyroxine-induced increases in T_re, blood FFA and LA levels during exercise in dogs.     

Brown adipose tissue in young mice: Activity and role in thermoregulation

Zusammenfassung Gewicht und die Bernsteinsäuredehydrogenase-Aktivität des braunen interskapularen Fettgewebes wurden bei Foeten und jungen Mäusen gemessen. Beide Variabeln zeigen ein Maximum bei der Geburt und ein Minimum im Alter von 5 Tagen. Die Temperaturmessungen des Gehirns und des braunen Fettgewebes zeigen, dass bei neugeborenen Mäusen bei 26°C die Temperatur des Gehirns höher ist als diejenige des braunen Fettgewebes, während im Alter von 12 Tagen das braune Fettgewebe wärmer ist.     

Effects of ACTH and diabetes on phospholipid metabolism in adrenal mitochondria.

Incorporation of 32P into adrenal mitochondrial phospholipids (PL) incrased in ACTH-treated rats, but it decreased in diabetics, inspite of the fact that these animals showed adrenal overacity. Since diabetics did not show increased 11 beta-hydroxylation. as opposed to ACTH-treated rats, it is suggested that the stimulation of this enzyme activity by exogenous ACTH is related to an increased turnover of PL at the mitochondrial membrane. The process is impaired in diabetics and prevents the stimulation of 11 beta-hydroxylation.