Sympatho-adrenal activity and metabolic responses in fasted rats—The role of interscapular brown adipose tissue

Hypothalamo-pituitary-adrenocortical and sympatho-adrenomedullar systems in stress response

“…However, when animals are trained to the same stressor the neuronal part of the sympathoadrenal system is activated with increased secretion of NA from its nerve terminals (53). Similar results are obtained when animals are exposed to cold; the adrenal medulla is activated at the beginning and sympathetic nervous system after prolonged exposure (57). The intense increment of A secretion was observed under the effect of immobilization, hemorrhage, pain and insulin-induced hypoglycemia (50).…”

“…As far as urinary NA secretion is concerned it was shown that animals response was most intense to cold stress, less intense to immobilization and crowding but the least to hypoglycemia (38,28). It is interesting that some results confirm the increased urinary NA secretion after fasting (28), which is contradictory to the statement that complete food restriction provokes dissociation of sympathetic nervous system and adrenomedullar functions expressed as a decrement of NA and increment of A urinary secretion (57,64). However, it was shown that insulin-induced hypoglycemia stimulates, in addition to A, NA secretion from adrenal glands (65).…”

“…Insulin-induced hypoglycemia provokes an increase in the adrenal TH activity and both iRNA for TH and iRNA for PNMT expression (63), whereas fasting induced hypoglycemia (48 h) causes an increase in adrenal DBH activity accompanied by the increased urine A concentration (28). Higher intensity of urinary A secretion was observed after fasting as compared to its secretion provoked by immobilization, hemorrhage and pain (57,37,38). As far as urinary NA secretion is concerned it was shown that animals response was most intense to cold stress, less intense to immobilization and crowding but the least to hypoglycemia (38,28).…”