Effect of Handling and Forced Immobilization on Rat Plasma Levels of Epinephrine, Norepinephrine, and Dopamine-β-Hydroxylase

Abstract

Forced immobilization of rats triggers activation of adrenal-medullary discharge of epinephrine (EPI) and sympathetic neuronal release of norepinephrine (NE). Plasma levels of EPI reach peak values, which are about 40-fold greater than in undisturbed rats, at about 20 min and then decline to about one-third the peak levels. Plasma levels of NE are increased about 6-fold throughout the immobilization interval. Decapitation produces an 80-fold increase in plasma levels of EPI and an 8-fold increase in NE. These striking decapitation-induced increases are potentiated about 3-fold by immobilization, presumably as a consequence of an immobilization-induced alteration in the "set" of responsivity of spinal cord mechanisms controlling sympathoadrenal medullary discharge. Even minor disturbances produce highly significant increases in plasma EPI and NE and special precautions must be observed when studies involving plasma catecholamines or their effects are performed in animals.

Effect of acute heat stress on rat adrenal medulla — a morphological and ultrastructural study

“…The discharge of whole granules from chromaffin cells into interstitium is well documented as one of ways of granule releasing [1]. It was already mentioned that the adrenaline in the blood circulation is produced from the adrenal A-cells [30,32,39].…”

The effect of restraint stress in early pregnancy in mice

“…However, the avascularity of the abnormal CL in these stressed mice and the associated decline in blood progesterone could be accounted for by vasoconstriction as a result of increased sympathetic activity in luteal blood vessels or increased blood catecholamines. Restraint stress triggers massive adrenal-medullary discharge of adrenaline and sympathetic neuronal release of noradrenaline (Kvetnansky et al, 1978). Decreased blood flow to the oviducts and uterus could also result from the rise in blood catecholamines and oviduct and uterine motility are also regulated by these compounds (Jansen, 1984).…”

Behavioral and physiological effects of psychological stress in rats

“…Although survival time was too short in our experiment to demonstrate the expected changes in adrenal weights, biochemical assays have shown elevated j * plasma epinephrine and norepinephrine as well as decreased adrenal epinephrine * following immobilization (20,21). Theorizing about the biological and evolutionary relevance of restraint (e.g., capture by a predator) is tempting.…”

“…In rodents, immobilization decreases adrenal catecholamine content, while elevating plasma epinephrine and norepinephrine levels (20,21). Immobilization also reduces immune responsiveness (11).…”