Sympathetic control of metabolic and hormonal responses to exercise in rats

Abstract

The importance of the sympatho-adrenal system for the pancreatic hormonal response to exercise and, furthermore, the role of glucagon and catecholamines for the hepatic glycogen depletion during exercise were studied. Rats were either surgically adrenomedullectomized and chemically sympathectomized with 6-hydroxydopamine or shamtreated. Two weeks later the rats had either rabbit-antiglucagon serum or normal rabbit serum injected. Subsequently the rats either rested or swam with a tail weight for 75 min. Immediately afterwards cardiac blood was drawn and liver and muscle tissue collected. In control rats in spite of an increase in blood glucose concentrati4ns during exercise plasma insulin concentrations were unchanged, while glucagon concentrations increased. In sympathectomized rats, compared to control rats, glucagon concentrations increased less, and insulin concentrations were higher, although glucose concentrations were lower during exercise. Sympathectomy completely abolished the exercise-induced decrease in liver and muscle glycogen concentrations, whereas neither glycogen depletion nor plasma catecholamine concentrations were influenced by the administration of glucagon antibodies. These findings indicate that the sympatho-adrenal system enhances glucagon secretion as well as muscular and hepatic glycogen depletion but inhibits insulin secretion in exercising rats. The increase in glucagon concentrations, however, does not enhance hepatic glycogen depletion at the work load used.

The physiological effects of Aralia, Panax and Eleutherococcus on exercised rats.

“…1. In agreement with several reports (22)(23)(24), the swimming exercise caused a marked increase in the lactic acid and glucose plasma levels not only in rats receiving the control solutions, but also in the rats receiving saponin extracts. The lactic acid plasma levels observed after the administration of saponin extracts to rats resting or swimming 1.0 hr were not statistically different than the control groups Table 2.…”

“…In this study, Araliaceae saponins did not statistically affect the lactic acid plasma levels of resting or exercised rats. The glucose plasma levels in swimming rats (1.0 hr, drowned) receiving Araliaceae saponins did not show any change other than that expected to occur in exercised animals (22)(23)(24). The decrease (2-16%) in glucose plasma levels in resting rats by some Araliaceae saponins might be due to accelerated lipogenesis (10, 28) or by a change in muscle carbohydrate metabolism to lipid oxidation (11).…”

GH secretion in acute exercise may result in post-exercise lipolysis

“…Unlike previous studies [21,22] there was no significant fall in insulin levels in response to exercise. The increase in insulin after exercise may be due to the rise in plasma glucose reported after acute exercise [23] or a rebound effect following sympathetic inhibition of insulin secretion during exercise [24]. It is unlikely that it was due to the increase in GH since a rise in insulin levels was not observed with the GH infusion.…”

Evidence for Participation of the Neurohypophysial Hormones in the Hyperglucagonemic Response to Hemorrhage in the Rat

“…In the case of OT, it has re cently been determined that during forced immobilization and swimming, circulating levels of the peptide in rats ap proach 100 pg/ml with no detectable elevation of AVP [16]. It would therefore be of interest to determine whether the increased release of glucagon associated with these stresses [10,20] remains unchanged in rats which have been pas sively immunized against OT. In the clinical arena, atten tion has previously been drawn to the abnormally high cir culating levels of AVP in patients suffering from uncon trolled diabetes mellitus, particularly those in a ketotic stale [26,29].…”