Adipose tissue cellularity and lipolysis. Response to exercise and cortisol treatment.

Abstract

A B S T R A C T Male rats at 5 wk of age were subjected to 13 wk of intensive treadmill running to study the effect of exercise on adipose tissue cellularity and lipolysis.

Regulation of Extramuscular Fuel Sources During Exercise

“…The increase in the capacity of these pathways is illustrated by the increased basal glycerol and palmitate flux rates and the greater rate of triglyceride-fatty acid cycling in highly trained human subjects (248). The increased ability to mobilize NEFAs occurs as a result of an increased adipocyte sensitivity to the catecholamines (11,34,66,139,194,319) and is mediated by an increased formation (139,319) and/or improved effectiveness of cAMP (139). This sensitization to the catecholamines can occur in the absence of an increase in {3receptor number or agonist-binding affinity on the plasma membrane of isolated adipocytes (34, 319).…”

Lipolysis, lipogenesis, and adiposity are reduced while fatty acid oxidation is increased in visceral and subcutaneous adipocytes of endurance-trained rats

“…[1][2][3][4] Importantly, analyses of NEFA rate of appearance (Ra) [4][5][6] during exercise revealed that this variable was significantly reduced as a result of training, which is also in support of a reduction in WAT lipolysis with endurance training. However, at odds with these findings are the results of studies measuring catecholamine-stimulated glycerol release in isolated adipocytes from humans [7][8][9][10][11] and rats, [12][13][14][15] which report increased WAT lipolysis after a period of endurance training. Additional studies have reported lipolysis to be either reduced in isolated rat adipocytes 16 or unaltered when assessed in situ by the microdialysis technique in human WAT 17 following a period of endurance training.…”

Contractile C2C12myotube model for studying exercise-inducible responses in skeletal muscle

“…In particular, IL-6 reportedly has positive effects on skeletal muscle glucose metabolism (13,66), and it is increasingly apparent that some of the health benefits of exercise might be mediated by these exercise factors, including IL-6, functioning in an autocrine, paracrine, and/or endocrine fashion. In this regard, effects of exercise are not limited to metabolic changes in working skeletal muscles but are also brought about by other responses such as the induction of lipolysis in adipocytes (5), body temperature increases (40), regulation of the immune system (59), and so on. The other exercise factor, IL-8, belongs to the ELR (glutamate-leucine-arginine)-containing CXC chemokine family (14,54); however, whether the other ELR chemokines, such as CXC ligand 1/KC (CXCL1/KC) and CXC ligand 5/LIX (CXCL5/LIX), are also exercise factors remains unknown.…”