Recent studies suggest that interleukin 6 (IL-6) is released from contracting skeletal muscles; however, the cellular origin, secretion kinetics, and signaling mechanisms regulating IL-6 secretion are unknown. To address these questions, we developed imaging methodology to study IL-6 in fixed mouse muscle fibers and in live animals in vivo. Using confocal imaging to visualize endogenous IL-6 pr...

Irisin was recently identified as a putative myokine that is induced by exercise. Studies suggest that it is produced by cleavage of the FNDC5 (fibronectin domain-containing protein 5) receptor; irisin corresponds to the extracellular receptor ectodomain. Data suggesting that irisin stimulates white-to-brown fat conversion have led to the hypothesis that it does so by binding an unknown recepto...

While the relationship between increased physical activity and cognitive ability has been conjectured for centuries, only recently have the mechanisms underlying this relationship began to emerge. Convergent evidence suggests that physical activity offers an affordable and effective method to improve cognitive function in all ages, particularly the elderly who are most vulnerable to neurodegene...

In the past few years, skeletal muscle has emerged as an important secretory organ producing soluble factors, called myokines, that exert either autocrine, paracrine or endocrine effects. Moreover, recent studies have shown that muscle releases microRNAs into the bloodstream in response to physical exercise. These microRNAs affect target cells, such as hormones and cytokines. The mechanisms und...

Regular exercise offers protection against all-cause mortality, primarily by protection against cardiovascular disease and Type 2 diabetes mellitus. The latter disorders have been associated with chronic low-grade systemic inflammation reflected by a two- to threefold elevated level of several cytokines. Adipose tissue contributes to the production of TNF-alpha, which is reflected by elevated l...

Pancreatic beta cells sense glucose flux and release as much insulin as required in order to maintain glycaemia within a narrow range. Insulin secretion is regulated by many factors including glucose, incretins, and sympathetic and parasympathetic tones among other physiological factors. To identify the mechanisms linking obesity-related insulin resistance with impaired insulin secretion repres...

Skeletal muscle has recently been identified as an endocrine organ. It has, therefore, been suggested that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert paracrine, autocrine, or endocrine effects should be classified as "myokines." Recent research demonstrates that skeletal muscles can produce and express cytokines belonging to distinctly dif...

For most of the last century, researchers have searched for a muscle contraction-induced factor that mediates some of the exercise effects in other tissues such as the liver and the adipose tissue. It has been called the 'work stimulus', the 'work factor' or the 'exercise factor'. In the search for such a factor, a cytokine, IL-6, was found to be produced by contracting muscles and released int...