Posts Tagged 'opioid receptors'

Exercise, Opioid Peptides and Immune Function

Exercise, Opioid Peptides and Immune Function

The J-shaped curve  illustrates the relationship between the exercise and upper respiratory tract infections:

The graph suggests a protective effect of moderate exercise and that conversely, intense training or a marathon gives a window of opportunity for infection.  The varying infection risks appear to be due to changes in immune function, markers of which showing an inverse J-shaped curve.

The boost to natural immune function from moderate exercise lasts up to several hours, with an increased activity of natural killer (NK) cells, which inactivate viruses and reduce the potential of tumour cells to metastasise.  This process may help explain the protective effect of exercise against various cancers shown in epidemiological studies.

The activation of opioid pathways in response to physical exercise is well known, as is immunomodulation mediated by opioid peptides.  Jonsdottir (2000) describes how evidence has accumulated that the endogenous opioid system is part of the regulatory pathway between the central nervous system and the immune system, as well as giving suggestions for the role of central opioid receptors in mediating the enhanced natural immunity following chronic exercise.  These include via both direct nerve fibre connections with cells or organs of the immune system, as well as through neuroendocrine signalling such as via the hypothalamic–pituitary–adrenal axis.