Does Acupuncture Contribute to the Treatment of Chronic Shoulder Pain (Csp)

Abstract

Oxytocin, a polypeptide containing nine amino acids, is produced in the paraventricular and the supraoptical nuclei of the hypothalamus. Oxytocin is secreted into the circulation to produce hormonal effects such as stimulation of milk ejection and uterine contractions. In addition, oxytocin is released from oxytocin containing nerve fibres that reach various areas in the brain, such as other parts of the hypothalamus, the amygdala, the raphe nuclei, the PAG, the striatum and the brainstem centres for control of autonomic function. Thus oxytocin may influence endocrine functions, but also exert anxiolytic and sedative effects, elevate pain threshold, decrease sympathetic nerve activity and increase vagal parasympathetic nerve activity. Taken together oxytocin induces a psycho-physiological pattern consistent with increased social behaviour, anti-stress and promotion of growth. These effects become particularly prominent if oxytocin is given repeatedly. Five daily injections of oxytocin elevate pain threshold for 10 days after the last injection and blood pressure may be reduced for up to three weeks in female rats. When the anti-stress is established it can be maintained by treatment given at longer intervals.The long-term effects of oxytocin and some of the acute effects are mediated by secondary changes in the activity in other transmitter systems. The pain relieving effects involve an increased activity in central opioid systems e.g. in the PAG, whereas the anti-stress effects are mediated by an enhanced activity in the α2 adrenoceptors in various brain areas reached by oxytocin containing nerves. Since these receptors exert an inhibitory effect on noradrenaline (NA) release, the activity in the central NA bundles emanating from the locus coeruleus, which is linked to arousal and aggression, is decreased. At the same time activation of EPI neurons in the brainstem lead to an inhibition of the peripheral sympathetic system, and an increase in the activity of the parasympathetic system, and as a consequence anti-stress and growth promotion is induced.Originally it was assumed that oxytocin was only released during labour and breastfeeding in response to activation of sensory nerves in the mammary gland and uterus. However, it has recently been established that oxytocin can be released in response to touch, warmth and light pressure from all parts of the body. Obviously stimulation of non-noxious somatosensory afferents does not only result in 'a localised sensation of touch', it also results in physical relaxation and a sense of well-being. In a rat model, in which the abdomen is being stroked with a frequency of 40 strokes per minute for 5 minutes, all the effects that can be induced by oxytocin (increased friendly social interaction and the anti-stress effects) are induced. Administration of an oxytocin antagonist inhibits the effects of the massage-like stroking acutely, but also the long-term effects seen after repeated treatments. Interestingly, the massagelike stroking induces more powerful effects if appl...