In most of the first stage of labour, high levels of circulating catecholamines cause maternal blood to be shunted away from the uterus and placenta which will slow uterine contractions (Lederman 1981b), and decrease the availability of blood to the fetus (Lederman 1981b). High adrenaline in early labour can both slow down the process of labour and make it more painful as it works against the release of both endorphins and oxytocin. Adrenaline levels are more responsive to psychological stresses such as pain and anxiety. Adrenaline is released in stressful situations (the fight or flight hormones) and in Chinese medicine are linked with the Kidneys. The hormones with the opposite effect are the catecholamines which include adrenaline, noradrenaline, cortisol and others.
Beta endorphin levels increase during labour allowing a labouring woman to transcend pain ( Brinsmead et al 1985). They help women cope with pain in labour, acting as natural painkillers. They are also ‘feel good’ hormones, released when we are feeling relaxed. Suzanne Yates BA(Hons) DipHSEC MRSS(T) APNT PGCE(PCET), in Pregnancy and Childbirth, 2010 Endorphins and catecholamines (adrenaline and noradrenaline)Įndorphins are closely linked with the release of oxytocin. The activity of these higher brain centres is the mechanism with which sensation may alter physiological function and provide emotional content. 15 From the PAG, neurons project to the hypothalamus, the intralaminar nuclei of the thalamus and to portions of the limbic system such as the amygdala. This is proven due to the fact that the acupuncture effect can be antagonised by naloxone, an opiate antagonist. It has been shown that acupuncture analgesia is largely mediated by the release of endogenous opiates by the PAG. The PAG sends signals to the raphe magnus when stimulated by opiates. So neurons from the PAG synapse in the raphe nucleus have the knock-on effect of serotonin release. Neurons, if stimulated here, activate neurons in the raphe nucleus, which project down into the dorsal horn of the spinal cord and prevent pain sensation. It appears that the release of endorphins is caused by acupuncture-related activation of a structure known as the periaqueductal grey (PAG), another region of the reticular formation which is key to the control of pain, fear and anxiety. It has been shown in numerous research studies that acupuncture increases the amount of endogenous opiates and this answers the question as to why acupuncture is so effective at providing relief from pain and drug withdrawal.
This means that when the use of the drug is discontinued they experience unpleasant sensations. Individuals who have become addicted to drugs such as heroin have abnormally stimulated their opiate receptors and so through the process of down-regulation, have a less active opiate system. It is important to note that, in the reward cascade, endorphin release (specifically met-enkephalin) inhibits the inhibitory neurotransmitter GABA, and consequently dopamine is also released. When endorphin activity is stimulated – either naturally or by chemical means – individuals experience relief of pain and sensations of improved well-being. In Auricular Acupuncture & Addiction, 2009 The role of endorphinsĮndorphins are the body's endogenous opiates. Whether this function is actually facilitated solely by β-endorphin molecules remains in debate. Frequently, the runner’s high experienced near the end of a long, challenging race is attributed to endorphin release and a composite surge of pain-relief peptides that block sensory receptors. In common language, an “endorphin-high” is attributed to any euphoric feeling elicited from either physical or emotional challenge, pain, or stress. Thus, the term “endorphins” has been assigned to numerous peptides with multiple functions ranging from pain cessation and analgesia to euphoria and neurotransmission. In Scotland, the laboratory of John Hughes and Hans Kosterlitz isolated a small peptide sequence from brain tissue isolated from pig and termed it “enkephalin.” 6,7 During the same period, investigators in the United States isolated an active molecule that they considered to have morphine-like activity and termed it “endorphin.” 14,17 As the field of neuropeptides blossomed, the term “endorphins” was used loosely in reference to all endogenous peptides with opioid-like activity, particularly morphine-like properties. Endogenous neuropeptides were first identified and named by two independent laboratories in the mid-1970s. The term ‘endorphins’ remains broader than the specific molecules that are truly endorphin derivatives. Zagon, in Handbook of Biologically Active Peptides (Second Edition), 2013 HistoryĮndorphins were the first identified endogenous opioid peptides.
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