Acupuncture is a type of treatment practiced in traditional Chinese medicine. In recent years, western medicine has begun to make use of acupuncture for the treatment of chronic pain and other illnesses. In this post, we will be discussing and summarizing the article “Acupuncture Effect and Central Autonomic Regulation” which will be available at the end of this post.
(Disclaimer: I am not a medical professional and all information provided in this post is from the article which is available in the “references” section at the bottom of the page. This post is meant only to provide a synopsis of the information covered in the original article.)
Acupuncture And The ANS
In traditional Chinese medicine, acupuncture is meant to balance the forces of Yin and Yang within the body. In a more scientific interpretation, this can be translated into acupuncture helping to regulate imbalances in sympathetic and parasympathetic activity. Sympathetic and parasympathetic responses are highly involved in the activities of the Autonomic Nervous System (ANS).
Acupuncture has been successful in the treatment of autonomic nerve-related disorders such as subfertility, circadian rhythm disorder, polycystic ovarian syndrome (PCOS), epilepsy, anxiety, and cardiovascular disease. Additionally, it may also influence some autonomic-related functions such as heart rate variability, muscle sympathetic nerve activities, heart and/or pulse rates, skin conductance, skin temperature, blood pressure, and pupil size.
Cliff Notes
The nervous system has a branch called the peripheral nervous system (PNS) and the PNS has a branch called the ANS. The ANS controls all of your unconscious body activities such as breathing and heart rate. The ANS is divided into a sympathetic and a parasympathetic branch. The sympathetic branch controls your “fight or flight” responses while the parasympathetic branch controls your “rest and digest” responses. Acupuncture is thought to help regulate the balance of sympathetic and parasympathetic activities.
Brain Regions Involved In ANS Regulation
The autonomic nervous system is essentially a continuation of the brain. That being said, some studies have shown that the autonomic effects of acupuncture are regulated by a mesencephalic and brainstem network (essentially, the midbrain and the brainstem) consisting of the dorsomedial prefrontal cortex, medulla oblongata, ventrolateral periaqueductal gray, and the hypothalamus.
The Hypothalamus
The hypothalamus is the most important brain region with regards to ANS function. The hypothalamus has been seen to be involved in the pathway of electroacupuncture (EA) effects on sympathetic activity. The electrical impulses generated in the skin transmit to the hypothalamus through nerve networks allowing for the regulation of autonomic activity.
There is a cell group within the hypothalamus known as the paraventricular nucleus (PVN) which is important for the regulation of the autonomic stress response as well as sympathetic vasomotor tone. Acupuncture has the potential to decrease the expression of corticotropin-releasing hormone along with a substance known as neuropeptide Y (NPY) in the PVN and generate some particular effects in regards to suppressing the sympathetic output in response to chronic stress.
Cliff Notes
The Hypothalamus is important for regulating ANS functions. Electroacupuncture transmits signals to the hypothalamus via nerves in the skin. It is thought that acupuncture triggers a reaction within the hypothalamus that creates a calming effect within the ANS.
The Medulla Oblongata
Certain regions of the medulla oblongata regulate central control of autonomic function. The rostral ventrolateral medulla (rVLM) is important in the regulation of arterial blood pressure within the central nervous system (CNS). Electroacupuncture has the potential to inhibit cardiovascular autonomic responses by regulating rVLM neurons. Furthermore, gamma-aminobutyric acid and opioids are involved in the long term electroacupuncture related repression of the sympathoexcitatory cardiovascular responses within the rVLM.
Within the ventrolateral division of the hindbrain lies the nucleus ambiguus (NAmb). The NAmb is thought to be an important origin site for preganglionic parasympathetic vagal motor neurons that work to regulate autonomic function through the release of acetylcholine. It is thought that simulation of a special acupoint is necessary to activate NAmb neurons and achieve a modulated effect on autonomic function.
Cliff Notes
The medulla oblongata is a region of the brain involved in ANS function. The NAmb is located within the medulla oblongata. It is thought that the stimulation of specific acupoints is necessary to achieve a modulated effect on the ANS.
The Ventrolateral Periaqueductal Gray
The ventrolateral periaqueductal gray (vlPAG) is an essential nuclei within the midbrain that processes incoming sensory information during electroacupuncture. It seems that the excitation of arcuate neurons from electroacupuncture can be attributed to stimulation from the vlPAG. Furthermore, it seems that the reciprocal reinforcement between the ventral hypothalamus and the midbrain serves to prolong the effects of electroacupuncture on baseline blood pressure.
Cliff Notes
The vlPAG is part of the midbrain that processes incoming sensory information from electroacupuncture. The vlPAG stimulates arcuate neurons. The midbrain and the hypothalamus work together to prolong the effects of acupuncture.
The Prefrontal Cortex
The prefrontal cortex (PFC) plays an important role in mediating somatic and behavioral responses in the autonomic centers in response to stress. The PFC was seen to primarily control sympathetic functions during mentally stressful tasks in a near-infrared spectroscopy (NIRS) study. It is possible that acupuncture may serve to increase parasympathetic activity and decrease sympathetic activity by inhibiting dorsomedial PFC activity.
Cliff Notes
The PFC is involved in regulating stress responses within the ANS. Acupuncture may have a calming impact by inhibiting PFC activity.
Neurotransmitters and Acupuncture
It has been observed that certain neurotransmitters such as amino acids, opioid peptides, catecholamines, and serotonin are involved in the modulation mechanisms of acupuncture within the ANS. It seems that various neurotransmitters may be the mediating factor behind the impacts of acupuncture treatments on different diseases. Amino acids, nerve growth factor (NGF), and endogenous opioids may also be involved in autonomic regulation and related acupuncture effects.
Cliff Notes
Neurotransmitters are involved in the impacts of acupuncture on the ANS. Several neurotransmitters in particular seem to be involved in this process.
Summary
This is a lot of information to digest, but essentially, acupuncture seems to produce a calming effect on the ANS. The exact mechanisms that acupuncture impacts are not entirely clear yet, but it has been seen to help in a number of disorders. Specific acupoint stimulation may be more effective in stimulating certain brain regions involved in autonomic regulation.
References
Li, Qian-Qian, et al. “Acupuncture Effect and Central Autonomic Regulation.” Evidence-Based Complementary and Alternative Medicine : ECAM, U.S. National Library of Medicine, 2013, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3677642/.
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