Acupuncture is often used, therapeutically, for substance addiction and withdrawal symptoms. There exists a series of studies, published in Neuroscience Letters, that provide both qualitative and quantitative research that validates the use, specifically, of body acupuncture for treatment of alcohol and morphine addiction. These studies demonstrate that acupuncture regulates the control and normalization of dopamine (DA) levels in the region of the brain called the nucleus accumbens (NAcc).
The NAcc is a region of the basal ganglia that is involved in “operant and emotional learning, response inhibition and behavioral flexibility” (Goto, 2008). It is often called the pleasure center and has been shown to play a central role in addiction and substance abuse.
Dopamine D1 receptors in the NAcc are individually innervated by afferent excitatory glutamate neurons from the amygdala and hippocampus. The functions of these limbic structures relate to the formation and storage of memory and emotional reactions.
D2 receptors in the NAcc are corporately innervated by tonic extra-synaptic DA which is released by DA neurons originating in the ventral tegmental area (VTA). These D2 receptors are presynaptically positioned on excitatory glutamate neurons which originate in the pre-frontal cortex (PFC) and have an inhibitory effect on these PFC neurons. Because the PFC neurons are inhibited, an increase in tonic, extrasynaptic DA results in a shift in control over the NAcc from the PFC to the limbic system. Processes that are attributed to the PFC include executive function, and higher thinking.
The NAcc innervates neurons in the ventral palladium via inhibitory GABA neurons. The ventral palladium, via inhibitory GABA neurons, inhibits the tonic firing of DA neurons from within the VTA; therefore, under normal circumstances homeostasis of DA levels is achieved. For example, an increase in NAcc DA levels results in less inhibition of the ventral palladium, causing the ventral palladium to have an increased inhibitory effect on the VTA, thus decreasing the tonic level of DA in the NAcc.
As a result of complex processes not explained here, the use of drugs such as alcohol, morphine and cocaine causes an increase in extrasynaptic DA levels within the NAcc. This shifts control of behavioral programming from the PFC, the region of conscious higher thought, to the limbic system, the region of emotional processing and memory resulting in positive reinforcement of the abusive behavior. Repeated use reinforces this behavior even more because synaptic plasticity acts to attenuate the synaptic gaps of limbic-NAcc synapses. Compounding the addiction is the fact that innervation on the NAcc from the PFC is necessary to introduce and enact new, alternative behaviors.
In carefully controlled experiments, acupuncture on Shenmen Ht-7 has been shown to have normalizing, biphasic regulating effects on NAcc DA levels in laboratory rats. This paper will comment on three of such studies, all of which were published in Neuroscience Letters, in 2005, 2006 and 2008 respectively.
In the first study, conducted by Kim et al. (2005), 31 rats were sensitized to morphine, or assigned to a saline or control group. After sensitizing the rats, they were subjected to a fifteen day withdrawal period followed by a final dose of morphine. Aside from the saline and control group, the rats were divided into groups that received acupuncture at Ht-7, SJ-8, and distal points on the tail. In vivo micro dialysis was used to monitor the extrasynaptic DA levels in the NAcc in the rats to monitor the effect of the acupuncture treatments.
The administration of morphine caused a marked increase in the DA level in the NAcc of all of the rats, except for the group that received acupuncture to Shenmen Ht-7. The implication of this result is that acupuncture to Ht-7 prevents the spike in extrasynaptic DA levels that would prevent the higher cognitive functions of the PFC from influencing habits, and prevents the expected shift of behavioral programming control to the limbic system.
The second study, conducted by Zhao et al. (2006), demonstrated biphasic regulation of DA in the NAcc by acupuncture of Shenmen Ht-7 in rats sensitized to ethanol. Similar to the previous study, rats were sensitized to an addicting substance that upon administration caused a marked increase in extrasynaptic DA levels in the NAcc. The test was conducted in two phases.
One phase involved a 72 hour withdrawal period followed by administration of a dose of ethanol with extrasynaptic levels of DA being monitored by in vivo micro dialysis. Groups consisted of rats that received saline, ethanol, ethanol and acupuncture to Ht-7, ethanol and acupuncture to Pc-6, and ethanol and acupuncture to points on the tail. Results were similar to those from the morphine study.
Like in the morphine study, the application of acupuncture to Ht-7 prevented an increase in extrasynaptic DA levels.
The second phase of the experiment involved a 72 hour withdrawal period that was not followed by administration of ethanol. The same groups were used, and the same variable was measured. In this case the rats that received acupuncture to Ht-7 were the only group that exhibited increased levels of extrasynaptic DA levels.
This result shows that acupuncture to Ht-7 can be used to alleviate the effects of withdrawal. Higher levels of extrasynaptic DA increases limbic control of behavior during this period of abstinence from alcohol and contributes to subjective feelings of pleasure. Positive reinforcement of abstinence results in a lowered dependence on ethanol.
The final study, by Lee et al. (2008), measured observable behavior changes in rats for the purpose of measuring the effect of acupuncture on ethanol withdrawal signs. The data observed concurred with the results from the study by Zhao et al., accrediting Ht-7 with regulating DA levels in the NAcc. More importantly, however, the study by Lee et al. also worked to uncover the mechanism by which acupuncture of Ht-7 increases extrasynaptic DA levels in the NAcc during the withdrawal phase.
Using GABAA and GABAB neurotransmitter agonists and antagonists, baclofen, SCH 50911, muscimol, and bicuculline to monitor their effect on acupuncture it was determined that acupuncture of Ht-7 results in the stimulation of GABAB receptors on GABA neurons in the VTA thus preventing depolarization of the GABA neurons. This results in disinhibition of the DA neurons that maintain extrasynaptic DA levels in the NAcc.
There was also evidence to show that another mechanism outside the DA mechanism is involved in regulating GABAA receptors on GABA neurons in the VTA. This mechanism also results in increased NAcc DA levels. However, the exact workings of this mechanism still needs to be researched. It will also be of interest to study the mechanisms by which acupuncture of Ht-7 lowers NAcc DA levels during intoxication.
These studies provide substantial evidence for the use of acupuncture of Ht-7 to relieve withdrawal symptoms, lessen the strength of addictions during withdrawal, and lessen the addictive effects of ethanol and morphine during intoxication. The study by Lee et al. (2008) also explains the effects of acupuncture of Ht-7 on the GABA system that facilitates the lessening of addiction and withdrawal symptoms.