Abstract

The purpose of this project was to investigate the mechanism of action of acupuncture on a critical neural substrate involved in alcoholism. Specifically, this study evaluated the effects of stimulation of the acupuncture Shenmen (HT7) point on inhibitory GABA neurons in the ventral tegmental area (VTA), a midbrain structure implicated in drug and alcohol abuse, and ethanol self-administration. In addition, the role of opioid receptors (ORs) in ethanol and acupuncture effects was explored. Using electrophysiological methods in mature rats, we evaluated the effects of HT7 stimulation and opioid antagonists on the VTA GABA neuron firing rate. With behavioral paradigms, we also assessed those effects on ethanol self-administration, using a modification of the sucrose fading procedure. We found that HT7 stimulation produced a biphasic modulation of VTA GABA neuron firing rate characterized by transient enhancement at the onset of stimulation followed by a prolonged inhibition and subsequent recovery in 5 min. HT7 stimulation blocked the typical suppression of VTA GABA neuron firing rate produced by a moderately intoxicating dose of ethanol. The late inhibition produced by HT7 stimulation as well as HT7 reversal of ethanol's effects on GABA neuron firing rate was blocked by the non-selective opioid receptor antagonist, naloxoneIn addition, HT7 acupuncture reduced ethanol self-administration without affecting sucrose consumption. More important, systemic administration of the δ-opioid receptor (DOR) antagonist, naltrindole blocked ethanol suppression of VTA GABA neuron firing rate and significantly reduced ethanol self-administration without affecting sucrose consumption. These findings suggest that DOR-mediated opioid modulation of VTA GABA neurons may be related to the role of acupuncture in modulating mesolimbic DA release and suppressing the reinforcing effects of ethanol. We confirmed that acupuncture stimulation may have a significant impact on the inhibitory neuron activity in the VTA and that acupuncture may serve as an effective adjunct to OR antagonist therapy for alcoholism.

Degree

College and Department

Family, Home, and Social Sciences; Psychology

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