An active ingredient in a Chinese herbal remedy for hangovers shows many promising effects in a series of animal experiments.

Medications approved for the treatment of alcoholism — disulfiram, naltrexone, and acamprosate — have had less than inspiring results. In this series of experiments, researchers gave rats alcohol, the novel herbal flavonoid dihydromyricetin (DHM), or both in combination, and the results suggest a novel approach to treating multiple aspects of alcohol dependence.

DHM reversed alcohol intoxication, as measured by the animals’ ability to right themselves after receiving alcohol; this effect was blocked by the benzodiazepine receptor antagonist flumazenil. DHM prevented alcohol tolerance and reduced alcohol intake in animals trained to prefer alcohol. During alcohol withdrawal, DHM ameliorated anxiety-like behavior (measured by time in the open arms of an elevated maze) and reduced susceptibility to pentylenetetrazol-induced seizures. In neuronal cultures, DHM antagonized potentiation of –aminobutyric acid (GABA) type A receptor currents by alcohol (flumazenil again blocked DHM’s effect), but DHM itself potentiated those currents, prevented up-regulation of GABA_A receptors during alcohol withdrawal, and inhibited binding of a benzodiazepine to the benzodiazepine receptor.

Comment: Doses of dihydromyricetin, which is derived from Hovenia dulcis, were equivalent to human doses used to treat hangovers. Apparently, DHM has a complex agonist effect on the benzodiazepine receptor, which is a component of the GABA_A receptor complex that facilitates hyperpolarizing chloride currents through the GABA-benzodiazepine receptor complex. Thus, DHM can block multiple effects of alcohol without causing impairment or dependence itself. DHM’s agonistic effect may also decrease up-regulation of the receptor complex and inhibit the action of picrotoxin, which reduces GABA_A currents, an inverse agonistic mechanism that contributes to the neuronal excitability associated with alcohol withdrawal. Previous human experience with Hovenia suggests that DHM may be ready for human testing.

Source: Journal Watch Psychiatry