Researchers at the University of California have isolated a flavonoid from the plant Hovenia Dulcis that can counter the effects of alcohol, relieve symptoms of hangover, and is shown to be a likely cure for alcohol withdrawal and dependence (Shen et al., 2012).
The plant Hovenia Dulcis, also known as the oriental raisin tree, has long been used in Chinese herbal medicine for the relieve of hangover symptoms and is listed in the Tang Materia Medica which dates back to 659 A.D. (Shen et al., 2012). Shen et al. have isolated the flavonoid in the Hovenia Dulcis plant that is attributed to the plant’s anti-alcohol effects.
Alcohol and our Brain
The effects of alcohol on our brain is very complicated.To be honest, I still haven’t found an explanation that I can fully understand even after my month long search for journal papers which explore this relationship. Although, I’m sure it’s just because of my shallow understanding of neurobiology rather than a lack of good research or explanation available.
From what I have gathered, alcohol plays a large role in upsetting the balance between the primary inhibitory neurotransmitter gamma aminobutyric acid (GABA) and the major excitatory neurotransmission glutamate (Enoch, 2008; Shen et al., 2012). These neurotransimitters decrease or increase the neuron activity in our brains. Substances like ethanol (alcohol), benzodiazepine (valium), and other anesthetics enhance the function of GABA and have sedative or hypnotic effects (Davies, 2003; Enoch, 2008; Shen et al., 2012). However, ethanol is not particularly potent compared with the other similar substances (Davies, 2003).
The Effects of Alcohol
The complex changes to the GABA neurotransmitter as a result of alcohol ingestion also activate and excite our Dopamine reward pathway. This is why we feel a sense of euphoria or “buzzed” at low blood alcohol concentrations (BAC) (Davies, 2003; Enoch, 2008). At higher BAC, our motor functions and speech become impaired (Davies, 2003), likely from the highly elevated function of the GABA neurotransmitters which cause the highly sedative effect.
We may start to lose our senses and starts to phase out when our BAC reaches ~0.2 to 0.3%, due to the numbing effect of the enhanced GABA function (Davies, 2003). At this point, vomiting and headaches can also occur from the build up of acetaldehyde (Davies, 2003), a byproduct of alcohol metabolism as explained in one of my previous posts. The sedative effect is so great at BAC higher than 0.5% that there is a potential of respiratory failures, which may even lead to death.
Alcoholism and GABA
If you drink a lot and drink frequently, changes occur to the effectiveness and function of the GABA receptors sites (where the GABA neurotransmitter does its magic). This is known as GABA receptors plasticity (Davies, 2003; Enoch, 2008; Shen et al., 2012). Prolong drinking makes the neurons fire a lot more (which are normally subdued by the GABA but is no longer the case). It also creates a tolerance for alcohol, meaning a higher BAC is need before you start feeling the euphoria (Gallegos, 1999). Additionally, the dopamine reward pathway (something that we like and want) becomes less sensitive to alcohol, which could lead to cravings for more alcohol and a negative reinforcement to want more (Enoch, 2008). In other words, GABA plasticity may be a cause of alcoholism.
The Hovenia Dulcis Plant and Anti-Intoxication
Shen et al. (2012) at the University of California have isolated Dihydromyricetin (DHM), a flavonoid from the Hovenia Dulcis plant, to be responsible for the well known anti-intoxication effects of the plant.
Shen et al. (2012) used an animal model, rats to be specific, to demonstrate the effects of DHM on alcohol intoxication. Their study shows that taking DHM with alcohol or up to 30 minutes before ingesting alcohol would significantly reduce the effect of the alcohol. They believed that the DHM blocks the alcohol effects at the GABA receptors (i.e. at sites where GABA work rather than influencing the GABA neurotransmitter themselves). Think of it like a lockout, where employees can’t get to their work station.
Notice the study only shows DHM blocks the effects of GABA, it doesn’t say anything about how DHM might affect your BAC level. Shen et al. (2012) cited older reports on the Hovenia Dulcis plant which show an increase in the body metabolism rate for both alcohol and acetaldehyde dehydrogenases. However, their study with DHM show this improvement to be quite modest. Perhaps another components of the Hovenia Dulcisplant are responsible for those effects. Shen et al. (2002) suggest that DHM may partly relieve hang over symptoms, but only partly. In other words DHM is expected to significantly reduce the tipsy-ness feeling, but not necessarily lower the BAC level.
Hovenia Dulcis and Alcoholism
The pot of gold at the end of the rainbow in this study is the fact that DHM seems to lessen the GABA receptor plasticity as a result of frequent heavy drinking (Shen et al., 2012). So taking DHM can effectively shift the GABA baseline level back to normal and reduce alcohol cravings. In fact, Shen et al. (2012) demonstrated some very interesting results with their voluntary alcohol intake experiments. Several groups of rats were given 2 bottles that they may freely drink from. The group with a choice of an alcohol+DHM mixture and water did not show any signs of alcohol dependence. The group that had a choice of alcohol and water begins building an alcohol dependence, with an increase in alcohol consumption after 3-4 weeks. As a side note, those must have been some pretty happy alcoholic rats!
By switching the alcoholic rats to an alcohol+DHM mixture, the alcohol dependence and the amount of alcohol consumed were reversed after a week. Shen et al. (2012) believe that DHM is a very realistic and viable candidate for medications for alcoholism by preventing and lessening the dependence of alcohol.
DHM and the Hovenia Dulcis plant also work great as an anti-intoxication medicine. As an added bonus, they also partly relieve other hang over symptoms. If you want to try the Hovenia Dulcis plant as a hang over cure yourself, a quick google search of Hovenia Dulcis tea will lead you to many brands and online store that sells them.
Davies M (2003). The role of GABAA receptors in mediating the effects of alcohol in the central nervous system. Journal of psychiatry & neuroscience : JPN, 28 (4), 263-74 PMID: 12921221
Enoch, M. (2008). The role of GABAA receptors in the development of alcoholism Pharmacology Biochemistry and Behavior, 90 (1), 95-104 DOI: 10.1016/j.pbb.2008.03.007
Shen, Y., Lindemeyer, A., Gonzalez, C., Shao, X., Spigelman, I., Olsen, R., & Liang, J. (2012). Dihydromyricetin As a Novel Anti-Alcohol Intoxication Medication Journal of Neuroscience, 32 (1), 390-401 DOI: 10.1523/JNEUROSci.4639-11.2012