Hypericum perforatum CO2 Extract and Opioid Receptor Antagonists Act Synergistically to Reduce Ethanol Intake in Alcohol-Preferring Rats

Genetically selected alcohol-preferring msP rats to study alcohol use disorder: Anything lost in translation?

For several decades, genetically selected alcohol-preferring rats have been successfully used to mimic and study alcohol use disorders (AUD). These rat lines have been instrumental in advancing our understanding of the neurobiology of alcoholism and enabling pharmacological studies to evaluate drug efficacy on alcohol drinking and relapse. Moreover, the results of these studies have identified genetic variables that are linked to AUD vulnerability. This is an up-to-date review that focuses on genetically selected Marchigian Sardinian alcohol-preferring (msP) rats. To support the translational relevance of the findings that are obtained from msP rats and highlight important similarities to AUD patients, we also discuss the results of recent brain imaging studies. Finally, to demonstrate the importance of studying sex differences in animal models of AUD, we present original data that highlight behavioral differences in the response to alcohol in male and female rats. Female msP rats exhibited higher alcohol consumption compared with males. Furthermore, msP rats of both sexes exhibit higher anxiety- and depressive-like behaviors in the elevated plus maze and forced swim test, respectively, compared with unselected Wistar controls. Notably, voluntary alcohol drinking decreases foot-shock stress and depressive-like behavior in both sexes, whereas anxiety-like behavior in the elevated plus maze is attenuated only in males. These findings suggest that male and female msP rats both drink high amounts of alcohol to self-medicate negative affective symptoms. For females, this behavior may be driven by an attempt to treat stress and depressive-like conditions. For males, generalized anxiety appears to be an important additional factor in the motivation to drink alcohol. This article is part of the special issue on 'Vulnerabilities to Substance Abuse.'

Plants with Anti-Addictive Potential

Drug addiction is prevalent among individuals of modern society, being a major cause of disability and premature loss of life. Although the drug addiction have profound social, economical and health impact in the world population, its management remains a challenge as available pharmacological treatments remains ineffective for most people. The limited efficacy and adverse effects have led to a search for alternative therapies to treat drug addiction. In this context, natural products are an important source for new chemical substances with a potential therapeutic applicability. Therefore, this chapter will present data obtained after an extensive literature search regarding the use of medicinal plants as a pharmacological alternative for drug addiction treatment.

Ethnopharmacological Applications Targeting Alcohol Abuse: Overview and Outlook

Excessive alcohol consumption is the cause of several diseases and thus is of a major concern for society. Worldwide alcohol consumption has increased by many folds over the past decades. This urgently calls for intervention and relapse counteract measures. Modern pharmacological solutions induce complete alcohol self-restraint and prevent relapse, but they have many side effects. Natural products are most promising as they cause fewer adverse effects. Here we discuss in detail the medicinal plants used in various traditional/folklore medicine systems for targeting alcohol abuse. We also comprehensively describe preclinical and clinical studies done on some of these plants along with the possible mechanisms of action.

The sesquiterpene beta-caryophyllene oxide attenuates ethanol drinking and place conditioning in mice

Approximately 20 million adults in the United States have an alcohol use disorder. In recent years, modulation of the behavioral effects of ethanol by phytochemicals has been explored. In this study, we used the ethanol-induced loss of righting reflex (LORR) assay to assess potency differences between the sesquiterpene phytochemical beta-caryophyllene (BCP) and its derivative caryophyllene oxide (BCPO). We also investigated the effects of BCPO on two bottle-choice ethanol drinking and the ethanol-induced conditioned place preference (CPP). We then determined whether there are any pharmacokinetic or pharmacodynamic interactions between BCPO and ethanol, using blood ethanol analysis and pretreatments with the selective cannabinoid receptor 2 (CB2) antagonist AM630, respectively. BCPO augmented the ethanol-induced LORR at a dose (30 mg/kg) tenfold lower than BCP (300 mg/kg). Swiss-Webster mice were found to split into stable high and low drinking groups. This same dose (30 mg/kg) of BCPO significantly decreased ethanol intake and preference for ethanol over water in mice that consumed high amounts of ethanol, without any effect on total fluid intake. BCPO had limited effects in mice that consumed low amounts of ethanol. BCPO also significantly attenuated the ethanol-induced CPP. Blood ethanol analysis showed no significant effect of ethanol on the pharmacokinetics of ethanol. Furthermore, the enhancement of the ethanol-induced LORR by BCPO was reversed by AM630. These findings demonstrate that BCPO more potently modulates the behavioral effects of ethanol than the parent compound BCP. Moreover, they suggest that BCPO modulates the behavioral effects of ethanol through pharmacodynamic rather than pharmacokinetic mechanisms.

Natural Products for the Prevention and Treatment of Hangover and Alcohol Use Disorder

Alcoholic beverages such as beer, wine and spirits are widely consumed around the world. However, alcohol and its metabolite acetaldehyde are toxic and harmful to human beings. Chronic alcohol use disorder or occasional binge drinking can cause a wide range of health problems, such as hangover, liver damage and cancer. Some natural products such as traditional herbs, fruits, and vegetables might be potential dietary supplements or medicinal products for the prevention and treatment of the problems caused by excessive alcohol consumption. The aim of this review is to provide an overview of effective natural products for the prevention and treatment of hangover and alcohol use disorder, and special emphasis is paid to the possible functional component(s) and related mechanism(s) of action.

Effects of A₂A adenosine receptor blockade or stimulation on alcohol intake in alcohol-preferring rats

RATIONALE

A(2A) adenosine receptors (A(2A)ARs) have been proposed to be involved in drug addiction; however, preclinical studies about the effects of A(2A)AR ligands on alcohol consumption have provided inconsistent results.

OBJECTIVES

The present study evaluated the effect of intraperitoneal injections of the A(2A)AR antagonist ANR 94, and the A(2A)AR agonists CGS 21680 and VT 7 on voluntary drinking and operant self-administration of 10% ethanol in Marchigian Sardinian alcohol-preferring (msP) rats.

RESULTS

Voluntary ethanol drinking was increased by ANR 94 in acute and subchronic experiments, while it was reduced by A(2A)AR agonists. The effect of CGS 21680 was abolished by a low dose of ANR 94, confirming its mediation by A(2A)ARs. Ethanol self-administration was reduced by CGS 21680 and VT 7, while ANR 94 slightly but significantly increased it. Blood alcohol levels were not modified by A(2A)AR agonists, indicating that their effect is not related to ethanol pharmacokinetics. The effect of VT 7 on ethanol drinking was behaviourally selective; ethanol and food intake were reduced, but water intake was increased, and total fluid intake was not different from that of controls. Moreover, VT 7 did not affect locomotor activity. CGS 21680 (0.1 mg/kg) did not modify total fluid intake, but 0.2 and 0.3 mg/kg reduced total fluid intake and locomotor activity.

CONCLUSION

These results provide evidence that A(2A)AR agonists reduce ethanol consumption in msP rats, which represent an animal model of alcohol abuse related to stress, anxiety and depression. A(2A)ARs may represent a potential target for treatment of alcohol abuse.

Phytotherapy of Alcoholism

Alcoholism is a medical, social, and economic problem where treatment methods mostly include difficult and long-lasting psychotherapy and, in some cases, quite controversial pharmacological approaches. A number of medicinal plants and pure natural compounds are reported to have preventive and therapeutic effects on alcoholism and alcohol dependency, but their constituents, efficacy and mechanism of action are mostly unknown so far. Recently, kudzu [ Pueraria lobata (Willd.) Ohwi], St. John's wort ( Hypericum perforatum L.), danshen ( Salvia miltiorrhiza Bge.), ginseng ( Panax ginseng C.A. Mey.), Japanese raisin tree ( Hovenia dulcis Thunb.), ibogaine ( Tabernanthe iboga H. Bn.), evening primrose ( Oenothera biennis L.), prickly pear fruit ( Opuntia ficus indica (L.) Mill.), purple passionflower ( Passiflora incarnata L.), thyme ( Thymus vulgaris L.), fenugreek seed ( Trigonella foenum-graecum L.), ginger ( Zingiber officinale Roscoe) and many others drew the attention of researchers. Can, therefore, drugs of natural origin be helpful in the treatment of alcoholism or in decreasing alcohol consumption?

Effect of Hypericum perforatum Extract in an Experimental Model of Binge Eating in Female Rats

Purpose. The present study evaluated the effect of Hypericum perforatum dry extract in an experimental model of binge eating (BE). Methods. BE for highly palatable food (HPF) was evoked in female rats by three 8-day cycles of food restriction/re-feeding and acute stress on the test day (day 25). Stress was induced by preventing access to HPF for 15 min, while rats were able to see and smell it. Hypericum perforatum dry extract was given by gavage. Results. Only rats exposed to both food restrictions and stress exhibited BE. The doses of 250 and 500 mg/kg of Hypericum perforatum extract significantly reduced the BE episode, while 125 mg/kg was ineffective. The same doses did not affect HPF intake in the absence of BE. The dose of 250 mg/kg did not significantly modify stress-induced increase in serum corticosterone levels, suggesting that the effect on BE is not due to suppression of the stress response The combined administration of 125 mg/kg of Hypericum perforatum together with Salidroside, active principle of Rhodiola rosea, produced a synergic effect on BE. Conclusions. The present results indicate for the first time that Hypericum perforatum extracts may have therapeutic properties in bingeing-related eating disorders.

Phytotherapeutic approach to alcohol dependence: new old way?

Alcohol abuse and dependence represent a worldwide problem from both medical and social points of view. In Italy it is estimated that there are about one million alcohol-dependent subjects. The pharmacological treatment of patients with alcohol dependence plays a key role in order to achieve alcohol abstinence and prevent relapse. At present, the possible utility of the complementary medicines in the treatment of alcohol dependence is controversial. In the last years, pre-clinical and clinical data from traditional medicines suggest that novel pharmacological approaches for treatment of alcoholism and alcohol abuse may stem from natural substances. The present review summarizes the findings of the effects of phytotherapy in alcohol addiction.

Natural products as tools for neuroscience: discovery and development of novel agents to treat drug abuse

Much of what we know about the neurosciences is the direct result of studying psychoactive natural products. Unfortunately, there are many gaps in our understanding of the basic biological processes that contribute to the etiology of many CNS disorders. The investigation of psychoactive natural products offers an excellent approach to identify novel agents to treat CNS disorders and to find new chemical tools to better elucidate their biological mechanisms. This review will detail recent progress in a program directed toward investigating psychoactive natural products with the goal of treating drug abuse by targeting kappa opioid receptors.

Potency of naltrexone to reduce ethanol self-administration in rats is greater for subcutaneous versus intraperitoneal injection

The opioid antagonist naltrexone (NTX) is used to treat alcohol dependence and may reduce alcohol consumption by selectively blocking opioid receptors. In rat experiments, discrepancy exists across studies regarding the potency of NTX to reduce ethanol consumption. One cause of this discrepancy may be the use of different routes of NTX administration (e.g., intraperitoneal vs. subcutaneous). The purpose of this study was to directly compare the effects of intraperitoneal and subcutaneous injections of NTX on ethanol self-administration. Rats pressed a lever for a sweetened ethanol solution (10% wt/vol in 0.1% saccharin) during 20 min daily sessions. One group received intraperitoneal injections of 1, 3, 10, and 30 mg/kg NTX before the sessions. Another group received subcutaneous injections of 0.03, 0.1, 0.3, and 1 mg/kg NTX before the sessions. The group that received subcutaneous NTX was also tested with a single intraperitoneal injection of 0.3 mg/kg NTX. Naltrexone significantly reduced ethanol self-administration, and NTX was more potent when administered via subcutaneous injection versus intraperitoneal injection. Ethanol intake (g/kg) was significantly reduced after subcutaneous injection of NTX 0.1 mg/kg and higher. In contrast, ethanol intake was significantly reduced after intraperitoneal injection of NTX 3 mg/kg and higher. A comparison of the NTX ED(50) values showed that subcutaneous NTX was approximately 30-fold more potent than intraperitoneal NTX. For the subcutaneous 0.3 mg/kg NTX dose, a detailed bin analysis showed that responding during the first 2 min after injection was similar to that during the first 2 min after a saline injection while responding after NTX decreased in subsequent bins. These findings suggest that researchers should carefully consider the route of NTX administration when discussing potency and selectivity of NTX's effects on ethanol-related behaviors in rats. These findings further support the notion that NTX acts by terminating responding early rather than reducing the initial responding.

Dysregulation of nociceptin/orphanin FQ activity in the amygdala is linked to excessive alcohol drinking in the rat

BACKGROUND

Alcoholism is a complex behavioral disorder in which interactions between stressful life events and heritable susceptibility factors contribute to the initiation and progression of disease. Neural substrates of these interactions remain largely unknown. Here, we examined the role of the nociceptin/orphanin FQ (N/OFQ) system, with an animal model in which genetic selection for high alcohol preference has led to co-segregation of elevated behavioral sensitivity to stress (Marchigian Sardinian alcohol-preferring [msP]).

METHODS

The msP and Wistar rats trained to self-administer alcohol received central injections of N/OFQ. In situ hybridization and receptor binding assays were also performed to evaluate N/OFQ receptor (NOP) function in naïve msP and Wistar rats.

RESULTS

Intracerebroventricular (ICV) injection of N/OFQ significantly inhibited alcohol self-administration in msP but not in nonselected Wistar rats. The NOP receptor messenger RNA expression and binding was upregulated across most brain regions in msP compared with Wistar rats. However, in msP rats [(35)S]GTPgammaS binding revealed a selective impairment of NOP receptor signaling in the central amygdala (CeA). Ethanol self-administration in msP rats was suppressed after N/OFQ microinjection into the CeA but not into the bed nucleus of the stria terminalis or the basolateral amygdala.

CONCLUSIONS

These findings indicate that dysregulation of N/OFQ-NOP receptor signaling in the CeA contributes to excessive alcohol intake in msP rats and that this phenotype can be rescued by local administration of pharmacological doses of exogenous N/OFQ. Data are interpreted on the basis of the anti-corticotropin releasing factor (CRF) actions of N/OFQ and the significance of the CRF system in promoting excessive alcohol drinking in msP rats.

Flavonoids as opioid receptor ligands: identification and preliminary structure-activity relationships

Flavonoids have been recognized as the active ingredients of many medicinal plant extracts due to interactions with proteins via phenolic groups and low toxicity. Here, we report the investigation of the flavonoid core as a potential new scaffold for the development of opioid receptor ligands. Biological results suggest that stereochemistry of the C2 and C3 positions is important for antagonist activity and selectivity. Our results also suggest that the actions of Hypericum perforatum may be mediated in part by opioid receptors.

Varenicline, an alpha4beta2 nicotinic acetylcholine receptor partial agonist, selectively decreases ethanol consumption and seeking

Alcohol dependence is a disease that impacts millions of individuals worldwide. There has been some progress with pharmacotherapy for alcohol-dependent individuals; however, there remains a critical need for the development of novel and additional therapeutic approaches. Alcohol and nicotine are commonly abused together, and there is evidence that neuronal nicotinic acetylcholine receptors (nAChRs) play a role in both alcohol and nicotine dependence. Varenicline, a partial agonist at the alpha4beta2 nAChRs, reduces nicotine intake and was recently approved as a smoking cessation aid. We have investigated the role of varenicline in the modulation of ethanol consumption and seeking using three different animal models of drinking. We show that acute administration of varenicline, in doses reported to reduce nicotine reward, selectively reduced ethanol but not sucrose seeking using an operant self-administration drinking paradigm and also decreased voluntary ethanol but not water consumption in animals chronically exposed to ethanol for 2 months before varenicline treatment. Furthermore, chronic varenicline administration decreased ethanol consumption, which did not result in a rebound increase in ethanol intake when the varenicline was no longer administered. The data suggest that the alpha4beta2 nAChRs may play a role in ethanol-seeking behaviors in animals chronically exposed to ethanol. The selectivity of varenicline in decreasing ethanol consumption combined with its reported safety profile and mild side effects in humans suggest that varenicline may prove to be a treatment for alcohol dependence.

Depressive-like behavior and high alcohol drinking co-occur in the FH/WJD rat but appear to be under independent genetic control

This review will consider the evidence supporting the view that a specific substrain of Fawn-Hooded rat (FH/Wjd) exhibits co-occurring depressive-like behavior and high alcohol intake independently. First, the FH/Wjd rat is compared with other Fawn-Hooded substrains (FH/Har, FHH/Eur, FHL/Eur) and it is concluded that only the FH/Wjd rat is both highly immobile in the forced swim test and drinks substantial amounts of 5-10% alcohol voluntarily. Next it is demonstrated that the FH/Wjd rat fulfils many of the criteria proposed for an animal model of alcoholism (becomes tolerant, becomes dependent and expresses withdrawal symptoms, bar-presses for alcohol). Other literature in addition to the high swim test immobility suggests that the FH/Wjd rat may also be an animal model of depression (high basal corticosterone levels, blunted hormonal responses to serotonergic agonists). To study the phenotypes more closely an inbred strain (ACI/N) of rat that drank little alcohol voluntarily and exhibited considerable swimming in the forced swim test (i.e., low immobility) was obtained. A systematic intercrossing of the parental strains and the resulting F1 progeny was carried out to generate more than 800 F2s. Swim test immobility, alcohol intake and preference and saccharin intake are four of the 7 variables assessed in each of these rats. Using classical quantitative genetics methods, it was determined that these four phenotypes exhibited modest heritability and were influenced by multiple genes. Correlation coefficients between immobility and the other measures were near zero, whereas alcohol intake and preference were highly correlated (r=0.9) and alcohol and saccharin intakes were modestly correlated (r=0.3). A final study showed that chronic fluoxetine treatment counteracted the high immobility but did not affect alcohol intake, similar to human studies. These findings suggest that although depressive-like behavior and high alcohol intake co-occur in the FH/Wjd rat, they are independently regulated.

Genetically selected Marchigian Sardinian alcohol-preferring (msP) rats: an animal model to study the neurobiology of alcoholism

The present article provides an up-to-date review summarizing almost 18 years of research in genetically selected Marchigian Sardinian alcohol-preferring (msP) rats. The results of this work demonstrate that msP rats have natural preference for ethanol characterized by a spontaneous binge-type of drinking that leads to pharmacologically significant blood ethanol levels. This rat line is highly vulnerable to relapse and presentation of stimuli predictive of alcohol availability or foot-shock stress can reinstate extinguished drug-seeking up to 8 months from the last alcohol experience. The msP rat is highly sensitive to stress, shows an anxious phenotype and has depressive-like symptoms that recover following ethanol drinking. Interestingly, these animals have an up-regulated corticotrophin releasing factor (CRF) receptor 1 system. Clinical studies have shown that alcoholic patients often drink ethanol in the attempt to self-medicate from negative affective states and to search for anxiety relief. We propose that msP rats represent an animal model that largely mimics the human alcoholic population that due to poor ability to engage in stress-coping strategies drink ethanol as a tension relief strategy and for self-medication purposes.

Natural medicines for alcoholism treatment: a review

Alcoholism is a serious problem throughout the world. The development of alcoholism remedies have medical, social and economical significance. In view of the pitfalls of psychological dependence and adverse behavioural effects of synthetic drugs, the development of low toxicity and high efficiency medicines derived from natural products exhibits expansive market prospects. Based on these considerations, we summarize briefly folk application of traditional hangover remedies and clinical application of herbal complex and patent medicines for alcoholism treatment. We have reviewed the effects of natural medicines on intake, absorption and metabolism of alcohol, as well as the protective effects on alcohol-induced acute and chronic tissue injury.

Reduction of ethanol intake by chronic treatment with Hypericum perforatum, alone or combined with naltrexone in rats

Acute treatment with extracts of Hypericum perforatum, the common plant usually called St. John's Wort, reduces voluntary ethanol intake in Marchigian Sardinian alcohol-preferring (msP) rats and acts synergistically with opioid receptor antagonists to further attenuate ethanol consumption. The present study evaluated the effect of chronic (once a day for 12 days) intragastric administration of a CO2 Hypericum perforatum extract (HPCO2), given alone or combined with naltrexone (NTX), on ethanol intake offered 2h/day in msP rats. Chronic treatment with HPCO2 markedly reduced ethanol intake at the dose of 125, but not at 7 mg/kg; the effect of 125 mg/kg was observed since the first day of treatment and remained constant across the 12 days. The same dose of HPCO2 slightly reduced the simultaneous intake of food only on day 3 and day 11 of treatment. Treated rats promptly recovered baseline ethanol intake when treatment did not precede access to ethanol (on day 8) or after the end of treatment (day 13 and day 14), suggesting that HPCO2 administrations did not induce conditioned aversion to alcohol. Chronic intraperitoneal treatment with NTX reduced ethanol intake at 3, but not at 0.5mg/kg. The synergistic effect on ethanol intake of HPCO2 and NTX was evident also in conditions of chronic treatment. HPCO2, 7 mg/kg, and NTX, 0.5mg/kg, evoked a pronounced and statistically significant reduction of ethanol intake, while being inactive. The effect on ethanol intake of the combined treatment remained stable over the 12 days of treatment; food intake was slightly reduced only on day 3 and on day 7 in response to 125 mg/kg of HPCO2 combined with NTX 0.5mg/kg, but no difference in body weight between controls and treated rats was observed at the end of treatment. Following 12-day treatment with 125 mg/kg of HPCO2, no difference was observed in the responsivity of msP rats to the effect on ethanol intake of several doses of the extract. In conclusion, the present results provide evidence for a selective and pronounced effect of HPCO2, alone or combined with naltrexone, on ethanol intake in conditions of chronic treatment, without development of tolerance. These findings further support the view that clinical trials for extracts of Hypericum perforatum in the treatment of alcoholism should be considered.

Effect of Hypericum perforatum CO2 extract on the motivational properties of ethanol in alcohol-preferring rats

AIMS

Extracts of Hypericum perforatum (HPE) attenuate voluntary ethanol intake in different lines of alcohol-preferring rats. The present study evaluated the effect of the intragastric (IG) administration of a CO(2) Hypericum perforatum extract (HPCO(2)) on operant ethanol self-administration, as well as on voluntary ethanol intake, after a period of ethanol deprivation in genetically selected Marchigian Sardinian alcohol-preferring rats.

METHODS

HPCO2 was administered by means of an indwelling IG catheter, 1 h before the tests. For the self-administration experiments, the rats were trained to self-administer 10% (v/v) ethanol in 30-min daily sessions under a fixed ratio 1 schedule of reinforcement. HPCO2 was also tested on 0.2% w/v saccharin self-administration. For the ethanol deprivation experiments, rats that had a previous experience with voluntary ethanol drinking were deprived of ethanol for 9 days, whereas water and food were freely available; HPCO2 was given by IG injection 1 h before the ethanol re-presentation.

RESULTS

HPCO2 in doses of 31 or 125 mg/kg but not 7 mg/kg, significantly reduced ethanol self-administration, while it did not modify saccharin self-administration. The same doses of the extract abolished the increased ethanol intake following ethanol deprivation.

CONCLUSIONS

These findings provide evidence that HPCO2 markedly reduces the reinforcing properties of ethanol in the self-administration paradigm, as well as the increase of ethanol intake following ethanol deprivation. These findings further support the view that the use of HPE may represent an interesting pharmacological approach in the treatment of alcohol abuse and alcoholism.

Natural and complementary therapies for substance use disorders

PURPOSE OF REVIEW

To review recent studies that have examined the efficacy of natural and complementary therapies as treatments for substance use disorders and their complications.

RECENT FINDINGS

Despite increasing interest in natural and complementary therapies for substance use disorders, rigorous clinical studies in this area are few in number. Recent clinical studies, although preliminary, have reported potential therapeutic effects for hypericum in the treatment of smoking cessation, for prickly pear extract in the prevention of alcohol hangover and magnesium supplementation as an adjunct to methadone treatment. Other clinical studies have reported negative findings for ginkgo as an adjunctive treatment for cocaine dependence, for artichoke in prevention of alcohol hangover, and acupuncture for alcohol withdrawal. Relevant findings from animal studies are also discussed. Neither vitamin E nor Liv 52 had a useful effect in alcohol-related liver disease. A study of silymarin in baboons, which was undertaken in an attempt to untangle the conflicting findings of human studies, reported a potential for this compound to prevent liver injury. There is increasing awareness of safety issues associated with complementary therapies. Safety issues pertinent to substance use treatment are discussed in this review.

SUMMARY

Several pharmacological and psychosocial treatments for substance use disorders are solidly evidence-based and improve both individual and public health outcomes. At this stage, there remains insufficient evidence to support the use of natural and complementary therapies as a primary intervention for substance use disorders. Further clinical trials are required to clarify the potential role of particular agents.

Plant derivatives in the treatment of alcohol dependency

The present review summarizes the findings of the effects of extracts of purified compounds from several plants on alcohol intake in alcohol-preferring rats. These include St. John's wort (Hypericum perforatum, HPE), kudzu (Pueraria lobata) and ibogaine (Tabernanthe iboga). Alcohol-preferring (P), Marchigian Sardinian (msP), high-alcohol-drinking (HAD), Fawn-Hooded (FH) rats were allowed to drink alcohol or water voluntarily to establish baseline levels. Pure compounds (puerarin, daidzin, daidzein or analogs) isolated from kudzu, extracts from HPE or ibogaine and its analog were given by either intraperitoneal or oral administration. After acute administration, all agents dose-dependently reduced alcohol intake with minimal effects on food intake. Puerarin and HPE were also effective following chronic treatment. Overall, it is clear that pure compounds (daidzin, puerarin), extracts from St. John's wort, ibogaine and an ibogaine analog suppress alcohol intake in animal models of excessive drinking with minimal effects on other appetitive behaviors. Although the true mechanisms of action of these compounds on alcohol intake are not fully understood, with the current information, it appears that these compounds exert their effects by modulating several neuronal systems implicated in drinking behavior. However, their role in the future of pharmacotherapy for alcoholism will depend upon the outcome of carefully conducted clinical trials.