Risk factors for migraine disease progression: a narrative review for a patient-centered approach.

BACKGROUND: In individuals with migraine, attacks may increase in frequency, severity, or both. Preventing migraine progression has emerged as a treatment goal in headache subspecialty practice, but there may be less awareness in general neurology or primary care settings where most people with migraine who seek treatment consult. Herein, we review the definition of and risk factors for migraine progression and consider strategies that could reduce its risk. METHODS: A group of headache expert healthcare professionals, clinicians, and researchers reviewed published evidence documenting factors associated with increased or decreased rates of migraine progression and established expert opinions for disease management recommendations. Strength of evidence was rated as good, moderate, or based solely on expert opinion, using modified criteria for causation developed by AB Hill. RESULTS: Migraine progression is commonly operationally defined as the transition from ≤ 15 to ≥ 15 monthly headache days among people with migraine; however, this does not necessarily constitute a fundamental change in migraine biology and other definitions should be considered. Established and theoretical key risk factors for migraine progression were categorized into five domains: migraine disease characteristics, treatment-related factors, comorbidities, lifestyle/exogenous factors, and demographic factors. Within these domains, good evidence supports the following risk factors: poorly optimized acute headache treatment, cutaneous allodynia, acute medication overuse, selected psychiatric symptoms, extra-cephalic chronic pain conditions, metabolism-related comorbidities, sleep disturbances, respiratory conditions, former/current high caffeine intake, physical inactivity, financial constraints, tobacco use, and personal triggers as risk factors. Protective actions that may mitigate migraine progression are sparsely investigated in published literature; our discussion of these factors is primarily based on expert opinion. CONCLUSIONS: Recognizing risk factors for migraine progression will allow healthcare providers to suggest protective actions against migraine progression (Supplementary Fig. 1). Intervention studies are needed to weight the risk factors and test the clinical benefit of hypothesized mitigation strategies that emerge from epidemiological evidence.

A systematic literature review identifying associations between outcomes and quality of life (QoL) or healthcare resource utilization (HCRU) in schizophrenia.

AIMS: There have been no systematic literature reviews (SLRs) evaluating the identified association between outcomes (e.g. clinical, functional, adherence, societal burden) and Quality-of-Life (QoL) or Healthcare Resource Utilization (HCRU) in schizophrenia. The objective of this study was to conduct a SLR of published data on the relationship between outcomes and QoL or HCRU. MATERIALS AND METHODS: Electronic searches were conducted in Embase and Medline, for articles which reported on the association between outcomes and QoL or HCRU. Inclusion and exclusion criteria were applied to identify the most relevant articles and studies and extract their data. A summary table was developed to illustrate the strength of associations, based on p-values and correlations. RESULTS: One thousand and two abstracts were retrieved; five duplicates were excluded; 997 abstracts were screened and 95 references were retained for full-text screening. Thrirty-one references were included in the review. The most commonly used questionnaire, which also demonstrated the strongest associations (defined as a p < 0.0001 and/or correlation ±0.70), was the Positive and Negative Syndrome Scale (PANSS) associated with HCRU and QoL (the SF-36, the Schizophrenia Quality-of-Life questionnaire [S-QOL-18], the Quality-of-Life Scale [QLS]). Other robust correlations included the Clinical Global Impression-Severity (CGI-S) with QoL (EQ5D), relapse with HCRU, and remission with QoL (EQ5D). Lastly, functioning (Work Rehabilitation Questionnaire [WORQ] and Personal and Social Performance Scale [PSP]) was found to be associated to QoL (QLS and Subjective Well-being under Neuroleptics Questionnaire [SWN]). LIMITATIONS: This study included data from an 11-year period, and other instruments less frequently used may be further investigated. CONCLUSIONS: The evidence suggests that the PANSS is the clinical outcome that currently provides the most frequent and systematic associations with HCRU and QoL endpoints in schizophrenia.

Phosphatidylethanol is superior to carbohydrate-deficient transferrin and γ-glutamyltransferase as an alcohol marker and is a reliable estimate of alcohol consumption level.

BACKGROUND: In clinical practice as well as research situations, it is of great importance to get reliable information about a patient's alcohol consumption. The aim of the study was to investigate the correlation of alcohol biomarkers (phosphatidylethanol [PEth], carbohydrate-deficient transferrin [CDT], γ-glutamyltransferase, aspartate aminotransferase, and alanine aminotransferase) to retrospective as well as diary-based alcohol self-reports and to examine whether it is possible to correlate a biomarker result to a more precise level of alcohol consumption. METHODS: One hundred and sixty alcohol-dependent patients were included in a randomized, placebo-controlled clinical trial of pharmacotherapy for alcohol dependence, of which 115 (76 men and 39 women) completed the study. Retrospective alcohol consumption data were collected at baseline, and alcohol diaries were used during the study. Blood samples for determination of alcohol biomarkers were collected on 5 occasions during the study. RESULTS: PEth and CDT showed a better correlation with alcohol consumption documented in the diary (PEth rs = 0.56 and CDT rs = 0.35) than with retrospective consumption data (PEth rs = 0.23 and CDT rs = 0.22). An even higher correlation (rs = 0.63) was seen between the 2 alcohol biomarkers PEth and CDT. At all consumption levels, PEth had the highest sensitivity of all biomarkers studied. CONCLUSIONS: PEth was the biomarker with the best correlation to self-reported alcohol consumption. PEth was superior to CDT owing to its substantially higher sensitivity but also due to its closer correlation to self-report. PEth values can be translated into an approximate level of alcohol consumption and PEth appears to be a more reliable measure of alcohol consumption than self-reports.

Varenicline for treatment of alcohol dependence: a randomized, placebo-controlled trial.

BACKGROUND: Alcohol dependence is a devastating illness affecting a large population, and new pharmacological treatments with good efficacy are greatly needed. One potential candidate is varenicline, a smoking cessation agent with partial agonist action at α4 ß2 nicotinic acetylcholine receptors. METHODS: A total of 160 subjects, 30 to 70 years of age, fulfilling DSM-IV criteria for alcohol dependence without any serious physical or mental disorders, were recruited through advertisement at 3 university clinics in Sweden during March 2009 to January 2011. After a 2-week placebo run-in period, subjects received 2 mg varenicline daily (titrated from 0.5 mg during first week) or placebo for 12 weeks in a double-blind manner. RESULTS: The primary outcome was the proportion of heavy drinking days, measured by self-reported alcohol consumption. Primary and secondary outcomes were calculated as a mean over the 10-week steady-state active treatment period. In the primary outcome analysis, no effect of varenicline over placebo was found (p = 0.73 for the intention to treat [ITT] and 0.92 for per protocol [PP]). Secondary outcome analysis found a significant reduction of specific alcohol marker phosphatidylethanol (PEth) in the blood in the varenicline group compared to placebo (p = 0.02 ITT). Craving (p = 0.048 PP) and Alcohol Use Disorders Identification Test (AUDIT) scores (p = 0.015 ITT) were also reduced in the active treatment group. PEth more strongly correlated with self-reported alcohol consumption than carbohydrate-deficient ttransferrin and γ-glutamyl transferase, and correlation coefficients were higher in the varenicline group than in the placebo group for all markers. CONCLUSIONS: Although the results of the main outcome of this study did not support an effect of varenicline in alcohol-dependent individuals, the secondary analyses of PEth, craving and AUDIT score support an effect of varenicline on alcohol consumption. The disclosure of a treatment effect and the lack of a clear placebo effect when using PEth as outcome variable, together with a nonsymmetric bias associated with self-reported data, strongly argue for using the specific biomarker PEth in studies of treatments of alcohol dependence.

Nicotinic acetylcholine receptors are required for the conditioned reinforcing properties of sucrose-associated cues.

RATIONALE: We recently demonstrated that blocking specific nicotinic acetylcholine receptors (nAChRs) abolishes the conditioned reinforcing properties of ethanol-associated cues in rat, suggesting nAChRs as promising pharmacological targets for prevention of cue-induced relapse. OBJECTIVES: The present study investigated the involvement of nAChR subtypes in the conditioned reinforcing properties of stimuli associated with a natural reward (sucrose). METHODS: Water-deprived rats were trained to associate a tone + light stimulus (CS) with the presentation of a 0.1 M sucrose solution for 10 consecutive days. On the subsequent day, the animals were tested on the stringent acquisition of a new instrumental response with conditioned reinforcement, following a systemic injection of the nonselective nAChR antagonist mecamylamine (MEC) or the selective α7 and α6/α3ß2ß3* nAChR antagonist methyllycaconitine (MLA). At testing, the rats were presented with two novel levers. Responding on the lever assigned as active (CR lever) resulted in a presentation of the CS alone, while pressing the inactive lever (NCR lever) had no programmed consequences. RESULTS: Control animals pressed the CR lever significantly more than the NCR lever, demonstrating that the CR had acquired conditioned reinforcing properties. Systemic MEC as well as MLA reduced the CR lever responses to the same level as for the NCR lever. CONCLUSIONS: These results demonstrate a role for the α7 and/or α6/α3ß2ß3* nAChRs in conditioned reinforcement to a natural reward and suggest neuronal nAChRs as common mediators of the impact of cues on incentive processes.

Glycine receptors in the nucleus accumbens involved in the ethanol intake-reducing effect of acamprosate.

BACKGROUND: We have previously demonstrated that strychnine-sensitive glycine receptors (GlyRs) in the nucleus accumbens (nAc) and nicotinic acetylcholine receptors (nAChRs) in the ventral tegmental area are involved in mediating ethanol (EtOH)-induced elevation of dopamine in the rat mesolimbic dopamine system. This neuronal circuitry was also demonstrated to mediate dopamine elevation in the nAc after both taurine, an endogenous agonist of GlyRs, and acamprosate, a synthetic derivate of homotaurine. The aim of this study was to investigate whether the EtOH intake-reducing effect of acamprosate involves accumbal GlyRs. METHODS: For this purpose, we used a voluntary EtOH consumption model where EtOH medium- and high-preferring rats were implanted with guide cannulae in the nAc. The animals received daily injections of acamprosate or 0.9% NaCl before accessing a bottle of 6% EtOH and a bottle of water. After 2 days, a microinjection of strychnine or vehicle preceded the daily systemic injection and bottle-access period. RESULTS: Acamprosate, but not saline, decreased EtOH intake. Pretreatment with Ringer in the nAc did not influence EtOH intake in saline or acamprosate-treated animals. Pretreatment with strychnine had no effect on EtOH intake in saline-treated animals, whereas it completely reversed the EtOH intake-reducing effect of acamprosate. CONCLUSIONS: Based on current and previous results, we suggest that acamprosate primarily interacts with accumbal GlyRs and secondarily with ventral tegmental nAChRs, in a similar manner to that previously observed with EtOH and taurine. The interaction between acamprosate and GlyRs does not only influence dopamine output in the nAc but also EtOH consumption, giving further support for our hypothesis that GlyRs are of importance in EtOH reinforcement.

The smoking cessation medication varenicline attenuates alcohol and nicotine interactions in the rat mesolimbic dopamine system.

Varenicline was recently approved as an aid for smoking cessation. Patients treated with varenicline have reported a concomitant reduction in their alcohol consumption. This compound has also been demonstrated to reduce alcohol seeking and consumption in alcohol high-preferring rats. Based on the extensive coabuse of nicotine and alcohol, the aim of the present study was to explore whether interactions among varenicline, nicotine, and ethanol in the brain reward system could indicate the use of varenicline also for alcohol dependence. Using the in vivo microdialysis method, we investigated the effects of systemic injections of varenicline on the extracellular accumbal dopamine levels in response to a systemic challenge of ethanol, nicotine, or the combination of nicotine and ethanol in the experimental rat. Acute systemic coadministration of varenicline and ethanol counteracted each others' respective enhancing effect on dopamine levels in the nucleus accumbens. However, after 5 days of varenicline pretreatment, acute combined varenicline and ethanol administration raised dopamine levels to the same extent as either drug alone. Furthermore, after varenicline pretreatment an acute injection of varenicline antagonized the dopamine stimulatory effect of acute nicotine as well as that of systemic coadministration of ethanol and nicotine. In contrast, a pronounced additive dopamine increase was observed when nicotine and ethanol were coadministered in vehicle-pretreated rats. The antismoking agent varenicline exhibits properties with respect to its interaction with ethanol and nicotine in the brain reward system that may be beneficial for treating patients with alcohol dependence with (and possibly also without) concomitant nicotine dependence.

Nicotinic acetylcholine receptors in the anterior, but not posterior, ventral tegmental area mediate ethanol-induced elevation of accumbal dopamine levels.

Ethanol-induced elevations of accumbal dopamine levels have been linked to the reinforcing properties of the drug. However, it has not yet been demonstrated where the primary point of action of ethanol is in the mesolimbic dopamine system, and there appear to be conflicting findings depending on methodology (electrophysiology, microdialysis, or intracranial self-administration). We have suggested that ethanol acts in the nucleus accumbens (nAc), where it activates a neuronal loop involving ventral tegmental nicotinic acetylcholine receptors (nAChRs) to elevate dopamine levels in the nAc. Application of ethanol in the nAc results in elevated dopamine levels in the same brain region, whereas administration in the anterior ventral tegmental area (VTA) fails to influence dopamine output. In the present study, we were able to repeat these findings. In addition, application of ethanol in the posterior VTA also failed to influence nAc dopamine levels. Perfusion of the nAChR antagonist mecamylamine in the anterior VTA completely blocked the elevation of accumbal dopamine levels observed after ethanol perfusion in nAc, whereas mecamylamine in the posterior VTA had no effect. To detect a possible influence on phasic dopamine release, the dopamine transporter inhibitor nomifensine was included in the accumbal perfusate. In addition, under these conditions, ethanol in the anterior or posterior VTA failed to influence dopamine release in the nAc. These results support previous suggestions of distinct functions of the anterior and posterior VTA and give further evidence for our hypothesis of a nAc-anterior VTA-nAc neuronal circuitry involved in the dopamine-activating effects of ethanol.

Nicotinic acetylcholine receptors in the ventral tegmental area mediate the dopamine activating and reinforcing properties of ethanol cues.

RATIONALE: Cues associated with alcohol can elicit craving, support drug-seeking and precipitate relapse. OBJECTIVES: We investigated the possible involvement of nicotinic acetylcholine receptors (nAChRs) in the ventral tegmental area (VTA) in the conditioned reinforcing properties of ethanol-associated stimuli in the rat. MATERIALS AND METHODS: First, using in vivo microdialysis, we analyzed the effect of VTA perfusion of the nonselective nAChR antagonist mecamylamine (MEC) or the selective alpha4beta2* nAChR antagonist dihydro-beta-erythroidine (DHbetaE) on the nucleus accumbens (nAc) dopaminergic response to the presentation of an ethanol-associated conditioned stimulus (CS). Second, rats were trained to associate a tone+light CS with the presentation of 10% ethanol and were subsequently tested on the acquisition of a new instrumental response with conditioned reinforcement (CR) after local VTA infusion of MEC, DHbetaE, or alpha-Conotoxin MII (alpha-CtxMII, a selective alpha3beta2* and alpha6* nAChR antagonist). RESULTS: The ethanol-associated CS elevated nAc dopamine, an effect that was blocked by VTA perfusion of MEC but not DHbetaE. Systemic administration of MEC or local VTA infusion of MEC or alpha-CtxMII selectively blocked ethanol-associated CR, whereas systemic DHbetaE had no effect. CONCLUSIONS: We hypothesize a novel mechanism by which alcohol-associated cues promote drug-seeking behavior via activation of dopamine-stimulating alpha-CtxMII-sensitive nAChRs in the VTA. Pharmacological manipulations of selective nAChRs may thus be possible treatment strategies to prevent cue-induced relapse.

Characterization of ethanol-induced dopamine elevation in the rat nucleus accumbens.

Ethanol-induced accumbal dopamine elevations have been linked to ethanol consumption. It is unclear, however, where along the mesolimbic dopamine system this effect is initiated and why the ethanol-induced dopamine elevations are transient, returning to pre-drug baseline before brain and blood ethanol levels decline. Using in vivo microdialysis, Experiment 1 investigated the effect of local ethanol application in the nucleus accumbens, the ventral tegmental area and the nucleus accumbens+the ventral tegmental area, on accumbal dopamine. Experiment 2 examined whether the rapid withdrawal of dopamine response to ethanol involves activation of GABA(A)-receptors, by analyzing the effect of accumbal co-perfusion of picrotoxin and ethanol. In Experiment 1, ethanol perfusion into the ventral tegmental area alone did not affect accumbal dopamine. Ethanol co-perfusion of one of the tested doses into the ventral tegmental+the nucleus accumbens produced higher dopamine levels than ethanol perfusion into the nucleus accumbens alone during 120-160 min following perfusion onset. In Experiment 2, accumbal ethanol perfusion caused a transient increase in nucleus accumbens dopamine. Co-perfusion of ethanol and picrotoxin produced a sustained dopamine elevation. These data support the hypothesis that the primary effect of ethanol on accumbal dopamine is in the nucleus accumbens, but that a secondary effect of nucleus accumbens ethanol perfusion, such as release of acetylcholine in the ventral tegmental area, enables ethanol to act as a nicotinic acetylcholine receptor co-agonist in this area. Moreover, recruitment of GABA(A)-receptor activity appears responsible for the second, declining phase with respect to dopamine levels following ethanol administration.

Ethanol-induced dopamine elevation in the rat--modulatory effects by subchronic treatment with nicotinic drugs.

Chronic nicotine administration is associated with increased ethanol consumption in laboratory animals and in humans. Some smokers report less sedation during acute ethanol intoxication after nicotine administration and the sedative effects from ethanol are mediated by inhibitory GABA(A)-receptors. In a series of in vivo microdialysis experiments we investigated whether subchronic pre-treatment with nicotinic drugs known to enhance ethanol consumption in the rat (nicotine or the peripheral nicotinic antagonist hexamethonium) could modulate the alterations in extracellular dopamine observed in response to administration of ethanol or the sedative GABA(A)-agonist diazepam. In the nucleus accumbens and the dorsal striatum, systemic and/or local ethanol administration resulted in transient increases in extracellular dopamine levels that returned to baseline before the local levels of ethanol started to decline. In hexamethonium pre-treated rats, however, the nucleus accumbens dopamine levels were time-locked to the ethanol levels in the same area after systemic or local ethanol administration. Perfusion of diazepam into the nucleus accumbens produced a significant reduction in nucleus accumbens dopamine in controls. Prior subchronic treatment with nicotine or hexamethonium abolished this effect. The present results suggest that subchronic treatment with the nicotinic acetylcholine receptor antagonist hexamethonium reduces a GABA(A)-R mediated counteraction of the nucleus accumbens dopamine response to ethanol. Additionally, we demonstrate that modulation of nicotinic receptors may reduce the sensitivity of GABA(A) receptors to benzodiazepines. These phenomena may offer a novel explanation to why nicotine and alcohol are often co-abused.

The glycine reuptake inhibitor Org 25935 decreases ethanol intake and preference in male wistar rats.

UNLABELLED: Previous findings from our group indicate that accumbal glycine receptors (GlyRs) are involved in mediating the dopamine (DA) activating effects of ethanol (EtOH), and that administration of glycine locally into the nucleus accumbens (nAc) reduces EtOH consumption in EtOH high-preferring rats. AIMS: The present study examines the influence of a systemically administered glycine reuptake inhibitor, Org 25935, on EtOH preference and intake, in male Wistar rats with an EtOH preference >60% (during continuous access to a bottle of EtOH, 6% v/v, and a bottle of water), called EP>60 rats, as well as in animals with an EtOH preference <60%, called EP<60 rats. Org 25935 is an inhibitor of the glycine transporter 1 (GlyT1) protein with negligible action on the glycine transporter 2 (GlyT2) protein. METHODS: Both EP>60 and EP<60 rats were limited to drink 2.5 h/day. Org 25935 or vehicle was administered intraperitoneally approximately 40 min before the rats were presented to a choice of drinking EtOH or water. RESULTS: Org 25935 decreased EtOH intake and EtOH preference, as compared with vehicle, whereas water intake was unaffected. This effect was dose-dependent, developed gradually and was sustained for up to 40 days, also after introduction of an alcohol deprivation period. CONCLUSION: It is suggested that Org 25935, and possibly also other GlyT1 inhibitors, can represent a new pharmacological treatment principle for alcohol dependence or abuse.

Investigation of central versus peripheral effects of estradiol in ovariectomized mice.

It is generally believed that estrogens exert their bone sparing effects directly on the cells within the bone compartment. The aim of the present study was to investigate if central mechanisms might be involved in the bone sparing effect of estrogens. The dose-response of central (i.c.v) 17beta-estradiol (E2) administration was compared with that of peripheral (s.c.) administration in ovariectomized (ovx) mice. The dose-response curves for central and peripheral E2 administration did not differ for any of the studied estrogen-responsive tissues, indicating that these effects were mainly peripheral. In addition, ovx mice were treated with E2 and/or the peripheral estrogen receptor antagonist ICI 182,780. ICI 182,780 attenuated most of the estrogenic response regarding uterus weight, retroperitoneal fat weight, cortical BMC and trabecular bone mineral content (P<0.05). These findings support the notion that the primary target tissue that mediates the effect of E2 on bone is peripheral and not central.

Involvement of accumbal glycine receptors in the regulation of voluntary ethanol intake in the rat.

BACKGROUND: Extracellular dopamine (DA) levels in the nucleus accumbens (nAc) increase after ethanol (EtOH) administration in the rat, a response that may be involved in the positive reinforcing effects of EtOH. The mechanisms underlying this DA activation and how they relate to EtOH reinforcement remain to be elucidated, but recent data indicate that glycine receptors (GlyRs) in the nAc may be involved. Here this hypothesis was further challenged by examining the influence of bilateral accumbal application of glycine (a GlyR agonist), strychnine (a GlyR competitive antagonist), or Ringer on EtOH intake and preference, as well as on the concomitant DA output in the nAc, in EtOH high-preferring male Wistar rats. METHODS: EtOH high-preferring male Wistar rats [EtOH preference >60% during continuous access to a bottle of EtOH (6% v/v) and a bottle of water] were limited to drink 1 hr/day (limited access drinking). Thereafter, the animals were equipped bilaterally with microdialysis probes aimed at the mAc, and were subjected to in vivo microdialysis (coupled to high-pressure liquid chromatography with electrochemical detection) and reversed microdialysis (for drug application) during two experimental days (balanced study), during which the animals were allowed a choice between EtOH and water. RESULTS: The EtOH consumption in rats that were perfused with Ringer in the nAc was approximately 0.9 g/kg/hr and associated with a significant increase in extracellular accumbal DA levels. In a subpopulation of rats, bilateral accumbal glycine (100 microM) perfusion produced a significant increase in accumbal DA output and a decrease in EtOH preference and intake. In these glycine responders, the EtOH consumed (approximately 0.7 g/kg/hr) did not produce a further increase of DA levels. In other rats, bilateral glycine perfusion did not change the accumbal DA output, and voluntary EtOH intake was not altered. In these glycine nonresponders, EtOH tended to increase accumbal DA levels. Bilateral accumbal strychnine (20 microM) perfusion significantly decreased DA output in the nAc, and the DA levels remained decreased despite a statistically significant increase of EtOH intake. Finally, the increase in accumbal DA levels observed after EtOH consumption in Ringer-treated rats was significantly larger in glycine responders than in glycine nonresponders. CONCLUSIONS: The present findings suggest that glycine and strychnine alter extracellular DA levels in the nAc, probably via GlyR stimulation and blockade, respectively, and concomitantly glycine and strychnine reciprocally alter also EtOH consumption in EtOH high-preferring male Wistar rats. The possibility of developing selective GlyR agonists and/or antagonists should be explored. Such agents could prove of value in the treatment of alcoholism.

Ethanol elevates accumbal dopamine levels via indirect activation of ventral tegmental nicotinic acetylcholine receptors.

It was previously demonstrated that the central nicotinic acetylcholine receptor antagonist mecamylamine perfused in the ventral tegmental area (VTA) counteracts the elevation of extracellular dopamine levels in the nucleus accumbens after systemic ethanol, as measured by in vivo microdialysis. In the present study we investigated the effect of different concentrations of ethanol perfused locally in the VTA or in the nucleus accumbens on extracellular accumbal dopamine levels. Ethanol (10-1000 mM) perfused in the VTA did not influence dopamine output in the nucleus accumbens. However, ethanol (300 mM) perfused in the nucleus accumbens increased accumbal dopamine levels to approximately the same extent (30%) as observed after systemic ethanol, whereas ethanol (1000 mM) decreased the dopamine output by approximately 50%. Next, the hypothesis that endogenous acetylcholine is required for the increased accumbal dopamine levels after ethanol was challenged. It was shown that in animals pre-treated with vesamicol, a potent inhibitor of vesicular acetylcholine storage, ethanol (300 mM) in the nucleus accumbens failed to elevate extracellular accumbal dopamine levels. Similarly, in animals perfused with mecamylamine in the VTA, but not in the nucleus accumbens, ethanol in the nucleus accumbens (300 mM) failed to increase accumbal dopamine levels. However, whereas dihydro-beta-erythroidine (antagonist for the nicotinic receptor subtype alpha4beta2) perfused in the VTA prevented the increase in accumbal dopamine after systemic nicotine, the antagonist was unable to prevent the dopamine elevating effects of ethanol. Finally, to investigate whether mecamylamine exerts its antagonizing effect of ethanol induced accumbal dopamine levels through an interaction with the NMDA receptor MK-801, the effects of the prototypic NMDA receptor antagonist were examined and compared to those of mecamylamine. After perfusion in the VTA, MK-801 enhanced accumbal dopamine levels by itself but did not antagonize the enhancing effect of ethanol. The present set of experiments indicate that the mesolimbic dopamine activating effects of ethanol may be due to an indirect rather than direct activation of ventral tegmental nicotinic acetylcholine receptors of a subtype composition different from the alpha4beta2. Furthermore, it is argued that the primary site of action of ethanol in its accumbal dopamine elevating effect may be located to the nucleus accumbens or nearby regions.