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Previous work, using membrane receptor binding techniques, demonstrated an increase in hippocampal MK-801 binding sites in mice after chronic ethanol ingestion. The current studies, using quantitative autoradiography, demonstrate that chronic ethanol ingestion also produces increases in MK-801 binding in cerebral cortex, striatum and thalamus, as well as in hippocampus. The persistence of changes in MK-801 binding paralleled the time-course for ethanol withdrawal seizure susceptibility. These results support the hypothesis that an increase in the number of NMDA receptor/channel complexes in hippocampus, and possibly other brain regions, plays a role in the generation or expression of ethanol withdrawal seizures.

AbstractObjective: The marked increase in the prevalence of obesity in the United States has recently been attributed to the increased fructose consumption. To determine if and how fructose might promote obesity in an animal model, we measured body composition, energy intake, energy expenditure, substrate oxidation, and several endocrine parameters related to energy homeostasis in mice consuming fructose.Research Methods and Procedures: We compared the effects of ad libitum access to fructose (15% solution in water), sucrose (10%, popular soft drink), and artificial sweetener (0% calories, popular diet soft drink) on adipogenesis and energy metabolism in mice.Results: Exposure to fructose water increased adiposity, whereas increased fat mass after consumption of soft drinks or diet soft drinks did not reach statistical significance (n = 9 each group). Total intake of energy was unaltered, because mice proportionally reduced their caloric intake from chow. There was a trend toward reduced energy expenditure and increased respiratory quotient, albeit not significant, in the fructose group. Furthermore, fructose produced a hepatic lipid accumulation with a characteristic pericentral pattern.Discussion: These data are compatible with the conclusion that a high intake of fructose selectively enhances adipogenesis, possibly through a shift of substrate use to lipogenesis.

This study is divided into two parts; each designed to answer a separate but related question: Which brain regions are activated in humans by the rewarding properties of ethanol administration? Is it possible to demonstrate a conditioned response to a stimulus paired with rising blood alcohol concentrations (BAC) in humans and can this response be observed in the brain using functional magnetic resonance images (fMRI) techniques? Part 1. In order to determine which brain regions are activated by the rewarding properties of ethanol administration, we propose to use Blood Oxygenation Level Dependent (BOLD) fMRI techniques to test the hypothesis that during the time of rising and peak BAC, mesolimbic, mesocortical, and nigrostriatal dopamine (DA) terminal areas of the brain will show significant increases in cerebral blood flow. Healthy, non-alcoholic subjects will be given intravenous (IV) ethanol or placebo infusions on separate days. The infusions will have three phases. On each day, during the first phase a saline infusion will be used to measure basal brain blood flow. The second phase will be an ethanol infusion delivered at rates calculated to produce a BAC of 0.08 plus or minus 0.005 g/dl at 10 minutes. The rate of the infusion for the next 10 minutes (third phase) will be calculated to maintain BAC at the target level of 0.08 plus or minus 0.005 g/dl for the duration of the infusion. On the placebo day, subjects will receive a saline infusion at the same set of rates for phases two and three as used during their ethanol infusion. Continuous multi-slice fMRI data will be collected during each infusion. Part 2. In order to investigate conditioned response to ethanol, three groups of healthy, non-alcoholic subjects will be given a series of IV infusions on separate days. The experimental group will receive ethanol infusion paired with a conditioned stimulus (CS) which will be presented while the BAC is rising. One control group (I) of healthy, non-alcoholic subjects will also be given a series of intravenous ethanol infusions on separate days, but these infusions will not be paired with a CS. The other control group (II) will be given only saline infusions during the CS presentation. After three training sessions, all three groups will undergo an fMRI scan during which the CS will be paired with saline infusion. This will allow the response to the CS alone to be observed. After 10 minutes of CS presentation, the ethanol infusion will begin and continue for another 15 minutes. Conditioned response (CR) will be demonstrated if the experimental group shows greater increase in BOLD signal than the control groups in motivation areas such as mesolimbic, mesocortical, and nigrostriatal dopamine (DA) terminal areas of the brain in response to the CS while they receive the saline infusion. Control group II will also undergo an fMRI scan and will be given saline infusion followed by ethanol infusion during their last 15 minutes in the scanner to control for the non-specific effects of repeated infusions & scans on BOLD response to ethanol. If we are able to produce a CR in brain regions associated with motivation, it may be possible to use this CR as an experimental model for human alcohol craving. This study is designed to answer four questions: 1. Which brain regions are activated in humans by the rewarding properties of ethanol administration? 2. How does ethanol administration affect the brain response to visual cues known to evoke positive or negative emotion? 3. Do individuals who regularly drink in ethanol in large amounts (heavy drinkers) differ from individuals who do not regularly drink large amounts of ethanol (social drinkers) in how ethanol affects brain function? 4. Does ethanol administration affect the brain regions activated in a risk-taking task in social drinkers and heavy drinkers? In order to determine which brain regions are activated by the rewarding properties of ethanol administration, we propose to use Blood Oxygenation Level Dependent (BOLD) fMRI techniques to test the hypothesis that during the time of rising and peak BAC, mesolimbic, mesocortical, and nigrostriatal dopamine (DA) terminal areas of the brain will show significant increases in cerebral blood flow. Healthy, subjects who are not seeking treatment for an alcohol use disorder will be given intravenous (IV) ethanol or placebo infusions on separate days. An ethanol infusion will delivered at rates calculated to produce a BAC of 0.08 plus or minus. An ethanol infusion will delivered at rates calculated to produce a BAC of 0.08 plus or minus 0.005 g/dl at 15 minutes. Then the rate of the infusion will be adjusted so that for the next 30 minutes (second phase) BAC will be maintained at the target level of 0.08 0.005 g/dl. On the placebo day, subjects will receive a saline infusion at the same set of rates as used during their ethanol infusion. Continuous multi-slice fMRI data will be collected during each infusion. During each infusion, BOLD response to visual stimuli designed to evoke emotion will also be examined. In addition, we will compare the BOLD response of healthy social drinkers to that of healthy heavy drinkers. We will also compare the BOLD response elicited by risk-taking during the ethanol infusion to that during the placebo infusion in both social and heavy drinkers.

Background:  A low level of response (i.e., a low LR) to alcohol is a genetically influenced phenotype that predicts later alcoholism. While the low LR reflects, at least in part, a low brain response to alcohol, the physiological underpinnings of the low LR have only recently been addressed. Methods:  Forty‐nine drinking but not yet alcoholic matched pairs of 18‐ to 25‐year‐old subjects (N = 98; 53% women) with low and high LRs as established in separate alcohol challenges were evaluated in 2 event‐related functional magnetic resonance imaging (fMRI) sessions (placebo and approximately 0.7 ml/kg of alcohol) while performing a validated stop signal task. The high and low LR groups had identical blood alcohol levels during the alcohol session. Results:  Significant high versus low LR group and LR group × condition effects were observed in blood oxygen level–dependent (BOLD) signal during error and inhibitory processing, despite similar LR group performance on the task. In most clusters with significant (corrected p < 0.05, clusters > 1,344 μl) LR group × alcohol/placebo condition interactions, the low LR group demonstrated relatively less, whereas the high LR group demonstrated more, error and inhibition‐related activation after alcohol compared with placebo. Conclusions:  This is one of the first fMRI studies to demonstrate significant differences between healthy groups with different risks of a future life‐threatening disorder. The results may suggest a brain mechanism that contributes to how a low LR might enhance the risk of future heavy drinking and alcohol dependence.

Alcoholism is associated with a higher incidence of smoking. In addition to the stimulatory effects of both ethanol and nicotine on the mesolimbic reward pathway, nicotine's ability to counteract some of the adverse effects of ethanol (e.g. ataxia) may be a powerful incentive for alcohol consumers to increase their tobacco (nicotine) intake. The cerebellum is believed to play an important role in ethanol-induced ataxia. In this study, we sought to test the hypothesis that nicotine would protect against toxic effects of ethanol in primary cultures of cerebellar granule cells. Moreover, it was postulated that the effects of nicotine would be mediated through nicotinic receptors. Primary cultures of cerebellar granule cells were prepared from 20-day embryos obtained from timed-pregnant Sprague Dawley rats. Cells were cultured for 10 days and were then exposed for 3 days to various concentrations of ethanol with and without pretreatment with nicotine and nicotinic antagonists. Cellular toxicity was evaluated by measuring the lactate dehydrogenase level. Administration of ethanol (10-100 mM) resulted in a dose-dependent toxicity. Pretreatment with nicotine 1-20 micro M resulted in a dose-dependent protection against ethanol-induced toxicity. The effects of nicotine were blocked by pretreatment with nicotinic antagonists such as mecamylamine 1-20 micro M, dihydro-beta-erythroidine 1.0 nM-1.0 micro M and methyllycaconitine 5 nM-5 micro M in a dose-dependent manner. Thus, ethanol-induced cytotoxicity in primary cultures of cerebellar granule cells is blocked by pretreatment with nicotine. The effects of nicotine, in turn, may be blocked by nicotinic antagonists, implicating both high and low affinity nicotinic receptors in mediating the actions of nicotine. The exact mechanism of ethanol-induced toxicity and/or neuroprotection through activation of nicotinic receptors in this paradigm remains to be elucidated. The neuroprotective effect of nicotine against ethanol-induced toxicity in cerebellar neurons may be a contributing factor to the high incidence of smoking among alcoholics.

AbstractAlthough the kappa-opioid receptor (KOR) and its endogenous ligand, dynorphin, are believed to be involved in ethanol drinking, evidence on the direction of their effects has been mixed. The nucleus accumbens (NAc) shell densely expresses KORs, but previous studies have not found KOR activation to influence ethanol drinking. Using microinjections into the NAc shell of male and female Long-Evans rats that drank under the intermittent-access procedure, we found that the KOR agonist, U50,488, had no effect on ethanol drinking when injected into the middle NAc shell, but that it promoted intake in males and high-drinking females in the caudal NAc shell and high-drinking females in the rostral shell, and decreased intake in males and low-drinking females in the rostral shell. Conversely, injection of the KOR antagonist, nor-binaltorphimine, stimulated ethanol drinking in low-drinking females when injected into the rostral NAc shell and decreased drinking in high-drinking females when injected into the caudal NAc shell. These effects of KOR activity were substance-specific, as U50,488 did not affect sucrose intake. Using quantitative real-time PCR, we found that baseline gene expression of the KOR was higher in the rostral compared to caudal NAc shell, but that this was upregulated in the rostral shell with a history of ethanol drinking. Our findings have important clinical implications, demonstrating that KOR stimulation in the NAc shell can affect ethanol drinking, but that this depends on NAc subregion, subject sex, and ethanol intake level, and suggesting that this may be due to differences in KOR expression.

C57BL/6J (C57) and DBA/2J (DBA) mice respond differently to drugs that affect dopamine systems, including alcohol. The current study compared effects of D1 and D2 receptor agonists and antagonists, and the interaction between D1/D2 antagonists and alcohol, on intracranial self-stimulation in male C57 and DBA mice to determine the role of dopamine receptors in the effects of alcohol on brain stimulation reward (BSR). In the initial strain comparison, dose effects on BSR thresholds and maximum operant response rates were determined for the D1 receptor agonist SKF-82958 (±-6-chloro-7,8-dihydroxy-3-allyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine; 0.1–0.56 mg/kg) and antagonist SCH 23390 (+-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepinehydrochloride; 0.003–0.056 mg/kg), and the D2 receptor agonist quinpirole (0.1–3.0 mg/kg) and antagonist raclopride (0.01–0.56 mg/kg). For the alcohol interaction, SCH 23390 (0.003 mg/kg) or raclopride (0.03 mg/kg) was given before alcohol (0.6–2.4 g/kg p.o.). D1 antagonism dose-dependently elevated and SKF-82958 dose-dependently lowered BSR threshold in both strains; DBA mice were more sensitive to SKF-82958 effects. D2 antagonism dose-dependently elevated BSR threshold only in C57 mice. Low doses of quinpirole elevated BSR threshold equally in both strains, whereas higher doses of quinpirole lowered BSR threshold only in C57 mice. SCH 23390, but not raclopride, prevented lowering of BSR threshold by alcohol in DBA mice. Conversely, raclopride, but not SCH 23390, prevented alcohol potentiation of BSR in C57 mice. These results extend C57 and DBA strain differences to D1/D2 sensitivity of BSR, and suggest differential involvement of D1 and D2 receptors in the acute rewarding effects of alcohol in these two mouse strains.

Rostromedial tegmental nucleus (RMTg) GABA neurons exert a primary inhibitory drive onto midbrain dopamine neurons and are excited by a variety of aversive stimuli. There is, however, little evidence that the RMTg-ventral tegmental area (VTA)-nucleus accumbens shell (Acb) circuit plays a role in the aversive consequences of alcohol withdrawal. This study was performed in adult male Long-Evans rats at 48-h withdrawal from chronic alcohol drinking in the intermittent schedule. These rats displayed clear anhedonia and depression-like behaviors, as measured with the sucrose preference, and forced swimming tests. These aberrant behaviors were accompanied by a substantial increase in cFos expression in the VTA-projecting RMTg neurons, identified by a combination of immunohistochemistry and retrograde-tracing techniques. Pharmacological or chemogenetic inhibition of RMTg neurons mitigated the anhedonia and depression-like behaviors. Ex vivo electrophysiological data showed that chemogenetic inactivation of RMTg neurons reduced GABA release and accelerated spontaneous firings of VTA dopamine neurons. Finally, using a functional hemispheric disconnection procedure, we demonstrated that inhibition of unilateral RMTg, when combined with activation of D1 and D2 dopamine receptors in the contralateral (but not ipsilateral) Acb, mitigated the anhedonia and depression-like behaviors in alcohol-withdrawal rats. These data show that the integrity in the RMTg-VTA-Acb pathway in a single hemisphere is sufficient to elicit depression-like behavior during ethanol-withdrawal. Overall, the present results reveal that the RMTg-VTA-Acb pathway plays a crucial role in the depression-like behavior in animals undergoing alcohol withdrawal, further advocating the RMTg as a potential therapeutic target for alcoholism.