Effect of acute alcohol intoxication on the opioid system in humans

Alterations in circadian rhythms following alcohol use: A systematic review

Increasing evidence suggest a bidirectional link between disrupted circadian rhythms and alcohol use disorders (AUD). A better understanding of these alcohol-induced changes in circadian rhythms will likely provide important therapeutic solutions. We conducted a systematic review based on the PubMed database examining biological rhythms in all stages of alcohol use: acute alcohol consumption, AUD, alcohol withdrawal, and abstinence. Different changes in circadian rhythms have been observed after a single acute alcohol intake, but also during AUD and alcohol withdrawal. Following a single acute alcohol intake, changes in biological rhythms are dose-dependent, reflected in the melatonin and cortisol secretions, and the core body temperature (CBT) rhythms. These alterations normalize the next morning and appear mostly for acute alcohol intake higher than 0.5 g/kg. These alterations are more severe during AUD and persist over time. In addition, interestingly, opposite patterns of the melatonin physiological ratio between diurnal and nocturnal secretion (N/D ratio < 1) have been observed during AUD and appear to be a marker of chronic daily use. During alcohol withdrawal, circadian rhythms desynchronization correlates with the severity of alcohol withdrawal symptoms and withdrawal complications such as delirium tremens. During abstinence a resynchronization of circadian rhythms of cortisol and CBT appears in most patients about 1 month after alcohol withdrawal. Disruption of melatonin circadian rhythms can persist after 3-12 weeks of abstinence. The circadian genetic vulnerability associated with biological rhythms alterations in alcohol use disorders increases the risk of relapses. Circadian-based interventions could play a critical role in preventing and treating AUD.

The opioid receptors as targets for drug abuse medication

The endogenous opioid system is largely expressed in the brain, and both endogenous opioid peptides and receptors are present in areas associated with reward and motivation. It is well known that this endogenous system plays a key role in many aspects of addictive behaviours. The present review summarizes the modifications of the opioid system induced by chronic treatment with drugs of abuse reported in preclinical and clinical studies, as well as the action of opioid antagonists and agonists on the reinforcing effects of drugs of abuse, with therapeutic perspectives. We have focused on the effects of chronic psychostimulants, alcohol and nicotine exposure. Taken together, the changes in both opioid peptides and opioid receptors in different brain structures following acute or chronic exposure to these drugs of abuse clearly identify the opioid system as a potential target for the development of effective pharmacotherapy for the treatment of addiction and the prevention of relapse.

Alcohol intoxication among Dutch adolescents: acute medical complications in the years 2000-2010

OBJECTIVE

To investigate acute medical complications of alcohol intoxication among adolescents presenting to Reinier de Graaf Hospital, a major nonacademic hospital in Delft, the Netherlands.

METHODS

The frequency of reduced consciousness, hypothermia, electrolyte disturbances, hypoglycemia, and acidosis along with alcohol intoxication was retrospectively studied in the medical records of patients aged 11 to 17 years admitted between January 1, 2000, and April 30, 2010.

RESULTS

Reduced consciousness (45%) and hypothermia (43.1%) were the most common clinical findings. More boys than girls experienced hypothermia (P = .028), probably because of the higher blood alcohol concentration level ( P = .026), which was associated with lower temperature (Pearson's r = -.37; P < .001). The most frequent electrolyte disturbance was hyperchloremia (31.1%), followed by low bicarbonate (22%), hypokalemia (11.9%), and hypernatremia (7.7%). Strikingly, none of the patients in this study suffered hypoglycemia. On the contrary, 13.6% of the patients were slightly hyperglycemic. Mild acidosis, both metabolic and respiratory, was observed among 28.8% of the patients, although the metabolic component predominated.

CONCLUSIONS

Acute medical complications because of alcohol intoxication appeared to be mild, and most remarkably none of the patients experienced hypoglycemia.

The effect of a low dose of alcohol on allopregnanolone serum concentrations across the menstrual cycle in women with severe premenstrual syndrome and controls

BACKGROUND

Neurosteroids have been proposed to play an important role in the interaction between alcohol and GABA(A) receptors and for the symptomatology of premenstrual dysphoric disorder (PMDD). The primary aim of this study was to investigate possible alcohol-induced changes in allopregnanolone serum concentrations across different menstrual cycle phases in women with severe premenstrual syndrome (PMS) and controls.

METHODS

The allopregnanolone and cortisol responses to a low-dose of alcohol were evaluated in 14 women with and 12 women without severe premenstrual syndrome in the follicular and late luteal phases. The effect of a 30-min intravenous alcohol infusion (0.2 g/kg) on allopregnanolone and cortisol serum concentrations was compared to placebo, and compared between cycle phases and groups. Blood samples for measuring allopregnanolone were taken at baseline 25, 55, and 75 min after the start of the alcohol infusion.

RESULTS

In the late luteal phase, the alcohol infusion decreased allopregnanolone levels, compared to baseline levels as well as to placebo. The difference in allopregnanolone levels between alcohol and placebo was evident 25 min (P < 0.01), 55 min (P < 0.01), and 75 min (P < 0.05) after start of the infusion. There was no change in allopregnanolone levels during the alcohol infusion in the follicular phase. Also, no difference in alcohol-induced allopregnanolone response between PMS patients and control subjects was detected. Cortisol levels declined during both the placebo and alcohol infusion, but did not differ with respect to which infusion had been given.

CONCLUSION

During the late luteal phase, independent of PMS diagnosis, the low-dose alcohol infusion resulted in decreasing peripheral allopregnanolone levels.

Plasma concentrations of beta-endorphin in smokers who consume different numbers of cigarettes per day

The harmful effects of smoking on health have been widely documented, although it is as yet unclear whether tobacco dependence is only psychological in nature, or both psychological and physical. We studied plasma concentrations of beta-endorphin, cortisol, and adrenocorticotropic hormone (ACTH) in healthy persons who consumed different numbers of cigarettes per day, and compared the findings with those in a control group of nonsmokers. Beta-endorphin levels were significantly higher than in controls only in persons who smoked fewer than 10 cigarettes per day. Cortisol levels were significantly higher in smokers who consumed more than 20 cigarettes per day. There were no significant differences between any of the groups in plasma ACTH concentrations.

The role of opioid-dopamine interactions in the induction and maintenance of ethanol consumption

1. Alcohol is one of the most widely used recreational drugs, but also one of the most widely abused, causing vast economic, social and personal damage. 2. Several animal models are available to study the reinforcing mechanisms that are the basis of the abuse liability of ethanol. Innate differences in opioid or dopamine neurotransmission may enhance the abuse liability of ethanol, as indicated by animal and human studies. 3. Opioid antagonists have been shown to be effective, both experimentally and clinically, in decreasing ethanol consumption, presumably since ethanol induces the release of endogenous opioid peptides in vivo. However, ethanol may also stimulate the formation of opiate-like compounds, which could interact with opioid (or dopamine) receptors. Ethanol may cause changes in neurotransmission mediated via opioid receptors that determines whether alcohol abuse is more or less likely. 4. Ethanol appears to facilitate dopamine release by increasing opioidergic activity, disinhibiting dopaminergic neurons (by inhibition of GABAergic neurotransmission) via mu-opioid receptors in the ventral tegmental area (VTA) and delta-opioid receptors in the nucleus accumbens (NAcc). The effects of ethanol would be antagonised by presynaptic kappa-opioid receptors present on dopaminergic terminals in the NAcc. 5. Mesolimbic dopamine release induced by ethanol consumption seems to indicate ethanol-related stimuli are important, focussing attention on and enabling learning of the stimuli. However, studies indicate that there are redundant pathways, and neural pathways 'downstream' of the mesolimbic dopamine system, which also enable the reinforcing properties of ethanol to be mediated.

Brain beta-endorphin immunoreactivity as an index of cocaine and combined cocaine-ethanol toxicities

The present study examines alterations in the cytoplasmic immunoreactivity of brain beta-endorphin, an endogenous opioid peptide regarded as the mediator of both euphoria and antinociceptive systems, in relation to toxicities due to cocaine and combined cocaine-ethanol. Beta-endorphin-immunoreactive cells were visualized and counted in adjacent sections from male rat brains at the level of the arcuate nucleus. In this region, cytoplasmic beta-endorphin immunoreactivity is prevalent. An intraperitoneal injection of cocaine (75 or 15 mg/kg) was given 15 min after an intraperitoneal injection of 3 g/kg ethanol or vehicle. With a fatally toxic dose (75 mg/kg) of cocaine, the number of neurons exhibiting cytoplasmic beta-endorphin immunoreactivity (immunoreactive nerve cells) was significantly increased immediately after the drug administration. Ethanol further enhanced the effects of both 15 and 75 mg/kg of cocaine. When the immunoreactivity was visually estimated by computer imaging analysis, lightly stained, weakly immunoreactive cells with photographic light absorption values greater than 50% were enhanced in the cocaine-ethanol groups compared to the cocaine only groups. Fatal toxicities were only observed in the groups treated with the high cocaine doses (75 mg/kg), with or without ethanol. In these groups, the number of strongly immunoreactive cells had increased significantly compared to the other groups. In the group treated with the high cocaine dose (75 mg/kg) plus ethanol, an increased frequency of late deaths that occurred over 1 h after the drug administration was observed, together with a decreased severity of cocaine-induced seizures and an early enhancement of weakly immunoreactive cells. Unlike the strongly immunoreactive cells, the weakly immunoreactive cells appeared to be continuously enhanced, based on an experiment examining beta-endorphin immunoreactivity at 24 h after an injection of 50 mg/kg cocaine.

Endogenous opiates: 1995

This article is the eighteenth installment of our annual review of research concerning the opiate system. It includes articles published during 1995 reporting the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects. The specific topics covered this year include stress: tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.