Soporific action of ethanol in mice: possible role of biogenic amines

Neurological correlates of brain reward circuitry linked to opioid use disorder (OUD): Do homo sapiens acquire or have a reward deficiency syndrome?

The extant literature confirms that an array of polymorphic genes related to- neurotransmitters and second messengers govern the net release of dopamine in the Nucleus Accumbens (NAc) in the mesolimbic region of the brain. They are linked predominantly to motivation, anti-stress, incentive salience (wanting), and wellbeing. Notably, in 2000 the Nobel Prize was awarded to Carlsson, Greengard, and Kandel for their work on the molecular and cellular function of dopaminergic activity at neurons. This historical psychopharmacological work involved neurotransmission of serotonin, endorphins, glutamate, and dopamine, and the seminal work of Blum, Gold, Volkow, Nestler, and others related to neurotransmitter function and related behaviors. Currently, Americans are facing their second and worst opioid epidemic, prescribed opioids, and easy access drive this epidemic of overdoses, and opioid use disorders (OUDs). Presently the clinical consensus is to treat OUD, as if it were an opioid deficiency syndrome, with long-term to life-long opioid substitution therapy. Opioid agonist administration is seen as necessary to replace missing opioids, treat OUD, and prevent overdoses, like insulin is used to treat diabetes. Treatment of OUD and addiction, in general, is similar to the endocrinopathy conceptualization in that it views opioid agonist MATs as an essential core to therapy. Is this approach logical? Other than as harm reduction, is using opioids to treat OUD therapeutic or harmful in the long term? This historical Trieste provides a molecular framework to understand the current underpinnings of endorphinergic/dopaminergic mechanisms related to opioid deficiency syndrome and generalized reward processing depletion. WC 249.

Declinol, a Complex Containing Kudzu, Bitter Herbs (Gentian, Tangerine Peel) and Bupleurum, Significantly Reduced Alcohol Use Disorders Identification Test (AUDIT) Scores in Moderate to Heavy Drinkers: A Pilot Study

It is well established that inherited human aldehyde dehydrogenase 2 (ALDH-2) deficiency reduces the risk for alcoholism. Kudzu plants and extracts have been used for 1,000 years in traditional Chinese medicine to treat alcoholism. Kudzu contains daidzin, which inhibits ALDH-2 and suppresses heavy drinking in rodents. Decreased drinking due to ALDH-2 inhibition is attributed to aversive properties of acetaldehyde accumulated during alcohol consumption. However not all of the anti-alcohol properties of diadzin are due to inhibition of ALDH-2. This is in agreement with our earlier work showing significant interaction effects of both pyrozole (ALDH-2 inhibitor) and methyl-pyrozole (non-inhibitor) and ethanol's depressant effects. Moreover, it has been suggested that selective ALDH 2 inhibitors reduce craving for alcohol by increasing dopamine in the nucleus accumbens (NAc). In addition there is significant evidence related to the role of the genetics of bitter receptors (TAS2R) and its stimulation as an aversive mechanism against alcohol intake. The inclusion of bitters such as Gentian & Tangerine Peel in Declinol provides stimulation of gut TAS2R receptors which is potentially synergistic with the effects of Kudzu. Finally the addition of Radix Bupleuri in the Declinol formula may have some protective benefits not only in terms of ethanol induced liver toxicity but neurochemical actions involving endorphins, dopamine and epinephrine. With this information as a rationale, we report herein that this combination significantly reduced Alcohol Use Disorders Identification Test (AUDIT) scores administered to ten heavy drinkers (M=8, F=2; 43.2 ± 14.6 years) attending a recovery program. Specifically, from the pre-post comparison of the AUD scores, it was found that the score of every participant decreased after the intervention which ranged from 1 to 31. The decrease in the scores was found to be statistically significant with the p-value of 0.00298 (two-sided paired test; p-value = 0.00149 for one-sided test). Albeit this being a small pilot, we are encouraged about these significant results, and caution any interpretation until larger controlled studies are executed.

The effect of convulsions on the rectification of central nervous system disorders in epileptic mice

Abnormal behavior in epileptic mice (El mice) may be rectified after convulsive seizures. This mechanism was investigated behaviorally through measurements of ethanol-induced sleeping time and locomotor activity, as well as immunohistochemically using a microphotometry system. Decreased ethanol-induced sleeping time and increased ethanol-dependent locomotor activity in El mice as compared to ddY mice (the mother strain of El mice) were rectified by convulsions as well as the intraventricular (IVT) administration of CaCl2, dopamine, or serotonin. Also, the lower dopamine levels in the neostriatum and nucleus accumbens septi in El mice as compared to ddY mice were improved by convulsions as well as the IVT administration of CaCl2. We have previously observed that a lower level of serum calcium in El mice causes a decrease in central biogenic amine synthesis through a calmodulin-dependent system. This may increase the susceptibility to epileptic convulsions and induce abnormal behavior. Combining the present results with our previous observations, we suggest that the convulsions in El mice will be induced when the balance of physiological functions is lost, as may be seen when the biogenic amine syntheses are decreased. The serum calcium level in El mice is increased by convulsions, and an elevated serum calcium level enhances brain biogenic amine synthesis through a calmodulin-dependent system. Subsequently, biogenic amines rectify physiological disorders in El mice.

The relationship between metal ion levels and biogenic amine levels in epileptic mice

The metabolism of various metal ions and biogenic amines in El mice, an inbred mutant strain susceptible to epilepsy, was investigated as a possible model for seizure mechanism. Serum Na, P, Ca, Mg, Fe and Zn levels in El mice were lower than those in ddY mice, the mother strain of El mice. Conversely, bone Ca, P, Na, Mg and Zn levels in El mice were higher than those in ddY mice. The results obtained by chemical analysis are consistent with radiographic observations. Possible mechanisms for the lower serum metal ion levels seen in El mice include a decrease in availability of these ions from bone. The dopamine (DA) level in El mouse brain was 15% lower than in ddY mice but could be raised by intraventricular administration of CaCl2. This result was supported a decreased ethanol-induced sleeping time in El as compared to ddY mice, with 'normalization' occurring after intraventricular administration of Da or CaCl2. The biogenic amine levels disorder in El mice is discussed on the basis of our pharmacological observation that biogenic amine synthesis is regulated by divalent cations via a calmodulin-dependent system. Our results suggest that the disorders of metal ion metabolism could be a mechanism for epileptic convulsions in El mice.

The ability of divalent cations to enhance ethanol-induced sleeping time

This investigation was carried out to determine if prolongation of ethanol-induced sleep by divalent cations is mediated by calmodulin (CaM) and biogenic amine. The effects of CaM antagonist, W-7:[N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide], serotonin (5-HT) synthesizing enzyme inhibitor, p-chlorophenylalanine (PCPA), and catecholamine synthesizing enzyme inhibitor, alpha-methyltyrosine (alpha MPT) on ethanol-induced sleeping time enhanced by divalent cations were studied in ddY male mice. The ethanol-induced sleeping time was increased by 70, 200, 180, 70, and 45% by intraventricular (IVT) injection of CaCl2 (10 mumol/kg), MnCl2 (15 mumol/kg), ZnCl2 (2.5 mumol/kg), CdCl2 (1 mumol/kg), and HgCl2 (1 mumol/kg), respectively, compared to the saline group. On the other hand, when mice were treated IVT with W-7 and their divalent cation, the sleeping time induced by ethanol was decreased compared to that of the cation without W-7 treated mice. Also, when mice were injected simultaneously with either PCPA or alpha MPT and CaCl2, ZnCl2, CdCl2, or HgCl2, the ethanol-induced sleeping time was less compared to those given saline together with their cation, respectively. These results would suggest a probable mechanism in which Ca++, Zn++, Cd++, and Hg++ prolong ethanol-induced sleeping time by activating biogenic amine synthesizing enzymes through cerebral CaM and CaM-dependent protein kinase.

Effect of calmodulin antagonists on calcium and ethanol-induced sleeping time in mice

This investigation was carried out to determine if calcium prolongation of ethanol-induced sleep is mediated by calmodulin and a calmodulin-dependent protein kinase. The duration of ethanol-induced sleeping time in ddY male mice was measured following the administration of CaCl2 (20, 40, 80 and 200 mumol/kg, intraperitoneally (IP) both with and without the calmodulin antagonists, W-7: [N-(6-Aminohexyl)-5-chloro-1-naphthalenesulfonamide] (4.2 micrograms/mouse, intraventricular (IVT) or trifluoperazine (TFP; 1.8 micrograms/mouse, IVT). When CaCl2 was administered in a dose dependent manner the duration of ethanol-induced sleep was prolonged. The prolongation was antagonized by W-7 and TFP. When mice were treated with W-7 or TFP together with serotonin (5-HT; 15 nmol/mouse, IVT), dopamine (DA; 30 nmol/mouse, IVT) or norepinephrine (NE; 30 nmol/mouse, IVT), the sleeping time induced by ethanol and calcium was enhanced. This finding suggests that W-7 and TFP selectively inhibit the synthesis of 5-HT, DA and NE, but they do not affect other neuronal functions of these biogenic amines. The results would suggest a probable mechanism in which Ca++ prolongs ethanol-induced sleeping time by activating tyrosine hydroxylase and tryptophan hydroxylase through intracerebral calmodulin and calmodulin-dependent protein kinase, which subsequently raise the levels of 5-HT, DA and NE.

Effects of TRH, ethanol, and TRH-ethanol combination on activity in rats with altered monoamine content

Investigations were undertaken with 5,7-dihydroxytryptamine and 6-hydroxydopamine treated rats to see whether activity changes induced by TRH, ethanol and the TRH-ethanol combination would be affected after reduced monoamine function. In keeping with earlier results, TRH increased activity, ethanol reduced activity and the TRH-ethanol combination produced activity counts greater than those for TRH alone. Neither the 5,7-dihydroxytryptamine-induced reduction of brain serotonin nor the 6-hydroxydopamine treatments which reduced brain catecholamines altered the hyperactivity induced by TRH or the TRH-ethanol combination. While reduction of brain serotonin did not affect the ethanol-induced changes in activity, preferential reduction of dopamine as well as reduction of both norepinephrine and dopamine significantly antagonized this measure of ethanol-induced depression. The reduction of dopamine alone produced the greatest effect on this action of ethanol. It can be concluded from the data that the increased locomotion induced by TRH and the TRH-ethanol combination does not depend upon endogenous monoamines, whereas the sedative effects of ethanol are apparently influenced by alterations in brain catecholamine function.

Modulating effects of biogenic amines on calcium and ethanol-induced sleeping time

The present study was carried out in order to clarify the mechanism of calcium prolongation of ethanol-induced sleep. p-Chlorophenylalanine (PCPA, 300 mg/kg), alpha-methyltyrosine (alpha MPT, 100 mg/kg) and diethyldithiocarbamate (DDC, 250 mg/kg) were administered intraperitoneally (IP) to mice to reduce the levels of serotonin (5-HT), dopamine (DA) and norepinephrine (NE) respectively in the brain. Sleeping time was then measured following the administration of ethanol (4.5 g/kg, IP) both with and without CaCl2 (20 mumol/kg, intravenous (IV)). When saline (IP) plus CaCl2 (IV) was administered, the duration of ethanol-induced sleep was prolonged by 100% as compared with saline (IP) plus saline (IV). Duration of ethanol-induced sleep was not changed by PCPA, alpha MPT and DDC. On the other hand, the prolongation of ethanol-induced sleep by CaCl2 was antagonized by PCPA, alpha MPT and DDC. Also, only the DA level in the cerebrum was increased by 25% by administration of CaCl2. We suggest that the increase in ethanol-induced sleeping time due to CaCl2 results from the increase in biogenic amines in the brain.

Reversal of ethanol intoxication in humans: an assessment of the efficacy of L-dopa, aminophylline, and ephedrine

The effect of postethanol treatment with L-Dopa, aminophylline and/or ephedrine was investigated. In one experiment, healthy, male, moderate drinkers ingested ethanol (0.8 g/kg) and then either L-Dopa (1.5 g), or placebo. In a second experiment, subjects ingested ethanol followed by aminophylline (200 mg), ephedrine (50 mg), aminophylline (200 mg) plus ephedrine (50 mg), or placebo. Double-blind, within-subjects, crossover designs were employed. Treatment with L-Dopa significantly reduced ethanol's effect on the electroencephalogram, motor coordination, and divided attention performance (t-test for paired data). Treatment with aminophylline and/or ephedrine also significantly reduced ethanol's effects on the electroencephalogram and motor coordination. The ethanol-antagonism may result from central noradrenergic stimulation.

Enhancement of ethonol-induced withdrawal convulsions by blockade of 5-hydroxytryptamine receptors

Male Swiss-Webster mice were made physically dependent on ethanol using the ethanol vapour inhalation technique. Animals pretreated with methysergide, a known 5-hydroxytryptamine receptor blocking agent, had significantly greater alcohol-induced withdrawal convulsions than saline pretreated controls. These findings suggest that the reduction of 5-HT at receptor sites may result in the augmentation of the withdrawal convulsions.

Suppression of ethanol withdrawal by dopamine

An ethanol-inhalation technique was used to determine a potential relationship between dopamine and central nervous effects produced by alcohol. Both L-DOPA and intracranially injected dopamine resulted in attenuation of ethanol-induced withdrawal convulsion scores, whereas, haloperidol, a known dopaminergic blocker was found to significantly increase convulsion scores.

Circadian rhythm of corticosterone in mice: the effect of chronic consumption of alcohol

The effect of chronic consumption of alcohol on the circadian variations of the plasma corticosterone investigated in DBA/2J male mice. After 15 weeks of alcohol consumption (3.8%w/v for the first week and 7.5% for subsequent weeks) the alcohol groups exhibited a flattened circadian corticosterone curve, the level being intermediate between the peak and trough values of the water control groups. The diurnal patterns of food and liquid consumption were still present at the 10th week of alcohol treatment in the alcohol groups, although the absolute amount of food and liquid consumed at each of the 6-h intervals was somewhat different between the alcohol and water groups. The blood alcohol showed a peak at early morning with the mean of 100 mg/100 ml, but the levels of alcohol during the remaining periods were remarkably stable, the means ranging from 30 to 46 mg/100 ml. Chronic consumption of alcohol, even relatively low concentrations, appears to affect the neural sites in the CNS controlling the circadian rhythm of ACTH release.

Potentiation of ethanol narcosis by dopamine- and l-DOPA-based isoquinolines

The isoquinolines, salsolinol and 3-carboxysalsolinol, prolong ethanol-induced narcosis in mice. Pretreatment with carbidopa increases the effect of 3-carboxysalsolinol but not of salsolinol. These results suggest that ethanol sleeping-time potentiation by l-LOPA may involve a partial conversion to the isoquinoline in vivo. A central depressant action of salsolinol or the 3-carboxy analogue is suggested.

Effects of catecholamine synthesis inhibition on ethanol-induced withdrawal symptoms in mice

alpha-Methyl-p-tyrosine, a catecholamine synthesis inhibitor, was studied to determine its effects against ethanol-induced withdrawal symptoms in mice. Signifilcant (P < 0.001) potentiation of the withdrawal convulsion score induced by ethanol vapour exposure for three days was observed in mice. The synergistic effect was not due to alteration of ethanol metabolism. These results indicate that reductions in catecholamines (dopamine and noradrenaline) augment seizure activity induced by subchronic exposure to ethanol.