The interaction of ethanol and amphetamine metabolism

Low-dose effect of ethanol on locomotor activity induced by activation of the mesolimbic system

Four experiments were designed to study the ability of 0.5 g/kg ethanol (EtOH) intraperitoneally to modify locomotor activity induced by drugs that interact with different sites in the mesolimbic system (MLS) of male Sprague-Dawley rats. Locomotor activity was measured in a doughnut-shaped circular arena after various treatments. EtOH alone did not alter locomotor activity in any of the experiments. Amphetamine (AMP, intraperitoneally or intraaccumbens) increased locomotor activity in a dose-dependent manner, and the presence of EtOH attenuated AMP-induced locomotor activity. Bilateral infusion of GABAA antagonist picrotoxin (PIC) into the ventral tegmental area also increased locomotor activity in a dose-dependent manner, and the presence of EtOH attenuated PIC-induced locomotor activity. On the other hand, the interaction between bilateral infusion of mu-receptor agonist Tyr-D-Ala-Gly-NMe-Phe-Gly-ol (DAGO) and EtOH on locomotor activity is complex. The highest dose of DAGO that significantly increased locomotor activity was not affected by the presence of EtOH. But, with lower doses of DAGO that either had no effect or a small increase in locomotor activity, the combination of EtOH and DAGO increased and attenuated locomotor activity, respectively. Results from this study support our hypothesis that a low dose of EtOH that does not modify behavior can interact with neurotransmitter systems in the brain and modify drug-induced locomotor activity. Modification of this drug-induced locomotor activity by a low dose of EtOH is dependent on the rate of ongoing locomotor behavior induced by drug and the neurotransmitter substrate that the drug modified to induce locomotor behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of methamphetamine and ethanol on learning and brain neurotransmitters in rats

The interactions of methamphetamine (MAMP) and ethanol (EtOH) on multiple active/passive avoidance performance and neurotransmitters in different brain regions were examined. After the acquisition schedules, rats were retrained under the influence of MAMP (2 mg/kg/day, IP), EtOH (2 g/kg/day, IP), and in combination over 20 days in rats (n = 6 per group). As a function of progress of drug treatment, MAMP-EtOH mixtures disrupt the learned avoidance performance and produced severe impairment of discriminative behavior caused by enhancement of excitability induced by MAMP when compared with MAMP only. At withdrawal, MAMP-EtOH-induced impairments of performance significantly persisted, whereas MAMP-only-induced impairments slightly recovered. At the eleventh day drug withdrawal, MAMP-only-induced alterations of neurotransmitter levels at different regions were alleviated by EtOH, but these did not return to normal levels. These data provide support for the direct antagonistic and indirect additive interactions following constant daily treatment with a combination of MAMP and EtOH. EtOH may be an important factor in MAMP abuse to MAMP-induced psychosis or neurotoxicity.

A novel and neurotoxic tetrahydroisoquinoline derivative in vivo: formation of 1,3-dimethyl-1,2,3,4-tetrahydroisoquinoline, a condensation product of amphetamines, in brains of rats under chronic ethanol treatment

Repeated amphetamine administration to rats under chronic ethanol intoxication resulted in the formation of 1,3-dimethyl-1,2,3,4-tetrahydroisoquinoline (1,3-DiMeTIQ), a novel metabolite of amphetamines. 1,3-DiMeTIQ was quantified with a sensitive, specific assay using gas chromatography-mass spectrometry. It was not found in the brains of rats given repeated amphetamine administration but no ethanol. The chronic ethanol-intoxicated rats subjected to repeated amphetamine administration exhibited behavioral abnormalities, such as repeated convulsions and curving of the back. 1,3-DiMeTIQ contents were markedly higher in the brain or plasma of rats manifesting abnormal behavior in comparison with those in rats behaving normally. Thus, the 1,3-DiMeTIQ content in the rat brain seems to have some relationship with behavioral abnormalities. This study also confirmed that 1,3-DiMeTIQ can cross the blood-brain barrier in the rat. Intraperitoneal 1,3-DiMeTIQ injections to rats caused behavioral symptoms similar to those observed in rats with chronic ethanol intoxication and repeated amphetamine administration. The effect of toxic doses of 1,3-DiMeTIQ on dopaminergic and serotonergic metabolism in the whole rat brain was also investigated.

Urinary excretion of p-hydroxylated methamphetamine metabolites in man. II. Effect of alcohol intake on methamphetamine metabolism

The effect of drinking alcoholic beverages on methamphetamine metabolism was investigated in man. The subjects, 97 males and 9 females, were divided into three groups by evaluation of their urinary pH; i.e., acidic, subacidic and neutral groups. The subjects in each group were further divided into ethanol-positive subjects and ethanol-negative subjects, depending on the presence or absence of ethanol in their urine. Gas chromatographic analysis showed the urinary concentrations of methamphetamine in the ethanol-positive subjects to be higher than those in the ethanol-negative subjects in both the acidic and subacidic urinary pH groups. Liquid chromatography, on the other hand, showed the urinary concentrations of p-hydroxymethamphetamine and p-hydroxyamphetamine for the ethanol-positive subjects to be lower than those for the ethanol-negative subjects in all three groups. The relative proportions of p-hydroxylated metabolites to unchanged methamphetamine in urine, therefore, were severely reduced in the ethanol-positive subjects. These results suggest that drinking alcoholic beverages probably results in a suppression of methamphetamine metabolism in man.

Structural and biotransformational membrane changes in the liver and intestine during chronic ethanol administration

The binding of a fluorescent probe 1-anilinonaphthalene-8-sulphonic acid (1,8-ANS) to liver microsomal membranes was markedly increased after chronic ethanol administration while the binding of a non-ionised probe phenylnaphthylamine (PNA) was not altered. The increase in 1,8-ANS binding is in accordance with the simultaneous increase of the ethoxycoumarin O-de-ethylase activity and cytochrome P-450 concentration. Also the intestinal ethyoxycoumarin O-de-ethylase activity and cytochrome P-450 concentration were increased. No changes in the aryl hydrocarbon hydroxylase or UDP-glucuronosyltransferase activities were found. The chronic ehtanol administration increased the phospholipid amount in the liver microsomes and altered the fatty acid composition of microsomal phospholipids by decreasing the amount of oleic acid and increasing linoleic acid proportion. The data suggest that chronic ethanol administration may effect the biotransformation enzyme activities by changing the structural properties of the membranes as well as increasing the cytochrome P-450 concentration.

Interaction between d-amphetamine and ethanol with respect to locomotion, stereotypies, ethanol sleeping time, and the kinetics of drug elimination

The interaction between d-amphetamine and ethanol with respect to locomotor activity, stereotyped behavior, and sleeping time was investigated in rats. Ethanol 0.8 g/kg i.p. enhanced and prolonged locomotor activity produced by d-amphetamine 1 mg/kg s.c. The increased motility after 5 mg/kg d-amphetamine was not influenced by alcohol 0.8 g/kg i.p. or 3.2 g/kg orally, but slightly protracted. Stereotyped head and paw movements, as well as stereotyped licking, were distinctly strengthened and protracted by 3.2 g/kg ethanol orally. The modified d-amphetamine motility and stereotypies can be explained by alcohol-induced proloneation of the life of d-amphetomine. The effect is produced by alcohol's inhibition d-amphetamine p-hydroxylation in rat liver. After 3.2 g/kg ethanol i.p., the sleeping time of male rats amounted to 153 min. Simultaneous administration of 5 mg/kg d-amphetamine s.c. reduced the sleeping time to 84 min. This is obviously based on a central antagonism.

Distribution and occurrence of amphetamine and p-hydroxyamphetamine in tissues of the rat after injection of d-amphetamine sulfate

The distribution of amphetamine and the formation and distribution of its principal metabolite p-hydroxyamphetamine after the injection of relatively small amounts of d-amphetamine was examined in the rat. Amphetamine entered all organs readily and was rapidly eliminated. p-Hydroxyamphetamine was rapidly synthesised and it is suggested that substrate inhibition of hepatic hydroxylating enzymes occurs. In the brain, amphetamine was homogeneously distributed between the seven brain regions examined whereas p-hydroxyamphetamine was predominantly concentrated in the striatum.

The effect of carbon disulphide on the stereotypic effect of dopamine agonists

Exposure to CS2 increased the intensity of apomorphine-induced stereotypy in male rats without increasing the reaction time. With amphetamine, an indirect agonist of dopamine, exposure to CS2 had a more intensive effect and significantly prolonged the length of reaction.

Effect of ethanol on toxicity and metabolism of amphetamine in the mouse

Ethanol, 3 g/kg i.p., did not significantly alter the acute toxicity of amphetamine in the mouse. However, the urinary metabolite pattern was changed, suggesting that ethanol suppressed metabolism of the stimulant during the initial 6 h period. After 24 h, the mouse metabolized the same fraction of a given dose of amphetamine, whether it was given as amphetamine alone or amphetamine mixed with 2,3 or 4 g/kg ethanol.