Stimulatory Effect Of Ethanol Research Articles

СКОРОСТЬ ПОТРЕБЛЕНИЯ КИСЛОРОДА ГОМОГЕНАТАМИ ГОЛОВНОГО МОЗГА ХРОНИЧЕСКИ АЛКОГОЛИЗИРОВАННЫХ КРЫС ПРИ ДЕЙСТВИИ ЭТАНОЛА И СУКЦИНАТА IN VITRO

Background. The problem of the development of alcohol dependence is relevant due to insufficient research of the processes occurring in the brain during prolonged exposure to ethanol. The aim of the research. To estimate the rate of oxygen consumption by homogenates of the cerebral cortex and cerebellum of rats under conditions of chronic alcohol intoxication, ethanol withdrawal, as well as the effect of ethanol and succinate on it in vitro. Material and methods. The rate of oxygen consumption by homogenates of the cerebral cortex and cerebellum of rats alcoholized for 8 months, as well as during the period of ethanol withdrawal on endogenous substrates, during incubation with ethanol solution and succinate was studied. Results. An increase in the rate of oxygen consumption of brain homogenates on endogenous substrates in chronic alcohol intoxication of rats, a decrease in the period of ethanol withdrawal on days 1 and 3, a stimulating effect of ethanol in the cerebral cortex on day 3 of abstinence, as well as a stimulating effect succinate in groups of control animals and with chronic alcohol intoxication were observed. Conclusions. Chronic alcoholization of rats leads to the development of the dependence of tissue respiration on the presence of ethanol in the cage. The absence of the stimulating effect of succinate in the ethanol withdrawal groups indicates the significant activation of the succinate dehydrogenase pathway in these animals.

Short-term selection for high and low ethanol intake yields differential sensitivity to ethanol's motivational effects and anxiety-like responses in adolescent Wistar rats

Alcohol use disorders are modulated by genetic factors, but the identification of specific genes and their concomitant biological changes that are associated with a higher risk for these disorders has proven difficult. Alterations in the sensitivity to the motivational effects of ethanol may be one way by which genes modulate the initiation and escalation of ethanol intake. Rats and mice have been selectively bred for high and low ethanol consumption during adulthood. However, selective breeding programs for ethanol intake have not focused on adolescence. This phase of development is associated with the initiation and escalation of ethanol intake and characterized by an increase in the sensitivity to ethanol's appetitive effects and a decrease in the sensitivity to ethanol's aversive effects compared with adulthood. The present study performed short-term behavioral selection to select rat lines that diverge in the expression of ethanol drinking during adolescence. A progenitor nucleus of Wistar rats (F0) and filial generation 1 (F1), F2, and F3 adolescent rats were derived from parents that were selected for high (STDRHI) and low (STDRLO) ethanol consumption during adolescence and were tested for ethanol intake and responsivity to ethanol's motivational effects. STDRHI rats exhibited significantly greater ethanol intake and preference than STDRLO rats. Compared with STDRLO rats, STDRHI F2 and F3 rats exhibited a blunted response to ethanol in the conditioned taste aversion test. F2 and F3 STDRHI rats but not STDRLO rats exhibited ethanol-induced motor stimulation. STDRHI rats exhibited avoidance of the white compartment of the light-dark box, a reduction of locomotion, and a reduction of saccharin consumption, suggesting an anxiety-prone phenotype. The results suggest that the genetic risk for enhanced ethanol intake during adolescence is associated with lower sensitivity to the aversive effects of ethanol, heightened reactivity to ethanol's stimulating effects, and enhanced innate anxiety.

Stimulatory effect of ethanol on libertellenone H biosynthesis by Arctic fungus Eutypella sp. D-1.

Libertellenone H (1) was a promising antitumor diterpenoid isolated from Arctic fungus Eutypella sp. D-1, however, its production was very limited. In this study, we investigated the effects of ethanol on cell growth and libertellenone H production. The mycelium in ethanol-feeding cultures was fragmented and dispersed, and the titer of libertellenone H was remarkably increased to 4.88 mg l(-1) in an optimal feeding manner, which was 16.4-fold higher than the control group. To provide an insight into the cell response to ethanol, genes critical to the libertellenone H biosynthesis were successfully cloned and their transcription levels were determined. The results suggested that the gene transcription levels of 3-hydroxy-3-methyl glutaric acyl coenzyme A reductase and geranylgeranyl diphosphate synthase were up-regulated by ethanol stimulation. The results from this study were helpful for further understanding of the ethanol function on diterpenes biosynthesis as well as developing more effective strategies for over-production of these desired secondary metabolites.

Explicit and Implicit Positive Alcohol Expectancies in Problem and Non-Problem Drinkers: Differences Across Age Groups from Young Adolescence to Adulthood.

Aims: Recent studies with animal models showed that the stimulant and sedative effects of alcohol change during the adolescent period. In humans, the stimulant effects of ethanol are most often indirectly recorded through the measurement of explicit and implicit alcohol effect expectancies. However, it is unknown how such implicit and explicit expectancies evolve with age in humans during adolescence.Methods: Adolescent (13–16 year old), young adult (17–18 year old), and adult (35–55 year old) participants were recruited. On the basis of their score on the Alcohol Use Disorder Identification Test (AUDIT), they were classified as non-problem (AUDIT ≤ 7) or problem (AUDIT ≥ 11) drinkers. The participants completed the Alcohol Expectancy Questionnaire (AEQ) and performed two unipolar Implicit Association Test (IAT) to assess implicit associations between alcohol and the concepts of “stimulation” and “sedation”.Results: Problem drinkers from the three age groups reported significantly higher positive alcohol expectancies than non-problem drinkers on all AEQ subscales. Positive alcohol explicit expectancies also gradually decreased with age, with adolescent problem drinkers reporting especially high positive expectancies. This effect was statistically significant for all positive expectancies, with the exception of relaxation expectancies that were only close to statistical significance. In contrast, stimulation and sedation alcohol implicit associations were not significantly different between problem and non-problem drinkers and did not change with age.Conclusion: These results indicate that explicit positive alcohol effect expectancies predict current alcohol consumption levels, especially in adolescents. Positive alcohol expectancies also gradually decrease with age in the three cross-sectional groups of adolescents, young adults, and adults. This effect might be related to changes in the physiological response to alcohol.

P.6.a.015 Alcohol pharmacokinetics in Korean healthy male

At the end of this procedure, a series of behavioural analyses, including novel object recognition and fear conditioning tests, were conducted in ethanol and water mice. In another series of ethanol and water mice, long term potentiation (LTP) on hippocampal slices was measured by recording synaptic responses of CA1 pyramidal neurons elicited by stimulation of the Schaffer collateral/commissural pathway. Finally, mouse brains from both ethanol and water groups were dissected to performed western blotting and methylated DNA immunoprecipitation (MeDIP) studies. Data were analyzed using Student’s t test, one-way or two-way analyses of variance. Results: A three week chronic and moderate ethanol consumption significantly reduced the DNA methylation of the different CpG islands within Bdnf gene in both the CA1 and CA3 subfields of the hippocampus, further demonstrating a chromatin remodelling effect of ethanol at plasticity gene level, in line with in the promoting effect of ethanol on hippocampal neurogenesis in C57BL/6J mice [3]. Ethanol also significantly augmented the phosphorylation of ERK, AKT and CREB proteins which belong to the BDNF signalling pathway. Conversely, learning and memory capacities were altered in both the novel object recognition and the fear conditioning tests suggesting the impairment in hippocampus-dependent memory. However, in the present condition of consumption, ethanol had no effects on the LTP recorded in the CA1 region of hippocampal slices. Conclusion: All together, these data provided supplementary evidences that the stimulating effect of ethanol on hippocampal BDNF expression could be due, in part, to a chromatin remodelling at the level of the Bdnf gene. High BDNF expression can in turn impact its signalling pathway efficiency, as shown by the high level of ERK, AKT and CREB phosphorylation in ethanol mice. However, ethanol was also showed to damp hippocampusdependent learning and memory capacities but without modifying synaptic plasticity. Whether the effects of ethanol on neuroplasticity and learning are unconnected or whether the increase in neuroplasticity observed in mice having consumed ethanol for 3 weeks could be an adaptive response to ethanol-induced learning deficits are questions to be addressed in future studies.

The renaissance of acetaldehyde as a psychoactive compound: decades in the making.

The renaissance of acetaldehyde as a psychoactive compound: decades in the making.

Role of CA2+/calmodulin on ethanol neurobehavioral effects.

The cAMP-dependent protein kinase A (PKA) signaling transduction pathway has been shown to play an important role in the modulation of several ethanol-induced behaviors. Different studies have demonstrated intracellular calcium (Ca(2+))-dependent activation of the PKA cascade after ethanol administration. Thus, the cAMP cascade mediator Ca(2+)-dependent calmodulin (CaM) has been strongly implicated in the central effects of ethanol. In this study, we assessed the role of the CaM inhibitor W7 on ethanol-induced stimulation, ethanol intake, and ethanol-induced activation of PKA. Swiss mice were pretreated with W7 (0-10mg/kg) 30min before ethanol (0-3.75g/kg) administration. Immediately, animals were placed during 20min in an open-field chamber. Ethanol (10%, v/v) intake in 2h was assessed using a limited access paradigm. Experiments with caffeine (0-15mg/kg), cocaine (0-4mg/kg), and saccharine (0.1%, w/v) were designed to compare their results to those obtained with ethanol. Western blot was assayed 45min after ethanol administration. Results showed that pretreatment with W7, reduced selectively in a dose-dependent fashion ethanol-induced locomotor stimulation and ethanol intake. The ethanol-induced activation of PKA was also prevented by W7 administration. These results demonstrate that CaM inhibition resulted in a selective reduction of ethanol-stimulating effects and ethanol intake. The PKA activation induced by ethanol was blocked after the CaM blockade with W7. These results provide further evidence of the key role of cellular Ca(2+)-dependent pathways on the central effects of ethanol.

Higher long-lasting ethanol sensitization after adolescent ethanol exposure in mice

Due to their maturing brain, adolescents are suggested to be more vulnerable to the long-term consequences of chronic alcohol use. Increased sensitization to the stimulant effects of ethanol is a possible consequence of ethanol exposure during adolescence. The aim of this study was to characterize the long-term alterations in the stimulant effects of ethanol and in the rate of ethanol sensitization in mice pre-exposed to ethanol during adolescence in comparison to mice pre-exposed to ethanol in adulthood. Adolescent and adult female Swiss mice were injected with saline or ethanol (2.5 or 4 g/kg) during 14 consecutive days. After a 3-week period of ethanol abstinence, mice were tested as adults before and after a second exposure to daily repeated ethanol injections. All mice pre-exposed to ethanol as adults or adolescents showed higher stimulant effects when re-exposed to ethanol 3 weeks later. However, this enhanced sensitivity to the stimulant effects of ethanol was of significantly higher magnitude in mice repeatedly injected with high ethanol doses (4 g/kg) during adolescence. Furthermore, the increased expression of ethanol stimulant effects in these mice was maintained even after a second procedure of ethanol sensitization. Adolescence is a critical period for the development of a sensitization to ethanol stimulant properties providing that high intermittent ethanol doses are administered. These results might contribute to explain the relationship between age at first alcohol use and risks of later alcohol problems and highlight the dangers of repeated consumption of high alcohol amounts in young adolescents.

Opposite motor responses elicited by ethanol in the posterior VTA: The role of acetaldehyde and the non-metabolized fraction of ethanol

Recent electrophysiological evidence suggests that ethanol simultaneously exerts opposite effects on the activity of dopamine (DA) neurons in the ventral tegmental area (VTA) through two parallel mechanisms, one promoting and the other reducing the GABA release onto VTA DA neurons. Here we explore the possible behavioural implications of these findings by investigating the role displayed by acetaldehyde (the main metabolite of ethanol) and the non-metabolized fraction of ethanol in motor activity of rats. We analyse the appearance of motor activation or depression after intra-VTA administration of ethanol in rats subjected to different pharmacological pre-treatments designed to preferentially test either the effects of acetaldehyde or the non-metabolized ethanol. Motor activity was evaluated after intra-VTA administration of 35 nmol of ethanol, an apparently ineffective dose that does not modify the motor activity of animals. Pharmacological pre-treatments were used in order to either increase (cyanamide, 10 mg/kg, ip) or decrease (D-penicillamine, 50 mg/kg, ip and sodium azide, 7 mg/kg, ip) acetaldehyde levels in the VTA. Pre-treatments aimed to augment acetaldehyde, increased motor activity of rats. Otherwise, pre-treatments intended to decrease local acetaldehyde levels evoked significant reductions in motor activity that were prevented by the local blockade (bicuculline, 17.5 pmol) of the GABAA receptors. Our findings suggest that the brain-generated acetaldehyde is involved in the stimulant effects of ethanol, whereas the non-biotransformed fraction of ethanol, acting through the GABAA receptors, would account for the depressant effects. The present behavioural findings suggest that ethanol dually modulates the activity of DA neurons.

Effects of Aripiprazole, an Atypical Antipsychotic, on the Motor Alterations Induced by Acute Ethanol Administration in Mice

Aripiprazole is an antipsychotic that acts as a partial agonist at dopamine receptors. As the effects of most drugs of abuse converge to enhance dopamine-mediated neurotransmission, the present study was designed to test the hypothesis that aripiprazole would inhibit the acute effects of ethanol, a widely abused substance. Male Swiss mice received acute injections and were evaluated for motor activity in three distinct tests. In the open field, ethanol (1.5, 2.5 and 3.5 g/kg) induced an increase in locomotion in a U-shaped dose-related fashion, whereas aripiprazole (0.1, 1 and 10 mg/kg) did not affect this parameter. All the doses of the antipsychotic were able to prevent the stimulant effects of 2.5 g/kg of ethanol. In the rotarod test, ethanol (2.5 and 3.5 g/kg) reduced the latency to fall from the apparatus, an effect also observed with the higher dose of aripiprazole. Contrary to what was observed in the open field, this antipsychotic did not interfere with the effects of ethanol in motor balance. Finally, we tested animals in the wire hang test, in which ethanol, but not aripiprazole, reduced latency to fall at all doses. In this test, aripiprazole did not change ethanol effects. The present data lead to the conclusion that aripiprazole prevents the stimulant effects of ethanol on locomotion, without interfering with the motor impairment induced by this drug.

Cilnidipine, an L/N-type calcium channel blocker prevents acquisition and expression of ethanol-induced locomotor sensitization in mice

Several evidences indicated the involvement of L- and N-type calcium channels in behavioral effects of drugs of abuse, including ethanol. Calcium channels are implicated in ethanol-induced behaviors and neurochemical responses. Calcium channel antagonists block the psychostimulants induced behavioral sensitization. Recently, it is demonstrated that L-, N- and T-type calcium channel blockers attenuate the acute locomotor stimulant effects of ethanol. However, no evidence indicated the role of calcium channels in ethanol-induced psychomotor sensitization. Therefore, present study evaluated the influence of cilnidipine, an L/N-type calcium channel blocker on acquisition and expression of ethanol-induced locomotor sensitization. The results revealed that cilnidipine (0.1 and 1.0μg/mouse, i.c.v.) attenuates the expression of sensitization to locomotor stimulant effect of ethanol (2.0g/kg, i.p.), whereas pre- treatment of cilnidipine (0.1 and 1.0μg/mouse, i.c.v.) during development of sensitization blocks acquisition and attenuates expression of sensitization to locomotor stimulant effect of ethanol. Cilnidipine per se did not influence locomotor activity in tested doses. Further, cilnidipine had no influence on effect of ethanol on rotarod performance. These results support the hypothesis that neuroadaptive changes in calcium channels participate in the acquisition and the expression of ethanol-induced locomotor sensitization.

Early role of the κ opioid receptor in ethanol-induced reinforcement

Effects of early ethanol exposure on later ethanol intake emphasize the importance of understanding the neurobiology of ethanol-induced reinforcement early in life. Infant rats exhibit ethanol-induced appetitive conditioning and ethanol-induced locomotor activation, which have been linked in theory and may have mechanisms in common. The appetitive effects of ethanol are significantly modulated by μ and δ opioid receptors, whereas μ but not δ receptors are involved in the motor stimulant effects of ethanol during early development. The involvement of the κ opioid receptor (KOR) system in the motivational effects of ethanol has been much less explored. The present study assessed, in preweanling (infant) rats, the modulatory role of the KOR system in several paradigms sensitive to ethanol-induced reinforcement. Kappa opioid activation and blockade were examined in second-order conditioned place preference with varied timing before conditioning and with varied ethanol doses. The role of KOR on ethanol-induced locomotion and ethanol-induced taste conditioning was also explored. The experiments were based on the assumption that ethanol concurrently induces appetitive and aversive effects and that the latter may be mediated by activation of kappa receptors. The main result was that blockade of kappa function facilitated the expression of appetitive ethanol reinforcement in terms of tactile and taste conditioning. The effects of kappa activation on ethanol conditioning seemed to be independent from ethanol's stimulant effects. Kappa opioid activation potentiated the motor depressing effects of ethanol but enhanced motor activity in control subjects. Overall, the results support the hypothesis that a reduced function of the KOR system in nondependent subjects should attenuate the aversive consequences of ethanol.

Studies on the sedative and hypnotic effects of oleamide in mice.

The hypnotic and sedative effects of oleamide (CAS 301-02-0) were studied in mice. Intraperitoneal injection of oleamide showed a time-related inhibition of the locomotor activity with the maximum effect appearing 30 min after drug administration. Oleamide, at the dose range of 43.7-700 mg/kg, dose-dependently inhibited the locomotor activity in mice. Oleamide could promote the hypnotic action induced by sodium pentobarbital. The interaction studies showed that oleamide potentiated the inhibitory effect of diazepam (CAS 439-14-5) and antagonized the stimulatory effect of ethanol, methamphetamine, and caffeine, respectively. These results provide further evidence for the hypnotic and sedative effects of oleamide, suggesting a potential therapeutic usefulness of this fatty acid amide.

NR2B-deficient mice are more sensitive to the locomotor stimulant and depressant effects of ethanol

The NR2B subunit of N-methyl d-aspartate glutamate receptors influences pharmacological properties and confers greater sensitivity to the modulatory effects of ethanol. This study examined behavioral responses to acute ethanol in a conditional knockout mouse model that allowed for a delayed genetic deletion of the NR2B subunit to avoid mouse lethality. Mice lacking the NR2B gene (knockout) were produced by mating NR2B[f/f] mice with CAMKIIa-driven tTA transgenic mice and the tetO-CRE transgenic mice. Adult male and female offspring representing each of the resultant genotypes (knockout, CAM, CRE and wildtype mice) were tested for open-field locomotor activity following acute low- and high-dose ethanol challenge as well as loss of righting reflex. Findings indicate that male and female mice lacking the NR2B subunit exhibited greater overall activity in comparison to other genotypes during the baseline locomotor activity test. NR2B knockout mice exhibited an exaggerated stimulant response to 1.5 g/kg (i.p.) and an exaggerated depressant response to 3.0 g/kg (i.p.) ethanol challenge. In addition, NR2B knockout mice slept longer following a high dose of ethanol (4.0 g/kg, i.p.). To evaluate pharmacokinetics, clearance rates of ethanol (1.5, 4.0 g/kg, i.p.) were measured and showed that female NR2B knockouts had a faster rate of metabolism only at the higher ethanol dose. Western blot analyses confirmed significant reduction in NR2B expression in the forebrain of knockout mice. Collectively, these data indicate that the NR2B subunit of the N-methyl d-aspartate glutamate receptor is involved in regulating low-dose stimulant effects of ethanol and the depressant/hypnotic effects of ethanol.

Alpha-lipoic acid, a scavenging agent for H2O2, reduces ethanol-stimulated locomotion in mice

The main system of central ethanol oxidation is mediated by the enzyme catalase. By reacting with H(2)O(2), brain catalase forms compound I (the catalase-H(2)O(2) system), which is able to oxidize ethanol to acetaldehyde in the brain. Previous studies have demonstrated that pharmacological manipulations of brain catalase activity modulate the stimulant effects of ethanol in mice. However, the role of H(2)O(2) in the behavioral effects of ethanol has not yet been clearly addressed. In the present study, we investigated the effects of alpha-lipoic acid (LA), a scavenging agent for H(2)O(2), on ethanol-induced locomotor stimulation. CD-1 mice were pretreated with LA [0-100 mg/kg, intraperitoneally (IP)] 0-60 min prior to administration of ethanol (0-3.75 g/kg, IP). In another experiment, animals were pretreated with LA (0, 25, or 50 mg/kg, IP) 30 min before cocaine (10 mg/kg, IP), amphetamine (2 mg/kg, IP), or caffeine (25 mg/kg, IP). After these treatments the animals were placed in an open-field chamber and their locomotor activity was measured for 20 min. LA 25, 50, and 100 mg/kg IP prevented ethanol-induced locomotor stimulation. LA did not affect the locomotor-stimulating effects of cocaine, amphetamine, and caffeine. Additionally, we demonstrated that LA prevents the inactivation of brain catalase by 3-amino-1,2,4-triazole, thus indicating that H(2)O(2) levels are reduced by LA. These data support the idea that a decrease in cerebral H(2)O(2) production by LA administration inhibits ethanol-stimulated locomotion. This study suggests that the brain catalase-H(2)O(2) system, and by implication centrally formed acetaldehyde, plays a key role in the psychopharmacological effects of ethanol.

Ethanol-induced sensitization depends preferentially on D1 rather than D2 dopamine receptors

Behavioral sensitization, defined as a progressive increase in the locomotor stimulant effects elicited by repeated exposure to drugs of abuse, has been used as an animal model for drug craving in humans. The mesoaccumbens dopaminergic system has been proposed to be critically involved in this phenomenon; however, few studies have been designed to systematically investigate the effects of dopaminergic antagonists on development and expression of behavioral sensitization to ethanol in Swiss mice. We first tested the effects of D1 antagonist SCH-23390 (0–0.03mg/kg) or D2 antagonist Sulpiride (0–30mg/kg) on the locomotor responses to an acute injection of ethanol (2.0g/kg). Results showed that all tested doses of the antagonists were effective in blocking ethanol's stimulant effects. In another set of experiments, mice were pretreated intraperitoneally with SCH-23390 (0.01mg/kg) or Sulpiride (10mg/kg) 30min before saline or ethanol injection, for 21days. Locomotor activity was measured weekly for 20min. Four days following this pretreatment, all mice were challenged with ethanol. Both antagonists attenuated the development of ethanol sensitization, but only SCH-23390 blocked the expression of ethanol sensitization according to this protocol. When we tested a single dose (30min before tests) of either antagonist in mice treated chronically with ethanol, both antagonists attenuated ethanol-induced effects. The present findings demonstrate that the concomitant administration of ethanol with D1 but not D2 antagonist prevented the expression of ethanol sensitization, suggesting that the neuroadaptations underlying ethanol behavioral sensitization depend preferentially on D1 receptor actions.

Post-junctional interactions between neuromuscular blocking agents and ethanol at the mouse neuromuscular junction.

Ethanol is known to have both pre-synaptic and post-synaptic effects at a range of loci in the mammalian nervous system, including the neuromuscular junction. However, the effects of ethanol on evoked synaptic transmission have not been previously studied at the mouse neuromuscular junction. Here, we report on the effects of ethanol on evoked neuromuscular transmission and the interaction of ethanol with non-depolarizing blocking drugs. Electrophysiological techniques to measure synaptic potentials and synaptic currents were employed in this study. Ethanol (≥100 mM) produced increases in the amplitudes of both spontaneous and evoked synaptic events. Under conditions in which neuromuscular transmission was blocked by (+)-tubocurarine, ethanol (12-100 mM) produced greater increases in evoked response amplitude than in spontaneous response amplitude recorded in the absence of (+)-tubocurarine. Ethanol (100 mM) did not affect evoked neurotransmitter release in low-calcium/high-magnesium solutions. With respect to the clinically used neuromuscular blocking drugs, ethanol (100 mM) interfered with the blocking action of vecuronium, but not cisatracurium. Under these conditions, the stimulant effect of ethanol on neuromuscular transmission is exclusively on the post-junctional elements, both to enhance transmission through nicotinic receptors and also via interactions with neuromuscular blocking agents. These actions of ethanol on neuromuscular transmission may affect the dosage of neuromuscular blockers required in patients who have imbibed significant amounts of alcohol.

DNA methyltransferase expression in sensitized and non‐sensitized mice to stimulant effect of ethanol

Recent studies indicated that DNA methylation in patients with alcoholism is increased. Since the development of behavioral sensitization to ethanol does not occur uniformly, we investigated the expression of DNA methyltransferases (DNMTs) in the medial pre‐frontal cortex (mPFC), nucleus accumbens, amygdala, and ventral tegmental area (VTA) of the mice with different profiles of locomotor activity after chronic ethanol administration. Male Swiss mice received 2.2 g/kg ethanol or saline intraperitoneally daily for 21 days, were tested weekly for locomotor activity. Ethanol‐treated mice were classified into sensitized and non‐sensitized groups (n=10) according to their locomotor activity during treatment. Real time PCR assays were used to measure levels of mRNAs encoding the gene of enzymes in the tissues. In the mPFC, non‐sensitized mice presented lower levels of DNMT3a gene expression than sensitized and control groups. Moreover, in the VTA sensitized mice presented lower levels of DNMT3a gene expression than non‐sensitized and control groups. Since methylation of DNA is an important epigenetic factor in regulation of gene expression these findings may have important implications for development of behavioral sensitization to ethanol in mice. Financial support: FAPESP, CNPq and AFIP.

Differential role of mu, delta and kappa opioid receptors in ethanol-mediated locomotor activation and ethanol intake in preweanling rats

The opioid system modulates ethanol intake and reinforcement in adult and preweanling rodents. While adult heterogeneous rats normally do not show ethanol-mediated locomotor stimulation, preweanling rats show it quite clearly. We recently observed that naloxone, a non-specific opioid antagonist, attenuated ethanol-induced locomotor activation in preweanling rats. In the present study we tested the role of specific opioid receptors (mu, delta and kappa) in ethanol-mediated locomotor stimulation and ethanol intake. In Experiment 1 13-day-old rats received naloxonazine (mu antagonist: 0, 7.5 or 15 mg/kg), naltrindole (delta antagonist: 0, 2 or 4 mg/kg) or nor-binaltorphimine (kappa antagonist: 0, 2, 4 or 8 mg/kg) before an intragastric administration of ethanol (0 or 2.5 g/kg), and subsequent locomotor activity assessment. In Experiment 2, the same opioid antagonists were administered on postnatal days 13 and 14 before consumption of ethanol (6%), saccharin (0.05%) or distilled water. In Experiment 1 only naloxonazine reduced ethanol-mediated locomotor stimulation. None of the opioid antagonists affected locomotor activity in water controls. In Experiment 2 naloxonazine and naltrindole suppressed ingestion of all the solutions tested. Similar to what has been reported in adult rodents, mu-opioid receptors seem to modulate ethanol-activating effects during early ontogeny. Hence, there seems to be a partial overlap of neurochemical mechanisms involved in the rewarding and stimulating effects of ethanol in preweanling rats. Mu-receptor antagonists reduced both ethanol-induced activity and ethanol intake, but it is unclear whether the latter effect is specific to ethanol or only a reflection of an effect on consummatory behavior generally, since mu and delta receptor antagonists also suppressed ingestion of water and sacccharin.

Ethanol and urea affect insulin secretion from islets and insulinoma cells by different mechanisms

Secretion of insulin could be stimulated by several ways. Comparison of glucose- and swelling-induced mechanisms in pancreatic islets revealed the involvement of a novel signal transduction pathway with specific features of osmotically stimulated peptide hormone release including Ca2+ independence and resistance to noradrenalin (NA) inhibition. Cell swelling can be induced by hypotonicity or small permeant molecules (e.g. ethanol, urea). Our experiments were aimed to compare the effect of these permeants on insulin secretion from natural system — freshly isolated pancreatic islets and rat insulinoma cell lines INS-1 and INS-1E. As expected glucose and both permeants (80 mM ethanol and urea in isosmotic medium) induced insulin release from islets and NA did not inhibit permeant-induced secretion. Although ethanol and urea induced similar swelling of tumor cells, they produced opposite effect on insulin secretion; while exposure to ethanol led to stimulation of insulin secretion, exposure to urea led to suppression in both types of neoplastic cells. Surprisingly, stimulating effect of ethanol was completely suppressed by NA in both tumor cell lines. Ethanol in hyperosmotic medium failed to stimulate and even inhibited insulin release from both tumor cell lines in present study indicating thus involvement of an osmotic component. In conclusion, the opposite effect of ethanol and urea on insulin secretion from insulinoma cells and sensitivity of ethanol stimulation to NA indicate utilization of different cellular signaling pathways in tumor cells as compared to natural β-cells. Participation of permeant effect in the mechanism of ethanol stimulation remains to be clarified.