Effect of lacosamide on ethanol induced conditioned place preference and withdrawal associated behavior in mice: Possible contribution of hippocampal CRMP-2

BACKGROUND

Excessive consumption of ethanol is known to activate the mTORC1 pathway and to enhance the Collapsin Response Mediator Protein-2 (CRMP-2) levels in the limbic region of brain. The latter helps in forming microtubule assembly that is linked to drug taking or addiction-like behavior in rodents. Therefore, in this study, we investigated the effect of lacosamide, an antiepileptic drug and a known CRMP-2 inhibitor, which binds to CRMP-2 and inhibits the formation of microtubule assembly, on ethanol-induced conditioned place preference (CPP) in mice.

METHODS

The behavior of mice following ethanol addiction and withdrawal was assessed by performing different behavioral paradigms. Mice underwent ethanol-induced CPP training with alternate dose of ethanol (2 g/kg, po) and saline (10 ml/kg, po). The effect of lacosamide on the expression of ethanol-induced CPP and on ethanol withdrawal associated anxiety and depression-like behavior was evaluated. The effect of drug on locomotor activity was also assessed and hippocampal CRMP-2 levels were measured.

RESULTS

Ethanol-induced CPP was associated with enhanced CRMP-2 levels in the hippocampus. Lacosamide significantly reduced the expression of ethanol-induced CPP and alleviated the levels of hippocampal CRMP-2 but aggravated withdrawal-associated anxiety and depression in mice.

CONCLUSION

The present study demonstrated the beneficial effect of lacosamide in attenuation of expression of ethanol induced conditioned place preference via reduction of hippocampal CRMP-2 level. These findings suggest that lacosamide may be investigated further for ethanol addiction but not for managing withdrawal.

PARP inhibition in vivo blocks alcohol-induced brain neurodegeneration and neuroinflammatory cytosolic phospholipase A2 elevations

Chronic alcoholism promotes brain damage that impairs memory and cognition. High binge alcohol levels in adult rats also cause substantial neurodamage to memory-linked regions, notably, the hippocampus (HC) and entorhinal cortex (ECX). Concurrent with neurodegeneration, alcohol elevates poly (ADP-ribose) polymerase-1 (PARP-1) and cytosolic phospholipase A2 (cPLA2) levels. PARP-1 triggers necrosis when excessively activated, while cPLA2 liberates neuroinflammatory ω-6 arachidonic acid. Inhibitors of PARP exert in vitro neuroprotection while suppressing cPLA2 elevations in alcohol-treated HC-ECX slice cultures. Here, we examined in vivo neuroprotection and cPLA2 suppression by the PARP inhibitor, veliparib, in a recognized adult rat model of alcohol-binging. Adult male rats received Vanilla Ensure containing alcohol (ethanol, 7.1 ± 0.3 g/kg/day), or control (dextrose) ± veliparib (25 mg/kg/day), by gavage 3x daily for 4 days. Rats were sacrificed on the morning after the final binge. HC and ECX neurodegeneration was assessed in fixed sections by Fluoro-Jade B (FJB) staining. Dorsal HC, ventral HC, and ECX cPLA2 levels were quantified by immunoblotting. Like other studies using this model, alcohol binges elevated FJB staining in the HC (dentate gyrus) and ECX, indicating neurodegeneration. Veliparib co-treatment significantly reduced dentate gyrus and ECX neurodegeneration by 79% and 66%, respectively. Alcohol binges increased cPLA2 in the ventral HC by 34% and ECX by 72%, which veliparib co-treatment largely prevented. Dorsal HC cPLA2 levels remained unaffected by alcohol binges, consistent with negligible FJB staining in this brain region. These in vivo results support an emerging key role for PARP in binge alcohol-induced neurodegeneration and cPLA2-related neuroinflammation.

Rosmarinic acid protects against chronic ethanol-induced learning and memory deficits in rats

OBJECTIVES

Ethanol consumption induces neurological disorders including cognitive dysfunction. Oxidative damage is considered a likely cause of cognitive deficits. We aimed to investigate the effects of rosmarinic acid (RA) in different doses for 30 days on chronic ethanol-induced cognitive dysfunction using the passive avoidance learning (PAL) and memory task in comparison with donepezil, a reference drug. We also evaluated the levels of superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation in hippocampus as possible mechanisms.

METHODS

Memory impairment was induced by 15% w/v ethanol (2 g/kg, i.g.) administration for 30 days. RA (8, 16, and 32 mg/kg, i.g.) or donepezil (2 mg/kg, i.g.) was administered 30 minutes before ethanol. The acquisition trial was done 1 hour after the last administration of RA and donepezil. At the end, animals were weighed and hippocami were isolated for analyzing of oxidant/antioxidant markers.

RESULTS

Ethanol caused cognition deficits in the PAL and memory task. While RA 16 and 32 mg/kg improved cognition in control rats, it prevented learning and memory deficits of alcoholic groups. RA 8 mg/kg did not influence cognitive function in both control and alcoholic rats. RA 32 mg/kg had comparable effects with donepezil in prevention of acquisition and retention memory impairment. The higher doses of RA not only prevented increased lipid peroxidation and nitrite content but also decreased SOD, CAT, GSH, and FRAP levels in alcoholic groups and exerted antioxidant effects in non-alcoholic rats.

DISCUSSION

We showed that RA administration dose-dependently prevented cognitive impairment induced by chronic ethanol in PAL and memory and disturbed oxidant/antioxidant status as a possible mechanism. The antioxidant, anticholinesterase, and neuroprotective properties of RA may be involved in the observed effects. Therefore, RA represents a potential therapeutic option against chronic ethanol-induced amnesia which deserves consideration and further examination.

Alcohol Teratogenesis: Mechanisms of Damage and Strategies for Intervention

There are multiple mechanisms by which alcohol can damage the developing brain, but the type of damage induced will depend on the amount and developmental timing of exposure, along with other maternal and genetic factors. This article reviews current perspectives on how ethanol can produce neuroteratogenic effects by its interactions with molecular regulators of brain development. The current evidence suggests that alcohol produces many of its damaging effects by exerting specific actions on molecules that regulate key developmental processes (e.g., L1 cell adhesion molecule, alcohol dehydrogenase, catalase), interfering with the early development of midline serotonergic neurons and disrupting their regulatory-signaling function for other target brain structures, interfering with trophic factors that regulate neurogenesis and cell survival, or inducing excessive cell death via oxidative stress or activation of caspase-3 proteases. The current understanding of pathogenesis mechanisms suggests several strategic approaches to develop rational molecular prevention. However, the development of behavioral and biologic treatments for alcohol-affected children is crucial because it is unlikely that effective delivery of preventative interventions can realistically be achieved in ways to prevent prenatal damage in at-risk pregnancies. Toward that end, behavioral training that promotes experience-dependent neuroplasticity has been effective in a rat model of cerebellar damage induced by alcohol exposure during the period of brain development that is comparable to that of the human third trimester.

Linear correlation between phenobarbital dose and concentration in alcohol withdrawal patients

INTRODUCTION

Barbiturates are potent drugs for treatment of alcohol withdrawal symptoms, but they entail a risk of over-dosage and respiratory depression. The purpose of the present study was to investigate the correlation between phenobarbital dose and phenobarbital blood concentration in patients withdrawing from long-term alcohol intoxication.

MATERIAL AND METHODS

A total of 497 patients who were hospitalized for treatment of alcohol withdrawal symptoms during an 18-month period were enrolled in the study. Phenobarbital 200 mg was administered orally every 30 or 60 minutes in response to the observed symptoms. Within the first 24 hours after admission, i.e. at 8 AM, blood was collected for determination of phenobarbital concentration, and the cumulated dose of phenobarbital at the time of the blood sampling was registered.

RESULTS

The mean cumulated phenobarbital dose at the time of the blood sampling was 877 mg +/- 557 mg, while the mean plasma phenobarbital concentration was 104 micromol/l +/- 62 micromol/l. A statistically significant linear correlation between phenobarbital dose and concentration was found for both males and females as 83% and 84% of the variation in drug concentration, respectively, could be explained by the phenobarbital dose. We observed no serious complications of the phenobarbital treatment--including respiratory problems or severe sedation.

DISCUSSION

The strong linear correlation between phenobarbital dose and concentration suggests that absorption of plasma phenobarbital from the gastrointestinal system is highly predictable.

Ethanol causes and lithium prevents neuroapoptosis and suppression of pERK in the infant mouse brain

Transient exposure of immature animals during the brain growth spurt period to ethanol triggers neuroapoptosis in the developing brain. Here we report that lithium, when administered in a single, well-tolerated dose to infant mice, suppresses spontaneous neuroapoptosis that occurs naturally in the developing brain, and prevents ethanol from triggering neuroapoptosis. To explore lithium's mechanism of action, we focused on kinase signaling systems (ERK, Akt, JNK) that are believed to play a regulatory role in cell survival, and found that very rapidly after ethanol administration there is a suppression of ERK phosphorylation, and that lithium stimulates ERK phosphorylation and prevents ethanol from suppressing this phosphorylation process. Ethanol also suppressed pAKT, but lithium did not counteract this effect. We also found that ethanol activates the JNK system, but this cannot explain the neurotoxic action of ethanol, because JNK activation did not occur in the same neuronal populations that are killed by ethanol.

[Thiamine metabolism disorders in the rat brain in experimental alcoholism and a possibility of their correction by vitamin E]

The influence of the chronic consumption of alcohol on biochemical reactions of thiamine metabolism in the rat brain is investigated. It is shown that the content of thiamine diphosphate (ThDP) in the brain tissue does not change at these conditions, though there is an essential decrease in the thiamine-kinase activity. The ability of the isolated nerve terminals (synaptosomes) to absorb labelled thiamine also decreases under this condition. The specified disturbances are probably the reason for deceleration of exchange of free (uncombined with proteins) thiamine and its phosphates in nervous cells, that results in the observed reduction in activity of pyruvate dehydrogenase complex (PDC) due to inactivation by phosphorylation. Thiamine-binding and thiaminetriphosphatase activities of thiamine-binding protein (ThBP) in the structure of synaptic plasma membranes (SPM), isolated from the rat brain in various experimental groups, have been investigated. The increase, with respect to control, in the both enzymes activity in SPM, isolated from the brain of rats with chronic alcoholism has been shown. Kinetic researches testify to an increase of affinity of SPM (ThBP) for thiamine and thiaminetriphosphate in these conditions. When vitamin E was given to animals with a model of chronic alcoholism the normalization of PDC activity in nervous cells was observed, that can testify to the transient character of these changes. Inability of vitamin E to normalize biological activities of ThBP in PMS, that has been analyzed, can testify to more deep disturbances in the structure of SPM or thiamine binding protein in their structure.

The neurotoxicity of alcohol

Patterns of drinking are changing throughout the world and in many countries this will be detrimental to the health and welfare of the local population. Even uncomplicated alcoholics who have no specific neurological or hepatic problems show signs of regional brain damage and cognitive dysfunction. Many of these changes are exaggerated and other brain regions damaged in patients who have additional vitamin B1 (thiamine) deficiency (Wernicke-Korsakoff syndrome). Quantitative neuropathology techniques and improvements in neuroimaging have contributed significantly to the documentation of these changes but mechanisms underlying the damage are not understood. A human brain bank targeting alcohol cases has been established in Sydney, Australia and provides fresh and frozen tissue for alcohol researchers. The tissues can be used to test hypotheses developed from structural neuropathological studies or from animal models and in vitro studies. Identification of reversible pathological changes and preventative medical approaches in alcoholism should enhance rehabilitation and treatment efforts, thereby mitigating debilitating morbidities and reducing mortality associated with this universal public health problem.

Grape seed flavanols, but not Port wine, prevent ethanol-induced neuronal lipofuscin formation

Lipofuscin is an end-product of lipid peroxidation which dramatically increases following ethanol consumption, as we have shown in hippocampal and cerebellar neurons. In this work, we corroborated observations indicating that supplementation of ethanol with 200 mg/l of grape seed flavanols prevents increased lipofuscin formation, an action that has been ascribed to the antioxidant properties of the flavanols. Because wine is an alcoholic beverage naturally rich in flavanols, we decided to study the effect of chronic ingestion of Port wine (PW), which also contains 20% ethanol and approximately 200 mg/l of flavanol oligomers, upon lipofuscin accumulation in the hippocampal CA1 and CA3 pyramidal neurons and in the cerebellar Purkinje cells. Six months old rats were fed with PW and results were compared with those obtained in ethanol-treated groups and pair-fed controls. After 6 months of treatment, the volume of lipofuscin per neuron was estimated using unbiased stereological methods. Treatment with PW resulted in an increase of lipofuscin in all neuronal populations studied when compared to controls and to rats treated with ethanol supplemented with flavanols. No differences were observed when comparisons were made with ethanol drinking rats. We conclude that PW, despite containing 20% ethanol and flavanols, does not prevent ethanol-induced lipofuscin formation as previously found in animals drinking ethanol plus flavanols. The reduced antioxidant capacity of PW might depend on the type and amount of flavanols present and on its content in sugars.

Anticonvulsive effects of kappa-opioid receptor modulation in an animal model of ethanol withdrawal

Although the neurochemical mechanisms contributing to alcohol withdrawal seizures are poorly understood, withdrawal seizures probably reflect neuronal hyperexcitability resulting from adaptation to chronic alcohol. Altered kappa-Opioid receptor (KOP-R) signaling has been observed in multiple seizure types; however, a role for this system in ethanol withdrawal seizures has not been systematically characterized. We hypothesized that pharmacological manipulations of the KOP-R would alter withdrawal in mice selectively bred for differences in ethanol withdrawal severity. Withdrawal Seizure-Prone (WSP) and Withdrawal Seizure-Resistant (WSR) mice were made physically dependent using chronic ethanol vapor inhalation, and the effects of the KOP-R antagonist nor-binaltorphimine or agonist U-50,488H on withdrawal severity were examined. Pretreatment with nor-binaltorphimine significantly increased handling-induced convulsion (HIC) severity in withdrawing WSR mice, with no observable effects in withdrawing WSP mice. In contrast, U-50,488H significantly decreased HIC severity in WSP mice, with no effects in WSR mice. During extended withdrawal (i.e. hours 12+), a rebound hyperexcitability was observed in WSP mice given agonist. Thus, administration of a KOP-R antagonist increased withdrawal severity in mice normally resistant to withdrawal seizures, while a KOP-R agonist reduced convulsion severity in animals susceptible to withdrawal seizures. These observations are consistent with differences in the KOP-R system observed in these lines at the molecular level, and suggest the KOP-R system may be a promising therapeutic target for management of ethanol withdrawal seizures. Finally, these findings underscore the importance of determining the potential for rebound increases in withdrawal severity during later withdrawal episodes.

Protective effects of melatonin against ethanol-induced reactive gliosis in hippocampus and cortex of young and aged rats

Evidence has been accumulated indicating that chronic ethanol consumption leads to direct or indirect changes in the viability of central nervous system cells. The effects of aging and chronic ethanol consumption on glial markers [glial fibrillary acidic protein (GFAP) and S100B] and oxidant and antioxidant status of rats were studied. Furthermore, protective effects of melatonin against aging and alcohol consumption were also assayed. Chronic ethanol administration to young and aged rats produced an increase in lipid peroxidation, and a decline in glutathione (GSH) levels, which was significantly reversed by the co-administration of melatonin. Lipid peroxidation status was markedly affected in aged rats treated with alcohol compared to the young rats. An age-related increase in GFAP and S100B levels were found in the cortex and hippocampus. Long-term alcohol exposure resulted in distinct elevation in GFAP content in young rats (P < 0.01) while there was less increase in the cortex of aged rats (P < 0.05). In old rats, hippocampal GFAP levels were not significantly changed by alcohol treatment (P > 0.05). Co-administration of melatonin with alcohol significantly reduced GFAP contents both in the hippocampus (P < 0.01) and cortex (P < 0.001) of aged rats. No significant effects of alcohol treatment were found on the levels of neuron-specific enolase (NSE) in aged rats. This finding suggests that melatonin exerts its protective effect on injured nervous tissues by scavenging free radicals and stabilizing glial activity against the damaging effects of ethanol and aging. Furthermore, this work suggests that the signal to initiate gliosis is mediated, at least indirectly, by free radical formation.

Attenuation of brain derived neurotrophic factor (BDNF) by ethanol and cytoprotective effect of exogenous BDNF against ethanol damage in neuronal cells

Ethanol-induced cell damage was investigated using human neuroblastomas SH-SY5Y cells, which can be differentiated by retinoic acid. With 100 mM or more of ethanol, cytotoxicity was significantly higher in undifferentiated cells than in differentiated cells. Thus, a severer effect of ethanol was observed in undifferentiated cells. In differentiated cells it was shown that the secreted amount of brain derived neurotrophic factor (BDNF) and the cyclic AMP responsive element binding protein (CREB) activity were significantly reduced by ethanol. These effects may be involved in ethanol-induced cell damage in differentiated cells. It was reported that neurotrophic factors have protective effects and that the hippocampus exclusively was damaged by ethanol. Since SH-SY5Y cell is a cell line (a neuronal cell model) and similar cytotoxic effect of ethanol was observed in both SH-SY5Y and primary culture neuronal cells, it will be favorable to use primary culture cells to test a protective effect of BDNF. Exogenous BDNF was shown to have a protective effect against ethanol-induced damage in primary culture neurons from rat hippocampi.

Green tea protection against age-dependent ethanol-induced oxidative stress

Ethanol intoxication leads to oxidative stress, which may be additionally enhanced by aging. The aim of this study was to investigate the influence of green tea as a source of water-soluble antioxidants on the ability to prevent oxidative stress in aged rats sub-chronically intoxicated with ethanol. Two-, 12-, and 24-mo-old male Wistar rats were divided into 4 experimental groups: (1) control, (2) green tea, (3) ethanol, and (4) ethanol and green tea. Ethanol intoxication produced age-dependent decrease in the activity of serum superoxide dismutase, glutathione peroxidase, and reductase and in levels of glutathione (GSH), vitamins C, E, and A, and beta-carotene. Changes in the serum antioxidative ability were accompanied by enhanced oxidative modification of lipid (increase in lipid hydroperoxides, malondiadehyde, and 4-hydroxynonenal levels) and protein (rise in carbonyl group levels). Green tea partially protected against changes in antioxidant enzymatic as well as nonenzymatic parameters produced by ethanol and enhanced by aging. Administration of green tea significantly protects cellular components such as lipids and proteins against oxidative modification. Results indicate that green tea effectively protects blood serum against oxidative stress produced by ethanol as well as aging.

Antioxidants and fetal protection against ethanol teratogenicity. I. Review of the experimental data and implications to humans

Ethanol is the most common human teratogen, and heavy drinking during pregnancy can result in serious adverse outcomes to the fetus. The cellular mechanisms by which ethanol induces damage in utero are not well understood, while induction of oxidative stress is believed to be one putative mechanism. Our objective is to review the data of antioxidant effects in experimental models of fetal alcohol syndrome. Prior to the description of the available experimental data, we will briefly review the mechanisms leading to ethanol-induced oxidative stress. Ethanol-induced oxidative damage to the fetus could be attenuated by a variety of antioxidants as was documented in whole animal and tissue culture studies. Experiments, retrieved from the literature search, are described and criticized. Although experimental data are still limited, the application of a treatment strategy that includes antioxidants is justified since antioxidant treatment in human pregnancy for pre-eclampsia was demonstrated to be safe and effective. The available experimental evidence and the safety of vitamins C and E in pregnancy suggest that experimental use of antioxidants in alcohol-consuming mothers should be seriously considered to reduce fetal alcohol damage.