Seizures during Ethanol Withdrawal Are Blocked by Focal Microinjection of Excitant Amino Acid Antagonists into the Inferior Colliculus and Pontine Reticular Formation

Physical dependence on ethanol can result in seizure susceptibility during ethanol withdrawal. In rats, generalized tonic-clonic seizures are precipitated by auditory stimulation during the ethanol withdrawal syndrome. Excitant amino acids (EAAs) are implicated as neurotransmitters in the inferior colliculus and the brain stem reticular formation, which play important roles in the neuronal network for genetic models of audiogenic seizures (AGSs). Ethanol blocks the actions of EAAs in various brain regions, including the inferior colliculus. In this study, dependence was produced by intragastric administration of ethanol for 4 days. During ethanol withdrawal, AGSs were blocked by systemic administration of competitive or noncompetitive NMDA antagonists 3-((±)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) or dizocilpine (MK-801). Focal microinjections of NMDA or non-NMDA antagonists into the inferior colliculus or the pontine reticular formation also inhibited AGSs. MK-801 was the most potent anticonvulsant systemically. When injected into the inferior colliculus, CPP had a more potent anticonvulsant effect than either MK-801 or the non-NMDA antagonist 6-cyano-7-nitroquinoxa-line-2,3-dione. The inferior colliculus was more sensitive than the pontine reticular formation to the anticonvulsant effects of both competitive NMDA and non-NMDA antagonists. The results of the present support the idea that continued ethanol administration may lead to development of supersensitivity to the action of EAAs in inferior colliculus and pontine reticular formation neurons. This may be a critical mechanism subserving AGS susceptibility during ethanol withdrawal.     

Changes in GABAergic and Non-GABAergic Synapses During Chronic Ethanol Exposure and Withdrawal in the Dentate Fascia of LS and SS Mice

Ethanol-sensitive LS_IBG and ethanol-insensitive SS_IBG mice were exposed to ethanol (23.5% ethanol-derived calories) for 4 months. Half of the animals was sacrificed at this time and the other half was withdrawn from the ethanol diet for 1 month. GABA immunoelectron microscopy was used to study the impact of the treatments on synaptic contacts in the dentate molecular layer. In the LS mice a significant loss of non-GABAergic axospinous synapses (26.7%; p < 0.05) was observed during ethanol exposure which was followed by a loss of GABAergic synapses on dendritic shafts (54.7%; p < 0.01) during withdrawal. In the SS mice there was a significant decrease in the non-GABAergic axospinous synapses (23.5%; p < 0.05) and a significant increase in axodendritic synapses (63.3%; p < 0.05) during ethanol exposure. The observed changes in the GABAergic and non-GABAergic innervation of the dentate fascia induced by ethanol were observed in the projection zone of the perforant path. They could adversely affect the hippocampal physiology with a consequent impairment of mnemonic functions.     

Role of Polyamines and NMDA Receptors in Ethanol Dependence and Withdrawal

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chair was John M. Littleton. The presentations were (1) Examination of ethanol spermine and acamprosate actions on native and recombinant NMDA receptors, by David Lovinger; (2) Ethanol inhibition of NMDA neurotoxicity on the polyamine site in cerebellar granule cells, by Sture Liljequist; (3) Alterations in expression of NMDA receptor subunits during ethanol exposure and withdrawal, by Raj Ticku; (4) Alterations in polyamine synthesis and release as a potential mechanism for ethanol dependence and withdrawal, by Izuru Matsumoto; (5) The role of polyamines in neurotoxicity induced by alcohol withdrawal in vitro, by John Littleton; and (6) Agmatine reduces some of the effects of "third trimester" alcohol exposure using a rodent model, by Susan Barron.     

Reduced Gene Expression for Dopamine Biosynthesis and Transport in Midbrain Neurons of Adult Male Rats Exposed Prenatally to Ethanol

BACKGROUND: Prenatal ethanol exposure affects brain dopaminergic neuronal systems, and many of these alterations are permanent. METHODS: The primary objective of this study was to determine the effects of prenatal ethanol exposure on adult mRNA expression for two key regulatory proteins in the mesolimbic and nigrostriatal dopaminergic cell groups which mediate behavioral responses to alcohol and other drugs of abuse: tyrosine hydroxylase (TH) and dopamine transporter (DAT) in the substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA). To also address the effects on noradrenergic regulation, we quantitated mRNA expression for TH and norepinephrine transporter (NET) in the noradrenergic loci of the locus coeruleus (LC). RESULTS: Daily dietary ethanol consumption by female Sprague-Dawley rats for 3 weeks before, and continuing throughout, pregnancy decreased both DAT (approximately 68%,p < 0.002) and TH (approximately 45%,p < 0.002) mRNA expression in the VTA of adult male offspring. This prenatal exposure also suppressed DAT mRNA expression in the SNpc (approximately 81 %;p < 0.03), although TH mRNA expression in this region was not significantly altered. Prenatal ethanol exposure did not alter significantly either TH or NET mRNA expression in the LC of adult male offspring, which suggests that this brain catecholaminergic response may be limited to DA neurons. CONCLUSION: These results demonstrated that prenatal maternal ethanol consumption suppresses mRNA expression for important regulatory proteins in the mesolimbic and nigrostriatal dopaminergic systems of adult male rat offspring. These persistent prenatal ethanol-induced changes in mRNA expression may thus contribute to the persistent effects of fetal ethanol exposure on the diverse behavioral and/or metabolic responses mediated by the mesolimbic and nigrostriatal dopaminergic systems in the adult.     

抗帕颗粒对帕金森病模型大鼠黑质纹状体TH阳性神经元的影响

目的：观察抗帕颗粒对帕金森病模型大鼠黑质纹状体TH阳性神经元的影响。方法：帕金森病(PD)大鼠80只，随机分为4组：对照组、美多巴组、抗帕颗粒组、抗帕颗粒联合美多巴组。于喂养4个月后取黑质纹状体组织免疫组化染色。检测TH阳性神经元的分布、密度。结果：美多巴组黑质TH阳性神经细胞及纹状体TH阳性终末较生理盐水组明显减少。而抗帕颗粒组增多20％～30％。联合组增多最显著达40％～50％。结论：抗帕颗粒可改善PD大鼠黑质纹状体TH阳性神经元的病理改变，抗帕颗粒联合美多巴治疗效果明显。     

人参再造丸联合美多巴对帕金森病模型大鼠黑质纹状体TH阳性神经元的影响

目的:观察人参再造丸联合美多巴对帕金森病模型大鼠黑质纹状体TH阳性神经元的影响.方法:PD鼠80只,随机分为4组:对照组、美多巴组、人参再造丸组、人参再造丸联合美多巴组.于喂养4个月后取黑质纹状体组织免疫组化染色,检测TH阳性神经元的分布、密度.结果:美多巴组黑质TH阳性神经细胞及纹状体TH阳性终末较生理盐水组明显减少,而人参再造丸组略有增多达5%～8%,联合组增多较显著达20%～25%.结论:人参再造丸对PD大鼠黑质纹状体毒性作用较轻,人参再造丸联合美多巴可改善TH阳性神经元的病理改变.     

Novel Synergistic Treatment of Ethanol Withdrawal Seizures in Rats with Dopamine and Serotonin Agonists

A recent observation in this laboratory of a simultaneous increase in striatal dopamine and a decrease in serotonin in ethanol-dependent rats during ethanol withdrawal prompted studies with combined dopaminergic + serotoninergic agonists to stop withdrawal seizures. Amphetamine (2 mg/kg) + fenfluramine (8 mg/kg) given jointly, but not separately, prevented ethanol withdrawal seizures as effectively as benzodiazepines (chlordiazepoxide), the current drugs of choice. The combination of amphetamine and fenfluramine, unlike chlordiazepoxide, significantly reduced intake of ethanol during and immediately following ethanol withdrawal.     

Differential Modulation by the Stress Axis of Ethanol Withdrawal Seizure Expression in WSP and WSR Mice

Withdrawal from both acute and chronic ethanol (EtOH) exposure is associated with increased neural excitability and increased activity of the hypothalamic-pituitary-adrenal axis. There is some evidence that glucocorticoids are necessary for EtOH withdrawal seizure expression. Lines of mice that were selected for severe (WSP) and minimal (WSR) EtOH withdrawal (as estimated from handling-induced convulsion scores) have been shown to differ in their stress response following an acute dose of EtOH. In this study we provide evidence that these lines of mice also differ in their sensitivity to the excitatory effects of glucocorticoids. EtOH withdrawal seizures of WSP mice were significantly increased by chronic and acute corticosterone treatment, whereas those of the WSR mice were unaffected. Neural excitability was decreased in the WSP mice when aminoglutethimide, a glucocorticoid synthesis blocker, was administered. Thus, it appears that genetic differences in EtOH withdrawal seizure severity may be due, in part, to differences in sensitivity to the excitatory effects of glucocorticoids.     

Sex Differences in Rats in the Development of and Recovery From Ethanol Dependence Assessed by Changes in Seizure Susceptibility

BACKGROUND: Previous investigations have found sex differences in rats in response to chronic ethanol exposure. The most dramatic differences were observed with anticonvulsant treatment during ethanol withdrawal, when seizure susceptibility is significantly increased. Sex differences in this response were found for both GABAergic and glutamatergic compounds. This study was aimed at exploring whether sex also influences the timing for the development of and recovery from ethanol dependence. METHODS: Ethanol was administered in a liquid diet, with pair-fed animals receiving dextrose, substituted isocalorically for the ethanol. Ethanol dependence and withdrawal were assessed by measurement of seizure thresholds after abrupt removal of the ethanol diet. Seizure thresholds were determined by slow, tail vein infusion of the gamma-aminobutyric acidA-receptor antagonist bicuculline. RESULTS: Male and female rats displayed differences in timing for both onset and recovery from ethanol dependence, as determined by changes in ethanol withdrawal seizure susceptibility. Female rats were slower to develop dependence and quicker to recover compared with male rats. Furthermore, acute ethanol administration did not alter seizure susceptibility in pair-fed control animals, but it was anticonvulsant in ethanol-withdrawn rats. Ethanol-withdrawn female rats showed a greater response to acute ethanol administration than did male rats. CONCLUSIONS: This set of experiments uncovered additional sex differences in one measure of ethanol dependence and withdrawal. Proposed mechanisms for the development of ethanol dependence involve alterations in subunit assembly of gamma-aminobutyric acidA and NMDA receptors or various posttranslational modifications. In consideration of these findings, whatever mechanisms underlie the development of ethanol dependence, there is a different sequence of events in male compared with female rats. Studies are ongoing to determine associations between behavioral measures of ethanol dependence/withdrawal and selective neuronal adaptations.     

Morphine-Induced Changes of Adenylate and Guanylate Cyclase in Locus Ceruleus,Periaqueductal Gray,and Substantia Nigra in Rats

Objectives: To observe the changes of adenylate cyclase (AC) and guanylate cyclase (GC) in the cerebral regions including the locus ceruleus, periaqueductal gray, and substantia nigra in rats that were physiologically dependent on morphine. We also investigated the relationship of enzymatic changes in these cerebral regions to the mechanism of morphine dependence. Methods: A morphine-dependent rat model was established and withdrawal symptoms evaluated. Enzyme histochemistry was used to detect the variations of AC and GC in cerebral regions. Results: Compared to controls, AC and GC significantly increased in morphine-dependent groups. Comparisons of four different morphine-dependent groups also showed AC and GC significantly differed at weeks 1, 2, 4, and 8. Conclusions: Results found that the content of AC and GC increased in these cerebral regions in rats that demonstrated morphine dependence and appeared to be closely linked to increases in AC and GC activity.     

Superior vena cava obstruction by tumour thrombus in invasive thymoma: diagnosis and surgical management

Thymomas are common mediastinal tumours. We report a rare case of thymoma invasion into the superior vena cava with resultant venous obstruction. The tumour was resected. The superior vena cava and left brachiochephalic vein were reconstructed with autologous pericardial patch.     

Differential Changes in Sucrose/Ethanol and Sucrose Maintained Responding by Independently Altering Ethanol or Sucrose Concentration

Increased reinforcing efficacy of sucrose/ethanol solutions in comparison to sucrose solutions has been previously demonstrated. However, the contribution of the components of the sucrose/ethanol solution is not well defined. The present study used a multiple schedule of reinforcement to evaluate the differential changes in reinforcer presentations as sucrose or ethanol concentrations were altered. Male Long-Evans rats were trained to press a lever on a multiple fixed ratio 4-fixed ratio 4 schedule which was composed of alternating 2-min components. During one component, 5% sucrose/10% ethanol was presented as the reinforcer and, in the second component, 5% sucrose was presented. Independent manipulations of the ethanol concentration (0,5, and 20%) in the sucrose/ethanol solution or sucrose concentration (0, 10, and 20%) in the sucrose solution were then performed. Increasing the ethanol concentration in the sucrose/ethanol solution resulted in decreases in reinforcer delivery but increases in ethanol intake (grams per kilogram) and total session caloric intake. Increasing the sucrose concentration in the sucrose solution resulted in significant increases in sucrose reinforcer delivery and total session caloric intake. During the concentration manipulations, the number of reinforcers presented of the unchanged reinforcer was not affected. Differential changes in the pattern of reinforcer presentation after ethanol and sucrose concentration manipulations during successive access periods suggest that sucrose and sucrose/ethanol maintained responding are differentially regulated. Changes in sucrose maintained responding after increases in the sucrose concentration were observed early in the session suggesting a strong influence of taste in regulating intake. Changes in sucrose/ethanol maintained responding after increases in the ethanol concentration occurred later in the session and suggest that postingestive effects (i.e., pharmacology) play a major role in the regulation of sucrose/ethanol intake. In addition, the differential patterns of sucrose/ethanol and sucrose maintained behavior suggest that the ethanol component of the sucrose/ethanol solution plays an important role in maintaining sucrose/ethanol reinforced behavior.     

Changes in lipid composition in hippocampus early and late after status epilepticus induced by kainic acid in wistar rats

Oxidative damage to biological membranes has been reported as a cause of alterations in many different diseases. We had previously reported lipid peroxidation in the kainic acid model of temporal epilepsy. In this study we evaluated earlier and later modifications in the lipid composition after status epileticus induced by kainic acid. Lipid composition was determined by thin-layer chromatography, in the cortex and hippocampus 12–14 h, 7–8, 75–80, or 140–150 days after the end of status epileticus. In the hippocampus there was a significant change in the lipid protein ratio after status epileticus and this was accompanied by an alteration in lipid composition in all tested times. These results suggested that lipid peroxidation induced by kainic acid could be accompanied by chronic changes in the lipid composition that could be related to the development of seizures.     

Antagonism of Ethanol by Pretreatment or Posttreatment with RO 15–4513 and Indomethacin Alone or in Combination

RO 15–4513, an inverse agonist at the GABA/benzodiazepine receptor Cl^- channel complex, antagonizes multiple effects of ethanol. Prostaglandin synthesis inhibitors, such as indomethacin, also antagonize several effects of alcohols. However, prostaglandin synthesis inhibitors and RO15–4513 each provide only partial antagonism of ethanol, typically seen as a dose-related effect with a maximum efficacy of ?50%. The purpose of this study was to: (1) compare the relative efficacy of these compounds for antagonizing ethanol; (2) compare the effectiveness of preethanol treatment versus postethanol treatment with each drug; and (3) compare the effect of RO 15–4513 and indomethacin in combination with the effects of each drug alone. The results show that indomethacin significantly decreased duration of loss of the righting reflex when administered either pre-or postethanol. Conversely, RO 15–4513 decreased duration of loss of the righting reflex only when given preethanol. When coadministered, RO 15–4513 and indomethacin did not show additive or synergistic effects. Compounds from these two drugs classes should continue to prove useful in elucidating ethanol's mechanisms of action.     

Ethanol-Induced Changes in Chloride Flux are Mediated by Both GABAA and GABAB Receptors

Low concentrations of ethanol (10-30 mM) in the presence of a GABAB receptor agonist, baclofen, promoted 36Cl- uptake into membrane vesicles (microsacs) prepared from mouse cortex. Neither ethanol nor baclofen alone altered chloride influx. The GABAB antagonists, phaclofen and 2-hydroxy-saclofen, completely blocked the increase in chloride flux produced by ethanol in the presence of either baclofen or GABA. Ethanol increased the chloride conductance produced by the GABAA agonists muscimol, isoguvacine, imidazolacetic acid and amino-propane sulfonic acid and this action of ethanol was blocked by phaclofen. The specific GABAA antagonist, bicuculline, blocked ethanol-induced increase in chloride flux in the presence of either baclofen or GABA. GABA-activated chloride channels were also studied in Xenopus oocytes expressing mouse brain mRNA. In this preparation, GABA action was enhanced by ethanol, pentobarbital, and diazepam, and 2-hydroxy-saclofen partially antagonized the action of ethanol without altering the effects of pentobarbital or diazepam. These results suggest that ethanol enhancement of GABAA receptor-chloride channel function also requires activation of GABAB receptors.     

Sorption and Micro-Scale Strength Properties of Coals Susceptible to Outburst Caused by Changes in Degree of Coalification

Coals from the south-western part of the Upper Silesian Coal Basin have a strong outburst susceptibility. The objective of this study was to identify the influence of coalification degree on methane sorption and micro scale strength properties of 24 coals from Jastrzębie Zdrój. Coal samples showed a reflectance R_o between 0.98 and 1.25%. Sorption measurements were carried out by gravimetric method. Sorption capacities were determined at mean deposit temperature of 35 °C. Using the unipore model and solution of Fick’s second law, the effective diffusion coefficients of methane in the studied coals were obtained. The Vickers method was used to study the microhardness and the modulus of elasticity. It has been shown that the increase in the coalification degree reduces the sorption capacity of coal and also reduces the rate of methane emission. Coals the most susceptible to outbursts, were the most brittle. With the increase in R_o, the methane seam pressure p increased as well as desorbable methane content DMC, both due to the reduction in the sorption capacity of coal. The increased dp index is a warning sign indicating an increased total methane content of coal seam, an increased seam pressure or an alternation of coal structure.