Dipyrone inhibits ethanol withdrawal and pentylenetetrazol‐induced seizures in rats

The effects of dipyrone, a nonnarcotic analgesic drug, on ethanol withdrawal and pentylenetetrazol (PTZ)‐induced seizures in male Wistar rats were investigated. Ethanol (7.2%) was given to rats by a liquid diet for 21 days. After 6 h of ethanol withdrawal, rats were exposed to an audiogenic stimulus (100 dB) for 60 sec for induction of seizures. Dipyrone (50, 100, and 200 mg/kg ip) and saline were administered to rats 30 min before audiogenic stimulus, and the effects of dipyrone on the seizures induced by audiogenic stimulus were evaluated. The effects of dipyrone on PTZ‐induced seizures were also evaluated in other individual groups of the rats. The same doses of dipyrone were injected in the rats ip 30 min before PTZ (50 mg/kg) injections. Immediately after PTZ injections, onset time and severity of the convulsions were recorded. Dipyrone significantly and dose‐dependently reduced both incidence and intensity of the ethanol withdrawal‐associated audiogenic seizures. It also inhibited significantly and dose‐dependently intensity but not onset time of the PTZ‐induced seizures. Dipyrone (50–200 mg/kg) did not produce any significant change in locomotor activity in naive rats. Our results suggest that dipyrone has some prominent anticonvulsant activities on both ethanol withdrawal and PTZ‐induced seizures in rats, and that using dipyrone may be a new and effective therapeutic approach in the treatment of seizures. Drug Dev. Res. 53:254–259, 2001. © 2001 Wiley‐Liss, Inc.     

Dopaminergic and serotonergic alterations in the rat brain during ethanol withdrawal: association with behavioral signs

Changes in dopaminergic and serotonergic levels and metabolites in cerebral cortex, corpus striatum and hippocampus were investigated during the first 6-h of withdrawal in ethanol-dependent Wistar rats. Ethanol was given by a liquid diet for 21 days. The concentration of ethanol was 7.2% (v/v) for the last 15 days of the exposure. After 2, 4 and 6 h of ethanol withdrawal, and after audiogenic stimulus (100 dB for 60 s) at 6 h of ethanol withdrawal, various brain regions were assayed for levels of dopamine (DA), DOPAC, HVA, serotonin (5-HT) and 5-HIAA. Behavioral signs of ethanol withdrawal and blood ethanol levels were also evaluated in other parallel groups of ethanol-dependent rats. Significant decreases in 5-HT levels and significant increases in HVA levels in striatum were found during the first 6 h of ethanol withdrawal and after the audiogenic seizures. In hippocampus, 5-HIAA levels were significantly reduced after 2 h of ethanol withdrawal and after the audiogenic seizures. 5-HIAA levels significantly increased after 2 h of ethanol withdrawal in cerebral cortex. Significant increases in both DA and 5-HT levels were also found in cerebral cortex after the audiogenic seizures. The results suggest that the levels of DA, 5-HT and their metabolites are altered by ethanol withdrawal. Furthermore, this may suggest that DA and 5-HT may be involved in the first 6 h of ethanol withdrawal syndrome in rats.     

Acute intracerebroventricular injections of the mast cell degranulator compound 48/80 and behavior in rats

The intracerebroventricular (ICV) injection of the mast cell degranulator Compound 48/80 (2.5-2.0 micrograms/kg) produced a marked behavioral syndrome in normotensive rats. The behaviors included head and body shakes, paw tremor, excessive grooming, unusual posture and gait, mild diarrhoea, piloerection, extreme agitation and irritability to touch, and a later phase of sedation. The highest doses (15 and 20 micrograms/kg) also produced catalepsy and episodes of "barrel rolling" (continuous rolling of 1-8 turns around the longitudinal axis). These behaviors were observed for approximately 15-30 min although the sedation and catalepsy were maintained for 90-120 min. A second ICV injection of the 10 micrograms/kg dose of Compound 48/80 given 2 hr after an initial injection of this dose, produced a much reduced response and the numbers of head and body shakes, and episodes of paw tremor and grooming were between 20-30% of those produced by the first injection. The reduced effect of the second injection indicates that the behavioral effects of Compound 48/80 may arise from the acute degranulation of mast cells rather than direct effects on neuronal populations or the cerebral vasculature.     

N-Methyl-D-aspartic acid- and metaphit-induced audiogenic seizures in rat model of seizures.

The effects of NMDA (N-methyl-D-aspartic acid) on metaphit (1-[1(3-isothiocyanatophenyl)-cyclohexyl]piperidine)-induced audiogenic seizures in adult male Wistar albino rats were studied with the aim of developing a suitable animal model of seizures. The animals were divided into four experimental groups: 1, saline control; 2, metaphit-injected; 3, metaphit + NMDA administered and 4, NMDA-treated. Upon the treatment, the rats were exposed to sound stimulation (100 +/- 3 dB, for 60 s) at hourly intervals and the incidence and severity (running, clonus and tonus) of seizures were analysed. In group 3, only the animals which did not exhibit any metaphit-induced audiogenic seizures over 8 h were given a subconvulsive NMDA dose after the eighth audiogenic testing. For EEG recordings, three gold-plated screws were implanted into the rat skull. In most animals, metaphit led to EEG abnormalities and elicited epileptiform activity recorded as spikes, polyspikes and spike-wave complexes. Maximum incidence and severity of metaphit-induced convulsions occurred 8 h after injection (incidence 9/12), abating gradually until disappearing 30 h later. NMDA alone provoked no seizure response but the initial signs characterized by isolated spike activity evolving into sporadic slow-wave complexes, thus representing a proconvulsive brain state, were observed. This compound led to stereotyped behaviour seen as asymmetric posture, loss of righting reflex and tonic hind limb extension lasting for 60-90 min. It also potentiated metaphit-induced audiogenic seizures. Potentiation of metaphit-related audiogenic seizures by NMDA was recorded in three out of 17 rats that had never displayed seizures in eight previous testings, with a maximum incidence of eight out of 17 animals, 13-14 h after metaphit administration and seizures lasted for 10 h.     

粉防己碱对小鼠吗啡戒断症状的影响

目的··：研究中药成分的钙拮抗剂粉防己碱（Ｔｅｔ）对小白鼠吗啡戒断症状的影响。方法··：以剂量递增法形成吗啡依赖模型,用纳洛酮催促戒断。结果··：ｓｃ给药,Ｔｅｔ１０ｍｇ·ｋｇ－１抑制“湿狗”样抖动、腹泻、前爪震颤症状;Ｔｅｔ３０ｍｇ·ｋｇ－１抑制打洞、上睑下垂、前爪震颤、体重下降等症状;Ｔｅｔ６０ｍｇ·ｋｇ－１抑制“湿狗”样抖动、打洞、腹泻、前爪震颤、体重下降等症状。３个剂量组的Ｔｅｔ都不影响小鼠的跳跃反应。结论··：Ｔｅｔ能抑制大部分吗啡戒断症状。     

Effects of chronic ethanol administration and ethanol withdrawal on cyclic guanosine 3',5'-monophosphate (cGMP) levels in the rat brain

The main objective of the present study is to investigate the possible effects of chronic ethanol consumption and ethanol withdrawal on cyclic guanosine 3', 5'-monophosphate (cGMP) levels in cerebral cortex, striatum, hippocampus and hypothalamus of rat brain. Ethanol was given to female Wistar rats (225-270g) by a liquid diet for 21 days. cGMP levels were measured in respective brain regions using an EIA kit at 7th, 14th and 21st days of ethanol ingestion and at 6th and 24th h of ethanol withdrawal. cGMP levels in cortex, striatum and hippocampus but not hypothalamus were found significantly increased at 14th and 21st days of ethanol consumption. The most prominent increase was observed in striatal tissues (approximately 350%). cGMP levels of striatum and hippocampus were still remaining significantly high at 6th h of ethanol withdrawal. Blood ethanol levels were found as 115.60, 50.0 and 7.0mg/dl just before and after 6 and 24h of ethanol withdrawal, respectively and audiogenic seizures also occurred at 6th h of ethanol withdrawal with an incidence of 75% in individual parallel groups. Our results suggest that changes of cGMP levels in cerebral cortex, striatum and hippocampus might participate in the mechanism of ethanol dependence and withdrawal in rats.     

三氟拉嗪抑制吗啡依赖大、小鼠纳洛酮催促的戒断症状

目的　研究三氟拉嗪对吗啡依赖大、小鼠纳洛酮催促戒断症状的影响 ,并探讨其机制。方法　吗啡依赖大、小鼠纳洛酮催促实验。结果　三氟拉嗪 (2～ 2 0mg·kg-1)呈剂量依赖性抑制吗啡依赖小鼠纳洛酮催促所致的跳跃、湿狗样抖动、前爪震颤和体重下降。三氟拉嗪 5～ 2 0mg·kg-1ip ,对吗啡依赖大鼠大部分纳洛酮催促的阳性戒断症状均具有明显的抑制作用 ,其中包括跳跃、湿狗样抖动、排泄物、体重下降、咬牙、流涎、腹泻、上睑下垂、激惹。作为DA1/DA2 受体激动剂 ,阿朴吗啡 (2～ 8mg·kg-1)对三氟拉嗪抑制吗啡依赖小鼠纳洛酮催促戒断症状无明显影响 ,而钙通道阻滞剂硝苯吡啶 (5～ 2 0mg·kg-1)则呈剂量依赖性加强三氟拉嗪对吗啡依赖小鼠纳洛酮催促戒断症状的抑制作用。结论　三氟拉嗪对吗啡依赖大、小鼠纳洛酮催促的戒断症状具有明显的抑制作用。对受体后钙调素生物活性的抑制作用可能是三氟拉嗪抗吗啡依赖大、小鼠躯体戒断症状主要机制 ,而中枢神经系统DA2 受体可能不参与三氟拉嗪对吗啡躯体戒断症状的抑制作用     

Oral administration of glycine and polyamine receptor antagonists blocks ethanol withdrawal seizures

Cessation of chronic administration of orally administered large amounts of ethanol for 7 days resulted in a markedly increased frequency of audiogenic seizures in Sprague-Dawley rats. Oral administration of the novel glycine receptor antagonist, L-701,324, produced a dose-dependent (2.5 and 5.0 mg/kg; –30 min) inhibition of ethanol withdrawal signs when measured about 12 h after withdrawal of the ethanol treatment. Similarly, using the same experimental paradigm, oral administration of the specific polyamine receptor antagonist, eliprodil, caused a dose-related (2.0 and 5.0 mg/kg; –30 min) inhibition of ethanol withdrawal-induced audiogenic seizure activity. The inhibition of ethanol withdrawal seizures produced by L-701,324 and eliprodil, respectively, was obtained at doses which by themselves did not change the locomotor activity in naive Sprague-Dawley rats. The findings that L-701,324 and eliprodil are potent inhibitors of seizure activity induced by cessation of chronic ethanol administration and the fact that they, in contrast to currently available NMDA receptor antagonists, do not produce psychotomimetic and/or sedative effects, suggest that these drugs may represent a new class of therapeutically useful pharmacological agents for the treatment of ethanol withdrawal seizures. Furthermore, since there is evidence that eliprodil produces its pharmacological actions through a specific inhibition of NMDAR1 and/or NMDAR2B subunits, these data may indicate that certain NMDA receptor subunits may be of particular importance for the mediation of seizure activity following the discontinuation of chronic ethanol exposure.     

Oral administration of glycine and polyamine receptor antagonists blocks ethanol withdrawal seizures

Cessation of chronic administration of orally administered large amounts of ethanol for 7 days resulted in a markedly increased frequency of audiogenic seizures in Sprague-Dawley rats. Oral administration of the novel glycine receptor antagonist, L-701,324, produced a dose-dependent (2.5 and 5.0 mg/kg; − 30 min) inhibition of ethanol withdrawal signs when measured about 12 h after withdrawal of the ethanol treatment. Similarly, using the same experimental paradigm, oral administration of the specific polyamine receptor antagonist, eliprodil, caused a dose-related (2.0 and 5.0 mg/kg; − 30 min) inhibition of ethanol withdrawal-induced audiogenic seizure activity. The inhibition of ethanol withdrawal seizures produced by L-701,324 and eliprodil, respectively, was obtained at doses which by themselves did not change the locomotor activity in naive Sprague-Dawley rats. The findings that L-701,324 and eliprodil are potent inhibitors of seizure activity induced by cessation of chronic ethanol administration and the fact that they, in contrast to currently available NMDA receptor antagonists, do not produce psychotomimetic and/or sedative effects, suggest that these drugs may represent a new class of therapeutically useful pharmacological agents for the treatment of ethanol withdrawal seizures. Furthermore, since there is evidence that eliprodil produces its pharmacological actions through a specific inhibition of NMDAR1 and/or NMDAR2B subunits, these data may indicate that certain NMDA receptor subunits may be of particular importance for the mediation of seizure activity following the discontinuation of chronic ethanol exposure.     

Myo-inositol attenuates the enhancement of the serotonin syndrome by lithium

Lithium elicits opposite effects on two behavioural syndromes in rats: enhancement of the 5-HT_1A-linked serotonin syndrome and attenuation of the 5-HT₂-linked wet dog shakes. The ability of intracerebroventricular (ICV)myo-inositol or forskolin to reverse the enhancement of the serotonin syndrome by lithium was tested in rats that were fed chronic dietary lithium or control diet and injected with the serotonin agonist 5-MeODMT (5-methoxy-N, N-dimethyltryptamine). Lithium enhanced the total serotonin syndrome score and particularly flat posture and tremor. Inositol, but not forskolin, mitigated the effects of lithium. Inositol was also injected in the lateral ventricle of rats pretreated with chronic dietary lithium or regular rat chow for 3 weeks and injected with carbidopa andl-5-hydroxytryptophan (5-HTP). Lithium attenuated wet dog shakes, but inositol had no significant effect on lithium-treated or control rats. These findings suggest that the enhancement of the serotonin syndrome by lithium may be related to lithium-induced inositol depletion.     

Effect of ethanol and ethanol withdrawal on 3H-muscimol binding and behaviour in the rat: a pilot study

Effect of acute and chronic exposure to and withdrawal from ethanol on 3H-muscimol binding in the forebrains and cerebelli and on withdrawal behaviour was investigated in 30 rats. Chronic exposure to and withdrawal from ethanol produced a significant reduction in the number of muscimol binding sites in the cerebelli. A negative correlation was observed between the number of muscimol binding sites in the forebrain and cerebellum in the chronic ethanol and withdrawal groups. Relatively high correlations were found between the number of muscimol binding sites and audiogenic seizures scores during withdrawal from ethanol. Since impaired GABAergic function is associated with increased susceptibility to seizures, there may be a casual relationship between the observed changes in muscimol binding and ethanol-induced audiogenic withdrawal seizures.     

The role of group I mGlu receptors in the expression of ethanol-induced conditioned place preference and ethanol withdrawal seizures in rats

In animal models, N-methyl-d-aspartate (NMDA) receptors antagonists inhibit physical dependence and the reinforcing effects of ethanol. The group I metabotropic glutamate (mGlu) receptors antagonists (mGlu1 and mGlu5) attenuate excitatory effect of glutamate by functional modulation of the glutamate/NMDA receptors. The objective of the present study was to evaluate the effects of a selective mGlu5 receptors antagonist—MTEP, and mGlu1 receptors antagonist—EMQMCM, on two processes relevant to alcohol addiction: the expression of ethanol-induced conditioned place preference (CPP) paradigm, and ethanol withdrawal audiogenic seizures in rats. Our experiments indicated that EMQMCM at the doses of 5 and 10 mg/kg, and MTEP at the doses of 2.5 and 5 mg/kg, significantly attenuated the expression of ethanol CPP. Furthermore, both group I mGlu receptor antagonists, i.e. EMQMCM at the dose of 10 mg/kg and MTEP at the dose of 5 mg/kg, attenuated audiogenic seizures induced by the sound stimulus 12 h after withdrawal of ethanol in dependent rats. Our study shows the importance of mGlu5 and mGlu1 receptors for the expression of ethanol-induced CPP and withdrawal seizures, although mGlu5 receptors antagonist (MTEP) was more potent than the antagonist of mGlu1 receptors (EMQMCM).     

Morphine withdrawal in mice selectively bred for differential sensitivity to ethanol

Mice which have been selectively bred for differences in sensitivity to acute doses of alcohol have also been shown to differ in severity of seizures upon withdrawal from chronic alcohol administration. We investigated the responsiveness of these mice to withdrawal from chronic morphine treatment. Mice were made dependent on morphine via pellet implantation, and withdrawal was precipitated with naloxone challenge. Mice which are less sensitive to the hypnotic effects of ethanol (short sleep: SS) displayed more jumping and wet dog shakes during withdrawal than did the more senstive long sleep (LS) mice. In addition, the amount of jumping was dependent on the dose of naloxone in both lines. Differences between lines in naloxone precipitated withdrawal may reflect differences in alterations in extrapyramidal dopaminergic activity, but other substrates for the observed differences cannot be discounted. Finally, the observed difference between SS and LS mice in severity of morphine withdrawal parallels the previously reported difference between these lines in seizure severity during withdrawal from alcohol.     

Changes in benzodiazepine-receptor activity modify morphine withdrawal syndrome in mice

The effects of different benzodiazepine-receptor ligands on morphine withdrawal were studied: a benzodiazepine agonist, flunitrazepam; a benzodiazepine antagonist, flumazenil; a partial inverse benzodiazepine agonist, Ro 15-4513; and a partial benzodiazepine agonist, Ro 16-6028. Benzodiazepine-ligands were administered i.p. 30 min before naloxone-induced morphine withdrawal syndrome. Jumping behaviour was significantly increased by Ro 15-4513 at 10 and 20 mg/kg. Flunitrazepam decreased jumps at all the doses used. Wet dog shakes were decreased by flumazenil and Ro 15-4513 and increased by Ro 16-6028 (only at the highest dose) and flunitrazepam. Our results show that the activation of the benzodiazepine receptor by agonists or high doses of partial agonists decreases jumping and increases wet dog shake behaviour, while the antagonists or the partial inverse agonists enhance jumping and decrease wet dog shakes. These modifications could be interpreted as an attenuation in the severity of the morphine withdrawal syndrome by benzodiazepine agonists.     

Appearance of wet dog shake behavior during cobalt experimental epilepsy in the rat and its suppression by reserpine

Rats rendered chronically epileptic by the implantation of cobalt in the right parietal cortex were simultaneously prepared with permanent cortical and temporalis muscle electrodes for longitudinal EEG and EMG recording. Animals treated similarly with glass rods served as the controls. Wet dog shakes were quantified by counting the characteristic artifacts produced in the EEG tracings upon their appearance. The number of wet dog shakes exhibited by the control rats remained at a low and constant level over 18 days of recording. In contrast, wet dog shakes in the chronically epileptic rats began to increase by the fourth day after cobalt placement and remained significantly elevated up to the 18th day. Administration of reserpine to naive rats or to cobalt epileptic rats on days 7 and 9 after implantation resulted in an almost complete suppression of wet dog shakes which endured over a period of 3–5 days. These results suggest that the abnormally elevated wet dog shake response of the cobalt-epileptic rats and the spontaneous wet dog shake behavior of normal rats may be mediated by common neural pathways.A preliminary report on this work appeared in Pharmacologist 16, 325 (1974).     

The role of GABA in morphine abstinence in rats

GABA mimetics such as baclofen, aminooxyacetic acid (AOAA) and diazepam decreased naloxone-precipitated abstinence wet dog shakes in morphine dependent rats. The GABA antagonists bicuculline and picrotoxin were not effective in small doses. The inhibition of wet dog shakes by baclofen, AOAA and diazepam was not reversed by bicuculline. This suggests that baclofen, AOAA and diazepam may inhibit morphine wet dog shakes not by direct GABA receptor stimulation. Inhibition by baclofen of wet dog shakes was reversed by 5-hydroxytryptophan (5-HTP) suggesting that the inhibiting effects of GABA mimetics are mediated by serotoninergic neurons.     

Electroencephalographic correlates of audiogenic seizures during ethanol withdrawal in mice

C57BL/6Bg mice had silver bead electrodes chronically implanted on the surface of the cortex and had their cortical EEG recorded during audiogenic seizures following ethanol withdrawal. For 7 days, the experimental groups were fed a liquid diet containing 6% v/v ethanol ad lib as the only source of food and water. The control group was fed a similar diet containing an isocaloric amount of sucrose. The cortical EEG's of experimental and control groups before, during, and after treatment were virtually identical. Only the experimental group was susceptible to audiogenic seizures. During audiogenic seizures, the cortical EEG showed no sign of spike waves or paroxysmal activity. This is in contrast to picrotoxin convulsions with these same mice as well as to spontaneous convulsions in animals following ethanol withdrawal. Similar EEG observations have been reported on audiogenic seizures from genetic and acoustically primed susceptibilities. Consequently, we suggest that all audiogenic seizure responses, including those during ethanol withdrawal, are a type of subcortical epilepsy.     

Dextromethorphan attenuates ethanol withdrawal syndrome in rats

The effects of dextromethorphan (DM), a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptors, have been investigated on ethanol withdrawal signs in rats. Ethanol (7.2% v/v) was given to rats in a liquid diet for 16 days. DM (10, 20, and 40 mg/kg) and saline were injected intraperitoneally at the third hour of ethanol withdrawal. DM (40 mg/kg) and ethanol dependent saline were also administered to ethanol naive rats. DM (40 mg/kg) did not produce any significant change in locomotor activity in ethanol naive rats. The effects of DM on locomotor activity and total ethanol withdrawal score were evaluated at the fourth and sixth hours of ethanol withdrawal. DM inhibited locomotor hyperactivity at these periods. DM also reduced total ethanol withdrawal score from the fourth hour to the sixth hour, and it significantly decreased audiogenic seizures. Seizure susceptibility after chronic ethanol exposure may be dependent upon sensitization or upregulation of NMDA processes and NMDA receptors. Our results suggest that inhibition of NMDA receptors by DM alleviates signs of ethanol withdrawal.     

The prevention of ethanol withdrawal seizures in rats by dipropylacetate

Dipropylacetate, an antiepileptic agent and γ-aminobutyric acid-transaminase inhibitor, was tested for its effect on withdrawal symptoms in rats made physically dependent on ethanol by intragastric administration. If given together with the last dose of ethanol or continuously during the intoxication period, the drug effectively prevented both audiogenic seizures and loss of pain responses during the withdrawal state. These symptoms were not prevented if the drug was given 12 hr after the withdrawal of ethanol, when no detectable levels of ethanol were present in the blood. Voluntary alcohol consumption of rats was slightly but insignificantly increased by dipropylacetate. Controlled clinical trials are needed before dipropylacetate can be recommended for prevention of seizures occurring after sudden cessation of prolonged ethanol intoxication in man.     

Ethanol withdrawal seizure susceptibility is associated with upregulation of L- and P-type Ca2+ channel currents in rat inferior colliculus neurons

Calcium currents in the inferior colliculus (IC) are thought to play an important role in ethanol withdrawal hyperexcitability. Here, we report on the modulation of Ca(2+) channel currents in acutely dissociated IC neurons of rats, exhibiting higher incidence of audiogenic seizures when subjected to ethanol withdrawal. Whole cell Ca(2+) channel currents were activated by depolarizing pulses from a holding potential of -90 mV, in 10 mV increments, using barium (Ba(2+)) as the charge carrier. The high threshold voltage-activated (HVA) Ca(2+) channel current density increased significantly in IC neurons following ethanol withdrawal. The gating parameters of HVA Ca(2+) channel currents were only slightly altered, while the fraction of current that did not fully inactivate at positive potentials increased significantly following ethanol withdrawal. Pharmacological dissection of HVA Ca(2+) channel currents suggested that the enhanced current, associated with increased incidence of audiogenic seizures following ethanol withdrawal, was carried by L- and P-type Ca(2+) channels. The upregulation of L- and P-type currents may be responsible for IC neuronal hyperexcitability associated with increased susceptibility to ethanol withdrawal seizures.