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Naltrexone effects on diazepam intoxication and pharmacokinetics in humans.

The opiate antagonist naltrexone (NTX) blocks relapse drinking in alcoholics and modifies some of the subjective effects of alcohol intoxication. Benzodiazepines have demonstrated cross-dependence and cross-tolerance to alcohol. Furthermore, benzodiazepine intoxication has effects on mood and psychomotor performance that are similar to alcohol intoxication. The effects of NTX on diazepam intoxication were investigated in non-drug abusing individuals. Eighteen men and eight women were randomly assigned to receive either 50 mg NTX or placebo PO, on two different occasions in a within-subjects, crossover, double-blind protocol. Diazepam was taken by mouth, 90 min after NTX. At -90, 45, 75, 135, 210 min, subjects were tested with repeated assessments of several mood and sensation scales and a computer-generated psychomotor test battery (CTB). Blood samples were also obtained and analyzed for serum diazepam levels. Diazepam induced several sensations and mood effects similar to those induced by alcohol. Negative mood states such as sedation, fatigue, and anxiety were higher for NTX than for placebo. Positive mood states such as friendliness, vigor, liking the effects of diazepam, and feeling high from diazepam were all lower for NTX than for placebo. There were no group differences on the CTB performance. NTX delayed the time to reach peak diazepam levels, so that peak levels occurred at 75 min for placebo compared to 135 min for NTX. A sub-analysis was conducted with 14 subjects who were FHP for alcoholism, but no differences were found on these outcome measures.

Adult↗

Characterization of the behavioral profile of the non-peptide CRF receptor antagonist CP-154,526 in anxiety models in rodents. Comparison with diazepam and buspirone.

The present series of experiments compared the behavioral effects of the novel non-peptide CRF antagonist CP-154,526 with those of diazepam and the 5-HT1A receptor partial agonist buspirone in classical animal models of anxiety including conflict tests (punished lever pressing and punished drinking tests in rats) and exploratory models (elevated plus-maze test in rats, light/dark choice and free-exploration tests in mice), and a recently developed mouse defense test battery (MDTB) which has been validated for the screening of anxiolytic drugs. Results from both conflict procedures showed that diazepam (2.5-10 mg/kg, i.p.) produced clear anxiolytic-like effects, whereas buspirone (2.5 mg/kg, i.p.) displayed anticonflict activity in the punished drinking test only. CP-154,526 (0.6-20 mg/kg) was devoid of significant activity in both procedures. In the elevated plus-maze, diazepam (2 mg/kg, i.p.) produced significant effects on traditional (i.e. spatio-temporal) and ethologically derived (i.e. risk assessment and directed exploration) indices of anxiety. Buspirone (1-4 mg/kg, i.p.) reduced risk assessment activities only, and CP-154,526 (0.6-20 mg/kg, i.p.) did not modify the indices of anxiety in the elevated plus-maze. In the light/dark test, diazepam (2.5-5 mg/kg, i.p.) and CP-154,526 (10-40 mg/kg, i.p.) affected all behavioral indices of anxiety, while buspirone reduced risk assessment activities at the highest doses only (10 and 15 mg/kg, i.p.). In the free-exploration test, diazepam (1 mg/kg, i.p.) reduced avoidance responses towards novelty, as indicated by the increase in exploratory activity in a novel compartment and the decrease in risk assessment. CP-154,526 failed to affect the former behavior and weakly reduced the latter (5 and 20 mg/kg, i.p.). Buspirone (1.25-5 mg/kg, i.p.) was inactive in this test. Finally, in the MDTB, diazepam (0.5-3 mg/kg, i.p.) attenuated all defensive reactions of mice confronted with a rat stimulus (i.e. flight, risk assessment and defensive attack) or with a situation associated with this threat (i.e. contextual defense). Buspirone (1.25-5 mg/kg, i.p.) reduced defensive attack and contextual defense, while CP-154,526 (5-20 mg/kg, i.p.) affected all defensive behaviors, with the exception of one risk assessment measure. The finding that CP-154,526 displayed positive effects in mice but not in rats may be due to increased sensitivity to environmental stress of the strains used (i.e. BALB/c, Swiss) and/or to the fact that animals were exposed to unavoidable stress stimuli which may lead to a significant activation of the CRF system. Although in mice the anxiety-reducing potential of CP-154,526 is superior to that of the atypical anxiolytic buspirone, it is smaller in terms of the magnitude of the effects and the number of indices of anxiety affected than that of diazepam.

Animals↗

Proactive interference and temporal context encoding after diazepam intake.

Two experiments were designed to test whether the memory impairment induced by benzodiazepines (BZDs) is due to impaired memory for temporal context. In both experiments, subjects were administered either diazepam (15 mg oral) or placebo, and a standard BZD impairment on prose recall as well as a decreased subjective arousal was found. Key tasks to explore temporal context memory were an A-B A-C proactive interference paradigm and a list discrimination task. Initial learning of both groups on these tasks was broadly matched. In experiment 1, diazepam did not increase susceptibility to proactive interference using semantically related words. However, in experiment 2, using unrelated word pairs, diazepam markedly increased the number of prior list intrusions. Furthermore, after diazepam intake, subjects were clearly impaired in learning unrelated word pairs. Subjects after diazepam intake were not impaired in the list discrimination task. We conclude that (1) diazepam impairs the forming of new associations, whether this is the formation of links between two or more targets or between targets and context, (2) a temporal context encoding deficit cannot account for a broader diazepam-induced memory impairment.

Adult↗

Effects of acute and repeated dose administration of caffeine and pentoxifylline on diazepam-induced mouse behavior in the hole-board test.

RATIONALE: The behavioral effects of methyl xanthines and their interactions with benzodiazepines have not been clearly established in animal models of anxiety. OBJECTIVE: The present study extended the previous studies to determine the effects of acute and repeated administration of caffeine, a non-specific phosphodiesterase (PDE) inhibitor and pentoxyfylline, a specific type-4 phosphodiesterase (PDE4) inhibitor on (1) baseline anxiety-like behavior and (2) the response to an acute challenge with diazepam on anxiety-like behavior in the hole-board test. METHODS: Mice were observed for the number of head-dips they made into the holes of the hole-board apparatus during a 5-min period, starting 30 min after acute (20 mg/kg) and repeated oral dose (20 mg/kg, twice a day for 4 days) administration of caffeine and pentoxifylline. In separate experiments, the response to an acute challenge with graded doses of diazepam (0.375 3 mg/kg, SC) was observed in naive mice or mice on acute and repeated dose regimen with methyl xanthines. RESULTS: Mice on acute but not after repeated dose regimen demonstrated a significantly increased number of hole-dips, indicating an anxiolytic-like effect of methylxanthines. Diazepam at the lower doses (0.375 and 0.75 mg/kg) but not at the highest doses (1.5 and 3 mg/kg) examined produced a significant anxiolytic-like effect. After an acute dose exposure of mice to caffeine and pentoxifylline, a rightward shift in the dose-response curve of diazepam was observed and particularly at 1.5 mg/kg dose, the net effect of diazepam was significantly enhanced which was, however, impaired upon repeated administration, more so with caffeine than with pentoxifylline. CONCLUSIONS: It is concluded that the xanthine drugs exert anxiolytic-like activity similar to diazepam in the hole-board test. In addition, they seem to modulate the anxiolytic effects of diazepam after both acute and repeated administration, probably as a result of an endogenous adenosinergic mechanism which may have therapeutic significance.

Analysis of Variance↗

Discriminative stimulus effects of flumazenil in untreated and in diazepam-treated rhesus monkeys.

RATIONALE: Long-term use of benzodiazepine agonists can have adverse effects (e.g., development of dependence), thereby limiting their clinical usefulness. OBJECTIVES: The goal of the current study was to examine the discriminative stimulus effects of flumazenil in untreated and diazepam-treated monkeys to determine whether this type of procedure could be used to examine benzodiazepine dependence. METHODS: Flumazenil (0.32 mg/kg s.c.) was established as a discriminative stimulus in eight monkeys receiving 5.6 mg/kg/day of diazepam (p.o.); four responded under a fixed ratio (FR)5 schedule of stimulus-shock termination (SST) and four responded under a FR5 schedule of food presentation. For comparison, 1.0 mg/kg flumazenil (s.c.) was established as a discriminative stimulus in four untreated monkeys responding under a FR5 schedule of SST. RESULTS: Flumazenil dose-dependently increased responding on the flumazenil-appropriate lever in all monkeys. In diazepam-treated monkeys, Ro 15-4513, ethyl beta-carboline-3-carboxylate and bretazenil substituted for flumazenil with pentylenetetrazole substituting in some monkeys; other drugs failed to substitute for flumazenil. Acute administration of 10.0 mg/kg diazepam (s.c.) shifted the flumazenil dose-effect curve threefold to the right of the control dose-effect curve. Temporary suspension of diazepam treatment produced a time-related increase in flumazenil-lever responding that was reversed by diazepam. In untreated monkeys, midazolam substituted for flumazenil, with other drugs, including those with primary mechanisms of action at non-gamma-aminobutyric acid(A) receptors, substituting in some monkeys. Ro 15-4513 did not substitute in any untreated monkey. CONCLUSIONS: The flumazenil discriminative stimulus appears to be pharmacologically selective in treated monkeys with only negative and low efficacy positive modulators substituting for flumazenil; in contrast, a variety of drugs substitute for flumazenil in untreated monkeys. This apparent difference in selectivity suggests that diazepam treatment modifies the flumazenil discriminative stimulus perhaps due to the development of dependence.

Animals↗

Effects of L-type Ca2+ channel modulation on direct myocardial effects of diazepam and midazolam in adult rat ventricular myocytes.

PURPOSE: Our objective was to determine whether an L-type Ca2+ channel modulation could alter myocardial depression induced by midazolam or diazepam in adult rat ventricular myocytes. METHODS: Freshly isolated rat ventricular myocytes were loaded with fura-2/AM and field-stimulated (0.3 Hz) at 28 degrees C. Amplitude and timing of intracellular Ca2+ concentration ([Ca2+]i) and myocyte shortening were simultaneously monitored in individual cells. RESULTS: Midazolam (3-100 microM) caused a decrease in both peak [Ca2+]i and shortening. Diazepam (30, 100 microM) increased myocyte shortening and peak [Ca2+]i; however, higher concentration of diazepam (300 microM) decreased shortening and peak [Ca2+]i. Bay K 8644 (0.01-10 microM), an L-type Ca2+ channel agonist, caused dose-dependent increases in peak [Ca2+]i and shortening. In contrast, verapamil (0.1-50 microM), an L-type Ca(2+) channel antagonist, caused dose-dependent decreases in peak [Ca2+]i and shortening. Dose-response curves to benzodiazepines on peak [Ca2+]i and shortening were not affected by pretreatment with Bay K 8644 (0.1 microM) or verapamil (1 microM). Diazepam (30, 100 microM), but not midazolam (3-30 microM), increased shortening and [Ca2+]i in the presence or absence of L-type Ca2+ channel modulators. Diazepam (30 microM) and midazolam (10 microM) had no effect on peak [Ca2+]i of a caffeine-induced [Ca2+]i transient, which was used as a measure of SR Ca2+ content. CONCLUSION: Midazolam and diazepam have differential effects on cardiac E-C coupling. Diazepam, but not midazolam, enhances cardiac E-C coupling independent of L-type Ca2+ channel modulation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

The role of albumin conformation in the binding of diazepam to human serum albumin.

The effect of hydrogen, chloride and calcium ions on the binding of diazepam to human serum albumin has been studied by circular dichroism and equilibrium dialysis. In all cases the molar ellipticity of the diazepam-albumin complex increases with pH over the pH range 5 to 9. Under these conditions the free concentration of diazepam at a constant low drug to protein ratio decreases with pH. This free concentration is higher in the presence of chloride and calcium ions. With a two state conformational model for albumin it was shown, that the pH dependences of molar ellipticity of the diazepam-albumin complex and of the free concentration of diazepam are linked. It was demonstrated that the N-B transition of albumin is involved in the pH dependent binding of diazepam. The consequences of these findings for equilibrium dialysis procedures in determining free plasma levels of diazepam are discussed.

Calcium↗

Specific changes in local cerebral glucose utilization in the rat brain induced by acute and chronic diazepam.

The effect of acute and long term administration of diazepam upon local cerebral glucose utilization (LCGU) in discrete regions of the central nervous system of the rat was studied by means of a quantitative autoradiographic [14C]2-deoxy-D-glucose technique. A single injection of diazepam (1.0 mg/kg and 2.5 mg/kg i.v.) reduced LCGU up to 30% in particular brain areas, such as the lateral and ventral thalamic nuclei, the medial geniculate body and the mamillary body, whereas the activity in many other structures was not significantly altered. That the effects may be mediated via specific benzodiazepine receptors was indicated by the ability of the selective benzodiazepine antagonist Ro 15-1788 (imidazobenzodiazepine) to attenuate these actions. Rats treated chronically with diazepam (20 mg/kg day for a period of 14 days) still displayed slight reductions of LCGU in certain areas affected acutely such as the lateral thalamic nucleus. In contrast to its effects in rats chronically treated with vehicle, an acute diazepam injection failed to significantly modify LCGU in rats chronically treated with diazepam. Furthermore, in chronic diazepam-treated animals Ro 15-1788 produced an increase of LCGU to values above control levels in those brain regions in which a decrement was seen upon acute diazepam administration to naive rats. These findings indicate an adaptation to and a possible development of physical dependence upon chronic drug treatment.

Animals↗

Aging: modulation of GABAA binding sites by ethanol and diazepam.

Modulation of gamma-aminobutyric acid (GABA) binding to the GABAA recognition site by ethanol and/or diazepam appears to change with the age of the animal. Brain tissue above the cerebellum of young, mature, and old rats was examined for an age-related change in the GABAA recognition sites 5 min after the rat was last habituated or received a single injection of the vehicle, ethanol and/or diazepam. The dose of ethanol injected was reduced in the senescent rats, so the brain levels of ethanol did not vary with age. An injection of ethanol and/or diazepam (180 micrograms/kg) did not significantly alter the GABAA recognition site in any age group relative to the habituated or vehicle-injected rats of that age group. However, the affinity of the GABAA recognition site was decreased by ethanol in mature and old rats relative to the affinity of the GABAA site after diazepam pretreatment in the presence and absence of ethanol, respectively. Finally, the combination of ethanol and diazepam elicited an increase in the number of GABAA binding sites relative to diazepam pretreatment in only the young rats. The present results indicate that the GABAA binding site is modulated by ethanol and diazepam in an age-dependent manner.

Aging↗

Diazepam inhibits calcium, calmodulin-dependent protein kinase in primary astrocyte cultures.

The effect of the anticonvulsants diazepam, phenytoin, and valproic acid on calcium, calmodulin-dependent protein phosphorylation in astrocytes was investigated. We found that diazepam inhibited calcium, calmodulin-stimulated phosphorylation in both supernatant and membrane fractions from primary cultures of rat astrocytes, whereas phenytoin and valproic acid (50-500 microM) had little to no effect. Phosphate incorporation in several protein bands, including the major substrates of 59 and 53 kDa, was inhibited by diazepam. A decrease in phosphate incorporation in these crude preparations was observed at 25 microM diazepam and 50% inhibition was attained at about 100 microM. Dibutyryl cyclic AMP-treated astrocytes were enriched in the 59 kDa phosphoprotein; this band was particularly sensitive to diazepam in these cells. These results indicate that diazepam is capable of inhibiting calcium, calmodulin-dependent protein kinase activity in astrocytes, thereby suggesting a possible site of diazepam action and a potential mechanism for a role of astrocytes in epileptogenesis.

Animals↗

Inhibition of Ca-channels by diazepam compared with that by nicardipine in pheochromocytoma PC12 cells.

The effects of diazepam on voltage-gated Ca channels were studied in PC12 pheochromocytoma cells using whole-cell voltage-clamp techniques. An inward current activated by a depolarizing voltage step to +10 mV from a holding potential of -60 mV in 10.8 mM Ba was larger than that activated in 10.8 mM Ca. The Ba current was completely blocked by a low concentration of Cd (30 microM) and was also sensitive to nicardipine (100 nM to 10 microM). Diazepam (1-100 microM) inhibited the Ba current in a concentration-dependent manner. Neither diazepam nor nicardipine affected the current-voltage relationship or the dependence on holding potentials of the Ba current. Both slightly accelerated the inactivation time course of the Ba current. When diazepam was applied to the cells in combination with nicardipine, the observed inhibition agreed with a value predicted assuming independent blockade by diazepam and by nicardipine. These results suggest that diazepam inhibits Ca channels in a manner similar to nicardipine, but that the binding sites for diazepam are different from those for nicardipine.

Animals↗

Postischemic diazepam is neuroprotective in the gerbil hippocampus.

In this study, we address the hypothesis that enhancement of gamma-aminobutyric acid (GABA) neurotransmission following an ischemic episode is neuroprotective in the hippocampus. Mongolian gerbils were subjected to transient forebrain ischemia for 5 min by occlusion of the carotid arteries and then administered diazepam (10 mg/kg i.p.) 30 min or 30 and 90 min following ischemia. Diazepam produced a significant decrease in both rectal and brain temperature (4-6 degrees C) in the sham and ischemic gerbils. 1 day following the onset of reperfusion, diazepam substantially reduced the hyperactivity normally induced by the ischemic episode. 7 days later, neuronal viability in the hippocampus was assessed. The single dose of diazepam completely protected the CA1 pyramidal cells of the hippocampus in 62% of the gerbils and the double dose of diazepam completely protected CA1 pyramidal neurons in 67% of the gerbils. There was a significant correlation between the degree of pyramidal cell degeneration in the CA1 area of the hippocampus measured 7 days following ischemia and the degree of hyperactivity measured 1 day following ischemia. Diazepam also prevented the loss of [35S]t-butylbicyclophosphorothionate ([35S]TBPS) binding to GABA-gated chloride channels in the dendritic fields of the CA1 area of the hippocampus. Our findings support the hypothesis that enhancement of GABA neurotransmission following an ischemic event may offset neuronal excitability and prevent neuronal death in specific brain regions. We conclude that GABA-enhancing drugs, such as diazepam, are attractive candidates as neuroprotective agents following ischemic insults.

Animals↗

Inhibition of morphine tolerance and dependence by diazepam and its relation to cyclic AMP levels in discrete rat brain regions and spinal cord.

Diazepam inhibits morphine tolerance and dependence and reverses a decrease in the met-enkephalin level in brain induced by morphine. In this study, we investigated whether inhibition of morphine-induced tolerance and dependence by diazepam involved a change in cyclic AMP levels in discrete rat brain regions and spinal cord. Male Sprague-Dawley rats were made tolerant and dependent by subcutaneous (s.c.) implantation of six morphine pellets (two pellets on the first day, and four on the second day). Diazepam (0.25 mg/kg b. wt) was injected once daily intraperitoneally (i.p.) for 5 days. Control rats were implanted with placebo pellets and injected once daily with saline or diazepam (i.p.). Tail-flick antinociception was measured 1 h after injections everyday. Animals were administered s.c. naloxone (10 mg/kg) to induce naloxone-precipitated withdrawal syndrome on the final day of the experiment (day 5), and the jumping behavior was observed for 30 min. Concomitant treatment with diazepam (0.25 mg/kg) significantly decreased the development of morphine tolerance and dependence. Diazepam (0.25 mg/kg) treated rats also showed a significant decrease in the jumping behavior compared to animals treated with morphine alone. Rats were sacrificed 2 h after the injection of saline or diazepam (0.25 mg/kg) on the fifth day. Cyclic AMP was estimated by RIA. In the control rats, the concentration of cyclic AMP in cortex was > hippocampus > cerebellum > hypothalamus > striatum > midbrain > pituitary > pons/medulla > spinal cord. There was no change in the concentration of cyclic AMP in any of the brain regions examined from morphine tolerant animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Development of tolerance to the anticonvulsant effect of diazepam in dogs.

In dogs the development of tolerance to the anticonvulsant effect of diazepam was followed by weekly determinations of the convulsive threshold for pentetrazole, 10-15 min after intravenous (i.v.) injection of 0.25 or 0.5 mg/kg diazepam. As soon as after 1 week of oral treatment with diazepam, 0.25 or 0.5 mg/kg three times daily (t.i.d.), the pentetrazole threshold showed a decline or even a fall to the control level in spite of unaltered or rising concentrations of diazepam and its active metabolites. Tolerance also developed when the dogs were treated with chlorazepate, 2 mg/kg t.i.d., between the weekly diazepam injections for threshold determination. The results favor a functional type of tolerance since there was no indication of a more rapid inactivation of diazepam. Treatment with desmethyldiazepam (2 mg/kg i.v. for threshold determination and oral treatment with the desmethyldiazepam precursor chlorazepate, 2 mg/kg t.i.d.) did not produce tolerance. In further experiments in dogs anesthetized, relaxed with suxamethonium and ventilated, a spike-wave activity in the EEG was induced and maintained by an injection and subsequent infusion of pentetrazole. Out of 6 dogs, receiving 4-5 i.v. injections of 0.25-0.5 mg/kg diazepam, 2 showed the phenomenon of acute tolerance, i.e. the effect of the drug on the spiking activity in the EEG became less from one injection to the next, and thus paralleled a situation which may be observed during treatment of clinical status epilepticus. No acute tolerance was observed in corresponding experiments with desmethyldiazepam.

Animals↗

Diazepam-induced decrease in histamine turnover in mouse brain.

The effect of diazepam on brain histamine turnover was examined in mice. The steady state levels of histamine and tele-methylhistamine remained unchanged following the i.p. administration of 0.2-20 mg/kg of diazepam. However, diazepam in doses over 5 mg/kg significantly decreased histamine turnover, as estimated from the accumulation of tele-methylhistamine after pargyline treatment. Other benzodiazepines such as chlordiazepoxide, nitrazepam and estazolam in high doses also decreased histamine turnover. The inhibitory effect of diazepam on histamine turnover was antagonized by the pretreatment with a benzodiazepine antagonist Ro 15-1788. The histamine turnover was significantly inhibited by 2 mg/kg of muscimol. Diazepam (0.2-1 mg/kg) markedly and dose-dependently potentiated the inhibitory effect of 1 mg/kg of muscimol from non-significant to highly significant levels. The potentiation by diazepam was also antagonized by Ro 15-1788. Therefore, diazepam probably decreases histamine turnover in the brain via the benzodiazepine-GABA receptor complex.

Animals↗

Diazepam-insensitive [3H]Ro 15-4513 binding in intact cultured cerebellar granule cells.

[3H]Ro 15-4513, a partial inverse agonist at the benzodiazepine receptor, binds to two sites in the rat cerebellum, only one of which is sensitive to diazepam. The diazepam-insensitive component, whose identity is unknown, is unique to this brain area. We studied the binding of [3H]Ro 15-4513 in cultured cerebellar granule cells to characterize its binding sites in a specified neuronal cell population and to determine the effects of ethanol on the binding. We also compared the properties of [3H]Ro 15-4513 binding in washed membranes of cultured cells and 14-day-old rat cerebella. [3H]Ro 15-4513 had two binding components in intact granule cells, one sensitive to diazepam, that probably represents binding to the benzodiazepine agonist site, the other sensitive to an antagonist (Ro 15-1788) and two inverse agonists (ethyl-beta-carboline-3-carboxylate, beta CCE and methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate, DMCM) of the benzodiazepine receptor (diazepam-insensitive binding). This diazepam-insensitive binding was stimulated by GABA; the maximal increase in binding was about 60% with an EC50 of 0.3 microM. The effect of GABA (10 microM) on the diazepam-insensitive binding was unaffected by 100 microM nipecotic acid but was partially inhibited by 100 microM bicuculline. The stimulation by GABA was also seen at 37 degrees C with washed membranes of 14-day-old rat whole cerebella in the presence of micromolar diazepam.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Long-term diazepam treatment produces changes in cholecystokinin receptor binding in rat brain.

This study examined the effect of chronic diazepam administration on central benzodiazepine and CCK-8 receptor binding in rat brain. After a two-week treatment with diazepam (5 mg/kg per day) tolerance developed towards the sedative but not towards the anxiolytic action of this drug as determined using elevated plus-maze and open field tests. The % entries the rats made onto open arms and % time the rats spent in open arms were markedly decreased 24 h after the last dose of diazepam, probably indicating withdrawal anxiety. There were no changes in [3H]flunitrazepam binding either 30 min or 24 h after the last diazepam dose. However, 30 min after the last diazepam administration the apparent number of sulphated [3H]CCK-8 binding sites was significantly increased in the primary olfactory cortex. Acute diazepam treatment (5 mg/kg) had no influence on [3H]flunitrazepam or sulphated [3H]CCK-8 binding in any brain region studied. Cessation of chronic diazepam treatment was followed after 24 h by an increase in the number of CCK-8 receptors in frontal cortex and hippocampus as compared to the vehicle group. These results demonstrate that certain alterations in CCK-8 receptor characteristics may be important in the anti-anxiety effect, tolerance, and withdrawal reaction reaction after benzodiazepine administration.

Animals↗

Antagonism of ethanol withdrawal convulsions in Withdrawal Seizure Prone mice by diazepam and abecarnil.

Abecarnil, a beta-carboline acting at benzodiazepine receptors, has been shown to have anxiolytic and anticonvulsant properties in a number of models. It has reduced muscle relaxant and incoordinating effects in comparison to diazepam. Given the wide clinical application of diazepam to prevent alcohol withdrawal seizures, a genetic animal model was employed to compare abecarnil with diazepam for its anti-withdrawal effects. Withdrawal Seizure Prone (WSP) mice, genetically selected to develop severe handling-induced convulsions after withdrawal from chronic ethanol treatment, were exposed to ethanol vapor for 24 h. WSP mice given doses of abecarnil or diazepam at the peak of withdrawal had significantly reduced handling-induced convulsion scores. While abecarnil was slightly more potent than diazepam, its effects were shorter-lasting. Similar results were seen in an experiment where withdrawal handling-induced convulsions were assessed after a single high-dose ethanol injection. Abecarnil and diazepam also reduced the smaller handling-induced convulsion scores seen in naive WSP mice. Single doses of abecarnil or diazepam did not lead to a rebound elevation of handling-induced convulsion scores suggestive of a withdrawal reaction.

Animals↗