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At least 163 records · Page 9Linked to original sources
PubMed1975

The synthesis and pharmacology of a novel benzodiazepine derivative, 1-(beta-methylsulfonylethyl)-5-(o-fluorophenyl)-7-chloro-1,3-dihydro-2H-1,4-benzodiazepin-2-one (ID-622).

The pharmacological profiles of a new benzodiazepine derivative, 1-(beta-methylsulfonylethyl)-5-(o-fluorophenyl)-7-chloro-1,3-dihydro-2H-1,4-benzodiazepin-2-one (ID-622), were shown. In anti-convulsant test, ID-622 was more potent than diazepam and medazepam when tested with pentylenetetrazol or bemegride, but was less potent than diazepam tested with strychnine or MES in mice. Taming effects of ID-622 were more potent than diazepam in both electroshock- and isolation-induced fighting mice tests, but were less potent in both septal rats and O.B. rats tests. ID-622 had only a weak influence on the spontaneous locomotor activity, and did not cause the righting reflex loss. In EEG, ID-622 increased fast activity and depressed hippocampal I-waves and amygdala after-discharge in cats. Acute toxicity of ID-622 was very low.

Animals↗
PubMed1981

Selective blockade of the discriminative stimulus effects of pentobarbital in pigeons.

The ability of CNS stimulants to block the discriminative effects of pentobarbital was studied in pigeons trained to discriminate IM pentobarbital (5 mg/kg) from saline. Pentobarbital, when administered alone, consistently produced greater than 90% pentobarbital-appropriate responding. The concomitant administration of pentobarbital and increasing doses of bemegride or pentylenetetrazol resulted in a dose-related decrease in pentobarbital-appropriate responses. In contrast, picrotoxin, another CNS stimulant, had little or no effect on pentobarbital-appropriate responding produced by pentobarbital.

Animals↗
PubMed1980

Discriminative stimulus effects of pentobarbital in pigeons.

Pigeons were trained to discriminate the IM injection of pentobarbital (5 or 10 mg/kg) from saline in a task in which 20 consecutive pecks on one of two response keys produced access to mixed grain. Pentobarbital (1.0--17.8 mg/kg) produced a dose-related increase in the percentage of the total session responses that occurred on the pentobarbital-appropriate key. The concomitant administration of bemegride (5.6--17.8 mg/kg) antagonized the discriminative control of behavior exerted by the training dose of pentobarbital. Benzodiazepines, diazepam (1.0 mg/kg) and clobazam (3.2 mg/kg), and barbiturates, methohexital (10 mg/kg), phenobarbital (56 mg/kg), and barbital (56 mg/kg), produced responding on the pentobarbital-appropriate key similar to that produced by pentobarbital. In contrast, narcotics such as morphine, ethylketazocine, cyclazocine, and SKF-10,047, at doses up to and including those that markedly suppressed response rates, produced responding predominantly on the saline-appropriate key. Similarly, the anticonvulsants, valproate, phenytoin, and ethosuximide occasioned only saline-appropriate behavior, indicating that not all anticonvulsants share discriminative stimulus effects with pentobarbital. Muscimol, a direct GABA agonist, and baclofen, a structural analogue of GABA, also failed to produce pentobarbital-appropriate responding. Ketamine, dextrorphan, and ethanol (0.3--3.2 g/kg, orally) produced intermediate levels of pentobarbital-appropriate responding, suggesting that the discriminative effects of these drugs may be somewhat like those of pentobarbital.

Animals↗
PubMed1985

Effects of a depressant/convulsant pair of glutarimides on neuronal activity in the isolated spinal cord of the immature rat.

The effect of depressant/convulsant pair of glutarimides on the isolated spinal cord of the immature rat was examined using extracellular recording. At concentrations of 300 microM the depressant beta-butyl-beta-methyl glutarimide enhanced the response of motoneurones and dorsal root fibres to gamma-aminobutyric acid (GABA) while the convulsant bemegride (beta-ethyl-beta-methyl glutarimide) decreased both responses to GABA. At this concentration both the convulsant and depressant reduced mono- and polysynaptic reflex activity. Neither the convulsant or depressant had prominent direct actions, with only a small hyperpolarization being produced by both glutarimides on dorsal root fibres. The overall depressant or convulsant properties of these glutarimides may be due in part therefore to a differential effect on the postsynaptic action of the inhibitory transmitter GABA. Furthermore, the depressant glutarimide reduced the excitatory effects of L-glutamate and the convulsant reduced the inhibitory effects of glycine on spinal neurones; thus, actions on these transmitters may also contribute to the overall effects of these glutarimides.

Amino Acids↗
PubMedDate not supplied

Delta9-tetrahydrocannabinol and pentobarbital as discriminative cues in the Mongolian Gerbil (Meriones unguiculatus)

Male Mongolian gerbils were trained to escape electric shocks in a T-shaped maze contingent upon the presence or absence of certain drug effects (state-dependency; StD). The drug discriminative cues used were those of either delta9-tetrahydrocannabinol (THC) or pentobarbital (P-barb.) vis-à-vis the respective vehicles. Several doses of THC (0.5-16.0 mg/kg) were used and compared with P-barb. (20.0 mg/kg), a dose at which the most rapid drug discrimination occurs in the rat. When drug discrimination was established dose-time- and transfer characteristics for the training drugs were studied. Possible potentiation and antagonism was also examined in the pentobarbital trained gerbils. It was found that none of the THC doses were discriminated as rapidly as that of P-barb. Decreasing the amounts of training drug administered or increasing the injection-test intervals resulted in a decline of the number of drug associated choices. There was a maximum of 40% drug choices between THC and P-barb at the transfer tests. Mixtures of the two compounds increased the number of drug choices in an additive or even more than additive manner. Amphetamine (4.0 mg/kg) did not interact with the P-barb. induced choice responding. The analeptic drug, bemegride was found effective in antagonizing the P-barb. cued choice behavior.

Amphetamine↗
PubMed1981

Fine structure of experimental epileptogenic focus produced by intracerebral implantation of cobalt-gelatin stick in rabbits.

The experimental epileptogenic focus produced by cobalt-gelatin stick implantation in the cerebral cortex of rabbits has been studied by electron microscopy. Since our cobalt focus was latent, the bemegride maneuver was intravenously performed to identify the cobalt lesion of the cortex as an epileptogenic focus. The cobalt lesion comprised three different zones. Of the three zones, the reactive zone showed a glio-mesenchymal scar and prominent ultrastructural changes. The major change of this zone was found in the neurons, neuropils and astrocytes. Electron-lucent neurons deprived of the usual neuropils surrounding them, widening of extracellular spaces and swollen dendrites in neuropils, and proliferating astrocytes were observed constantly throughout the experimental period. These findings may be significant for the genesis of this type of epilepsy.

Animals↗
PubMed1970

Physiological and drug-induced changes in the glycogen content of mouse brain.

1. The effect of the method of killing on the concentration of glycogen in mouse brain was determined. The cerebral glycogen content of mice killed by immersion in liquid nitrogen did not differe significantly from that of animals decapitated and the heads immediately frozen. A delay before freezing led to the rapid loss of brain glycogen, with a 17% fall at 10 s and an 82% loss after 5 min.2. Hyperglycaemia, induced by the administration of D-glucose, resulted in an 8.3% loss of brain glycogen after 120 min. Insulin hypoglycaemia produced a 10.7% fall in glycogen at 60 min followed by an 11.2% increase at 120 min.3. Exposure to either high (32 degrees C) or low (10 degrees C) ambient temperatures caused a depletion of brain glycogen.4. A circadian rhythm of brain glycogen concentration was found, with a nadir which was coincident with the peak of locomotor activity and body temperature.5. Drugs from several pharmacological classes were studied for their in vivo effect on the concentration of glycogen in mouse brain.6. Brain glycogen was increased by all the depressant drugs tested, and by some drugs which had little effect on behaviour (diphenhydramine, phenytoin and propranolol), or which caused excitation (caffeine and nialamide).7. Glycogen was depleted only by amphetamine-like compounds or by bemegride-induced convulsions.8. The results are discussed with particular reference to the possible relation between catecholamines and glycogen metabolism in the brain.

Amphetamine↗
PubMed1970

Effects of drugs acting alone and in combination on the motor activity of intact mice.

1. When administered to intact white mice, the central depressants-diphenhydramine, promethazine, chlorpromazine, gammahydroxybutyrate, gammabutyrolactone, hyoscine, and pethidine-produced sedation in small doses, but excitement and convulsions in higher doses. When given to mice pretreated with subanaesthetic doses of phenobarbitone these drugs abolished the righting reflex both in convulsant doses (hyoscine excepted) and in non-convulsant doses. These effects are similar to the effects previously observed with local anaesthetics.2. Meprobamate, diazepam and chlorpromazine produced a loss of righting reflex both when given alone and following phenobarbitone. When given alone in higher doses, chlorpromazine induced convulsions.3. The central stimulants bemegride and picrotoxin antagonized the loss of righting reflex produced by phenobarbitone, but nikethamide, caffeine and strychnine did not alter the depressant effects of phenobarbitone.4. On the basis of these and previous studies with intact white mice a tentative classification of drugs having generalized depressant and stimulant effects on the central nervous system was proposed and discussed.

Adjuvants, Anesthesia↗
PubMed1970

Effects of general stimulant drugs on the electrical responses of isolated slabs of cat's cerebral cortex.

1. In the neuronally isolated cortex of the cat, local application of bemegride, picrotoxin, nikethamide, caffeine and strychnine facilitated the surface positive response of the isolated cortex and lowered the stimulus threshold for this response. Excepting nikethamide, they all produced convulsive discharge in the isolated cortex unrelated to the applied stimulus.2. Local application of glutamate to the cortex produced spreading depression, which was sometimes preceded by spontaneous positive bursting.3. In contrast to the "general depressants" which produce a relatively consistent pattern of effects on the electrical responses of isolated cortex, the "general stimulants", although they all have excitatory effects on isolated cortex, each produced a greatly different type of electrical response in the isolated cortex, suggesting that several different mechanisms of action are responsible for their effects.

Action Potentials↗
PubMed1978

Presynaptic actions of gamma-aminobutyric acid and some antagonists in a slice preparation of cuneate nucleus.

1 A slice preparation of the rat cuneate nucleus is described which is suitable for electrophysiological studies on the presynaptic action of drugs. 2. Superfusion of a slice with gamma-aminobutyric acid (GABA) depolarized the afferent nerves in a concentration-related manner. The responses were Cl-dependent. Depolarizations to high concentrations of GABA often faded. Glycine and L-glutamate had little effect. 3 (+)-Bicuculline antagonized GABA in an apparently competitive manner (pA2 = 5.35) at low response levels. Strychnine was 10 times less potent. Responses to high concentrations of GABA were sometimes potentiated by (+)-bicuculline and strychnine. 4 Bemegride and leptazol both antagonized GABA, but with low potency and in a manner which was clearly not competitive.

Aminobutyrates↗
PubMed1982

Postsynaptic effects of some central stimulants at the neuromuscular junction.

1 Miniature endplate currents (m.e.p.cs) were recorded with extracellular electrodes from sartorius muscles of toads. 2 Central excitant analogues of amylobarbitone (3M2B) and halothane (DBE) decreased the amplitude and time constant of decay of m.e.p.cs and hence reduced the amplitude of miniature endplate potentials. The decay remained exponential with single time constant. 3 A central excitant analogue of ether (indoklon) reduced the amplitude of m.e.p.cs and made their decay biphasic. The decay could be fitted by the sum of two exponentials. 4 Bemegride, a central excitant, prolonged m.e.p.cs. Their decay remained exponential with single time constant. The effect was not due to inhibition of acetylcholinesterase. 5 All of the drugs tested, including amylobarbitone, reduced the temperature-sensitivity of the decay of m.e.p.cs. 6 The biphasic decay of m.e.p.cs caused by indoklon could not be explained simply by supposing that the drug blocked open endplate channels unless it was assumed that the normal rate of channel closing also increased and became much less temperature-sensitive than normal.

Amobarbital↗
PubMed1983

Effects of drugs on the cerebral circulation of the dog in relation to the cerebral oxygen consumption.

Drug effects were studied on the cerebral circulation by measuring the sagittal sinus outflow in the anaesthetized dog following the method of Michenfelder and by monitoring cerebral oxygen consumption. Systemic aortic pressure, heart rate and spinal fluid pressure were also studied. Since dilatation of cerebral vessels was observed in nearly all the preparations after inhalation of CO2, it was thought that gross extracerebral contamination was virtually eliminated in this preparation. A close correlation was observed between the oxygen consumption of the brain as a whole and the sagittal sinus outflow (r = 0.93, P less than 0.001); therefore it became feasible to differentiate the direct effects of drugs on cerebral blood vessels from indirect ones attributable to changes in the cerebral oxidative metabolism. Sodium pentobarbitone (5 mg kg-1, i.v.), reduced the cerebral venous outflow and caused a decrease in the oxygen consumption. Pentylenetetrazol (30 mg kg-1 i.v.) and bemegride (5 mg kg-1 i.v.) produced an increase in the blood flow and a corresponding increase in the cerebral oxygen consumption. Thus, it was concluded these substances had no direct effects on the cerebral blood vessels. Acetazolamide (10 mg kg-1, i.v.), a carbonic anhydrase inhibitor, produced a marked and sustained vasodilatation after a latent period of 0.5-1 min. There was no increase in the cerebral oxygen consumption. A similar pattern was seen after CO2 had been inhaled. Methylergometrine and dihydroergotamine (20 micrograms kg-1 i.v.) induced a prolonged vasoconstriction of the cerebral vascular bed without any changes in the oxygen consumption of the brain. Therefore this method can discriminate between indirect or direct effects of drugs on cerebral vascular outflow.

Acetazolamide↗
PubMed1978

Secondarily generalized convulsive seizures induced by daily amygdaloid stimulation in rhesus monkeys.

Amygdaloid kindling in rhesus monkeys resulted in development of secondarily generalized convulsive seizures in an average of 196 days. Prior pharmacologic (bemegride) kindling accelerated this seizure development in one animal. None of the animals reached the stage 5 primary generalized seizure of baboons (Papio papio), even after 400 daily amygdaloid stimulations. Seizure stage instability, with frequent regression to an earlier stage, and the difficulty of establishing a generalized seizure triggering threshold in most of the rhesus monkeys, contrasts with our experiences in Papio papio. Thus, differences in the speed of kindling and in the quality of kindled convulsion between rhesus monkeys and epileptic baboons probably reflect the presence or absence of an epileptogenic predisposition in these two species. The difficulty of developing convulsive seizure in rhesus monkeys suggests that this species is particularly suited for the study of partial complex seizure. These studies indicate that the abrupt onset of human epilepsy with a fully developed convulsive seizure must represent and overwhelming central pathophysiologic event resulting from an endogenous, exogenous or a combined insult interacting with a genetically predisposed seizure susceptibility.

Amygdala↗
PubMed1981

Further studies on the determinant role of brain level of pentobarbital for the development of acute hypnotic tolerance.

Controlling the brain level of pentobarbital and the duration of hypnosis at the initial treatment in relation to development of acute hypnotic tolerance was studied. Simultaneous treatment of bemegride or TRH with pentobarbital attenuated the hypnotic effect of pentobarbital in a dose dependent manner, but neither the brain level of pentobarbital nor the development of tolerance was modified by this treatment. The effect of TRH was further demonstrated in rats by concomitant intracarotidal infusion with pentobarbital maintaining the brain concentration of pentobarbital and also the duration of exposure of the brain to pentobarbital under a constant condition. On the other hand, THC significantly prolonged the hypnosis induced by pentobarbital but did not potentiate the effect of pentobarbital to develop acute tolerance. Thus, the brain level of pentobarbital at the initial treatment is the primary determinant for the development of acute tolerance and the duration of hypnosis is not the essential factor in this mechanism.

Animals↗
PubMed1975

An analysis of the drugs acting on cerebral energy metabolism.

The behaviour of (a) the redox potential of the lactate/pyruvate system and the changes of the redox potential of the lactate/pyruvate system across the brain; (b) the energy charge potential of the adenylate pool, was studied in the brain of curarized beagle dogs. The influence of certain drugs (amobarbital, nicergoline, theophylline, papaverine, bamethan, dipyridamole, bemegride) on these parameters was evaluated under control conditions, during hypoxemia and during post-hypoxiemic recovery. On the whole, the action on energetic metabolism appears to be unrelated to the action believed to be exerted by drugs on cerebral vessels.

Adenine Nucleotides↗
PubMed1978

Anti-convulsant effect of phthalazino-[2,3b]-phthalazine-5(14H), 12(7H)-dione (L-5418). II. Electroencephalographic study.

L-5418 has an anti-convulsant effect which is similar to that of diphenylhydantoin. The effects of L-5418 on EEG activity in rabbits with acute and chronic implantation of electrodes were studied in comparison with those of currently available anti-convulsants. Intravenous administration of L-5418 increased a slow-wave sleep pattern in the spontaneous EEG, which was also induced by diphenylhydantoin. With respect to the focal seizure in the cerebral cortex induced by local application of penicillin, L-5418 showed suppressive effects on the frequency and duration of seizure discharge, and on the spread of seizure discharge to other parts of the brain. The efficacy was about twice that of diphenylhydantoin. L-5418 and dephenylhydantoin did not increase the threshold of seizures induced by bemegride while trimethadione raised the threshold. L-5418 also showed suppressive effects twice as active as diphenylhydantoin on after-discharge induced by electrical stimulation of the hippocampus and amygdala. This suppressive effect on after-discharge of the limbic system may be parallel with the suppressive effect on psychomotor seizure. From these results of L-5418 on an experimental model of epilepsy, it is suggested that L-5418 has suppressive effects similar to that of diphenylhydantoin on convulsion and the efficacy proved to be twice that of diphenylhydantoin in the EEG study.

Animals↗
PubMed1984

Studies on the muscle relaxation effects of ethyl loflazepate (CM6912) and evaluation as an anti-anxiety drug.

A new anti-anxiety drug, CM6912 (ethyl loflazepate, ethyl 7-chloro-2,3-dihydro-5-(2-fluorophenyl)-2-oxo-1H-1,4-benzodiazepine-3- carboxylate), was investigated for its effects on the alpha- and gamma-motor systems and on the cooperative muscular motions and for its interactions with other CNS drugs. The results obtained are as follows: Muscular discharges (EMG) induced by decerebrate rigidity were unaffected by 10 mg/kg (p.o.) of CM6912, but the amplitudes of the EMG were reduced by 50% for 3 hr by 30 mg/kg of CM6912 at 30 min after administration. Diazepam (10 mg/kg) also decreased the amplitudes of the EMG even at 5 min after administration, indicating that diazepam had a stronger than CM6912. Both monosynaptic spinal reflex (MSR) and polysynaptic spinal reflex (PSR) were unaffected by CM6912 (100 mg/kg). Dorsal root reflex potential was slightly enhanced by CM6912 (100 mg/kg), but not at a dose of 30 mg/kg. Diazepam (10 mg/kg) did not decrease MSR, but slightly reduced PSR. Dorsal root reflex potential was almost doubled by diazepam. The frequency of spontaneous discharges of Gla spindle afferent fiber of the extensor muscle of the hindlimb of anesthetized cats was unchanged by 10 mg/kg CM6912, but was suppressed by diazepam at the same dose while at a dose of 30 mg/kg, it was reduced mildly by CM6912, and markedly by diazepam. ED50 values for the antagonistic action on bemegride-induced convulsions were 0.30 mg/kg for CM6912 and 0.49 mg/kg for diazepam at 1 hr after administration, and they were 0.30 mg/kg and 0.67 mg/kg for CM6912 and diazepam, respectively, at 4 hr. The potentiating action of CM6912 on chlorprothixene-induced anesthesia was far weaker than that of diazepam. The suppressive potency of CM6912 on the adaptability to the rotarod was about half that of diazepam, and the muscle relaxant action of CM6912, examined by the inclined board test and the hanging test, was found to be similar to that of diazepam. These results suggest that CM6912 is less potent than diazepam in reducing muscular tone and in inducing sleep, while it has a stronger and longer-lasting anti-anxietic activity than diazepam.

Adaptation, Psychological↗
PubMed1994

Pharmacological studies on a new dihydrothienopyridine calcium antagonist, S-312-d. 5th communication: anticonvulsant effects in mice.

S-312, S-312-d, but not S-312-l, L-type calcium channel antagonists, showed anticonvulsant effects on the audiogenic tonic convulsions in DBA/2 mice; and their ED50 values were 18.4 (12.8-27.1) mg/kg, p.o. and 15.0 (10.2-23.7) mg/kg, p.o., respectively, while that of flunarizine was 34.0 (26.0-44.8) mg/kg, p.o. Although moderate anticonvulsant effects of S-312-d in higher doses were observed against the clonic convulsions induced by pentylenetetrazole (85 mg/kg, s.c.) or bemegride (40 mg/kg, s.c.), no effects were observed in convulsions induced by N-methyl-D-aspartate, picrotoxin, or electroshock in Slc:ddY mice. S-312-d may be useful in the therapy of certain types of human epilepsy.

Administration, Oral↗