Caffeine and theophylline counteract diazepam effects in man

A total of 237 healthy subjects were studied in four placebo-controlled double-blind trials with parallel treatment groups. The subjects ingested a capsule (diazepam or placebo) and decaffeinated coffee with or without added caffeine or theophylline. Diazepam (10 and 20 mg) impaired dose dependently cognitive skills as measured by digit symbol substitution and letter cancellation, the balance of extraocular muscles, flicker fusion, and tapping speed. With diazepam 10 mg statistically significant effects were seen on digit symbols and exophoria only. Theophylline (10 mg/kg) increased tapping speed and heart rate, whereas other objective measurements were negative for the effects of theophylline or caffeine (250 and 500 mg) alone. Subjectively they reduced calmness, and caffeine also increased alertness. Caffeine 250 mg counteracted diazepam induced (10 mg) impairment of cognitive skills and relaxation of extraocular muscles whereas caffeine 500 mg counteracted the same effects of diazepam 20 mg, respectively. Theophylline antagonized diazepam-induced impairment in digit symbol substitution and tapping speed tests. Subjectively, caffeine and theophylline counteracted diazepam induced drowsiness and mental slowness. The results suggest, therefore, that the ample use of methylxanthines compensates various side-effects of benzodiazepines in man. It may also increase the need of sedation and thus the consumption of benzodiazepines.     

CGS8216 noncompetitively antagonizes the discriminative effects of diazepam in rats

The benzodiazepine antagonist properties of CGS8216 were evaluated in rats trained to discriminate between saline and 1.0 mg/kg of diazepam in a two-choice, stimulus-shock termination procedure. CGS8216 (0.3 to 100 mg/kg) administered alone, either s.c., p.o. or i.p., occasioned only saline-appropriate responding. When administered concomitantly with a constant 1.0 mg/kg dose of diazepam, CGS8216 produced dose-related decreases in drug-appropriate responding. CGS8216 was most potent by the i.p. route, and approximately tenfold less potent by the oral route. CGS8216 was dermatotoxic after s.c. administration. CGS8216 i.p. had a long duration of action. A dose of 30 mg/kg completely antagonized the discriminative effects of the 1.0 mg/kg training dose of diazepam when the antagonist was administered 8 hr before the start of the test session. In order to determine the type of antagonism by CGS8216, the dose-effect curve for diazepam was redetermined in the presence of varying doses of CGS8216 (0.3 to 3.0 mg/kg, i.p.). CGS8216 produced a dose-related rightward shift in the diazepam dose-effect curve, but also decreased the slope and appeared to decrease the maximal effect. These results are consistent with the interpretation that CGS8216 antagonizes diazepam in a noncompetitive manner. It may do so because either it interacts with a subpopulation of benzodiazepine receptors, it functions as a pseudo-irreversible antagonist due to its high affinity, or because it is an antagonist with agonist properties.     

Ro 15-1788 antagonizes the discriminative stimulus effects of diazepam in rats but not similar effects of pentobarbital

The benzodiazepine antagonist properties of Ro 15-1788 were evaluated in rats trained to discriminate between saline and either 1.0 mg/kg of diazepam or 10 mg/kg of pentobarbital in a two-choice discrete-trial shock avoidance procedure. When administered alone, 1.0 mg/kg of diazepam and 10 mg/kg of pentobarbital produced comparable amounts of drug-appropriate responding (> 84%), whether rats were trained to discriminate between diazepam or pentobarbital and saline. Ro 15-1788 (3–32 mg/kg, p.o.), administered 10 min before diazepam or pentobarbital, produced a dose-related blockade of the discriminative effects of diazepam in both groups of rats, but was completely ineffective in blocking the discriminative effects of pentobarbital. The dose-effect curve for the discriminative effects of diazepam was shifted to the right in a parallel fashion 3- and 13-fold by 10 and 32 mg/kg of Ro 15-1788, respectively, indicating that Ro 15-1788 acts as a surmountable, competitive antagonist of diazepam. When administered alone, Ro 15-1788 (32–100 mg/kg, p.o.) produced primarily saline-appropriate responding, although 100 mg/kg of Ro 15-1788 produced drug-appropriate responding in one out of eight rats. When administered orally 30 min after diazepam, Ro 15-1788 (32 mg/kg) completely reversed within 10 min the discriminative effects of diazepam. The blockade of diazepam's discriminative effects by 32 mg/kg of Ro 15-1788 appeared to last at least as long (approximately 2 hr) as the effects of diazepam alone.     

Caffeine effects on buccal muscles of Aplysia

1. Caffeine (35-70 mM) elicited contractions of Aplysia buccal muscle El. In a Ca2+-free medium, in which ACh-elicited contractions rapidly fail, caffeine elicited contractions of approximately the same size as in normal medium. 2. 5-HT (10(-8) M and 10(-7) M) did not enhance caffeine-elicited contractions. 3. Lower concentrations (1-10 mM) of caffeine inhibited ACh-elicited contractions. Caffeine (7 mM) reduced the contraction by 80%. 4. Caffeine (7 mM) reduced ACh-elicited depolarization by 60%. 5. Caffeine (7 mM) increased 45Ca2+ influx into Aplysia buccal muscle I5. The stimulation of influx of 45Ca2+ by 10(-3) M ACh was non-additive with the stimulation caused by caffeine, and 7 mM caffeine reduced the influx caused by 10(-3) M ACh.     

Gender-related differences in diazepam effects on performance

In order to investigate the possible differences of diazepam effects in the two sexes, two placebo-controlled double-blind studies were conducted on healthy volunteer students. In one study the subjects received diazepam 10 mg alone or combined with 0.5 g/kg of alcohol in a parallel group design; in the other 0.2 mg/kg of diazepam or placebo were given in a cross-over manner. In both trials diazepam impaired the psychomotor skills of women more than men. The difference was similar in tasks measuring cognitive (digit symbol substitution), motor (balance of extraocular muscles) and sensory (critical flicker fusion) performances. Tapping speed was affected to a similar degree in both genders. Diazepam 10 mg did not cause impairment of body balance, a parameter sensitive to alcohol. The combined effect of diazepam and alcohol was of similar magnitude in both sexes in all objective tests. Subjectively the women felt themselves clumsier than did the men. The calming effect was similar in both groups. The results suggest that while the performance of women may be more vulnerable than men to impairment by diazepam they also are aware of it. The difference of effects is of such magnitude that it may cause bias in experiments unless carefully balanced groups are used.     

Teratogenic effects of diazepam in the hamster.

Pregnant hamsters were treated with different doses of oral and intravenous diazepam during the period of organogenesis. Teratogenic effects of diazepam were observed following oral treatment on days 8 and 10 and following intravenous treatment on day 11 of gestation. Types of malformations included cleft palate, exencephaly, limb anomalies, and hemorrhage. A dose-effect relationship was not observed. Comparison with reported literature seems to indicate that diazepam may be a mild teratogen in some species.     

Metallothionein-III antagonizes the neurotoxic and neurotrophic effects of amyloid beta peptides

Metallothionein-III (MT-III) protects cerebral cortical neurons in established culture from the toxic effect of amyloid beta peptides (Abetas). Protection is concentration dependent and approaches 100% at 0.1 microM. The EC(50) value estimated at 5 microM Abeta(1-40) is 2 nM. At higher concentrations (>0.1 microM), MT-III also antagonizes the trophic effect of Abeta(1-40) on cerebral cortical neurons in early cultures. Because only the fibrillar, SDS-resistant form of Abeta aggregates are thought to be neurotoxic, we analyzed and compared Abeta(1-40) aggregates formed in the presence and absence of MT-III using SDS-PAGE. Results show that aggregates formed in the absence of MT-III are predominantly SDS-resistant whereas those formed in its presence are mostly SDS-soluble. Neither MT-I nor -II exhibits any of the effects of MT-III. On the basis of these results, we propose that MT-III alleviates Abetas' neurotoxic effect by abolishing the formation of toxic aggregates of Abetas and that it may play a specific and important role in protecting the brain from the deleterious effects of Abetas.     

Noradrenalin antagonizes effects of serotonin and acetylcholine in the seawater eel intestine

After inhibiting ion and water transport with 10^-6 mol·l^-1 serotonin and 10^-6 mol·l^-1 methacholine, a muscarinic agonist of acetylcholine, 10^-5 mol·l^-1 (±)noradrenaline restored the serosa-negative transepithelial potential difference and short-circuit current in a step-like manner, accompanied by an increase in water absorption across the seawater eel intestine. Such recovery by noradrenalin was not obtained after pretreatment with 10^-7 mol·l^-1 eel atrial natriuretic peptide. This means that the inhibitory mechanisms of serotonin and acetylcholine are different from those of atrial natriuretic peptide. Similarly, 10^-7 mol·l^-1 clonidine and guanabenz (₂-agonists) also reversed the inhibitory action of serotonin and methacholine, but 10^-7 mol·l^-1 phenylephrine (₁-agonists) and 10^-7 mol·l^-1 isoproterenol (-agonist) did not antagonize serotonin and methacholine actions. Further, the enhancement by 10^-5 mol·l^-1 noradrenalin was blocked by 10^-4 mol·l^-1 yohimbine (₂-agonists) and 10^-4 mol·l^-1 prazosin (₁-agonists), but not by 10^-4 mol·l^-1 propranolol (-antagonist). Although relatively high dosage is required to obtain a significant effect, and discrimination between ₁- and ₂- is not successful in the present study, these results suggest that noradrenalin acts on an -type receptor. The -type receptor may exist on the enterocytes, since the effects of noradrenalin are observed even in the presence of 10^-6 mol·l^-1 tetrodotoxin. Interestingly, the tissue resistance also increased in parallel with increase in the short-circuit current after treatment with noradrenalin in the posterior part of the seawater eel intestine.Abbreviations ACh acetylcholine - 5-HT serotonin - eANP eel atrial natriuretic peptide - I _sc short-circuit current - MCh methacholine - NA noradrenalin - PD transepithelial potential difference - R _t tissue resistance - TTX tetrodotoxin - VIP vasoactive intestinal peptide     

Differential mediation of the anticonvulsant effects of carbamazepine and diazepam

Possible mechanisms of action of carbamazepine and diazepam on amygdala-kindled seizures were studied using compounds acting at the central and "peripheral-type" benzodiazepine binding sites. Ro-15-1788, a selective antagonist at the central benzodiazepine site, blocked the anticonvulsant effect of diazepam, but not of carbamazepine. In contrast, Ro5-4864, which acts at the "peripheral-type" benzodiazepine site, blocked the anticonvulsant effect of carbamazepine, but not of diazepam. The effect of Ro5-4864 was itself reversed by PK-11195, a compound that displaces Ro5-4864 binding in vitro and in vivo. These data indicate that the anticonvulsant effects of carbamazepine and diazepam on amygdala-kindled seizures are differentially mediated and suggest that the "peripheral-type" benzodiazepine binding site is functionally involved in the anticonvulsant effect of carbamazepine.     

Caffeine: cardiorespiratory effects and tissue protection in animal models

The aim of this review is to analyze the cardiorespiratory and tissue-protective effects of caffeine in animal models. Peer-reviewed literature published between 1975 and 2021 was retrieved from CAB Abstracts, PubMed, ISI Web of Knowledge, and Scopus. Extracted data were analyzed to address the mechanism of action of caffeine on cardiorespiratory parameters (heart rate and rhythm), vasopressor effects, and some indices of respiratory function; we close this review by discussing the current debate on the research carried out on the effects of caffeine on tissue protection. Adenosine acts through specific receptors and is a negative inotropic and chronotropic agent. Blockage of its cardiac receptors can cause tachycardia (with arrhythmogenic potential) due to the intense activity of β1 receptors. In terms of tissue protection, caffeine inhibits hyperoxia-induced pulmonary inflammation by decreasing proinflammatory cytokine expression in animal models. The protection that caffeine provides to tissues is not limited to the CNS, as studies have demonstrated that it generates attenuation of inflammatory effects in pulmonary tissue. It inhibits the effects of some pro-inflammatory cytokines and prevents functional and structural changes.     

Cytogenetic effects of diazepam in peripheral lymphocytes of self-poisoned persons.

The frequencies of chromosomal aberrations and of micronuclei were determined in lymphocyte cultures of 25 patients who attempted suicide with diazepam, 6-12 h, 72 h and 30 days after self-poisoning. These data were compared with those of healthy controls. The frequencies of numerical aberrations showed a significant increase immediately after self-poisoning. However, this effect could not be detected on the 3rd and 30th days after self-poisoning.     

Slit antagonizes netrin-1 attractive effects during the migration of inferior olivary neurons

Inferior olivary neurons (ION) migrate circumferentially around the caudal rhombencephalon starting from the alar plate to locate ventrally close to the floor-plate, ipsilaterally to their site of proliferation. The floor-plate constitutes a source of diffusible factors. Among them, netrin-1 is implied in the survival and attraction of migrating ION in vivo and in vitro. We have looked for a possible involvement of slit-1/2 during ION migration. We report that: (1) slit-1 and slit-2 are coexpressed in the floor-plate of the rhombencephalon throughout ION development; (2) robo-2, a slit receptor, is expressed in migrating ION, in particular when they reach the vicinity of the floor-plate; (3) using in vitro assays in collagen matrix, netrin-1 exerts an attractive effect on ION leading processes and nuclei; (4) slit has a weak repulsive effect on ION axon outgrowth and no effect on migration by itself, but (5) when combined with netrin-1, it antagonizes part of or all of the effects of netrin-1 in a dose-dependent manner, inhibiting the attraction of axons and the migration of cell nuclei. Our results indicate that slit silences the attractive effects of netrin-1 and could participate in the correct ventral positioning of ION, stopping the migration when cell bodies reach the floor-plate.     

3-Bromopyruvate antagonizes effects of lactate and pyruvate, synergizes with citrate and exerts novel anti-glioma effects

Oxidative stress-energy depletion therapy using oxidative stress induced by D-amino acid oxidase (DAO) and energy depletion induced by 3-bromopyruvate (3BP) was reported recently (El Sayed et al., Cancer Gene Ther., 19, 1–18, 2012). Even in the presence of oxygen, cancer cells oxidize glucose preferentially to produce lactate (Warburg effect) which seems vital for cancer microenvironment and progression. 3BP is a closely related structure to lactate and pyruvate and may antagonize their effects as a novel mechanism of its action. Pyruvate exerted a potent H₂O₂ scavenging effect to exogenous H₂O₂, while lactate had no scavenging effect. 3BP induced H₂O₂ production. Pyruvate protected against H₂O₂-induced C6 glioma cell death, 3BP-induced C6 glioma cell death but not against DAO/D-serine-induced cell death, while lactate had no protecting effect. Lactate and pyruvate protected against 3BP-induced C6 glioma cell death and energy depletion which were overcome with higher doses of 3BP. Lactate and pyruvate enhanced migratory power of C6 glioma which was blocked by 3BP. Pyruvate and lactate did not protect against C6 glioma cell death induced by other glycolytic inhibitors e.g. citrate (inhibitor of phosphofructokinase) and sodium fluoride (inhibitor of enolase). Serial doses of 3BP were synergistic with citrate in decreasing viability of C6 glioma cells and spheroids. Glycolysis subjected to double inhibition using 3BP with citrate depleted ATP, clonogenic power and migratory power of C6 glioma cells. 3BP induced a caspase-dependent cell death in C6 glioma. 3BP was powerful in decreasing viability of human glioblastoma multiforme cells (U373MG) and C6 glioma in a dose- and time-dependent manner.     

Caffeine analogs: effects on ryanodine-sensitive calcium-release channels and GABAA receptors

1. Caffeine at 0.3–10 mM enhanced the binding of [³H]ryanodine to calcium-release channels of rabbit muscle sarcoplasmic reticulum. A variety of other xanthines were as efficacious as caffeine or nearly so, but none appeared markedly more potent.2. Caffeine at 1 mM markedly inhibited binding of [³H]diazepam to GABA_A receptors in rat cerebral cortical membranes.3. Other xanthines also inhibited binding with certain dimethylpropargylxanthines being nearly fivefold more potent than caffeine.4. Caffeine at 1 mM stimulated binding of [³⁵S]TBPS to GABA_A receptors as did certain other xanthines.5. The dimethylpropargylxanthines had little effect. 1,3-Dipropy1-8-cyclopentylxan- thine at 100 M had no effect on [³H]diazepam binding, but markedly inhibited [³⁵S]TBPS binding.6. Structure–activity relationships for xanthines do differ for calcium-release channels and and for different sites on GABA_A receptors, but no highly selective lead compounds were identified.     

Phytoplankton primary production in several karst lakes in central Russia

The phytoplankton primary production was studied in different types of six soft-water, weakly-mineralized karst lakes: Kschara, Sankhar, Yukhor, Poridovo, Svetlen’koye, and Bol’shiye Garavy (Vladimir oblast). The following aspects were studied: seasonal dynamics, vertical distribution of the photosynthetic intensity, relative algal photosynthetic activity, the relationships between production processes and water transparency, BOD₅, and the concentrations of total forms of nitrogen and phosphorus. It was revealed that the maximal photosynthesis rate depends more on the total nitrogen than on the total phosphorus. A close correlation was found between the maximal photosynthesis rate and BOD₅.     

Immunomodulating effects of tofizopam (Grandaxin) and diazepam in vitro

Benzodiazepines (BDZs) are known to act not only in the central nervous system, but on peripheral cells and tissues binding to the peripheral-type benzodiazepine receptors. In the present study, the influence of two different BDZs (diazepam (Dz) and tofizopam (Tof) on several immune functions has been examined in vitro. Some differences between Dz and Tof in their effects on human lymphocyte proliferative response, changes in glucocorticoid-induced suppression of cell proliferation and influence on cytokine production (tumor necrosis factor-alpha (TNF-alpha) and interleukin-2 (IL-2)) have been determined. Dz suppressed mitogen-induced peripheral blood mononuclear cell (PBMC) proliferation, enhanced dexamethasone-induced inhibition of PBMC proliferative response, and suppressed lymphocyte production of TNF-alpha and IL-2. Tof usually enhanced PBMC proliferation and IL-2 production in low and moderate doses, but in high doses it suppressed both. Tof in all investigated doses enhanced dexamethasone-induced suppression of lymphocyte proliferation and depressed TNF-alpha production. Thus, both Dz and Tof are shown to have immunomodulating effects in vitro. Tof, opposite to Dz even in the therapeutic doses, is able to enhance in vitro mitogen-induced lymphocyte proliferation and IL-2 production.     

Psychotropic effects of diazepam in male mice with alternative psycho-emotional statuses

Effects of diazepam (0.1, 0.5 and 1 microg/kg, i. p.) on communicative, anxious behaviors, exploratory activities and sexual motivation of C57BL/6J male mice with alternative psychoemotional statuses (intact and anxious) were studied. Increased level on anxiety was formed by sensory contacts technique. Behavioral effects of diazepam depend on initial psycho-emotional status of animals. The compound has an anxiolytic effect in new situation on anxious males but does not have it in situation of social contacts. Diazepam reinforces initial sexual interest in anxious mice; however, it does not enable correct exhaustion of sexual motivation. Furthermore, the compound provokes development of the exhaustion in intact male mice.