Repetitive antidotal treatment is crucial in eliminating eye pathology, respiratory toxicity and death following whole-body VX vapor exposure in freely moving rats.

Exposure to the chemical warfare nerve agent VX is extremely toxic, causing severe cholinergic symptoms. If not appropriately treated, death ultimately ensues. Based on our previously described whole-body vapor exposure system, we characterized in detail the clinical outcome, including respiratory dynamics, typical of whole-body exposure to lethal doses of VX vapor in freely moving rats. We further evaluated the efficacy of two different antidotal regimens, one comprising a single and the other repeated administration of antidotes, in countering the toxic effects of the exposure. We show that a 15 min exposure to air VX concentrations of 2.34-2.42 mg/m3 induced a late (15-30 min) onset of obvious cholinergic signs, which exacerbated over time, albeit without convulsions. Marked eye pathology was observed, characterized by pupil constriction to pinpoint, excessive lacrimation with red tears (chromodacryorrhea) and corneal damage. Respiratory distress was also evident, characterized by a three-fourfold increase in Penh values, an estimate of lung resistance, and by lung and diaphragm histological damage. A single administration of TAB (the oxime TMB-4, atropine and the anticholinergic and antiglutamatergic benactyzine) at the onset of clinical signs afforded only limited protection (66% survival), with clinical deterioration including weight loss, chromodacryorrhea, corneal damage, increased airway resistance and late death. In contrast, a combined therapy of TAB at the onset of clinical signs and repeated administration of atropine and toxogonin (ATOX) every 3-5 h, a maximum of five i.m. injections, led to 100% survival and a prompt recovery, accompanied by neither the above-described signs of eye pathology, nor by bronchoconstriction and respiratory distress. The necessity of recurrent treatments for successful elimination of VX vapor toxicity strongly supports continuous penetration of VX following termination of VX vapor exposure, most likely from a VX reservoir formed in the skin due to the exposure. This, combined with the above-described eye and respiratory pathology and absence of convulsions, are unique features of whole-body VX vapor exposure as compared to whole-body vapor exposure to other nerve agents, and should accordingly be considered when devising optimal countermeasures and medical protocols for treatment of VX vapor exposure.

Sexual function in adult male rats after prenatal modulation of the cholinergic system.

Prenatal administration of the n-cholinolytic ganglerone to pregnant female rats at different periods of gestation was found to lead to long-term changes in sexual behavior in pubescent offspring: there was a reduced dynamic of acquiring sexual experience and a very low level of sexual activity, with significant impairment to the motivational and ejaculatory components of sexual behavior. The number of males with reduced sexual activity in the experimental groups was significantly greater than that in control offspring. The results obtained here provide evidence that impairments of sexual function in adult offspring induced by prenatal administration of the n-cholinolytic ganglerone at 9-11 and 12-14 days of gestation and, to a lesser extent, the m-cholinolytic metamyzil at 9-11 days of gestation, were due to impairment to the central mechanisms regulating sexual function due to stable changes in neurotransmitter activity in the hippocampus and hypothalamus, along with a significant reduction in the blood testosterone level.

[The sexual function of mature rat males after prenatal modulation of cholinergic system].

The data obtained have shown that prenatal exposure of pregnant rat females of 9-19-day pregnancy to N-cholinolytics as compared to M-cholinolytics produce long-term behavioural changes in pubescent rat progeny. Pubescent rat progeny had low dynamics of gaining sexual experience and decreased sexual activity with equal disturbance of motivation and coitus. The number of males with absence of sexual activity was above that of the control group. We suggest that sexual dysfunction of offspring adulthood was provoked by introduction of ganglerone (N-cholinolytic) which had been injected on 9-11 and 12-14 days of gestation, and metamyzil (M-cholinolytic) injected on 9-11 days of gestation. Apparently, regulation of neuronal mechanisms for sexual function is disturbed as a consequence of lasting change in neurotransmitter activity. It is suggested that dopaminergic activity in brain limbic structures was affected the most. The significant decrease in blood testosterone values has also been elucidated.

Role of the cholinergic mechanisms of the ventrolateral preoptic area of the hypothalamus in regulating the state of sleep and waking in pigeons.

Maintenance of waking in pigeons was found to be linked with the mechanisms of activation of muscarinic (M-) cholinergic receptors of the ventrolateral preoptic area of the hypothalamus. "Muscarinic" waking was characterized by an increase in the power of the EEG spectrum at 0.75-12 Hz and an increase in brain temperature. Activation of nicotinic (N-) cholinergic receptors in this area was associated with an increase in the duration of slow sleep, a decrease in the spectral EEG power at 0.75-7 Hz, and a decrease in brain temperature in this state; hyperactivation of these receptors led to the development of waking, where waking episodes were associated with significant decreases in brain temperature. Blockade of M-and N-cholinergic receptors resulted in changes in the sleep-waking cycle and thermoregulation which were oppose to those seen on receptor activation. It is suggested that M-and N-cholinergic receptors of the ventrolateral preoptic area of the pigeon hypothalamus are involved in regulating sleep and waking, their effects being associated with influences on the GABAergic system of this area.

Role of cholinergic structures in individual resistance of rat circulatory system to posthemorrhagic hypoxia.

Experiments employing ultrasound technique showed that nonselective blockade of central muscarinic cholinoceptors with amizyl significantly increases the number and lifespan of rats highly resistant to acute massive blood loss. This pretreatment increased individual resistance of the circulatory system to posthemorrhagic hypoxia (blood pressure and portal blood flow rate). Preliminary blockade of central nicotinic cholinoceptors and peripheral muscarinic cholinoceptors with cyclodol and methacin, respectively, had no effect on the percentage of rats highly and low resistant to acute blood loss. Preliminary blockade of peripheral muscarinic cholinoceptors with methacin prevented the decrease in the cardiac output in low resistant animals during the posthemorrhagic period.

Inhibition effects of benactyzine and drofenine on human serum butyrylcholinesterase.

Benactyzine and drofenine are widely used anticholinergic drugs. Benactyzine is used to treat organophosphate poisoning and drofenine acts on smooth muscle to stop muscle spasms. Both of these drugs are esters. After they enter the bloodstream, they will interact with butyrylcholinesterase (BChE; acylcholine acyl hydrolase: EC 3.1.1.8), which has an ability to hydrolyze a wide variety of esters. Therefore, the kinetic analysis of their inhibitory effects on human serum BChE was examined using butyrylthiocholine as substrate. Both drugs were competitive inhibitors of BChE and the Ki values of benactyzine and drofenine were calculated to be 0.010 +/- 0.001 and 0.003 +/- 0.000 mM, respectively, using the Systat (version 5.03, 1991) nonlinear regression analysis software package. According to these parameters, drofenine is a more potent competitive inhibitor of BChE than benactyzine.

The influence of anticholinergic drug selection on the efficacy of antidotal treatment of soman-poisoned rats.

The influence of some anticholinergic drugs (atropine, benactyzine, biperiden, scopolamine) on the efficacy of antidotal treatment to eliminate soman (O-pinacolyl methylphosphonofluoridate)-induced disturbance of respiration and circulation and to protect experimental animals poisoned with supralethal dose of soman (1.5 x LD(50)) was investigated in a rat model with on-line monitoring of respiratory and circulatory parameters. While the oxime HI-6 in combination with atropine prevented soman-induced changes in monitored physiological parameters insufficiently and very shortly, the combination of HI-6 with benactyzine or biperiden is able to prevent soman-induced alteration of respiration and circulation much more longer. Nevertheless, only rats treated with HI-6 in combination with scopolamine were fully protected against the lethal toxic effects of soman within 2 h following soman challenge. Our findings confirm that anticholinergic drugs with the strong central antimuscarinic activity, such as benactyzine, biperiden and especially scopolamine, seem to be more effective adjuncts to HI-6 treatment of severe acute soman-induced poisoning than atropine.

[Effect of biotransformation on the receptor selectivity of muscarinic antagonists in vivo]. / Vliianie protsessov biotransformatsii na retseptornuiu izbiratel'nost' muskarinovykh antagonistov v usloviiakh tselostnogo organizma.

In the experiments in vivo it is found that the receptor selectivity of muscarine antagonist glypine is time-dependent unlike atropine, amedine, benzhexol, benactyzine, and thropacin. Using modulation of the metabolic system activity it is shown that upon biotransformation glypine forms active metabolites that differs in receptor selectivity of the action.

[The effect of panpal prophylaxis on acetylcholinesterase activity in the blood, diaphragm and various parts of the brain in rats during treated and untreated poisoning with the organophosphorus insecticide phosdrine]]. / Vliv profylaxe panpalem na aktivitu acetylcholinesterázy v krvi, bránici a ruzných cástech mozku potkana v prubehu nelécené a lécené intoxikace organofosforovým insekticidem fosdrinem.

In experiments on male rats the paper investigated the effect of pharmacological prophylaxis with Panpal (pyridostigmine in combination with benactyzine and trihexyphenidyl) on the activity of acetylcholinesterase in the whole blood, diaphragm, and selected parts of the brain (frontal cortex, pontomedular region, hippocampus, cerebellum) at hour 1 and 3 of untreated and treated (oxime HI-6 with atropine) intoxication with the organophosphorous insecticide phosdrine. Whereas in the CNS Panpal did not produce statistically significant changes in the activity of acetylcholinesterase in the course of untreated and treated phosdrine intoxication, in the blood and diaphragm Panpal markedly intensified phosdrine-induced inhibition of the acetylcholinesterase activity and, in addition, decreased the reactivating effect of the oxime HI-6. The data give evidence of the importance of the combination of the prophylactically used reversible acetylcholinesterase inhibitor pyridostigmine with anticholinergics, which could eliminate the consequences of a pyridostigmine-induced decrease in the activity of the enzyme in the periphery.

[Narrow-band changes in the spectral composition of the EEG under the influence of an agonist and antagonist of the cholinergic neuromediator system]. / Uzkopolosnye izmeneniia spektral'nogo sostava EEG pod vliianiem agonista i antagonista kholinergicheskoi neiromediatornoi sistemy.

The EEG effects of intake of the mean therapeutic single dose of cholinomimetic amiridin (20 mg) or cholinolytic amizyl (2 mg) were studied in 7 healthy subjects. After the intake of the drugs with agonistic and antagonistic action, significant opposite changes in the EEG spectral density were observed in the frequency ranges of 0.6-6.7, 7.7-11.4, and 24.8-29.7 Hz. Amizyl produced an enhancement of the spectral density of the delta-, theta- and beta 2 activity and reduction of the alpha-rhythm power, while under the action of amiridin the spectral density of these rhythms changed in opposite directions. The oppositely directed changes in the alpha range were most pronounced. The peak frequency of amiridin-induced shift was equal to 9.8-10 Hz, and the same value of the spectral change induced by amizyl was 10.8-11.4 Hz. It is suggested that the spectral power density of the alpha-rhythm is an EEG index of the level of cholinergic activation.

[Involvement of central and peripheral cholinergic structures in regulation of cerebral electric activity and cardiac function in rabbits during hypoxia]. / Rol' tsentral'nykh i perifericheskikh kholinérgicheskikh struktur v reguliatsii élektricheskoi aktivnosti mozga i serdechnoi deiatel'nosti krolikov v usloviiak gipoksii.

In the normoxic conditions, prior to the "ascent" of rabbits, the i.v. injection of M-choline blocking benactyzine slowed down the ECG rhythm already within the next few minutes. Irritation of the reticular formation against this background did not initiate the reaction of activation; yet, heart rate was essentially unaltered by benactyzine. This was ascribed to low effectiveness of the benactyzine M-cholinergic mediation with respect to the cardiac function in contrast to the electric activity of the brain cortex due to, apparently, the abundance of M-choline receptors in this structure. The effect of N-cholinolytic ganglerone on the spontaneous and induced cortical activities was weak and, as compared with benactyzine, more expressed upon the heart rate. These choline blockers combined with hypoxia and the benactyzine-produced slow ECG waves on the initial phase (4000-5000 m) brought about neither spontaneous nor induced by the reticular formation irritation activation of ECG. At the maximal "altitude" (8500-9000 m) the benactyzine-synchronized ECG rhythm tended to become deeper assuming the low delta-type activity observed at the same "altitude" without i.v. benactyzine. With this ECG, irritation of Dieters' formation was impotent to trigger the reaction of activation.

Specific characteristics of cholinergic mechanisms of short-term memory in monkeys for different types of visual information: the effects of amizil.

Experiments on rhesus macaques were used to study the relationship between the characteristics of delayed visual differentiation and stimulus properties in conditions of pharmacological treatment with the m-cholinoreceptor blocker amizil, with the aim of identifying how modification of cholinergic structures affects different types of information. Disturbances to short-term memory for all stimuli consisted of reductions in the duration of retention and increases in motor reaction times, but occurred at different doses of the blocker: amizil at a dose of 0.3 mg/kg significantly decreased the retention duration for information relating to spatial relationships. Delayed discrimination of shape, contrast, and size worsened after treatment with amizil at a dose of 0.45-0.50 mg/kg, while decreases in the duration of short-term storage of information relating to color started after amizil doses of 0.6-0.8 mg/kg. It is suggested that the short-term memory system includes a set of neurophysiological mechanisms in which the cholinergic structures are organized differently and whose specific properties result in differences in the characteristics of short-term storage of different types of visual information.

[The effect of pharmacologic prophylaxis with Panpal on acetylcholinesterase activity in the diaphragm and various parts of the brain in rats during treated and untreated Soman poisoning]. / Vliv farmakologické profylaxe Panpalem na aktivitu acetylcholinesterázy v bránici a ruzných cástech mozku potkana v prubehu nelécené a lécené intoxikace somanem.

BACKGROUND: The pharmacological prophylaxis protecting the organism against organophosphorus compounds could increase the effect of antidotal treatment of poisoning with organophosphates. METHODS AND RESULTS: The influence of the pharmacological prophylaxis with Panpal (pyridostigmine in combination with benaetyzine and trihexyphenidyle) on acetylcholinesterase activity in diaphragm and various parts of brain at 1 and 3 h following non-treated and treated (the oxime HI-6 in combination with atropine) soman poisoning was tested on male rats. While Panpal did not significantly influence the acetylcholinesterase activity in brain following non-treated as well as treated soman poisoning. Panpal increased so many-induced acetylcholinesterase inhibition following non-treated poisoning and decreased the reactivating effect of the oxime HI-6 following treated soman poisoning in diaphragm. CONCLUSIONS: Our data confirm the importance of the combination of reversible acetylcholinesterase inhibitor pyridostigmine with anticholinergic drugs in the pharmacological prophylaxis of soman poisoning because of the elimination of consequences of pyridostigmine-induced increasing in acetylcholinesterase inhibition in the peripheral compartment.

[The effect of parasympatholytics on the therapeutic effectiveness of the oxime HI-6 against organophosphorus compounds (Soman, substance VX, Fosdrin) in mice]. / Vliv vybraných parasympatolytik na terapeutickou úcinnost oximu HI-6 proti organofosforovým slouceninam (Soman, látka VX, Fosdrin) u mysí.

BACKGROUND: Causal antidotal therapy of acute intoxications with organophosphorus compounds involving administration of the parasympatholytic and cholineesterase reactivator (oxime) has not been resolved so far satisfactorily despite knowledge of the basic mechanism of action of these noxious substances. METHODS AND RESULTS: In experiments on mice the therapeutic effect of parasympatholytics atropine, benactyzine and biperidene (Akineton) combined with oxime HI-6 on the toxicity of highly toxic organophosphates soman and substance VX and the organophosphorus insecticide phosdrine was compared as regards their influence on the LD50 of these noxious substances during 24-hour survival of experimental animals. Two levels of antidotes were tested. These findings confirm that the LD50 value of untreated intoxication with all three organophosphorus compounds is most increased by oxime HI-6 combined with benactyzine regardless of the antidote dosage. CONCLUSIONS: Oxime HI-6 is the most effective against highly toxic organophosphates and organophosphorus insecticides when combined with the centrally acting parasympatholytic benactyzine.

Importance of cholinolytic drug selection for the efficacy of HI-6 against soman in rats.

The influence of cholinolytic drugs (atropine, benactyzine, biperiden) on the efficacy of the oxime HI-6 (1-[[[(4-aminocarbonyl)pyridinio]methoxy ]methyl]-2-[hydroxyimino)methyl]pyridinium dichloride monohydrate) on soman-induced anticholinesterase and stressogenic effects was studied in rats. Soman-induced acetylcholinesterase inhibition in blood and diaphragm and the stressogenic effects of soman, i.e. an increase in plasma corticosterone level and liver tyrosine aminotransferase activity, were more significantly diminished by HI-6 in combination with benactyzine or biperiden in comparison with HI-6 plus atropine. These findings support a hypothesis that benactyzine as well as biperiden can increase the efficacy of the oxime HI-6 in comparison with atropine. They demonstrate the importance of cholinolytic drug selection in the treatment of soman poisoning in rats. Ltd.

[The specific nature of the cholinergic mechanisms of short-term memory in monkeys for different types of visual information: the characteristics of the effect of amizil]. / Spetsifika kholinergicheskikh mekhanizmov kratkovremennoi pamiati u obez'ian dlia razlichnykh tipov zritel'noi informatsii: osobennosti vliianiia amizila.

Short-term storage of visual information in monkeys seems to be determined by a set of cholinergic mechanisms, each of them dealing with a certain type of visual objects. These mechanisms are involved into the visual information processing and forming spatial discriminative features caused by the visual-vestibular interaction.

Differential effects of anticholinergic drugs on paired discrimination performance.

Working and reference memory processes were simultaneously evaluated during the performance of a paired discrimination (PD) task in which visual and spatial discrimination trials were combined within the same session. Atropine (1 and 5 mg/kg), scopolamine (0.02-0.20 mg/kg), benactyzine (1-4 mg/kg), trihexyphenidyl (1-10 mg/kg), and aprophen (5-20 mg/kg) were all found to increase the number of errors performed by overtrained rats during the spatial but not during the visual trials. Although all the anticholinergic drugs tested induced specific working memory impairment at low doses, they differentially affected other, simultaneously recorded, behavioral parameters. Thus, while atropine affected most of the recorded parameters, aprophen induced only a mild effect. Benactyzine was found to have the most specific effect on working memory, with only minimal side effects, a combination that supports its use as the preferred psychopharmacological model of working memory impairment.

[Changes in the brain neuraminidase activity under the action of tsiklozil and amizil]. / Izmenenie aktivnosti neiraminidaz golovnogo mozga pri deistvii tsiklozila i amizila.

The effect of cyclozyl and amizyl on the activity of soluble and membrane-bound neuraminidase of the rat brain is studied in the in vivo and in vitro experiments. Within 60 min after subcutaneous injection of cyclozyl in a dose of 0.5 microgram/kg of body weight the activity of soluble neuraminidase decreased by 45.5% whereas the activity of membrane-bound neuraminidase remained the same. In the experiments in vitro the activity of both enzyme forms did not change when the content of cyclozyl and mixture of general gangliosides in the incubation media was 2.0, 20.0, and 200.0 micrograms. Amizyl (2 micrograms) in the presence of general gangliosides increased the neuraminidase activity whereas in the presence of disialoganglioside GD1b reduced the activity. Various lipids (phospholipids, phospholipids + cholesterol, cerebroside + sulfatides) surrounding the enzyme exerted different effect on the activity of both neuraminidase forms. Thus we suggest active interaction of the system "gangliosides-soluble and membrane-bound neuraminidase" with M-cholinolytics (cyclozyl and amizyl) and important role of this "substate-enzyme" system in M-cholinoreceptor functioning.

An ethologically based, stimulus and gender-sensitive nonhuman primate model for anxiety.

1. Adult male and female squirrel monkeys were tested for behavioral responses to 5 min. social separation (alone in test room) followed by 30-sec. exposure to 2 humans wearing a leather capture glove. 2. Trials were preceded by intramuscular injection of an anticholinergic drug, benactyzine hydrochloride, in doses of 0.0, 0.6, 1.0, 2.0, and 3.0 mg/kg. 3. Measured behaviors were number and type of vocalization and locomotor activity (duration in sec) in each of the two testing conditions. 4. A dose-response relationship for bark/yap vocalizations during the 30-sec trials was established, with 1.0 mg/kg being the most effective dose. 5. Males and females differed in the number of barks/yaps produced during 30-sec. trials at every drug dose. 6. The present testing paradigm provides the basis for efficiently determining the extent of gender differences in dose/response relationships for drugs of possible therapeutic value in the treatment of anxiety-related behavioral disorders.

[Comparison of the effect of selected anticholinergic agents on cholinergic and noncholinergic effects of GV substances during acute poisoning in rats]. / Srovnání efektu vybraných anticholinergik na cholinergní a necholinergní úcinky GV látky behem akutní intoxikace potkana.

In experiments on male rats, the effect of selected cholinolytic agents (atropine, benactyzine, G 3063) in combination with the reactivator of cholinesterases HI-6 on the cholinergic and non-cholinergic effects of GV substance in the course of acute sublethal intoxication was compared. The cholinergic affects of GV substance were examined by means of the changes in the activity of cholinesterases in whole blood, the CNS, diaphragm and liver, the noncholinergic stressogenic effects by means of the changes in the level of corticosterone in plasma and the activity of tyrosine amino transferase in the liver. It follows from the changes in the activity of cholinesterases that the cholinergic effects of GV substance are least influenced by atropine, whereas benactyzine and G 3063 exert an approximately similar effect. The difference in the effect is evident especially in the 24th hour of intoxication. Similarly stressogenic effects of GV substance are least influenced by an antidotal combination of atropine and HI-6. It means that the centrally acting cholinolytic agents benactyzine and G 3063 are more advantageous for the therapy of GV substance poisonings than the peripherally acting atropine.