[Agonist of V2 vasopressin receptor reduces depressive disorders in post-stroke patients].

Poststroke depression is one of the common psychiatric complications after stroke. Thus, the research of new ways for treatment depressed mood after stroke is actual. The previous researches revealed vasopressin to be effective in patients with memory, speech and motor function disorders after stroke. The purpose of the study was to investigate influence of vasopressin on depression after stroke. Fourteen patients with affective disorders have been treated with subendocrine doses of 1-desamino-8-D-arginin-vasopressin (DDAVP) daily by intranasal application during 1,5-2 months. Vasopressin was effective in correcting both apatoadinamic and anxious depression. Treatment effect was durable, lasts for 0,5-1 year after the first course of therapy. The results of this pilot study demonstrate perspective of using selective agonist of vasopressin V2 receptors, DDAVP, in therapy of post-stroke depression.

Effect of zinc chloride on picrotoxin-induced hyperkinesis depends on its concentration in solution injected into rat neostriatum.

The hyperkinekic effect (increase in spontaneous activity and development of choreomyoclonic hyperkinesis of the extremities and body) of picrotoxin injected into the rostral neostriatum of rats in a dose of 2 µg was reduced if the drug was injected together with ZnCl(2) in a concentration of 0.1 µg/µl. ZnCl(2) in a concentration of 1 µg/µl did not modulate the effects of picrotoxin, while in a concentration of 3 µg/µl it increased spontaneous motor activity in the open field test without affecting the symptoms of choreomyoclonic hyperkinesis.

Effects of intracisternal administration of insulin on the time dynamics of behavior in rats.

The effects of intracisternal administration of insulin at doses of 2.5, 25, 50, and 200 ng on the behavior of rats in an open field test and elevated plus maze were studied at 45 min, 24 h, and nine days after single doses. On day 1, doses of 2.5 and 25 ng increased the probability of orientational-investigative behavior and locomotion in the open field, while doses of 50 and 200 ng, conversely, produced some tendency to decreases in investigative behavior (mainly at the dose of 50 ng). On day 2 after dosage with insulin, the tendency to increased investigative activity persisted only in rats given a dose of 25 ng of insulin, while on day 9 this was increased in all experimental animals independently of the insulin dose given. In the elevated plus maze, insulin doses of 2.5 and 200 ng decreased anxiety in rats during the first 5 min of testing on day one, while doses of 2.5 and 25 ng reduced anxiety in the second 5 min. On day 2, the level of anxiety increased (at doses of 50 and 200 ng) or tended to increase (at doses of 2.5 and 25 ng); on day 9, anxiety decreased in all experimental rats. Studies of the time dynamics of the behavior of rats showed that single doses of insulin had aftereffects in CNS structures, consisting of weakening of non-associative memory in the open field test on days 2 and 9 and increases in anxiety in the elevated plus maze on day 2, followed by weakening of anxiety on day 9.

[The influence of intracysternal insulin administration on the rat temporal behaviour dynamics].

Rat behaviour in the open field and elevated plus-maze was analyzed in rats after intracysternal administration of 2.5, 25, 50 and 200 ng of insulin in 45 min, 24 hrs and on the 9th day after single injection. Dose-dependent changes in 45 min occurred in both behavioural tests: insulin in low doses (2.5 and 25 ng) increased probability of locomotion and investigative activity in open field, while insulin in high doses (50 and 200 ng) did not alter locomotor activity and showed tendency to weakening of the investigative behavior (especially in the dose of 50 ng). Tendency was found in 24 hrs to increase probability of investigative behavior in open field after injection of 25 ng of insulin, although on the 9th day after insulin administration this behaviour increased in all experimental groups for all used doses. Insulin in the doses 2.5 and 200 ng decreased anxiety in elevated plus-maze in 45 min during the first five min; the doses 2.5 and 25 ng at the second five min exerted the same effect. In 24 hrs, the anxiety level increased for the doses 50 and 200 ng, and there was a tendency for an increase in the doses 2.5 and 25 ng; anxiety was decreased on the 9th day for all used doses of insulin. Thus, single insulin administration induced weakness of non-associative memory in open field on the day 2 and day 9 as well as increase of anxiety level on the day 2 and decrease of anxiety level on the day 9 in elevated plus-maze.

Effects of intracerebroventricular administration of beta-amyloid on the dynamics of learning in purebred and mongrel rats.

The effects of intracerebroventricular administration of the beta-amyloid peptide fragment Abeta(25-35) on the dynamics of the acquisition of a conditioned reflex in a Y maze were studied in Wistar and mongrel rats. The dynamics of decreases in the number of errors were assessed using an exponential mathematical model describing the transfer function of a first-order system in response to stepped inputs using non-linear regression analysis. This mathematical model provided a good approximation to the learning dynamics in inbred and mongrel mice. In Wistar rats, beta-amyloid impaired learning, with reduced memory between the first and second training sessions, but without complete blockade of learning. As a result, learning dynamics were no longer approximated by the mathematical model. At the same time, comparison of the number of errors in each training sessions between the control group of Wistar rats and the group given beta-amyloid showed no significant differences (Student's t test). This result demonstrates the advantage of regression analysis based on a mathematical model over the traditionally used statistical methods. In mongrel rats, the effect of beta-amyloid was limited to an a slowing of the process of learning as compared with control mongrel rats, with retention of the approximation by the mathematical model. It is suggested that mongrel animals have some kind of innate, genetically determined protective mechanism against the harmful effects of beta-amyloid.

[Dose-dependent effects of intracisternally administered insulin on rat's behavior and glucose level].

Rat behavior in the open field and elevated plus-maze as well as glycaemia level were analyzed in rats after intracisternal administration of 2.5, 25, 50 and 200 ng of insulin. Dose-dependent changes were found in both behavioral tests: insulin in low doses (2.5 and 25 ng) increased probability of locomotion and investigative activity in open field, while insulin in high doses (50 and 200 ng) did not alter locomotor activity and showed tendency to weakening of the investigative behavior (especially in the dose of 50 ng). Significant decrease of rat anxiety level during the first 5 minutes of testing was found after administration of 2.5 and 200 ng of insulin and during the next 5 minutes after administration of 2.5 and 25 ng of insulin in elevated plus-maze. The glucose level in rats was increased in 1-2 hours after insulin administration, though glycaemia level did not exceed normal values. Thus revealed alterations of behavior are supposed to be the result of direct insulin influence on central mechanisms of activation and/or suppression of underlying behavioral characteristics of animals.

Regression analysis of relationship between liver weight and body weight after partial hepatectomy in rats.

A method for evaluation of the initial weight of the liver is developed for calculating the regeneration coefficient after partial hepatectomy on the basis of linear regression analysis. Experiments on rats showed that the model reflecting the relationship between liver weight and body weight for calculation of regeneration coefficient after partial resection of the liver expressed by the equation P0=0.033 x M can be used for screening of potential hepatoprotectors for quantitative evaluation of the regeneration processes.

[Effect of the population density on growth and regeneration in the snail Achatina fulica]. / Vliianie plotnosti populiatsii na rost i regeneratsionnuiu sposobnost' ulitki Achatina fulica.

In the laboratory, the growth rate of the giant African snail Achatina fulica, as estimated by the weight and shell length was shown to decrease when the population density increased from 10 to 60 snails/m2 of the total terrarium area for five months. In the second experiment, when the population density increased from 48 to 193 snails/m2, the growth rate had already decreased by six weeks. In the groups with a high population density the feeding behavior was weakened, expressed by a greater amount of nonconsumed food, according to visual observations, than in the groups with lower population densities. At the population density of 10 to 60 snails/m2, the proliferative activity in the course of the optic tentacle regeneration, as expressed by the mitotic index, did not differ reliably within five months. In the second experiment, the mitotic indices at the population densities of 96 and 193 snails/m2 within 1.5 months exceeded that of 48 snails/m2. Recommendations are given concerning the population density from the viewpoint of commercial growth of the snails. It was proposed that, based on the analysis of the mechanism underlying the inhibition of feeding behavior in populations with extra high densities, one may develop a new approach to the production of chemical agents to control land snails as agricultural pests.

Characteristics of cholinoreceptors on identified TAN neurons of the ground snail Achatina fulica.

The characteristics of cholinoreceptors located on neurons TAN1, TAN2, and TAN3 of the ground snail Achatina fulica were studied by incubation of the central ganglia in a bath with cholinotropic preparations during intracellular recording of background neuron spike activity. Acetylcholine, nicotine, the selective n-cholinoreceptor agonist suberyldicholine, and the selective n-cholinoreceptor agonist 5-methylfurmethide concentration-dependently inhibited background spike activity to the level of complete blockade at concentrations of 500 microM. The m-cholinoblocker metamizil (500 microM) completely prevented the inhibitory activity of concentrations of 5-methylfurmethide of up to 500 microM. The central n-cholinoblocker etherophen (500 microM) completely blocked the inhibitory activity of 500 microM suberyldicholine. However, metamizil and etherophen added separately only partially decreased the inhibitory effects of acetylcholine but could not completely block the effect of acetylcholine. At the same time, mixtures of metamizil and etherophen (500 microM each) completely blocked the inhibition of background spike activity induced by acetylcholine. These results show that both classes of cholinoreceptors act on TAN neurons in the same direction.

[The embryo-protective action of antifein derivatives in chloridin-induced teratogenesis]. / Embrioprotektivnoe deistvie proizvodnykh antifeina pri khoridinindutsiruemom teratogeneze.

We studied the effect of propyl- and ethylnorantifein on chloridine-induced abnormalities of extremities in rat embryos. Chloridine (50 and 25 mg/kg, given through the gastric tube) was administered to rats on day 14 of pregnancy, and its embryotoxic effect was estimated from the state of fetuses and implantation sites on day 20 of prenatal development. Propylnorantifein had fetoprotective properties both after intraperitoneal (10 mg/kg) and after intraamniotic (6 and 0.06 micrograms) administration. Ethylnorantifein under similar conditions does not change the action of chloridine, and it prevents the appearance of developmental abnormalities only at the concentration of 0.06 microgram/embryo. These data are discussed in connection with different effects of antifein derivatives on chromatin proteinkinase, which phosphorylates HMG nonhistone proteins.

[The characteristics of the cholinoreceptors on the identified TAN neuron of the giant African snail Achatina fulica]. / Osobennosti kholinoretseptorov na identifitsirovannom neirone TAN nazemnoi ulitki Achatina fulica.

Acetylcholine, nicotine, a selective agonist of N-cholinoreceptors suberildicholine dibromide, as well as a selective agonist of M-cholinoreceptors 5-methylfurmethide inhibited spike discharges in a dose-dependent manner up to a complete ceasing of the firing in cholinoreceptors situated on the identified neurone TAN of African giant snail Achatina fulica. M-cholinoblocker metamizylum completely prevented the inhibitory effect of methylfurmethide. Central cholinoblocker aetherophen completely prevented the inhibitory effect of suberildicholine dibromide. Metamizylum or aetherophen used alone were only able to decrease the inhibitory effect of acetylcholine, whereas a mixture of these agents suppressed completely the acetylcholine-induced inhibition. The findings suggest that, on the TAN membrane, nicotinic and muscarinic cholinoreceptors co-exist and function in one and the same direction.

[The effect of glutamic acid on the defensive and feeding behavior of the snail Helix lucorum]. / Vliianie gliutaminovoi kisloty na oboronitel'noe i pishchevoe povedenie vinogradnoi ulitki.

Behavioural effects of glutamic acid injection into the body cavity were investigated in the land snail Helix lucorum. An injection itself induced some non-coordinated defensive reactions leading to a partial withdrawal into a shell. The defensive tentacle reflex was facilitated probably due to an activation of the tentacle muscles. The defensive reflex of the pneumostome closure changed in different directions depending on the injected dose of glutamic acid. Feeding behaviour was inhibited by a high dose of glutamic acid. The most pronounced inhibition of the feeding behaviour was induced by N-methyl-DL-aspartic acid.

[The effect of ethanol on the food behavior of the snail Achatina fulica]. / Vliianie étanola na pishchevoe povedenie ulitki Achatina fulica.

The feeding behaviour of the land snails Achatina fulica was used for investigation of the effects of different doses of ethanol. The time from the beginning of food (carrot) exposure till the removal of the carrot from the needle was measured. Regression analysis revealed the opportunity of approximation with exponential mathematical model of feeding behaviour time progressive decrease during food exposure. 1% ethanol solution injected into cephalopedal sinus inhibited the feeding behaviour to a small extent whereas 5% and 10% ethanol led to the facilitation of this behaviour. The increase of ethanol concentration from 20% to 40% in injected solution enhanced the inhibitory effect. The feeding behaviour is proposed to be employed as a model for investigation of ethanol neuronal effects.

[The evolutionary aspects of the dynamic acquisition of simple conditioned reflexes]. / Evoliutsionnye aspekty dinamiki vyrabotki prostykh uslovnykh refleksov.

The dynamics of elaboration of simple classical and instrumental conditioned reflexes in snails, rats, cars, dogs and humans was investigated. The dependence between the number of correct responses (in percentages) and the number of reinforcements was significantly approximated with exponential equation including the coefficient describing the initial level of conditioning. Regression analysis gave the opportunity to compare the dynamics of conditioning in different animal species.

[Regression analysis of an instrumental conditioned tentacular reflex in the edible snail]. / Regressionnyi analiz instrumental'nogo uslovnogo tentakuliarnogo refleksa u vinogradnoi ulitki.

Regression analysis revealed the opportunity of approximation with exponential mathematical model of the learning curves of conditioned tentacle reflex. Retention of the reflex persisted for more than three weeks. There were some quantitative differences between conditioning of the right and the left tentacle. There was formation of the reflex in every session during spring period, but there was no retention between sessions. The conditioned tentacle reflex may be employed in neuropharmacological studies.