The effect of phenamine and caffeine on the ability to extrapolate in rats]

Solution of an extrapolation problem was studied on 28 albino rats (Way strain and laboratory population) and 68 hybrids (the first generation) of wild and laboratory rats in experiments with a screen--the search of food after the disappearance of the food stimulus from the animal's sight. Administration of caffeine (20 mg/kg) and d,l-amphetamine (0.1 mg/kg), though not changing the share of correct solutions, diminishes the number of "refusals" to solve it. Increased motor activity and diminished emotionality of the rats due to administration of the drugs, recorded in an open field test, are likely to cause a decrease in the number of refusals. Administration of d,l-amphetamine facilitates the process of conditioning which contributes to the greater number of positive solutions of the repeatedly presented task.     

The effect of phenamine and caffeine on caudate inhibition of conditioned reflex avoidance reactions in cats]

In cats with a preliminarily learned conditioned avoidance reaction, stimulation of the caudate nucleus inhibited behavioral response by lengthening its latency and reducing the number of conditioned reactions. Intensity of the inhibitory effect did not substantially depend on the localization of electrodes in the head or body of the nucleus and weakened within a few experimental days. D,1-amphetamine (0.5 to 4 mg/kg) and caffeine (10 to 10 mg/kg) suppressed the caudate inhibition, but the action of the drugs was manifested in different ways. The influence of large doses of d,1-amphetamine was characterized by a serious disturbance of behaviour and caudate inhibition of conditioned responses.     

The effect of caudate nucleus stimulation on phenamine stereotypy in cats]

Large doses of d,1-amphetamine produce in cats a stereotype behaviour: its chronic administration results in low variability of the behaviour of one and the same animal and a stable set of motor automatisms. This makes it possible to use the cyclography for an objective estimation of the d,1-amphetamine-induced stereotypy. Low-frequency stimulation of the caudate nucleus head weakens or completely blocks the sterotype movements when current intensity is subthreshold for behavioral arrest reaction. The pecularities of the caudate control its similarity to the action of haloperidol and the absence of influence of the stimulation of the capsula interna and some thalamic nuclei on the stereotypy lead to the assumption that it is due to the depression of the inhibitory function of the caudate nucleus brought about by the intensification of the nigro-striatal dopaminergic transmission.     

Positive effect of pyavit on formation and retention of the passive avoidance conditioned reaction in rats

In the paper are presented the results of the study of Pyavit, a complex leech preparation from, whose effects on the memory may be dependent on DNA methylation (one of the mechanisms of gene expression regulation). A positive effect of Pyavit on formation and retention of passive avoidance conditioned reaction was demonstrated in rat experiments.     

The effect of striatectomy on retraining rats to an avoidance habit in a U-shaped maze]

The capacity of rats to reversal learning changing of the direction of the avoidance response was determined in the Y-shaped maze. Four training sessions--each time in a new direction (to the right or to the left) for running were conducted in the course of one experiment. The results obtained in 4 groups of animals were compared: intact, with bi- and unilateral striatectomy and with bilateral destruction of the parietal cortex. The majority of the intact rats preferred running in the right direction. The character of the preference changed after striectomy: the rats ran more regularly in the direction at the side of which the striatum was injured more. Bilateral striatectomy also led to increase in the number of errors, to the increase in the latency and disturbance of a passive component of the avoidance response.     

Study of the correlation between the effects of phenamine and reserpine on models of the caudate arrest reaction]

Chronic experiments were conducted on cats. It was revealed that the effect of d, 1-amphetamine reducing the inhibitory effects of the caudate nucleus on the motor function persisted after the reserpinization of the animals. Reduction of the inhibitory function of the caudate nucleus in the form of increased threshold of the causate retardation of movement under the effect of d,1-amphetamine was expressed more 24 hours after the administration of large doses of reserpine (0.3 mg'kg). This could be the result of increased sensitivity of dopaminergic receptors of the niqro-striate routes to the mediator by the principle of denervation.     

Changes in brain monoamine oxidase activity in conditioned passive avoidance reaction in rats]

Activity of the enzyme monoamine oxidase (MAO) and kinetic parameters (Km, Vmax) for the 5-hydroxytryptamine (5-HT) and dopamine deamination were examined in the brain of rats with conditioned passive avoidance recall. Changes of the 5-HT and dopamine deamination were found in amygdala, striatum and frontal cortex. MAO activity was not changed in hippocampus. In amygdala the rate of 5-HT deamination was significantly increased and kinetic studies revealed increased affinity of the enzyme for 5-HT. The metabolism of dopamine in amygdala was unchanged. In frontal cortex the deamination of 5-HT was not changed, but the dopamine deamination significantly decreased. This decrease was due to lowering of MAO affinity for dopamine. In striatum the metabolism of both 5-HT and dopamine was reduced, and kinetic studies showed the lowering of Vmax for 5-HT and dopamine deamination.     

The effect of training conditions on passive avoidance performance in rats

Male outbred rats were trained for step-through avoidance in different experimental conditions: 1) in a two-compartment chamber with a small dark compartment and a chamber with illuminated suspended platform; 2) with or without acquaintance with experimental chamber 24 hours prior to learning; 3) with or without a possibility of the chamber exploration 3 min immediately before training procedure; 4) with inescapable or escapable pain reinforcement (5 electric footshocks, 0.45 mA, 1 s, with 2-s between-shock intervals); 5) with 2 or 5 inescapable footshocks of the same rate, duration, and intensity. The acquired performance was tested 24 h after training. It was shown that the procedure of exploration of the experimental chamber 24 prior to training improved the reproduction and the same procedure conducted immediately before training impaired the reproduction of the acquired behavior. Different training conditions improved the reproduction of the acquired behavior in the chamber with a suspended platform to a greater extent than in the two-compartment chamber. The decrease in the number of pain stimuli from 5 to 2 or the possibility to escape the punishment during training did not significantly change the reproduction.     

Evaluation of the effect of arginine vasopressin on the formation of the conditioned reaction of active avoidance in rats

The effect was studied of arginine-vasopressin (AVP) intraperitoneal administration in a doze of 0.001 mg/kg on elaboration of conditioned reaction (CR) of active avoidance in rats. Estimation of reaction dynamics by dynamic delta index allowed to increase the informational value of the experimental data with taking into account the direction of reaction shift and individual characteristic of the animal. AVP improved the elaboration of active avoidance CR, lowered variability of individual learning ability and did not influence the change of the number of intersignal reactions and short-latency escapes in the process of learning. It is suggested that the main site of AVP effect is the animal's reaction to conditioned sound stimulus.     

Identification of serotonin-modulated protein fraction and study of its role in passive avoidance reaction in rats]

The effect 10(-3) M serotonin and norepinephrine solutions application on the brain occipital cortex on discrete water soluble protein fractions content was investigated in narcotized rats. It was revealed that application of serotonin solution caused repeated decrease in N6 fraction content. Immunoglobulins against N6 fraction being injected into the lateral ventricle of rat brain increased the number of photocell crossing and the presence probability of rats at the dark compartment entrance region in passive avoidance schedule. The conclusion of selective serotonin participation in regulation of brain cortex discrete proteins turnover and of these proteins involvement in searching behavior was made.