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.

[Neuropeptide induction of compensatory processes at aphasias]. / Neiropeptidnaia induktsiia kompensatornykh protsessov pri afaziiakh.

Dynamic changes of speech function were studied in patients with persistence aphatic disorders after stroke under the conditions of application of V2 vasopressin receptor agonist (1-desamino-8-D-arginin-vasopressin). A course of intranasal administration of the medical drug by using the double blind control showed a reliable reduction of frustration severity of expressive and impressive speech in patients with aphasias of different forms and degrees. A correlation of positive influence of vasopressin on speech, verbal memory and attention was found at efferent motor aphasias. The achieved effects preserved during a two-year catamnestic observation period. A repeated course of therapy resulted in an additional improvement of speech. Neuropeptide restored initially, in patients with aphasias, relatively simple forms of speech and later--complicated ones. This resulted in an improvement of speech functions which are regulated by both cerebral hemispheres. Supposedly, neuropeptide optimized the activity of both the right and left cerebral hemispheres. The stability of the obtained effects is explained by induction, due to vasopressin, of compensatory processes leading to reorganization of intercentral connections.

[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 clinical evaluation of vasopressin in the treatment of aphasias]. / Klinicheskaia otsenka primeneniia vazopressina v lechenii afazii.

At residual stage of stroke 64 patients with different forms of aphasia were administered intranasally subendocrine doses of 1-desamino-8-D-argininvasopressin (adiuretin-SD). It was established that peptide activates expressive and impressive speech of patients. Improvement of speech occurred in 79% of cases.

Population profile of brain asymmetry in rats after intra-amniotic administration of vasopressin.

The effects of intra-amniotic administration of 1-desamino-8-D-arginine-vasopressin (DDAVP) at 14 days of embryogenesis on movement asymmetry in neonatal and mature mongrel white rats were studied. Controls consisted of intact and sham-operated animals, as well as rats given intra-amniotic saline. The population profile of asymmetry was assessed in terms of the tail position of rats aged two days, and also in terms of the direction of excursions in a T-maze in three-months males. The proportion of animals showing asymmetrical tail poses was no more than 36% in controls; the ratio of left-asymmetrical and right-asymmetrical intact rats was 2:1. DDAVP increased the number of rats with asymmetrical tail poses by a factor of 1.5-2.6, and right-asymmetrical individuals became predominant. This effect was demonstrated graphically as a bell-shaped dose-response curve with a peak response at doses of 3 x 10(-8) and 3 x 10(-6) mg. The selection probability for the right-hand side of the maze in experimental animals was 0.71 +/- 0.06, which was significantly higher than in animals of the three control groups, which showed no preference for the direction of excursions. These results indicate lateralization of the action of DDAVP in the developing central nervous system, leading to a predominance of right-sided motor responses in neonatal and mature rats.

Activity of adenylate cyclase and 5'-nucleotidase in the sensorimotor and limbic structures of the brain in rats after manipulatory training.

Adenylate cyclase (AC) and 5'-nucleotidase (NT) activities were measured in the limbic (amygdala, hippocampus) and sensorimotor (cortex, striatum) structures of the brain in three groups of rats: untrained rats and rats which were good and poor learners in training to perform movements involving pushing against an obstruction. After training, AC activity decreased in all structures studied. Activity decreased in the cortex and striatum to a greater extent in good learners, and in the amygdala in poor learners. NT activity decreased in all brain structures apart from the striatum, to a greater extent in rats which were less able to learn to produce movements involving prolonged pushing. The striatum was the only structure in which increases in NT activity occurred, from the lowest initial level in the control group. 1.0 +/- 0.04 microgram P(i)/mg protein/min, to 1.3 +/- 0.1 micrograms P(i)/mg protein/min in poor learners and to 2.0 +/- 0.1 micrograms P(i)/mg protein/min in good learners. Interhemisphere asymmetries in AC activity in the cortex and hippocampus were seen, along with an interhemisphere difference in NT activity in the amygdala. Thus, the activity of enzymes involved in adenine and cAMP biosynthesis changed in different ways in the limbic and sensorimotor structures of the brain, depending on the ability of rats to learn. The increase in NT activity after training of rats, which was limited to the striatum, may reflect a special role for the purinergic system in these structures in mediating sensation-regulated movements.

[The biochemical characteristics of the sensorimotor cortex in right-handed, left-handed and ambidextrous rats]. / Nekotorye biokhimicheskie osobennosti sensomotornoi kory krys-pravshei, levshei i ambidekstrov.

The activity of acetylcholinesterase (AChE), 5'-nucleotidase (NT), adenylate cyclase (AC) in P2 fraction of sensory-motor cortex was studied in right-handed, left-handed and ambidexters rats on the 2-nd and 45-th day after revealing preferable forepaw at taking feedstuff out of horizontal tube (1 case, 10 presentations). By bilateral (averaging right and left hemispheres) values of AChE, NT and AC ambidexters differ from animals with absolute motor preference and right-handed rats differ from left-handed ones (2-nd day). In 1.5 month differences between ambidexter and animals with preferable extremity are revealed by NT and AC activity. Chemical brain asymmetry is revealed for ambidexters (AChE, 45-th day), right-handed rats (NT, 45-th day) and left-handed animals (AC, 2-nd day). Functional importance of biochemical characteristics studied is discussed.

[Population profile of brain asymmetry in rats after intra-amniotic administration of vasopressin]. / Populiatsionnyi profil' asimmetrii mozga krys posle vnutriamnioticheskogo vvedeniia vazopressina.

Vasopressin administration induced a right-sided bias in the rat litter, the asymmetry being similar to a right-sided bias in the turning behaviour of adult male rats in the T-maze. The findings suggest the nigrostriatal system to be responsible for the lateralising effect of vasopressin in the brain.

Neurochemical characteristics of the rat neostriatum and motor cortex after the development of a unilateral manipulatory reflex.

Indicators of the activity of acetylcholinesterase (ACE), 5'-nucleotidase (NT), adenylate cyclase (AC) in the sensorimotor cortex and the neostriatum (NS) of the right and left cerebral hemispheres of control rats and rats trained to perform a food-procuring movement by pressing against an obstacle with the forelimb. An identical level of the averaged bilateral values of the activity of NT and AC in both of the structures in question and an increased ACE activity in the NS were found in the control animals. After the development of a manipulatory skill, the activity of AC decreased in the cortex and the NS in the presence of unchanged ACE activity, while NT activity decreased in the cortex and increased in the NS. The bilateral values of the activity of the enzymes differed significantly in well and poorly trained rats. At the same time, the activity of the enzymes was similar in character in the dominant and subdominant hemispheres for each group of animals. Overall the neurochemical changes obtained can be regarded as specific correlates of the developed unilateral manipulatory reactions that are characteristic for the structures in question of both cerebral hemispheres.

[Adenylate cyclase and 5'-nucleotidase activities in the sensorimotor and limbic structures of the rat brain after training in a manipulative skill]. / Aktivnost' adenilattsiklazy i 5'-nukleotiday v sensomotornykh i limbicheskikh strukturakh mozga krys posle obucheniia manipuliatornomu navyku.

The activities of adenylate cyclase (AC) and 5'-nucleotidase (NT) were studied in the limbic (amygdala, hippocampus) and sensorimotor (cortex, striatum) brain structures of three rat groups: control (without training), not well and well learning to perform movements with pushing the operandum. It was found, that after training the activity of AC was decreased in all structures studied. Moreover, in the cortex and the striatum the decrease was more pronounced in the group of well learning rats, while in the amygdala--in not well learning ones. The activity of NT in all brain structures, excepting the striatum, was more significantly decreased in the rats with low ability to learn the movements with prolonged pushing. Only in the striatum the increase of NT activity (initially the lowest in the control animals--1.0 +/- 0.04 microgram P(i)/mg protein/min) up to 1.3 +/- 0.1 in not well and up to 2.0 +/- 0.1 in well learning animals was found. The interhemispheric [correction of intrahemispheric] asymmetry of AC activity in the cortex and of NT in the hippocampus was revealed. Thus, the changes of the activity of the enzymes, participating in the biogenesis of adenosine (NT) and c-AMP (AC) are different in the limbic and sensorimotor structures dependently on learning ability of rats. The increase of NT activity after learning only in the striatum could reflect a specific role of purinergic system of this brain structure in the regulation of sensory controlled movements.

[Problem of chemical structural specificity of the brain]. / Problema khimicheskoi strukturospetsifichnosti mozga.

The structurally specific chemical factors (SSCF) are considered as are differentiation-, regeneration- and normal function-promoting factors of embryonic and adult brain tissue. From this point of view the authors' data concerning SSCF expression after brain lesion are discussed. Analysis is made of the importance of further studies into the identification of these factors and elucidation of the biological role they play in the compensatory processes after brain damage in order to develop new approaches to the treatment of brain diseases.

[The activity of postural asymmetry factors in symmetrical sections of the rat spinal cord]. / Aktivnost' faktorov poznoi asimmetrii v simmetrichnykh otdelakh spinnogo mozga krysy.

The distribution of the low-molecular weight and high-molecular weight postural asymmetry factors (FPA) activity in the left and right parts of the lumbal region of the rat spinal cord was studied. Low-molecular weight FPA induces flexion of the hind limb ipsilateral to the half of the spinal cord from which FPA was isolated, while high-molecular weight FPA induces contralateral flexion. The activities of the low- and high-molecular weight FPAs in each half of the spinal cord are comparable in normal rat. After the suction lesion of the motor areas in the left hemisphere the increase of the low-molecular weight FPA activity in the right half of the lumbal region of the spinal cord was observed.

[Effect of a brain extract containing the postural asymmetry factor on the frog neuromuscular synapse]. / Vliianie ékstrakta mozga, soderzhashchego faktor poznoi asimmetrii, na nervno-myshechnyi sinaps liagushki.

The influence of the rat brain extract containing a postural asymmetry factor on the synaptic transmission in the right and left preparations of the frog cutaneus-pectoralis muscle was studied. The extract (2.10(-4) mg/ml) increased the quantal content of end-plate potentials (e.p.p.) in synapses of the right muscle and decreased it in synapses of the left muscle. In both right and left muscles relative changes in quantal content of e.p.p. correlated with relative changes in binomial parameter n. The results indicate an asymmetrical influence of the extract containing a postural asymmetry factor on the transmitter release in synapses of the right and left muscles.

[Dynamics of the activities of postural asymmetry factors and of the recovery of motor function in damage to the neocortex of the left and right hemispheres]. / Dinamika aktivnosti faktorov poznoi asimmetrii i vosstanovleniia dvigatel'noi funktsii pri povrezhdenii neokorteksa levogo i pravogo polusharii.

The role of postural asymmetry factors in the recovery of motor function after unilateral cortical lesions was investigated. The differences in the time-course of motor reactions recovery after left- and right-sided cortical damage was found. A more effective compensation of motor defects in animals with left-sided damage was accompanied by stable activity of postural asymmetry factors. The reported results indicate an important role of postural asymmetry factors in the early compensatory intra-central rearrangements.