[COMPARATIVE STUDY OF NIGROSTRIATAL SYSTEMS IN WISTAR RATS AND RATS PRONE TO SEIZURES].

In this work we analyzed the levels of functional activity of dopaminergic, GABA-ergic and glutamatergic neurons in the nigrostriatal system of control Wistar rats and Krushinsky-Molodkina (KM) rats prone to audiogenic seizures. In KM rats we have revealed disturbed activity of GABA- and dopaminergic neurons in substania nigra whereas the level of glutamatergic neurotransmission remained unchanged. We have also observed no significant differences in GAD65/67 and phospho-tyrosine hydroxylase contents in the striatum of KM and control Wistar rats. However, a high level of D1 dopamine receptor and a decreased level of D2 receptor found can mediate the upregulation of glutamatergic neurotransmission. Indeed, the expression of vesicular glutamate transporter type 2 (VGlut2) and NR2B subunit of NMDA receptor was increased in the striatum of KM rats. In striatal glutamatergic fibers phosphorylated ERK1/2 kinases have been revealed; at the same time, in KM rats an increased ERK1/2 activity has been detected both in striatum and substantia nigra. This finding correlated with activation of exocytosis rate as evidenced by downregulation of SNAP25 level. Apart from other reasons, the activation of glutamatergic system may be a result of disruption of the inhibitory effect of the dopamine- and GABAergic systems of substantia nigra that innervate striatum. We suppose that the increased activity of striatal glutamatergic neurons of KM rats without an adequate inhibition by GABA- and dopaminergic systems may be one of the reasons of high convulsive susceptibility in KM rats.

[A study of participation of Hdj1 co-chaperone in the modulation of sleep and behavior using micro RNA technology in vivo].

Data obtained for the last 12 years and modern hypotheses on key function of sleep and the role of Heat Shock Protein 70 kDa (HSP70) molecular chaperones family in sleep modulation are insufficient to determine assotiation of sleep quantity to the level of chaperones in the basic "center" of sleep in the ventrolateral preoptic area (VLPA) of the hypothalamus. In the present study, to reduce the content of Hdj1 major co-chaperone of Hsp70 in the VLPA we employed a novel approach based on lentiviral construction containing specific Hdj1-shRNA. The immunoblotting data showed that in 6 weeks after infection the level of Hdj1 in VLPA was reduced by 80% that was accompanied by a considerable increase in the quantity of slow-wave sleep and a marked decrease in the level of anxiety; earlier we found that elevation of Hsp70 level in the rat brain resulted in similar changes. It is suggested that the increase in quantity of slow wave sleep and the decrease in the level of anxiety can be related to a sustained disorder in the integration between molecular systems based on chaperones Hdj1 and Hsp70 and to a compensatory increase in the Hsp70 chaperone activity/level in VLPA.

[Effects of thermal preconditioning on convulsive activity in rats with inheritable form of audiogenic epilepsy].

Effects of thermal preconditioning universal recognized method of increase in concentration of inducible Heat shock protein 70 kDa (Hsp70i) on characteristics of convulsive activity in Krushinskii-Molodkina (KM) rats with inheritable audiogenic epilepsy were studied. For the first time, it was found that short-term thermal preconditioning (41 degrees C during 5 minutes) increased duration of the latency of audiogenic seizure onset. Thermal preconditioning resulted in an increase in concentration of Hsp70i in amygdale, hypothalamus, midbrain; the uttermost increase was observed in hippocampus and inferior colliculus: the brain areas responsible for initiation of audiogenic seizures. A coincidence was found in the term of increase in concentration of Hsp70i and the latency of seizure onset (on day 4 after thermal preconditioning). Results of this research confirm the proposition that inducible Hsp70i is capable of taking part in the processes of seizure development in rats with inheritable form of audiogenic epilepsy.

[Chaperones in regulation and restoration of physiological functions].

Protective effects of the HSP70 expression in heat stress, sleep deprivation, epilepsy, enhanced anxiety, psycho-emotional stress, physical loads, are described, and data on the HSP70 effects upon characteristics of sleep and somatic-visceral functions in homeothermic animals are cited. Prospects of using the HSP70 "inductors" are discussed as well as the HSP70 preparations use in therapy of large range of pathological conditions.

[Sleep changes during degeneration of neurons in the substantia nigra induced by inhibitor of proteasomes lactacystin in rats].

A decrease in activity of ubiquitin proteasome system results in accumulation of toxic forms of protein and cell degeneration, including dopamine (DA)-ergic neurons in the substantia nigra; these neurons are remarkable for their low proteolytic activity of proteosomes that makes them more vulnerable, especially when subjected to the neurotoxin action or Parkinson's disease (PD). The goal of the present study is to develop a model on the basis of inhibition of proteasome activity of nigral cell degeneration which is not accompanied by disturbances in motor behavior but leads to changes in sleep-wake cycle characteristic of the non-motor behaviour. We determined the optimal dose of natural inhibitor of proteasome lactacystin (0.4 mkg) and developed a preclinical model of PD in Wistar rats. We established that on the 14th day following lactacystin double (with one-week interval) bilateral injection into the substantia nigra the developing effects involved 28 % degeneration of DA-ergic neurons in the compact part of the substantia nigra, absence of disorders in motor behaviour, and increase in the total time of rapid eye movement sleep by 37 % at the second half of inactive day phase. These data and an increase in the level of key enzyme of DA synthesis tyrosine hydroxylase (TH) in survived neurons in the substantia nigra as well as the presence of the inverse correlation dependency (r = -0.8, p < 0.01) between the number of survived neurons and the level of TH inside them suggest a hypothesis that the increase in the duration of rapid eye movement sleep could be a non-motor marker of the preclinical stage of PD reflecting a reservation of compensatory potentials in the nigrostriatal system.

[Protein 70 kDa in control of sleep and thermoregulation].

Studies of expression of molecular chaperones of the family of Heat Shock Proteins 70 kDa (HSP70) in the mouse and rat brain during sleep deprivation do not answer the question whether the HSP70 produce somnogenic effect. In the present work there are studied effects of exogenous Hsp70 that is known to be able to penetrate into living cells in vitro and to acquire properties of endogenous chaperone. Hsp70 was microinjected into the third brain ventricle of rats and pigeons at the beginning of the inactive period of the day when under natural conditions the sleep duration increases and the somato-visceral parameters decrease. Hsp70 was found to enhance this natural process and to produce an additional increase in the total time of slow-wave sleep, a more pronounced inhibition of the muscle contractive activity, and a deeper decrease in the brain temperature. A similarity in effects of Hsp70 in rats and pigeons was revealed. In both species the somnogenic effect of Hsp70 in is realized by activation of mechanisms of maintenance of in longer episodes of in slow-wave sleep. The hypothermic Hsp70 effect seems to be associated with a decrease in the muscle contractive activity level, rather than with an enhancement in peripheral vasodilation and with an increase of heat loss. A hypothesis is put forward that the neuroleptic effect of Hsp70 that includes the somnogenic, myorelaxing, and hypothermic effects is mediated by activation of GABAA receptors of the main inhibitory brain system.