Expression of NLRP3 Inflammasomes in Neurogenic Niche Contributes to the Effect of Spatial Learning in Physiological Conditions but Not in Alzheimer's Type Neurodegeneration.

A common feature of neurodegenerative disorders, in particular Alzheimer's disease (AD), is a chronic neuroinflammation associated with aberrant neuroplasticity. Development of neuroinflammation affects efficacy of stem and progenitor cells proliferation, differentiation, migration, and integration of newborn cells into neural circuitry. However, precise mechanisms of neurogenesis alterations in neuroinflammation are not clear yet. It is well established that expression of NLRP3 inflammasomes in glial cells marks neuroinflammatory events, but less is known about contribution of NLRP3 to deregulation of neurogenesis within neurogenic niches and whether neural stem cells (NSCs), neural progenitor cells (NPCs) or immature neuroblasts may express inflammasomes in (patho)physiological conditions. Thus, we studied alterations of neurogenesis in rats with the AD model (intra-hippocampal injection of Aß1-42). We found that in Aß-affected brain, number of CD133+ cells was elevated after spatial training in the Morris water maze. The number of PSA-NCAM+ neuroblasts diminished by Aß injection was completely restored by subsequent spatial learning. Spatial training leads to elevated expression of NLRP3 inflammasomes in the SGZ (subgranular zones): CD133+ and PSA-NCAM+ cells started to express NLRP3 in sham-operated, but not AD rats. Taken together, our data suggest that expression of NLRP3 inflammasomes in CD133+ and PSA-NCAM+ cells may contribute to stimulation of adult neurogenesis in physiological conditions, whereas Alzheimer's type neurodegeneration abolishes stimuli-induced overexpression of NLRP3 within the SGZ neurogenic niche.

TIGHT JUNCTIONS PROTEINS IN CEREBRAL ENDOTHELIAL CELLS DURING EARLY POSTNATAL DEVELOPMENT.

Formation and functional plasticity of the blood-brain barrier is associated with the molecular events that occur in the brain neurovascular unit in the embryonic and early postnatal development. To study the characteristics of barriergenesis under physiological conditions, as well as recovering from perinatal hypoxia and early life stress, we examined the expression of proteins of cerebral endothelial tight junctions (JAM, ZO1, CLDN5) in rats aged 7, 28 and 70 days of postnatal development (P7­P70). Under physiological conditions, we have found that the number of endothelial cells expressing JAM, ZO1, CLDN5 slightly increases in the cortex, hippocampus and amygdala of the brain in the period from P7 to P70. Perinatal hypoxia significantly increased the number of cells expressing proteins of tight junction proteins (JAM, CLDN5) up to the age P28­P70, whereas the number of cells expressing ZO1 was reduced in the same period of time. Early life stress led to an imbalance between the number of cells expressing ZO1 proteins and that expressing tight junctions proteins, but these changes were in opposite direction to that observed in perinatal hypoxia

[Astroglia-mediated regulation of cell development in the model of neurogenic niche in vitro treated with Aß1-42]. / Astrotsit-oposredovannye mekhanizmy reguliatsii neirogeneza v modeli neirogennoi nishi in vitro pri deistviin Aß1-42.

Neurogenesis is a complex process which governs embryonic brain development and is importants for brain plasticity throughout the whole life. Postnatal neurogenesis occurs in neurogenic niches that regulate the processes of proliferation and differentiation of stem and progenitor cells under the action of stimuli that trigger the mechanisms of neuroplasticity. Cells of glial and endothelial origin are the key regulators of neurogenesis. It is known that physiological neurogeneses is crucial for memory formation, whereas reparative neurogenesis provides partial repair of altered brain structure and compensation of neurological deficits caused by brain injury. Dysregulation of neurogenesis is a characteristics of various neurodevelopmental and neurodegenerative diseases, particularly, Alzheimer's disease which is very important medical and social problem. In the in vitro model of the neurogenic niche using hippocampal neurospheres as a source of stem/progenitor cells and astrocytes, we studied effects of astrocyte activation on the expression of markers of different stages of cell proliferation and differentiation. We found that aberrant mechanisms of development of stem and progenitor cells, caused by the beta-amyloid (Aß1-42), can be partially restored by targeted activation of GFAP-expressing cells in the neurogenic niche.

Catecholamine control of enzymes involved in isocitrate oxidation of rat liver mitochondria.

Treatment of rats or liver homogenates with catecholamines (isoproterenol or noradrenaline) increased activities of both NAD+ -dependent isocitrate dehydrogenase and NAD(P)+-transhydrogenase (in the direction of hydrogen transfer NADPH----NAD+) with no change in NADP+ -dependent isocitrate dehydrogenase. These effects were realized via beta-adrenoceptors. Cyclic AMP mimicked the catecholamine action on incubation with liver homogenate. The effects of catecholamines and cyclic AMP were not additive.

[Role of the mitochondrial inner membrane in activation of NAD-isocitrate dehydrogenase by catecholamines]. / Rol' vnutrennei membrany mitokhondrii v mekhanizme aktivatsii NAD- izotsitratdegidrogenazy katekholaminami.

After ultrasonic treatment of rat liver mitochondria and the following sedimentation of the submitochondrial particles all the NAD-isocitrate dehydrogenase (NAD-ICDH) activity detected occurred in the supernatant fraction. The structures of internal side of the inner mitochondrial membrane proved to regulate the NAD-ICDH activity. Administration of adrenaline into rats stimulated the NAD-ICDH activity by 20-40% in mitochondria and mitoplasts measured after ultrasonic treatment. Activation of the enzyme was not observed in the supernatant fraction after sedimentation of submitochondrial particles. The data obtained suggest that inner mitochondrial membrane is a factors responsible for regulation of NAD-ICDH activity during cAMP-dependent stimulation of mitochondria by catecholamines.

Disorders of folliculogenesis are associated with abnormal expression of peripheral benzodiazepine receptors in granulosa cells.

We studied apoptosis and expression of peripheral benzodiazepine receptors in granulosa cells of dominant follicles from women with endocrine sterility. The expression of peripheral benzodiazepine receptors in granulosa cells depends on the degree of granulosa cell apoptosis and type of disorders in follicular steroidogenesis, which suggests the involvement of peripheral benzodiazepine receptors into the regulation of folliculogenesis in health and disease.

Apoptosis of leukocytes as a marker of neutrophil-endotheliocyte interaction in coronary heart disease.

We studied the mechanism of interaction of peripheral blood neutrophils with endothelial cells (expression of cell adhesion molecules and production of NO) and the role of neutrophil apoptosis in the development of endothelial dysfunction. The effects of mitochondrial dysfunction of neutrophils on the development of apoptosis of these cells after their interaction with endothelial cells were analyzed.

[Activation succinate dehydrogenation in rat liver by noradrenaline, cAMP and acute cooling]. / Aktivatsiia degidrirovaniia suktsinata v pecheni krys pod vliianiem noradrenalina, tsAMF i ostrogo okhlazhdeniia.

Administration of noradrenaline in a dose of 11 mumol/kg activates succinate dehydrogenase (SDH) in the rat liver. On incubation of liver homogenate with noradrenaline (10(-6) M), cAMP (10(-6) M) and NaF (10(-2) M), a nonhormonal activator of adenylate cyclase, SDH was found to be activated by 20--30% in all the cases. The effects of noradrenaline and cAMP did not sum up. It seems likely that SDH activation by catecholamines is mediated by cAMP. Acute cooling (--17 degrees C) stimulates SDH via endogenous catecholamines, since this effect is completely reversed by the beta-adrenolytic inderal.

[Regulation of mitochondrial transhydrogenase activity by catecholamines]. / Reguliatsiia aktivnosti mitokhondrial'noi transgidrogenazy katekholaminami.

Administration of catecholamines to rats or their addition to liver and heart homogenates activates (by 30-50%) mitochondrial transhydrogenase in the direction of hydride-ion transfer NADPH----NAD+ via beta-adrenoreceptors and cAMP. Glucagon administration also increases by 48% the transhydrogenase activity of liver mitochondria. cAMP (1 microM) incubated with both liver homogenates and mitochondria exerts an independent activating effect on transhydrogenase. The effect of cAMP is specific and is expressed as an increase of V. The integrity of mitochondrial membranes is crucial for the manifestation of cAMP effect. Possible mechanisms of cAMP action on the transhydrogenase activity and the significance of this regulation for mitochondrial energetics are discussed.

[Different cooperativity of some oxidoreductases to specialized and nonspecialized regulators]. / Raznaia kooperativnost' nekotorykh oksidoreduktaz po otnosheniiu k spetsializirovannym i nespetsializirovannym reguliatoram.

The activation of 2 different mouse liver enzymes: cytozolic disulfide reductase (DSR) and mitochondrial NAD-isocitrate dehydrogenase (ICDH), by catecholamines and especially by 3',5'-AMP is characterized by negative cooperativity; substrate (both enzymes), protamine and EDTA (DSR) produce the positive cooperativity type of activation; DSR activation by isopropyl noradrenaline and serotonine is characterized by hyperbolic kinetics. Consequently, one and the same enzyme can combine positive cooperativity to non-specialized regulators (substrate, protamine, EDTA) with negative cooperativity to specialized regulators (3',5'-AMP, catecholamines). The systems, switching on by catecholamines and 3',5'-AMP, are oligomeric, and the degree and even the type of cooperativity can modify depending on the kind of catecholamine. The negative cooperativity is revealed in literature for many effects of catecholamines and 3',5'-AMP. Probably, it guarantees the broad range of regulations. Dose effect curves for 3',5'-AMP, catecholamines and other hormones should be analyzed on the basis of allosteric protein kinetics. A simple nomogram is given to estimate nH less than 1.

[The role of inner membrane in the realization of cAMP-dependent activation of mitochondrial enzymes]. / Znachenie vnutrennei membrany v realizatsii cAMP-zavisimoi aktivatsiifermentov mitokhondrii.

It was shown that the increase in the activities of transhydrogenase and NAD(+)-dependent isocitrate dehydrogenase after incubation of mitochondria with cAMP is due to the stimulating effect of cAMP on mitochondria, but not to the increased stability of mitochondria to the incubation procedure. Treatment of mitochondria with trypsin prevents the action of cAMP on the both enzymes. The integrity of the inner mitochondrial membrane is necessary for the manifestation of cAMP effect. Pretreatment of mitochondria with the local anesthetic, lidocaine, prevents the activation of NAD(P)(+)-transhydrogenase and NAD(+)-dependent isocitrate dehydrogenase during subsequent incubation of mitochondria with cAMP. It is concluded that the role of the inner mitochondrial membrane consists in the reception of the cAMP signal for the internal compartment of mitochondria, i.e. for mitoplasts. Peripheral protein(s) on the external side of the inner mitochondrial membrane seems to play a role in cAMP reception.

Blebbing of thymocyte plasma membrane and apoptosis are related to impairment of capacitance Ca2+ entry into cells.

We studied the role of disturbances in cell Ca(2+) homeostasis in plasma membrane blebbing and death of thymocytes. Capacitance Ca(2+) channels of the plasma membrane and intracellular Ca(2+) stores are involved in the induction and progression of changes in the membrane and cytoskeleton and apoptosis induced by acrylonitrile.