Localization of the dopamine receptors of types 1 and 2 on the bodies of POMC-expressing neurons of the arcuate nucleus of the hypothalamus in mice and rats.

Using immunofluorescent techniques, we have demonstrated the presence of two main types of dopamine receptors, D1 and D2, on the bodies of neurons of the arcuate nucleus of the hypothalamus expressing the precursor of peptides of the melanocortin family proopiomelanocortin in C57Bl/6J mice and Wistar rats. These data show close functional relationship between the dopamine and melanocortin systems of the brain and involvement of dopamine in the control of synthesis and secretion of peptides of the melanocortin family.

Metabolic parameters and functional state of hypothalamic signaling systems in AY/a mice with genetic predisposition to obesity and the effect of metformin.

The metabolic parameters and functional state of hypothalamic systems in mice with the Yellow mutation in the Agouti locus and with obesity of the melanocortin type and the effect of metformin (MF) treatment (9 days, 200 mg/kg/day) were studied. The MF treatment led to decreased body weight and to normalization of glucose tolerance in mice. In the hypothalamus, MF restored the decreased activity of Akt kinase, the main component of leptin pathway, and normalized the increased expression of subtype 1B serotonin receptor. The obtained data suggest the efficiency of MF to treat obesity of the melanocortin type.

[Analysis of development of morphofunctional interconnections between CART- and AGRP-ergic neurons with dopaminergic structures in ontogenesis of mammals].

There are obtained data indicating that morphogenesis and, probably, formation of structurally functional interaction of the CART- and dopaminergic neurons occur as early as during embryonic development. Meanwhile development of the AGRergic system and formation of its structural and functional communications are observed in the course of postnatal development of rat. Analysis of literature and re- sults of our own investigation show that differentiation of dopaminergic neurons in hypothalamus and midbrain occurs on the background of development of CARTergic neurons and in the absence of AGRP. Taking into account our data on activating action of the CART-peptide and inhibitory effect of AGRP on dopaminergic brain neurons, we believe that the leading component at formation of functional interactions of these systems is the later maturing AGRPergic system.

[Biodistribution of the recombinant heat shock protein rhHsp70 in intracranial C6 glioma models in Wistar rats and subcutaneos B16/F10 melanoma in C57BL/6 mice].

For the first time, the biodistribution of recombinant heat shock protein in rhHsp70 rats with grafted intracranial C6 glioma was evaluated. It was assessed using the fluorescent antibody accumulation chaperone rhHsp70 conjugated with fluorochrome Alexa Fluor 555 in tumor cells by intratumoral or intravenous administration. Assessment of the distribution and accumulation of labeled protein was carried out on the model of subcutaneous B16/F10 melanoma in C57BL/6 mice with the use of single-photon emission computer tomography. After 60 minutes after intravenous administration rhHsp70-I123 (20 MBq, 5 mg chaperone) accumulation of the drug mainly in the liver and tumor tissue was showed. The coefficient of the differential accumulation of the labeled protein KDN(tumor/background) was 3.14. It was turned out that comparing the level of fixation of rhHsp70-I123 in the liver and the tumor KDN(tumor/ liver) = 0.76. After 24 hours from the time of injection of rhHsp70-I123 it was observed increase the level of fixation of the labeled protein in the liver and melanoma: KDN(tumor/background) = 3.43; KDN(tumor/liver = 0.78.

[A role of AGRP on dopamine brain neurons regulation].

In rats and mice in different dopaminergic brain structures the immunoreactive axons with agouti-related protein (AGRP) were identified. The double immunofluorescence method shows the presence of AGRP-immunoreactive processes around the bodies of dopaminergic neurons. In experiments in vitro after incubation of brain tissue from ventral tegmental area or hypothalamus with AGRP (83-132) the significant decrease of tyrosine hydroxylase optical density was indicated. The data indicate possible direct inhibitory action of AGRP on tyrosine hydroxylase level in dopaminergic brain neurons and its role as a modulator of the functional activity of dopaminergic neurons.

[Participation of Agouti related peptide in machanisms of wakefulness-sleep cycle regulation].

Agouti-related protein (AGRP) is expresses in hypothalamic neurons in human and animals. Immunohistochemical study in rats Wistar rats demonstrates significant changes AGRP optical density in the neurons of arcuate hypothalamic nucleus as well as in processes in the hypothalamus and nucleus accumbens after the 6 hours of sleep deprivation (increase) and after 2 hours of post-deprivative sleep (decrease). Comparison of these results with earlier obtained shows the opposite trend changes in AGRP optical density and speed limiting enzyme of dopamine synthesis-tyrosine hydroxylase in the hypothalamus and in striatonigral system. The increase of AGRP was accompanied by a decrease of tyrosine hydroxylase and the decrease of AGRP, apposite, it increases. The obtained data demonstrate the role ofAGRP as a modulator of the functional activity of the dopaminergic brain neurons. The problem of the relationship of various functions of organism (food behavior, sleep, stress) is discusses by their participation in the regulation of the same neurotransmitter systems.

[Effect of retinol on interaction of the protein period1, oxytocin, and GABA at the prenatal period of formation of the circadian clock-mechanism in rats].

Clock-gene proteins are expressed in mammals in neurons of the hypothalamus suprachiasmatic nucleus and of other CNS structures, in muscles, viscercal organs, and vessels, and form circadian rhythms of many functions. Little is known about the factors of formation of the circadian mechanism at the prenatal period. In rats the E20 stage is characterized by a high level of oxytocin and selective expression of the first protein of the clock-genes PER1. The foal of the present study was to check the suggestion about the positive feedback between PER1 and oxytocin at the prenatal period as well as to elucidate a possible role of PER1 in regulation of interactions between oxytocin and GABA at the period of formation of the cerebral circadian mechanism of clock-genes. With aid of western-blotting, we analyzed the nuclear and cytoplasmic fractions from anterior hypothalamus homogenate in pregnant females and embryos of rats (E20). The retinol metabolites through their nuclear receptor RORalpha are known to be bound to promoters of genes of oxytocin and per 1. Next day after administration of retinol to the females, a rise of PER1 content was noted in their cytoplasm, whereas in their embryos the PER1 content was elevated in the nucleus. In the embryo cytoplasm there was a significant rise of production of oxytocin receptors and a decrease of the level of enzymes of GABA synthesis (glutamate decarboxylases 67 and 65). The results indicate the oxytocin- and retinol-dependent increase of the PER1 expression and the subsequent change of ratio of efficiency of oxytocin and GABA at the prenatal stage of formation of the circadian clock-mechanism of the rat embryo anterior hypothalamus.

[Immunohistochemical study of CART-peptide in striato-nigral projections at dopamine loss].

The increase of CART-peptide optical density was found immunohistochemically in nucleus accumbens neurons and in their terminals in substantia nigra in Wistar rats after 28% reduction of dopaminergic neurons in a substantia nigra (in the model of lactacystin induced proteo some disfunction). At the same time after in vitro incubation of nigro-accumbal brain slice with AMPT (alpha-methyl-paratirosine--dopamine inhibitor) for 4 h the reduction of tyrosine hydroxylase optical density (the enzyme limiting dopamine synthesis) in substantia nigr neurons was found and optical density of CART-peptide in nucleus accumbens and substantia nigra was also revealed. In both experiments data about activation of CARTergic neurons in stria to-nigral projections testifies on participation of CART-peptide in compensatory brain mechanisms at dopamine loss and its role as modulator of dopaminergic brain neurons functional activity.

[Raction of dopaminergic and vasopressinergic systems in sleep deprivation in rats].

Six hours sleep deprivation experiments were carried out on rats after threefold injection of D1 dopamine receptor antagonist SCH 39 166. Immunohistochemical study of striatum revealed the increase in D1 and D2 dopamine receptor and glutamate immunoreactive material during the sleep deprivation and 2 h of postdeprivation period. The level of AMPA glutamate receptors increased under the sleep deprivation and decreased in the postdeprivation period. The data obtained are discussed in association with dynamic of changes of vasopressin immunoreactivity in neurosecretory supraoptical and paraventricular nuclei of hypothalamus in these experiments and in experiments without D1 receptor antagonist pretreatment.