Михайлова Е. В.
Kosicin Yu.M
Romanova I.V.

Introduction. Melanocortin peptides (alpha, beta, gammaMSH and ACTH) are formed from a common precursor, proopiomelanocortin (POMС), which is expressed in mammals both in the brain and in peripheral tissues. The effects of melanocortin peptides are mediated through five types of melanocortin receptors (MCR). In mammalian brains, POMC expression was detected in neurons of the arcuate hypothalamic nucleus (ARC) and in the nucleus tractus solitaries (NTS). The effects of melanocortin peptides are mainly discussed in connection with type 3 and type 4 MCR (MCR3/MCR4), which are involved in the regulation of food intake and energy balance. It was shown that MCR type 1 (MCR1) is expressed in peripheral tissues and is involved in the regulation of melanogenesis. The several results show the expression of MCR1 in the brain, in particular in connection with neuroinflammation. The aim of the study was to analyze the expression of MCR1 in ARC and NTS – brain structures where POMC neurons were detected. The study was conducted on C57Bl / 6J mice. Methods: double fluorescence immunolabeling and confocal microscopy. Immunohistochemical studies were performed on frontal brain sections (16 μm) mounted on glasses. For the reactions a mixture of primary mouse antibodies to POMC (Abcam) and rabbit antibodies to MCR1 (Elabscience), a mixture of secondary antibodies conjugated with fluorochromes (Invitrogen): donkey to mouse-Alexa-568 and chicken to rabbit-Alexa-488 and nuclear colorant DAPI were used. Sections were analyzed using a DMI6000 confocal microscope with a SP5 II laser unit (Leica Microsystems, Germany). Lasers with an excitation wave length of 488, 568 nm and 355 nm for DAPI were used. Images were analyzed using the Leica LAS AF software; preparations for the demonstration were performed using Photoshop CS3. The results of the ARC study demonstrate immuno-expression of MCR1 both in the bodies of POMC-immunopositive neurons and in other ergism structures. In NTS, immuno-expression of MCR1 was detected in the bodies of POMC neurons are localized in various regions of this structure, both in large and small cell regions. Conclusions. Data on the expression of MCR1 in POMC-neurons indicate the functional role of MCR1 as an autoreceptor, which was previously discussed in the literature in connection with the expression of MCR3 in brain POMC-neurons.

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