N. A. Loginova - Ph.D. (Biol.), Research Scientist, Laboratory of Functional Neurocytology, Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia. E-mail: nadinvnd@yandex.ru
N. V. Panov - Assistant, Laboratory of Functional Neurocytology, Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia. E-mail: nikolay.panov1966@yandex.ru
A. A. Prokuratova - Junior Research Scientist, Laboratory of Functional Neurocytology, Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia. E-mail: unsinn2@yandex.ru
E. V. Goloborodko - Research Scientist, Laboratory of Functional Neurocytology, Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia. E-mail: evgenij.goloborodko@mail.ru
N. S. Kositsyn - Dr.Sc. (Biol.), Professor, Honored Scientist of Russian Federation, Principal Research Scientist, Laboratory of Functional Neurocytology, Institute of Higher Nervous Activity and Neurophysilogy of RAS, Moscow, Russia. E-mail: nikolay.kositzyn@mail.ru
M. M. Svinov - Ph.D. (Biol.), Head of the Laboratory, Functional Neurocytology, Institute of Higher Nervous Activity and Neurophysiology of RAS, Moscow, Russia. E-mail: svinov@ihna.ru

It is assumed that gap junctions (GJs) play ambiguous role in a recovery after CNS injury [1]. On the one hand GJs can pass necrotic and apoptotic factors provoking cell death. On the other hand they allow different ions and substances to pass from health cells to injured cells for providing cell survival [2, 3]. The aim of our study was to investigate the distribution of connexin-43 (Cx43) (astrocytic GJ) in the penumbra, just in the area where reversible morphological changes in our previous studies were observed [4], after weak and middle cerebral ischemia in rat brain. We used adult male Wistar rats (m = 300-350 g). Cerebral ischemia was produced by photochemical thrombosis in the somatosensory cortex of the rat brain. The intensity of laser brightening was 15 and 35% for 2 minutes for weak and middle cerebral ischemia. A day after ischemia the rat brains were taken for immunohistochemical studies. Brain slices were stained by rabbit polyclonal antibodies to Cx43 (Sigma). We have estimated the number of GJ by the number of fluorescent point per the area (506,25 µm2) in the intact or penumbral zone. We have counted five areas in each slice. It was used nonparametric Mann-Whitney analysis for independent samples for estimating the differences between two groups. We have found that the number of GJs contained Cx43 have been increased in the penumbra compared to intact zone in both (weak and middle ischemia) cases (p < 0.05 and p < 0.00001 respectively). Thus, according to our previous studies and present research, we suppose that increase of GJs between astrocytes and neurons can ensure cell survival. The reported study was supported by RFBR, research project No. 14-04-32121 мол_a.