Remyelination in experimentally demyelinated connexin 32 KnockOut mice

Abstract

-The aim of this study was to evaluate the role of connexin 32 (Cx 32) during remyelination of the peripheral nervous system, through a local injection of either 0,1% ethidium bromide solution or saline in the sciatic nerve of Cx 32 knockout mice. Euthanasia was performed ranging from 1, 2, 3, 7, 15, 21 to 30 days after injection. Histochemical, immunohistochemical, immunofluorescence and transmission electron microscopical techniques were used to analyze the development of the lesions. Within the sciatic nerves, Schwann cells initially showed signs of intoxication and rejected their sheaths; after seven days, some thin newly formed myelin sheaths with uneven compactness and redundant loops (tomacula) were conspicuous. We concluded that the regeneration of lost myelin sheaths within the PNS followed the pattern already reported for this model in other laboratory species. Therefore, these results suggest that absence of Cx 32 did not interfere with the normal pattern of remyelination in this model in young mice.KEy WordS: connexins, myelin, Knockout mice. Remielinização em camundongos Knockout para conexina 32 desmielinizados experimentalmenteResumo -Este estudo visou avaliar o papel da conexina 32 (Cx 32) durante a remielinização no sistema nervoso periférico. Uma injeção local de 0,1% de solução de brometo de etídio foi realizada no nervo ciático de camundongos deletados para a Cx 32, com eutanásia dos animais aos 1, 2, 3, 7, 15, 21 e 30 dias pós-injeção. Avaliações histoquímicas, imunoistoquímicas, por imunofluorescência e por microscopia eletrônica de transmissão foram utilizadas na análise do desenvolvimento das lesões. Nos nervos ciáticos, células de Schwann mostraram inicialmente sinais de intoxicação e rejeitaram suas bainhas. Após sete dias, observaramse finas bainhas neoformadas, com compactação desigual e alças redundantes (tomácula). Conclui-se que a regeneração de bainhas de mielina perdidas no SNP seguiu o padrão já relatado deste modelo em outras espécies de laboratório. Portanto, estes resultados sugerem que a ausência da Cx 32 não interferiu com o padrão normal de remielinização em camundongos jovens neste modelo. PAlAvrAS-CHAvE: conexinas, mielina, camundongos Knockout. . Each Schwann cell produces one internode of myelin, very rarely two. The signal for Schwann cell differentiation does not come from the axon alone, rather than from the axon 2 and the extracellular matrix, which provides collagen as a third element for myelination in the peripheral nervous system (PNS). Collagen fibers are produced and secreted by Schwann cells themselves 3 . The relationship of the axon and the ensheathing

A neural network for intermale aggression to establish social hierarchy

“…Over the past decades, neuroscientists have struggled to identify the emergent properties gained from a neural network upon introduction of electrical synapses. Connexin 36 (Cx36) knockout animal models have been instrumental in this effort, yet did not succeed in providing conclusive answers [93][94][95][96][97][98] . This is due to the upregulation of other connexins in the knock-out animals leading to decreased, but not absent, electrical connectivity 99,100 .…”