Influence of irradiation on collagen content during wound healing in diabetic rats

Abstract

Influ en ce of ir ra di a ti on on col la gen con tent du ring wound he a ling in di a be tic rats Influên cia da ir ra di a ção so bre o con te ú do de co lá ge no, du ran te a ci ca tri za ção, em ra tos di a bé ti cos So lan ge Ma ria de Alme i da* Rí vea Inês Fer re i ra** Frab Nor ber to Bós co lo*** ABSTRACT: The aim of the pre sent ex pe ri men tal re se arch was to in ves ti ga te the ef fects of elec tron ir ra di a ti on on the col la gen con tent and on the or ga ni za ti on of the gra nu la ti on tis sue of skin, in di a be tic rats. In this study, 48 Wis tar rats were as sig ned to 4 groups: con trol, ir ra di a ted, di a be tic and ir ra di a ted di a be tic. First, di a be tes mel li tus was in du ced in the last two groups, by me ans of a sin gle in tra ve nous in jec ti on of strep to zo to cin. Fif te en days la ter, all ani mals un derwent a sur gery in or der to cre a te an ex ci si o nal wound on the ir an te ri or dor sal skin. On the third post-ope ra ti ve day, only an ap pro xi ma tely 1-cm-wide area around the wounds was ex po sed to 1 Gy of 6 MeV elec tron beam ra di a ti on, which was de li ve red in a sin gle dose. Wound he a ling was exa mi ned by me ans of po la ri zed light mi cros copy at 4-, 7-, 13-and 21-day time in ter vals af ter woun ding. Ba sed upon an es sen ti ally qua li ta ti ve eva lu a ti on, it was pos si ble to conclu de that lo cal elec tron ir ra di a ti on and di a be tes' as so ci a ted dysfunc ti ons ca u sed a de cre a se in the col la gen con tent of newly-for med tis sue, which was more pro noun ced in ir ra di a ted di a be tic ani mals. The ma cro mo le cu lar or ga ni za ti on of gra nu la ti on tis sue was de la yed in ir ra di a ted, di a be tic and ir ra di a ted di a be tic ani mals, in re la ti on to what was ob ser ved in con trol ani mals. DESCRIPTORS: Ra di a ti on; Di a be tes mel li tus; Col la gen; Wound he a ling. RESUMO:O objetivo desta pesquisa ex per i men tal foi estudar os efeitos da irradiação por elétrons sobre o conteúdo de colágeno e a organização macromolecular do tecido de granulação, na pele de ratos diabéticos. Para tanto, 48 ratos da linhagem Wistar foram separados em 4 grupos: controle; irradiado; diabético e diabético irradiado. Inicialmente, a di abe tes melito foi induzida, nos dois últimos grupos, por meio da administração intravenosa de estreptozotocina. Após quinze dias da indução, todos os animais foram submetidos a uma cirurgia para a produção de uma ferida excisional, na região dor sal an te rior. No terceiro dia pós-operatório, aplicou-se uma dose única de 1 Gy, de feixes de elétrons com 6 MeV de energia, em uma área externa que compreendia cerca de 1 cm lateralmente às bordas das feridas. Amostras teciduais dos 4 grupos foram examinadas por microscopia de luz polarizada aos 4, 7, 13 e 21 dias pós-operatórios. Por meio de uma avaliação essencialmente qualitativa, foi possível concluir que a irradiação lo cal por elétrons e as disfunções associadas à di a be tes determinaram um decréscimo no conteúdo de colágeno do tec...

Effect of low-dose electron radiation on rat skin wound healing

“…Wound contraction has been ascribed to fibroblastic activity (8,10). Furthermore, the main components of the extracellular matrix, GAGs and collagen fibers, are synthesized by fibroblasts (7,10,11,13,14).…”

“…However, even with a low-dose, local effects of electron radiation can occur and the surrounding normal tissue can be affected. This interaction can be related to some alterations in wound healing after surgery for tumor extirpation (10).…”

“…It should be mentioned that the newly formed tissue will not necessarily have the same characteristics as the tissue it replaces. This means that tissue repair can be modified by some intrinsic and extrinsic factors (10). Ionizing radiation is an extrinsic factor that influences the tissue repair process (5,8,10).…”

“…Despite the great number of previous investigations in radiobiology (4,5,7,8,10,(13)(14)(15)(16)(17), few studies have focused on the quantitative analysis of glycosaminoglycans (GAGs) in the granulation tissue of locally irradiated skin. Scientific evidences indicate that the influence of irradiation on connective tissue leads to the degradation of ground substance and produces severe disturbances in the metabolism of GAGs (10).…”

“…Scientific evidences indicate that the influence of irradiation on connective tissue leads to the degradation of ground substance and produces severe disturbances in the metabolism of GAGs (10).…”