OBJECTIVE: Normal endothelial cells respond to shear stress by elongating and aligning in the direction of fluid flow. Hyperglycemia impairs this response and contributes to microvascular complications, which result in deleterious effects to the endothelium. This work aimed to evaluate cheek pouch microvessel morphological characteristics, reactivity, permeability, and expression of cytoskeleton and extracellular matrix components in hamsters after the induction of diabetes with streptozotocin. METHODS: Syrian golden hamsters (90-130 g) were injected with streptozotocin (50 mg/kg, i.p.) or vehicle either 6 (the diabetes mellitus 6 group) or 15 (the diabetes mellitus 15 group) days before the experiment. Vascular dimensions and density per area of vessels were determined by morphometric and stereological measurements. Changes in blood flow were measured in response to acetylcholine, and plasma extravasation was measured by the number of leakage sites. Actin, talin, α-smooth muscle actin, vimentin, type IV collagen, and laminin were detected by immunohistochemistry and assessed through a semiquantitative scoring system. RESULTS: There were no major alterations in the lumen, wall diameters, or densities of the examined vessels. Likewise, vascular reactivity and permeability were not altered by diabetes. The arterioles demonstrated increased immunoreactivity to vimentin and laminin in the diabetes mellitus 6 and diabetes mellitus 15 groups. DISCUSSION: Antibodies against laminin and vimentin inhibit branching morphogenesis in vitro. Therefore, laminin and vimentin participating in the structure of the focal adhesion may play a role in angiogenesis. CONCLUSIONS: Our results indicated the existence of changes related to cell-matrix interactions, which may contribute to the pathological remodeling that was already underway one week after induction of experimental diabetes.

Evidências indicam que pacientes diabéticos são mais significativamente afetados por problemas de origem endodôntica. Este estudo avaliou radiográfica e histologicamente o desenvolvimento de inflamação perirradicular em ratos controle e diabéticos depois da indução de infecção pulpar. As polpas dos primeiros molares inferiores de ratos normais ou diabéticos foram expostas e deixadas em contato com a cavidade oral por 21 e 40 dias. Em seguida, os animais foram sacrificados, as mandíbulas removidas cirurgicamente, fixadas em formalina e depois radiografadas em posição padronizada. As imagens radiográficas das lesões perirradiculares foram escaneadas e as imagens computadorizadas avaliadas quanto à área total das lesões usando software específico. Espécimes representativos foram preparados também para análise histológica. A análise radiográfica revelou que os ratos diabéticos apresentaram lesões periradiculares significativamente maiores quando comparados com os ratos normais, independentemente do período experimental (p<0.05). O exame histológico de espécimes representativos revelou lesões perirradiculares mais extensas e com exsudato inlflamatório severo no grupo de ratos diabéticos quando comparado com o grupo controle. Os dados deste estudo indicam que ratos diabéticos podem ser mais propensos a desenvolver lesões perirradiculares extensas, possivelmente devido à diminuição da capacidade de defesa contra patógenos microbianos.

Evidence suggests that diabetic patients are more significantly affected by problems of endodontic origin. This study sought to radiographically and histologically examine the development of periradicular inflammation in control and in diabetic rats after induction of pulpal infection. The pulps of the mandibular first molars of normal and streptozotocin-induced diabetic rats were exposed and left in contact with their oral cavities for 21 and 40 days. Afterwards, the animals were sacrificed, the mandibles were surgically removed, fixed in formalin and then radiographed in a standardized position. The radiographic images of the periradicular lesions were scanned and computerized images were evaluated for the total area of the lesions using a specific software. Representative specimens were also prepared for histopathological analysis. Radiographic analysis revealed that diabetic rats presented significantly larger periradicular lesions when compared with control rats, regardless of the experimental period (p<0.05). Histopathological examination of representative specimens revealed larger periradicular lesions and more severe inflammatory exudate in the group of diabetic rats when compared with the control group. Data from the present study indicated that diabetic rats can be more prone to develop large periradicular lesions, possibly due to reduction in the defense ability against microbial pathogens.