ABSTRACT:The use of a simple and reproducible model is inevitable for objective statement of the effects of external factors on wound healing. Hence, present study was conducted to establish an excisional model of skin wound healing in corticosteroid treated, and streptozotocine induced diabetic rats as well as to standardized the semi-quantitative and quantitative evaluation of selected parameters. Round full thickness skin wounds were performed on the back of male Sprague-Dawley rats. Animals were sacrificed two, six, and fourteen days after surgery. Sections were stained with hematoxylin-eosin and van Gieson. Both semi-quantitative (wound reepithelization; presence of: inflammatory cells, fibroblasts, new wessels, and collagen) and quantitative methods (polymorphonuclear leucocytes/tissue macrophages ratio, percentage of re-epithelization, area of the granulation tissue) were used to evaluate the histological changes during wound healing. As compared to the control group the wound healing process of both experimental groups was decelerated. Interestingly, wound reepithelization and angiogenesis were significantly inhibited only in the steroid rats while epithelization was accelerated in diabetic rats. In conclusion, when compared to primary sutured wound healing it can be concluded that the excisional model is more appropriate for histological assessment of the effect of various factors on wound healing. In addition, administration of corticosteroids represents simple and inexpensive model of a complex skin wound healing impairment.

Vidinsk˘ B., P. Gal, T. Toporcer, F. Longauer, L. Lenhardt, N. Bobrov, J. Sabo: Histological Study of the First Seven Days of Skin Wound Healing in Rats. Acta Vet. Brno 2006, 75: 197-202.The aim of this study was to elaborate a histological model of incisional skin wound healing in Sprague-Dawley rats. Under aseptic conditions two paravertebral full thickness skin incisions were performed on the back of 42 anesthetized male rats. Histological sections from tissue specimens were stained by hematoxylin and eosin, van Gieson, PAS + PSD, Mallory's phosphotungstic hematoxylin and azur and eosin and evaluated during the first seven days after surgery. Histological evaluation revealed that the regeneration of injured epidermis was completed five days after surgery. The inflammatory phase was recorded during the first three days of healing with the culmination of this phase between day one and day two. The beginning of the proliferative phase was dated to the first day and the peak during day five and day six. The initiation of the maturation and remodeling phase of the healing process was observed six days after wounding. At the layer of striated muscle, the centronucleated cells were described for the first time six days after surgery. The wound healing process of rat skin was histologically described during the first seven days. Results of this work can serve as an experimental model for further research using external pharmacological and physical factors (laser light, magnetic field) by which the wound healing can be favourably influenced.Sprague-Dawley rats, inflammatory phase, proliferative phase, maturation in remodeling phase, histology

The neurohormone melatonin is primarily involved in the regulation of circadian rhythms, but also acts as an antioxidant and anticarcinogenic agent, especially in breast cancer. Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a widely known polyphenolic agent from red wine, which has been shown to exert antioxidant, anti-inflammatory and anticarcinogenic effects. The objective of this study was therefore to investigate the effects of melatonin in combination with resveratrol in a rat model of experimental mammary carcinogenesis. Female Sprague-Dawley rats aged 31 days were used in the experiment. Mammary carcinogenesis was induced by N-methyl-N-nitrosourea (NMU), which was administered in two intraperitoneal doses (50 mg/kg of body weight). Chemoprevention with resveratrol and melatonin started 2 weeks before the first dose of NMU and lasted until the end of the experiment. The basic parameters evaluated were: tumour incidence, latency period, tumour frequency per group and tumour volume. In addition, oestrogen receptors ERα and ERß, melatonin receptor MT1, proliferating cell nuclear antigen and vascular endothelial growth factor were determined by immunohistochemical staining. The combination of resveratrol and melatonin reduced tumour incidence by approximately 17% and significantly decreased the quantity of invasive and in-situ carcinomas. Food intake declined in the second and seventh weeks after the administration of carcinogen. Resveratrol in combination with melatonin returned food intake to the level of intact controls. Resveratrol in combination with melatonin has some protective effects on NMU-induced rodent breast cancer. Further studies are necessary to confirm these effects of this promising combination.

The optimal parameters for low-level laser therapy (LLLT) for wound healing are still open to discussion. Hence, our study was aimed at comparing the effects of different power densities of LLLT at 670 nm in rats. Four round full-thickness skin wounds were placed on the backs of 16 rats which were divided into two groups (non-steroid and steroid-treated). Three wounds were stimulated daily with a diode laser (daily dose 5 J/cm(2)) at different power densities (5, 15 and 40 mW/cm(2), respectively), and the fourth wound served as a control. Six days after surgery all animals were killed and samples removed for histological evaluation. Significant acceleration of fibroblast proliferation and new vessel formation was observed in wounds treated at the selected power densities. No significant differences were found in corticosteroid-treated rats. In conclusion, LLLT with the methodology used improved wound healing in non-steroid rats, but was not effective after corticosteroid-treatment.

Oestrogen deprivation is one of the major factors responsible for many age-related processes, including poor wound healing in women. Previously, it has been shown that oestrogens have a modulatory effect in different wound-healing models. Therefore, in this study, the effect of selective oestrogen receptor (ER) agonists (PPT - ER-α agonist, DPN - ER-β agonist) on excisional and incisional wound-healing models was compared in ovariectomised rats in vivo as well as on human dermal fibroblasts (HDF) and human umbilical endothelial cells (HUVEC) in vitro. In the in vivo study, 4 months after either ovariectomy or sham ovariectomy, Sprague-Dawley rats were randomly divided into four groups and subjected to two incisional and excisional wounds: (i) control - sham operated, vehicle-treated; (ii) ovariectomised, vehicle-treated; (iii) ovariectomised, PPT treated; (iv) ovariectomised, DPN treated. In the in vitro study, HDFs and HUVECs were used. After treatment with ER agonists, cells were processed for immunocytochemistry and gelatin zymography. Our study shows that stimulation of ER-α leads to the differentiation of fibroblasts into myofibroblasts both in vivo and in vitro. On the other hand, the formation of extracellular matrix was more prominent, and wound tensile strength (TS) was increased when ER-β was stimulated. In contrast, stimulation of ER-α led to a more prominent increase in the expression of MMP-2 and decrease in wound TS. New information is presented in this investigation concerning oestrogen replacement therapy (ERT) in different wound-healing models. This study demonstrates that the ERT should be both wound and receptor-type specific.