Sprague-Dawley Rats Controls Research Articles

Bypassed and Preserved Stomach Resulted in Superior Glucose Control in Sprague-Dawley Rats with Streptozotocin-Induced Diabetes

Recent studies suggest the possibility of the stomach playing a role in diabetes remission after bariatric surgery. In this study, we investigated whether bypassing the stomach alleviates diabetes in diabetic rodent model. Eighteen moderately obese and diabetic Sprague-Dawley rats were randomly assigned to Esophagoduodenostomy with or without gastric preservation (EDG and EDNG/total gastrectomy, respectively), and SHAM groups. Bodyweight, food intake, fasting glucose level, oral glucose tolerance test result (OGTT), and hormone levels (insulin, glucagon-like peptide-1, ghrelin, gastrin and glucagon) were measured preoperative and postoperatively. Postoperatively, bodyweight and food intake did not differ significantly between the EDG and EDNG groups. Postoperative fasting blood glucose and OGTT results declined significantly in the EDG and EDNG group when compared with the respective preoperative levels. Postoperative glucose control improvements in EDNG group was significantly inferior when compared to EDG. Compared preoperatively, postoperative plasma ghrelin and gastrin levels declined significantly in EDNG group. Preoperative and postoperative plasma GLP-1 level did not differ significantly among all the groups. Postoperatively, EDG group had significantly higher insulin and lower glucagon levels when compared with SHAM. In conclusion, bypassing and preserving the stomach resulted in superior glucose control improvements than total gastrectomy.

Phenytoin silver: a new nanocompound for promoting dermal wound healing via comprehensive pharmacological action.

Phenytoin, an antiepileptic drug, has been widely used for wound healing. Inspired by previous studies, phenytoin silver (PnAg), a sparingly soluble silver nanocompound, was synthesized which exhibited good therapeutic efficacy in tissue repair with low toxicity (LD50 >5 g/kg). In vivo studies showed that PnAg could accelerate dermal wound healing and strong inflammation control in Sprague-Dawley rats (SD rat) and Bama minipigs. Due to its low solubility, PnAg led to low toxicity and blood enrichment in animals. Furthermore, PnAg could upregulate the promoter activity of Jak, Stat3, and Stat3 downstream proteins. Therefore, PnAg may serve as an effective therapeutic compound for wound healing through regulating the gp130/Jak/Stat3 signaling pathway.

Oral bioavailability and pharmacodynamic activity of hesperetin nanocrystals generated using a novel bottom-up technology.

In the present study, nanocrystalline solid dispersion (NSD) was developed to enhance the release rate and oral bioavailability of hesperetin (HRN). NSD of HRN was prepared using a novel bottom-up technology platform. It is a spray drying based technology to generate solid particles, containing drug nanocrystals dispersed in small molecule excipients. HRN and mannitol were used in a 5:5 ratio, and an average crystallite size of HRN in NSD with mannitol was found to be 137.3 ± 90.0 nm. An in vitro release study revealed a statistically significant release rate enhancement for HRN nanocrystals (46.3 μg/mL/min) as compared to that of the control (29.5 μg/mL/min). Further, a comparative oral bioavailability study of NSD and control in Sprague-Dawley rats established significant improvement in Cmax and oral bioavailability (AUC0-∞) by 1.79- and 2.25-fold, respectively, for HRN nanocrystals. The findings of oral bioavailability were corroborated by intestinal uptake and Caco-2 cell uptake studies, wherein HRN, when administered in nanocrystalline form, showed higher penetration in intestinal mucosa and higher uptake in Caco-2 cells. Finally, the therapeutic efficacy of HRN nanocrystals was tested by a reactive oxygen species (ROS) generation assay and carrageenan induced anti-inflammatory model. HRN nanocrystals markedly inhibited ROS generation in MCF-7 cells, and carrageenan induced inflammation in rats. The process of NSD formation was found to be based on classical nucleation theory wherein mannitol contributed to NSD formation by acting as a plasticizer and crystallization inducer, and by providing sites for heterogeneous nucleation/crystallization.

Cytokine effects on phagocytosis of rod outer segments by retinal pigment epithelial cells of normal and dystrophic rats.

Phagocytosis of rod outer segments (ROS) is an important function of retinal pigment epithelial (RPE) cells. Since the details of the process are not fully known, we studied effects of cytokines produced by RPE and photoreceptor cells on phagocytosis of ROS by rat RPE cells. RPE cells were isolated and cultivated from two strains of rats: Sprague-Dawley (SD) rats with normal phagocytosis and Royal College of Surgeons (RCS) rats, which have genetic deficiencies in ROS phagocytosis. A double immunofluorescence staining technique was used to study the effects in vitro of several cytokines on phagocytosis of ROS. We found that transforming growth factor beta-1 (TGF-beta 1) had dose-dependent effects on RPE cells of both strains of rat: at a concentration of 10 ng/ml, TGF-beta 1 significantly (p < 0.01) reduced total ROS (to 74% of control in SD rats and to 51% of control in RCS rats), reduced bound ROS (to 56% of control in SD rats and to 48% in RCS rats), and increased the ratio of ingested ROS to total ROS (to 140% in SD rats but not significantly in RCS rats). Treatment of medium with anti-TGF-beta 1 antibody before incubation of RPE cells of SD rats with TGF-beta 1 decreased the magnitude of these effects. The cytokine acidic fibroblast growth factor (aFGF, 10 ng/ml) affected RPE cells of SD rats only, decreasing ROS ingested to 56% of control and the ratio of ingested ROS to total ROS to 64% of control. We also examined effects of basic fibroblast growth factor and insulin-like growth factor. None of the cytokines tested increased ingestion of ROS by RPE cells of RCS rats. Our results suggest that TGF-beta 1 and aFGF have roles in regulating ROS phagocytosis by normal and dystrophic RPE cells in the rat.