Effects of sildenafil on nanostructural and nanomechanical changes in mitochondria in an ischaemia-reperfusion rat model.

Sildenafil exerts cardioprotective effects by activating the opening of mitochondrial ATP-sensitive potassium channels to attenuate ischaemia-reperfusion (IR) injury. In the present study, we used atomic force microscopy (AFM) to investigate changes in mitochondrial morphology and properties to assess sildenafil-mediated cardioprotection in a rat myocardial infarction model. To investigate the cardioprotective effects of sildenafil, we used an in vivo Sprague-Dawley rat model of IR. Rats were randomly divided into three groups: (i) sham-operated rats (control; n = 5); (ii) IR-injured rats treated with vehicle (normal saline; IR; n = 10); and (iii) IR-injured rats treated with 0.75 mg/kg, i.p., sildenafil (IR + Sil; n = 10). Morphological and mechanical changes to mitochondria were analysed by AFM. Infarct areas were significantly reduced in sildenafil-treated rats (7.8 ± 3.9% vs 20.4 ± 7.0% in the sildenafil-treated and untreated IR groups, respectively; relative reduction 62%; P < 0.001). Analysis of mitochondria by AFM showed that IR injury significantly increased the areas of isolated mitochondria compared with control (24 150 ± 18 289 vs 1495 ± 1139 nm(2) , respectively; P < 0.001), indicative of mitochondrial swelling. Pretreatment with sildenafil before IR injury reduced the mitochondrial areas (7428 ± 3682 nm(2) ; P < 0.001; relative reduction 69.2% compared with the IR group) and ameliorated the adhesion force of mitochondrial surfaces. Together, these results suggest that sildenafil has cardioprotective effects against IR injury in a rat model by improving the morphological and mechanical characteristics of mitochondria.

Biochemical and clinical correlation of intraplaque neovascularization using contrast-enhanced ultrasound of the carotid artery.

OBJECTIVE: Several biomarkers reflecting inflammatory or proteolytic activity have been known to represent plaque vulnerability. Moreover, a recent study confirmed that contrast-enhanced ultrasound (CEUS) can visualize intraplaque neovascularization (IPN) and demonstrate plaque vulnerability. In this study, we tried to demonstrate that IPN detected by CEUS was correlated with several well-known biomarkers and clinical outcome in patients with coronary artery disease (CAD). METHODS: Patients with stable CAD were screened by conventional carotid ultrasound and patients with carotid plaque thickness more than 2 mm were performed by CEUS for the presence of IPN. Plasma levels of biomarkers and clinical outcomes were evaluated. RESULTS: Among consecutive 89 patients fulfilled the inclusion criteria, 30 patients without IPN (group 1) and 59 patients with IPN (group 2) were analyzed. There were no significant difference in baseline characteristics except for mean age (62.9±10.1 yrs versus 68.4±9.6 yrs, p=0.015). On multivariate analysis, only MMP-9 (p=0.021, 95% CI 1.002-1.027) showed a significant association with IPN. But patients with IPN showed only trend for a history of cardiovascular disease (CVD) (44% versus 30%, p=0.19) and one-year cardiovascular events (CVE) (6.8% versus 3.3%, p=0.50) compared to group 1. Maximum plaque thickness (p=0.04, 95% CI 1.230-6.322) showed a significant correlation with the clinical outcome including CVD or CVE. CONCLUSION: MMP-9 correlated with IPN on CEUS. For clinical implication, however, large prospective studies are needed.

Low-intensity treadmill exercise and/or bright light promote neurogenesis in adult rat brain.

The hippocampus is a brain region responsible for learning and memory functions. The purpose of this study was to investigate the effects of low-intensity exercise and bright light exposure on neurogenesis and brain-derived neurotrophic factor expression in adult rat hippocampus. Male Sprague-Dawley rats were randomly assigned to control, exercise, light, or exercise + light groups (n = 9 per group). The rats in the exercise group were subjected to treadmill exercise (5 days per week, 30 minutes per day, over a 4-week period), the light group rats were irradiated (5 days per week, 30 minutes per day, 10 000 lx, over a 4-week period), the exercise + light group rats were subjected to treadmill exercise in combination with bright light exposure, and the control group rats remained sedentary over a 4-week period. Compared with the control group, there was a significant increase in neurogenesis in the hippocampal dentate gyrus of rats in the exercise, light, and exercise + light groups. Moreover, the expression level of brain-derived neurotrophic factor in the rat hippocampal dentate gyrus was significantly higher in the exercise group and light group than that in the control group. Interestingly, there was no significant difference in brain-derived neurotrophic factor expression between the control group and exercise + light group. These results indicate that low-intensity treadmill exercise (first 5 minutes at a speed of 2 m/min, second 5 minutes at a speed of 5 m/min, and the last 20 minutes at a speed of 8 m/min) or bright-light exposure therapy induces positive biochemical changes in the brain. In view of these findings, we propose that moderate exercise or exposure to sunlight during childhood can be beneficial for neural development.