Metabolic syndrome (MetS) is associated with an increased risk of cerebrovascular diseases, including cerebral ischemia. Microvascular dysfunction is an important feature underlying the pathophysiology of cerebrovascular diseases. In this study, we aimed to investigate the impacts of ischemia and reperfusion (IR) injury on the cerebral microvascular function of rats with high-fat diet-induced MetS. We examined Wistar rats fed a high-fat diet (HFD) or normal diet (CTL) for 20 weeks underwent 30 min of bilateral carotid artery occlusion followed by 1 h of reperfusion (IR) or sham surgery. Microvascular blood flow was evaluated on the parietal cortex surface through a cranial window by laser speckle contrast imaging, functional capillary density, endothelial function and endothelial–leukocyte interactions by intravital videomicroscopy. Lipid peroxidation was assessed by TBARs analysis, the expression of oxidative enzymes and inflammatory markers in the brain tissue was analyzed by real-time PCR. The cerebral IR in MetS animals induced a functional capillary rarefaction (HFD IR 117 ± 17 vs. CTL IR 224 ± 35 capillary/mm2; p < 0.05), blunted the endothelial response to acetylcholine (HFD IR −16.93% vs. CTL IR 16.19% from baseline inner diameter p < 0.05) and increased the endothelial–leukocyte interactions in the venules in the brain. The impact of ischemia on the cerebral microvascular blood flow was worsened in MetS animals, with a marked reduction of cerebral blood flow, exposing brain tissue to a higher state of hypoxia. Our results demonstrate that during ischemia and reperfusion, animals with MetS are more susceptible to alterations in the cerebral microcirculation involving endothelial dysfunction and oxidative stress events.

This study investigated the role of opioid receptor (OR) subtypes as a mechanism by which endurance exercise promotes cardioprotection against myocardial ischemia-reperfusion (IR) injury. Wistar rats were randomly divided into one of seven experimental groups: 1) control; 2) exercise-trained; 3) exercise-trained plus a non-selective OR antagonist; 4) control sham; 5) exercise-trained plus a kappa OR antagonist; 6) exercise-trained plus a delta OR antagonist; and 7) exercise-trained plus a mu OR antagonist. The exercised animals underwent 4 consecutive days of treadmill training (60 min/day at ∼70% of maximal oxygen consumption). All groups except the sham group were exposed to an in vivo myocardial IR insult, and the myocardial infarct size (IS) was determined histologically. Myocardial capillary density, OR subtype expression, heat shock protein 72 (HSP72) expression, and antioxidant enzyme activity were measured in the hearts of both the exercised and control groups. Exercise training significantly reduced the myocardial IS by approximately 34%. Pharmacological blockade of the kappa or mu OR subtypes did not blunt exercise-induced cardioprotection against IR-mediated infarction, whereas treatment of animals with a non-selective OR antagonist or a delta OR antagonist abolished exercise-induced cardioprotection. Exercise training enhanced the activities of myocardial superoxide dismutase (SOD) and catalase but did not increase the left ventricular capillary density or the mRNA levels of HSP72, SOD, and catalase. In addition, exercise significantly reduced the protein expression of kappa and delta ORs in the heart by 44% and 37%, respectively. Together, these results indicate that ORs contribute to the cardioprotection conferred by endurance exercise, with the delta OR subtype playing a key role in this response.

Despite the advancements in evidence-based medicine, many hospitals still maintain high rates of patients undergoing prolonged preoperative fasting. The goal of this study is to determine the prevalence of prolonged fasting time among patients undergoing elective surgeries at a Brazilian university hospital and its associations with clinical and sociodemographic variables. This cross-sectional study was conducted between May and November 2019 and included patients of all ages undergoing elective surgeries. Out of the 293 patients analyzed, 64.2% were male, with ages ranging from 1 to 85 years, and 93.9% were classified as ASA I or II. The prevalence of preoperative fasting exceeding 8 h was 89.4%. An average fasting time exceeding 11 h was observed across all age groups. Patients who underwent procedures in the afternoon had an average fasting time that was 24% longer than those in the morning period (14.9 vs. 12 h, p < 0.001). Surgery time (r = 0.134, p < 0.03) and anesthesia times (r = 0.121, p < 0.04) demonstrated a weak correlation with fasting time. Despite the international consensus on preoperative fasting time, our study demonstrated low adherence to current recommendations. Therefore, healthcare professionals should ensure the comprehension of fasting guidelines, and further studies should aim to identify effective solutions to mitigate prolonged fasting.