Diabetes Mellitus Alters the Immuno-Expression of Neuronal Nitric Oxide Synthase in the Rat Pancreas

Serine protease inhibitor AEBSF(4-(2-aminoethyl)-benzenesulfonyl fluoride) decreased ischemic brain injury through inhibiting endoplasmic reticulum stress, oxidative stress, and autophagy in rats

4-(2-Aminoethyl)-benzenesulfonyl fluoride (AEBSF) is a serine protease inhibitor that may alleviate endoplasmic reticulum (ER) stress, a significant contributing factor to cerebral ischemia/reperfusion injury. The molecular crosstalk between ER stress, oxidative stress and autophagy represents a vicious cycle that can be pharmacologically targeted to minimize neuronal death after acute injuries to the central nervous system. However, the neuroprotective effects of AEBSF in the context of cerebral ischemia/reperfusion injury remain unknown. In this study,we reported the neuroprotective effect of AEBSF against cerebral ischemia/reperfusion injury and explored the mechanisms involved, particularly its role in reducing ER stress, oxidative stress and autophagy. Rats were pretreated with AEBSF or a vehicle before a 90 min middle cerebral artery occlusion (MCAO) followed by 24 h of reperfusion. Our results demonstrate that AEBSF treatment reduced infarct volume and improved neurological function compared to vehicle treated rats after 24 h of reperfusion. Furthermore,AEBSF treatment decreased the expression of caspase-3, suggesting a decrease in neuronal apoptosis. Additionally, AEBSF treatment lowered levels of key ER stress biomarkers, including glucose-regulated protein 78 (GRP78), phosphorylated eukaryotic initiation factor 2α (p-eIF2α), and CCAAT-enhancer-binding protein homologous protein (CHOP), while the levels of inositol-requiring enzyme 1α (IRE1α) remained unchanged. AEBSF also decreased the oxidative stress biomarker neuronal nitric oxide synthase (nNOS) and its related molecule pro-MMP-9. Importantly, treatment with AEBSF reversed the trends of autophagy biomarker LC3B II/α-tubulin, Beclin1, and SQSTM1 at 24 h after reperfusion. In conclusion, AEBSF significantly mitigates ischemic brain damage and promotes neurological recovery by inhibiting ER stress, oxidative stress, and autophagy, highlighting its potential as a therapeutic option for ischemic stroke.

Screening of Amino Acids as a Safe Energy Source for Isolated Rat Pancreatic Acini

OBJECTIVES

Amino acids play an essential role in protein synthesis, metabolism, and survival of pancreatic acini. Adequate nutritional support is important for acute pancreatitis treatment. However, high concentrations of arginine and lysine may induce acute pancreatitis. The study aimed to identify the most suitable l -amino acids as safe energy sources for pancreatic acinar cells.

MATERIALS AND METHODS

Pancreatic acini were isolated from male Wistar rats. Effects of amino acids (0.1-20 mM) on uncoupled respiration of isolated acini were studied with a Clark electrode. Cell death was evaluated with fluorescent microscopy and DNA gel electrophoresis.

RESULTS

Among the tested amino acids, glutamate, glutamine, alanine, lysine, and aspartate were able to stimulate the uncoupled respiration rate of isolated pancreatic acini, whereas arginine, histidine, and asparagine were not. Lysine, arginine, and glutamine (20 mM) caused complete loss of plasma membrane integrity of acinar cells after 24 hours of incubation. Glutamine also caused early (2-4 hours) cell swelling and blebbing. Aspartate, asparagine, and glutamate only moderately decreased the number of viable cells, whereas alanine and histidine were not toxic. DNA fragmentation assay and microscopic analysis of nuclei showed no evidence of apoptosis in cells treated with amino acids.

CONCLUSIONS

Alanine and glutamate are safe and effective energy sources for mitochondria of pancreatic acinar cells.

Adropin’s Role in Energy Homeostasis and Metabolic Disorders

Adropin is a novel 76-amino acid-peptide that is expressed in different tissues and cells including the liver, pancreas, heart and vascular tissues, kidney, milk, serum, plasma and many parts of the brain. Adropin, encoded by the Enho gene, plays a crucial role in energy homeostasis. The literature review indicates that adropin alleviates the degree of insulin resistance by reducing endogenous hepatic glucose production. Adropin improves glucose metabolism by enhancing glucose utilization in mice, including the sensitization of insulin signaling pathways such as Akt phosphorylation and the activation of the glucose transporter 4 receptor. Several studies have also demonstrated that adropin improves cardiac function, cardiac efficiency and coronary blood flow in mice. Adropin can also reduce the levels of serum triglycerides, total cholesterol and low-density lipoprotein cholesterol. In contrast, it increases the level of high-density lipoprotein cholesterol, often referred to as the beneficial cholesterol. Adropin inhibits inflammation by reducing the tissue level of pro-inflammatory cytokines such as tumor necrosis factor alpha and interleukin-6. The protective effect of adropin on the vascular endothelium is through an increase in the expression of endothelial nitric oxide synthase. This article provides an overview of the existing literature about the role of adropin in different pathological conditions.

The Problem of Wound Healing in Diabetes—From Molecular Pathways to the Design of an Animal Model

Chronic wounds are becoming an increasingly common clinical problem due to an aging population and an increased incidence of diabetes, atherosclerosis, and venous insufficiency, which are the conditions that impair and delay the healing process. Patients with diabetes constitute a group of subjects in whom the healing process is particularly prolonged regardless of its initial etiology. Circulatory dysfunction, both at the microvascular and macrovascular levels, is a leading factor in delaying or precluding wound healing in diabetes. The prolonged period of wound healing increases the risk of complications such as the development of infection, including sepsis and even amputation. Currently, many substances applied topically or systemically are supposed to accelerate the process of wound regeneration and finally wound closure. The role of clinical trials and preclinical studies, including research based on animal models, is to create safe medicinal products and ensure the fastest possible healing. To achieve this goal and minimize the wide-ranging burdens associated with conducting clinical trials, a correct animal model is needed to replicate the wound conditions in patients with diabetes as closely as possible. The aim of the paper is to summarize the most important molecular pathways which are impaired in the hyperglycemic state in the context of designing an animal model of diabetic chronic wounds. The authors focus on research optimization, including economic aspects and model reproducibility, as well as the ethical dimension of minimizing the suffering of research subjects according to the 3 Rs principle (Replacement, Reduction, Refinement).