Skeletal Muscle Atrophy Induced by Diabetes Is Mediated by Non-Selective Channels and Prevented by Boldine.

Individuals with diabetes mellitus present a skeletal muscle myopathy characterized by atrophy. However, the mechanism underlying this muscular alteration remains elusive, which makes it difficult to design a rational treatment that could avoid the negative consequences in muscles due to diabetes. In the present work, the atrophy of skeletal myofibers from streptozotocin-induced diabetic rats was prevented with boldine, suggesting that non-selective channels inhibited by this alkaloid are involved in this process, as has previously shown for other muscular pathologies.

TNF-α Plus IL-1β Induces Opposite Regulation of Cx43 Hemichannels and Gap Junctions in Mesangial Cells through a RhoA/ROCK-Dependent Pathway.

Connexin 43 (Cx43) is expressed in kidney tissue where it forms hemichannels and gap junction channels. However, the possible functional relationship between these membrane channels and their role in damaged renal cells remains unknown. Here, analysis of ethidium uptake and thiobarbituric acid reactive species revealed that treatment with TNF-α plus IL-1β increases Cx43 hemichannel activity and oxidative stress in MES-13 cells (a cell line derived from mesangial cells), and in primary mesangial cells.

Interferon-γ and high glucose-induced opening of Cx43 hemichannels causes endothelial cell dysfunction and damage.

Both IFN-γ or high glucose have been linked to systemic inflammatory imbalance with serious repercussions not only for endothelial function but also for the formation of the atherosclerotic plaque. Although the uncontrolled opening of connexin hemichannels underpins the progression of various diseases, whether they are implicated in endothelial cell dysfunction and damage evoked by IFN-γ plus high glucose remains to be fully elucidated. In this study, by using live cell imaging and biochemical approaches, we demonstrate that IFN-γ plus high glucose augment endothelial connexin43 hemichannel activity, resulting in the increase of ATP release, ATP-mediated Ca dynamics and production of nitric oxide and superoxide anion, as well as impaired insulin-mediated uptake and intercellular diffusion of glucose and cell survival.

Diabetes alters the involvement of myofibroblasts during periodontal wound healing.

Objectives: Myofibroblasts constitute a specific cell phenotype involved in connective tissue healing. Diabetes alters the wound healing response. However, it is not clear whether diabetes modifies the involvement of myofibroblasts in periodontal wounds.

Role of a RhoA/ROCK-Dependent Pathway on Renal Connexin43 Regulation in the Angiotensin II-Induced Renal Damage.

In various models of chronic kidney disease, the amount and localization of Cx43 in the nephron is known to increase, but the intracellular pathways that regulate these changes have not been identified. Therefore, we proposed that: "In the model of renal damage induced by infusion of angiotensin II (AngII), a RhoA/ROCK-dependent pathway, is activated and regulates the abundance of renal Cx43". In rats, we evaluated: 1) the time-point where the renal damage induced by AngII is no longer reversible; and 2) the involvement of a RhoA/ROCK-dependent pathway and its relationship with the amount of Cx43 in this irreversible stage.

The 12-HHT/BLT2/NO Axis Is Associated to the Wound Healing and Skin Condition in Different Glycaemic States.

Type 2 diabetes affects over 340 million people worldwide. This condition can go unnoticed and undiagnosed for years, leading to a late stage where high glycaemia produces complications such as delayed wound healing. Studies have shown that 12-HHT through BLT2, accelerates keratinocyte migration and wound healing.

The streptozotocin-high fat diet induced diabetic mouse model exhibits severe skin damage and alterations in local lipid mediators.

Background: Type 2 diabetes (T2D) can go undiagnosed for years, leading to a stage where produces complications such as delayed skin wound healing. Animal models have been developed in the last decades to study the pathological progression in this disease. Streptozotocin (STZ), that has a selective pharmacological toxicity toward pancreatic β cells, in addition to high fat diet has been widely used to induce diabetes however no evidence has shown its effects on the skin integrity.

Connexin 43 Hemichannel Activity Promoted by Pro-Inflammatory Cytokines and High Glucose Alters Endothelial Cell Function.

The present work was done to elucidate whether hemichannels of a cell line derived from endothelial cells are affected by pro-inflammatory conditions (high glucose and IL-1β/TNF-α) known to lead to vascular dysfunction. We used EAhy 926 cells treated with high glucose and IL-1β/TNF-α. The hemichannel activity was evaluated with the dye uptake method and was abrogated with selective inhibitors or knocking down of hemichannel protein subunits with siRNA.

Boldine Improves Kidney Damage in the Goldblatt 2K1C Model Avoiding the Increase in TGF-β.

Boldine, a major aporphine alkaloid found in the Chilean boldo tree, is a potent antioxidant. Oxidative stress plays a detrimental role in the pathogenesis of kidney damage in renovascular hypertension (RVH). The activation of the renin-angiotensin system (RAS) is crucial to the development and progression of hypertensive renal damage and TGF-β is closely associated with the activation of RAS.

Angiotensin II-Induced Mesangial Cell Damaged Is Preceded by Cell Membrane Permeabilization Due to Upregulation of Non-Selective Channels.

Connexin43 (Cx43), pannexin1 (Panx1) and P2X₇ receptor (P2X₇R) are expressed in kidneys and are known to constitute a feedforward mechanism leading to inflammation in other tissues. However, the possible functional relationship between these membrane channels and their role in damaged renal cells remain unknown. In the present work, we found that MES-13 cells, from a cell line derived from mesangial cells, stimulated with angiotensin II (AngII) developed oxidative stress (OS, thiobarbituric acid reactive species (TBARS) and generated pro-inflammatory cytokines (ELISA; IL-1β and TNF-α).

Effects of ascorbic acid on spermatogenesis and sperm parameters in diabetic rats.

Diabetes mellitus in human and animal models has been correlated with low sperm count, testicular abnormalities, high levels of germ cell death, and oxidative stress. In this study, we focus on three questions: (1) Is germ cell apoptosis stage-specific in diabetic male rats? (2) Could ascorbic acid (AA) reverse oxidative and histological damage and restore testicular dysfunction? (3) Could AA treatment restore fertility parameters in diabetic rats? Adult Sprague-Dawley rats were divided into four groups: control, diabetic, control plus AA, and diabetic plus AA. Seminiferous tubules underwent severe histological damage, together with a change in frequency of some stages of the seminiferous cycle, and germ cell apoptosis was increased in a stage-dependent manner in diabetic rats.

Increased RhoA/Rho-Kinase Activity and Markers of Endothelial Dysfunction in Young Adult Subjects with Metabolic Syndrome.

Background: Metabolic syndrome, a chronic condition associated with higher risk of cardiovascular diseases, is increasingly prevalent in young adults. Dyslipidemia, proinflammatory cytokines, endothelial dysfunction signs, and RhoA/Rho-kinase (ROCK) activation are considered risk factors of cardiovascular diseases. The occurrence of these factors in young patients with metabolic syndrome but without type 2 diabetes or hypertension has not been fully studied.

Antioxidant and anti hyperglycemic role of wine grape powder in rats fed with a high fructose diet.

Background: Metabolic syndrome is a growing worldwide health problem. We evaluated the effects of wine grape powder (WGP), rich in antioxidants and fiber, in a rat model of metabolic syndrome induced by a high fructose diet. We tested whether WGP supplementation may prevent glucose intolerance and decrease oxidative stress in rats fed with a high fructose diet.

Boldine prevents renal alterations in diabetic rats.

Diabetic nephropathy alters both structure and function of the kidney. These alterations are associated with increased levels of reactive oxygen species, matrix proteins, and proinflammatory molecules. Inflammation decreases gap junctional communication and increases hemichannel activity leading to increased membrane permeability and altering tissue homeostasis.

Basic fibroblast growth factor reduces functional and structural damage in chronic kidney disease.

Chronic kidney disease (CKD) is characterized by loss of renal function. The pathological processes involved in the progression of this condition are already known, but the molecular mechanisms have not been completely explained. Recent reports have shown the intrinsic capacity of the kidney to undergo repair after acute injury through the reexpression of repairing proteins (Villanueva S, Cespedes C, Vio CP.

EPAC expression and function in cardiac fibroblasts and myofibroblasts.

Unlabelled: In the heart, cardiac fibroblasts (CF) and cardiac myofibroblasts (CMF) are the main cells responsible for wound healing after cardiac insult. Exchange protein activated by cAMP (EPAC) is a downstream effector of cAMP, and it has been not completely studied on CF. Moreover, in CMF, which are the main cells responsible for cardiac healing, EPAC expression and function are unknown.

Cyclooxygenase-2 and hypoxia-regulated proteins are modulated by basic fibroblast growth factor in acute renal failure.

Acute renal failure (ARF) can be caused by injuries that induce tissue hypoxia, which in turn can trigger adaptive or inflammatory responses. We previously showed the participation of basic fibroblast growth factor (FGF-2) in renal repair. Based on this, the aim of this study was to analyze the effect of FGF-2 signaling pathway manipulation at hypoxia-induced protein levels, as well as in key proteins from the vasoactive systems of the kidney.

Differential regulation of collagen secretion by kinin receptors in cardiac fibroblast and myofibroblast.

Unlabelled: Kinins mediate their cellular effects through B1 (B1R) and B2 (B2R) receptors, and the activation of B2R reduces collagen synthesis in cardiac fibroblasts (CF). However, the question of whether B1R and/or B2R have a role in cardiac myofibroblasts remains unanswered.

Methods: CF were isolated from neonate rats and myofibroblasts were generated by an 84 h treatment with TGF-β1 (CMF).

Glucose increases intracellular free Ca(2+) in tanycytes via ATP released through connexin 43 hemichannels.

The ventromedial hypothalamus is involved in regulating feeding and satiety behavior, and its neurons interact with specialized ependymal-glial cells, termed tanycytes. The latter express glucose-sensing proteins, including glucose transporter 2, glucokinase, and ATP-sensitive K(+) (K(ATP) ) channels, suggesting their involvement in hypothalamic glucosensing. Here, the transduction mechanism involved in the glucose-induced rise of intracellular free Ca(2+) concentration ([Ca(2+) ](i) ) in cultured β-tanycytes was examined.

Hemichannels in the neurovascular unit and white matter under normal and inflamed conditions.

In the normal brain, cellular types that compose the neurovascular unit, including neurons, astrocytes and endothelial cells express pannexins and connexins, which are protein subunits of two families that form plasma membrane channels. Most available evidence in mammals indicated that endogenously expressed pannexins only form hemichannels, and connexins form both gap junction channels and hemichannels. While gap junction channels connect the cytoplasm of contacting cells and coordinate electrical and metabolic activities, hemichannels communicate intra- and extracellular compartments and serve as diffusional pathways for ions and small molecules.

Hypoxia in high glucose followed by reoxygenation in normal glucose reduces the viability of cortical astrocytes through increased permeability of connexin 43 hemichannels.

Brain ischemia causes more extensive injury in hyperglycemic than normoglycemic subjects, and the increased damage is to astroglia as well as neurons. In the present work, we found that in cortical astrocytes from rat or mouse, reoxygenation after hypoxia in a medium mimicking interstitial fluid during ischemia increases hemichannel activity and decreases cell-cell communication via gap junctions as indicated by dye uptake and dye coupling, respectively. These effects were potentiated by high glucose during the hypoxia in a concentration-dependent manner (and by zero glucose) and were not observed in connexin 43(-/-) astrocytes.

Effect of tamoxifen and retinoic acid on bradykinin induced proliferation in MCF-7 cells.

Chemopreventive approaches for the treatment of breast cancer have been validated clinically and with in vitro studies. The combined action of tamoxifen/all-trans retinoic acid was advantageous in MCF-7 cells, reducing cell proliferation, Bcl-2 and c-Myc protein levels and increasing E-Cadherin protein levels and Gap junctional Intercellular Communication. We further investigated their combined effect in the presence of bradykinin, a pro-inflammatory agent, previously reported to contribute to the proliferation of breast cancer cells.

Modulation of brain hemichannels and gap junction channels by pro-inflammatory agents and their possible role in neurodegeneration.

In normal brain, neurons, astrocytes, and oligodendrocytes, the most abundant and active cells express pannexins and connexins, protein subunits of two families forming membrane channels. Most available evidence indicates that in mammals endogenously expressed pannexins form only hemichannels and connexins form both gap junction channels and hemichannels. Whereas gap junction channels connect the cytoplasm of contacting cells and coordinate electric and metabolic activity, hemichannels communicate the intra- and extracellular compartments and serve as a diffusional pathway for ions and small molecules.

Effect of ischemic acute renal damage on the expression of COX-2 and oxidative stress-related elements in rat kidney.

Acute renal failure (ARF) is a clinical syndrome characterized by deterioration of renal function over a period of hours or days. The principal causes of ARF are ischemic and toxic insults that can induce tissue hypoxia. Transcriptional responses to hypoxia can be inflammatory or adaptive with the participation of the hypoxia-inducible factor 1alpha and the expression of specific genes related to oxidative stress.