Role of mitochondrial ATP-sensitive potassium channels inurocot postconditioning-induced protection of rat cardiomyocytes / 中华麻醉学杂志

Objective To evaluate the role of mitochondrial ATP-sensitive potassium (mito-KATP) channels in urocortin postconditioning-induced protection of rat cardiomyocytes.Methods Clean-grade healthy male Sprague-Dawley rats,aged 16-20 weeks,weighing 200-250 g,were used in this study.Cardiomyocytes of rats were isolated,cuhured and divided into 4 groups (n =28 each) using a random number table method:control group (group C),H/R group (group HR),urocortin postconditioning group (group U) and 5-hydroxydecanoate (5-HD,mito-KAw channel blocker) plus urocortin postconditioning group (group HU).In group C,the cells were continuously cultured for 150 min in an incubator filled with 95％ O2-5％ CO2 at 37 ℃.In group HR,the cells were exposed to 40-min hypoxia in an incubator filled with 95％ N2-5％ CO2 at 37 ℃,followed by 110-min reoxygenation.In group U,the cells were exposed to 40-min of hypoxia,followed by 10-min reoxygenation,and then cultured in a cuhure medium containing 10-8mmol/L urocortin for 30 min,followed by 70-min reoxygenation.In group HU,the cells were cultured for 10 min in a culture medium containing 10-4mmol/L 5-HD,and the other treatments were similar to those previously described in group U.At the end of reoxygenation,the opening of mitochondrial permeability transition pore (mPTP) and mitochondrial membrane potential (MMP) were measured by fluorescence spectrophotometry.The expression of Bax and Bcl-2 was determined by Western blot,and the cell viability was measured by CCK-8 assay.Results Compared with group C,the viability of cardiomyocytes and MMP were significantly decreased,the opening of mPTP was increased,the expression of Bcl-2 was down-regulated,and the expression of Bax was up-regulated in the other 3 groups (P＜0.05).Compared with group HR,the viability of cardiomyocytes and MMP were significantly increased,the opening of mPTP was decreased,the expression of Bcl-2 was up-regulated,and the expression of Bax was down-regulated in group U,and the opening of mPTP was decreased (P ＜ 0.05),and no significant change was found in the other parameters in group HU (P＞0.05).Compared with group U,the viability of cardiomyocytes and MMP were significantly decreased,the opening of mPTP was increased,the expression of Bcl-2 was down-regulated,and the expression of Bax was up-regulated in group HU (P＜0.05).Conclusion The mechanism by which urocortin postconditioning attenuates H/R-induced damage to rat cardiomyocytes is associated with promoting mito-KATP channel opening and inhibiting mPTP opening.

Multi-facets of Corticotropin-releasing Factor in Modulating Inflammation and Angiogenesis

The family of corticotropin-releasing factor (CRF) composed of 4 ligands including CRF, urocortin (Ucn) 1, Ucn2, and Ucn3 is expressed both in the central nervous system and the periphery including the gastrointestinal tract. Two different forms of G protein coupled receptors, CRF1 and CRF2, differentially recognize CRF family members, mediating various biological functions. A large body of evidence suggests that the CRF family plays an important role in regulating inflammation and angiogenesis. Of particular interest is a contrasting role of the CRF family during inflammatory processes. The CRF family can exert both pro- and anti-inflammatory functions depending on the type of receptors, the tissues, and the disease phases. In addition, there has been a growing interest in a possible role of the CRF family in angiogenesis. Regulation of angiogenesis by the CRF family has been shown to modulate endogenous blood vessel formation, inflammatory neovascularization and cardiovascular function. This review outlines the effect of the CRF family and its receptors on 2 major biological events: inflammation and angiogenesis, and provides a possibility of their application for the treatment of inflammatory vascular diseases.

The Effect of Urocortin 1 on Motility in Isolated, Vascularly Perfused Rat Colon / 대한소화기학회지

BACKGROUND/AIMS: Urocortin 1, a corticotropin-releasing factor related peptide, increases colonic motility under stressful conditions. We investigated the effect of urocortin 1 on colonic motility using an experimental model with isolated rat colon in which the blood flow and intestinal nerves were preserved. Furthermore, we assessed whether this effect was mediated by adrenergic or cholinergic nerves. METHODS: Colonic motility was measured in the proximal and distal parts of resected rat colon. The colon resected from the peritoneum was stabilized, and then urocortin 1 (13.8, 138, 277, and 1,388 pM) was administered via a blood vessel. Motility index was measured in the last 5 min of the 15 min administration of urocortin 1 and expressed as percentage change from baseline. Subsequently, the change in motility was measured by perfusing urocortin 1 in colons pretreated with phentolamine, propranolol, hexamethonium, atropine, or tetrodotoxin. RESULTS: At concentrations of 13.8, 138, 277, and 1,388 pM, urocortin 1 increased the motility of proximal colon (20.4+/-7.2%, 48.4+/-20.9%, 67.0+/-25.8%, and 64.2+/-20.9%, respectively) and the motility of distal colon (3.3+/-3.3%, 7.8+/-7.8%, 71.1+/-28.6%, and 87.4+/-32.5%, respectively). The motility induced by urocortin 1 was significantly decreased by atropine to 2.4+/-2.4% in proximal colon and 3.4+/-3.4% in distal colon (p<0.05). However, tetrodotoxin, propranolol, phentolamine, and hexamethonium did not inhibit motility. CONCLUSIONS: Urocortin 1 increased colonic motility and it is considered that this effect was directly mediated by local muscarinic cholinergic receptors.

Corticotropin-releasing Hormone and Its Biological Diversity toward Angiogenesis

Angiogenesis is the formation of new blood vessels from existing ones and an underlying cause of numerous human diseases, including cancer and inflammation. A large body of evidence indicates that angiogenic inhibitors have therapeutic potential in the treatment of vascular diseases. However, detrimental side effects and low efficacy hinder their use in clinical practice. Members of the corticotropin-releasing hormone (CRH) family, which comprises CRH, urocortin I-III, and CRH receptors (CRHR) 1 and 2, are broadly expressed in the brain and peripheral tissues, including the intestine and cardiovascular system. The CRH family regulates stress-related responses through the hypothalamic-pituitary-adrenal axis. Therapeutic agents that target CRH family members offer a new approach to the treatment of various gastrointestinal disorders, including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and colorectal cancer. Since the discovery that CRHR 2 has anti-angiogenic activity during postnatal development in mice, studies have focused on the role of the CRH system in the modulation of blood vessel formation and cardiovascular function. This review will outline the basic biological functions of the CRH family members and the implications for the development of novel anti-angiogenic therapies.