Department of Pharmacy, Birla Institute of Technology and Sciences (BITS) Pilani, Hyderabad Campus, Jawahar Nagar, Shameerpet, Hyderabad, Telangana, 500078, India.
Department of Molecular Biology, Central University of Jammu, India.
Eur J Pharmacol. 2021 Sep 5;906:174223. doi: 10.1016/j.ejphar.2021.174223. Epub 2021 Jun 1.
Protein kinase R (PKR) plays a main role in inflammation, insulin resistance, and glucose balance. It is activated by various stress signals and is key mediators of diabetes and associated complications. In the present study, we investigated the effect of PKR inhibition on myocardial dysfunction, inflammatory, cell death and interrelated signalling pathways in isoproterenol induced myocardial ischemia in vivo in wistar rats and in vitro in cultured cardiomyocytes. H9C2 rat cardiomyocytes were treated with 10 μM Isoproterenol (ISO). For in vivo studies, rats were divided into 4 groups: control, ischemic group (ISO), preventive group, curative group and each group consist of 8 rats. Myocardial Ischemia (MI) was induced with two subsequent doses of ISO (100 mg/kg, s.c.). The rats were treated with PKR inhibitor, C16 (166.5 μg/kg, i.p.) for 14 days. Heart rate, systolic, diastolic and mean arterial pressures were measured by non-invasive BP apparatus. Cardiac biomarkers were measured by commercial kits. Ischemic Zone, Morphological abnormalities and fibrosis of heart was detected by TTC, haematoxylin & eosin staining, Masson's and Sirius red staining respectively. Protein expression was done by western blotting and immune histochemistry. mRNA expression was done by RT-PCR. MI was characterized by declined myocardial performance along with elevation of cardiac biomarkers and associated with increased expression of PKR, oxidative-nitrosative stress, activated various inflammatory pathways (nuclear factor kappa light chain enhancer of activated B cells -NF-κB); Mitogen-activated protein kinases-MAPK; c-Jun N-terminal kinase-JNK), increased expression of inflammatory markers (Tumour necrosis factor alpha-TNF-α), markers of fibrosis (Alpha smooth muscle actin -α-SMA; Transforming growth factor beta-TGF-β), enhanced cell death (Ischemic zone) and increased expression of extracellular regulated-kinases (ERK-1/2) and advanced glycation end products (AGE's). Interestingly, inhibition of PKR attenuated myocardial dysfunction, cardiac fibrosis, oxidative/nitrosative stress, inflammation, cell death, and inter-related signalling pathways. Our findings report that inhibition of PKR improves the ischemic mediated inflammation, apoptosis, cardiac hypertrophy and fibrosis in MI induced rats. Hence, inhibition of PKR might be one of intervention therapy for the treatment of myocardial ischemia.
蛋白激酶 R (PKR) 在炎症、胰岛素抵抗和葡萄糖平衡中发挥主要作用。它被各种应激信号激活，是糖尿病及相关并发症的关键介质。在本研究中，我们研究了 PKR 抑制对异丙肾上腺素诱导的体内大鼠心肌缺血和体外培养心肌细胞中心肌功能障碍、炎症、细胞死亡和相关信号通路的影响。H9C2 大鼠心肌细胞用 10μM 异丙肾上腺素（ISO）处理。对于体内研究，将大鼠分为 4 组：对照组、缺血组（ISO）、预防组、治疗组，每组 8 只大鼠。用两次异丙肾上腺素（100mg/kg，sc）诱导心肌缺血。大鼠用 PKR 抑制剂 C16（166.5μg/kg，ip）治疗 14 天。通过非侵入性血压仪测量心率、收缩压、舒张压和平均动脉压。通过商业试剂盒测量心脏生物标志物。通过 TTC、苏木精和伊红染色、Masson 和 Sirius 红染色分别检测缺血区、心脏形态异常和纤维化。通过 Western 印迹和免疫组织化学检测蛋白表达。通过 RT-PCR 检测 mRNA 表达。心肌缺血表现为心肌功能下降，同时心脏生物标志物升高，并伴有 PKR 表达增加、氧化应激、各种炎症途径（核因子κB 轻链增强子的激活 B 细胞-NF-κB）；丝裂原激活蛋白激酶-MAPK；c-Jun N 末端激酶-JNK）、炎症标志物（肿瘤坏死因子-α-TNF-α）、纤维化标志物（α平滑肌肌动蛋白-α-SMA；转化生长因子-β-TGF-β）表达增加，细胞死亡增加（缺血区），细胞外调节激酶（ERK-1/2）和晚期糖基化终产物（AGEs）表达增加。有趣的是，PKR 抑制可减轻心肌功能障碍、心脏纤维化、氧化/硝化应激、炎症、细胞死亡和相关信号通路。我们的研究结果表明，PKR 抑制可改善异丙肾上腺素诱导的大鼠缺血性炎症、细胞凋亡、心肌肥大和纤维化。因此，PKR 抑制可能成为治疗心肌缺血的一种干预治疗方法。
