Role of insulin in oleic acid-induced acute lung injury in rat model

Abstract

Objectives: Acute lung injury (ALI) is an inflammatory condition, therefore, this study was undertaken to determine the effect of insulin (an immunomodulatory agent) in oleic acid (OA)-induced ALI in rat model. Materials and Methods: The experiments were performed on adult male albino rats (total n = 18). The trachea, jugular vein and carotid artery of anaesthetised adult rats were cannulated to keep the respiratory tract patent, deliver saline/drugs and recording of blood pressure, respectively. Animals were divided into three groups. In Group I (control group), normal saline (75 μL) was injected and this group served as control group. In Group II (OA group), OA (75 μL) was administered to induce ALI in rats. In Group III (insulin + OA), OA (75 μL) was injected in insulin pre-treated rats. Respiratory frequency (RF), heart rate (HR) and mean arterial pressure (MAP) were recorded on computerised chart recorder; arterial blood sample was collected to determine PaO2/FiO2. Further, pulmonary water content was determined, and histological examination of the lung was done in all animals. Results: Injection of OA produced ALI indicated by significant increase in RF by 30 min followed by progressive decrease and ultimately death of animal. Significant increase in the pulmonary water content and decrease in PaO2/FiO2 were observed in these animals. Histological examination of lungs showed damage to the lung parenchyma. An immediate decrease in HR and MAP followed by some improvement and then progressive decrease was also observed. Conclusions: Insulin (an immunomodulatory agent) pre-treatment delayed initiation of OA-induced ALI as indicated by protection against OA-induced severe alteration in the RF in the initial stage and less lung injury in histological examination, although; it could not alter the overall course of the disease.