PECULIARITIES OF RESPIRATORY CELLULAR IMPLICATIONS IN STREPTOZOTOCIN-INDUCED DIABETES: A FOCUS ON TYPE I ALVEOLOCYTES

Abstract

Introduction. The escalating global prevalence of diabetes mellitus has ignited concerns, given its multifaceted repercussions that extend beyond conventional metabolic considerations. Recent scientific inquiries have firmly established a profound association between diabetes mellitus and abnormalities within the respiratory system, unveiling a nuanced interplay that transcends mere glycemic control. This study delves into the intricate and far-reaching influence of diabetes on the respiratory system, recognizing it as a vulnerable target organ susceptible to systemic repercussions. Compelling epidemiological evidence underscores a heightened prevalence of respiratory complications among individuals grappling with diabetes. This observation prompts a meticulous exploration of the pathophysiological underpinnings of this intricate relationship, spanning from molecular intricacies to clinical manifestations.
 The aim was to deepen our understanding of the impact of diabetes mellitus on the respiratory system by investigating the pathological alterations in type I alveolocytes within an experimental model of diabetes mellitus.
 Methods. In this experimental model we used 88 male Wistar rats (170-210 g). The rats were divided into three groups: Group 1 (n=10) consisted of intact rats; Group 2 (n=40) served as the control group, and Group 3 (n=38) constituted the experimental group where diabetes was induced by intraperitoneal administration of streptozotocin (Sigma, USA) diluted in 0.1 M citrate buffer with pH 4.5 at a dosage of 60 mg/kg of body weight. The control group received an equivalent volume of 0.1 M citrate buffer solution with a pH of 4.5 via intraperitoneal injection. All procedures were performed under sodium thiopental anesthesia at a dose of 60 mg/kg of body weight. Tissue samples were collected at intervals of 14, 28, 42, and 70 days post streptozotocin injection.
 For electron microscopy analysis, fragments of lung tissue were immersed in a 2.5% glutaraldehyde solution for fixation, followed by fixation in a 1% osmium tetroxide solution. After dehydration, the specimens were embedded in Epon Araldite. Sections, obtained through a "Tesla VS-490" ultramicrotome, underwent examination using a "PEM-125K" electron microscope.
 Results. Throughout the experiment, discernible changes in type I alveolocytes were observed. At 14 days, nuclei exhibited rounding or oval shape with uniform chromatin distribution. Mitochondria displayed small size, and the Golgi apparatus (GA) and granulated endoplasmic reticulum (GER) showed no significant alterations. By 28 days, nuclei adopted an oval shape, chromatin localized peripherally, and mitochondria exhibited diverse morphologies. Increased micropinocytotic vesicles indicated heightened cellular activity. At 42 days, hyperhydration became pronounced, nuclei displayed lower electron density, and cellular components showed advanced changes. By 70 days, dystrophic-destructive changes included low electron density nuclei, disorganized mitochondria, and fragmented GA and GER.
 Conclusion. This comprehensive ultrastructural analysis unveils the progressive impact of diabetes on type I alveolocytes, elucidating unique facets of pulmonary alterations over time. This study contributes to a growing body of knowledge, shedding light on the dynamic nature of pulmonary changes in diabetes mellitus, ultimately urging further exploration for a holistic understanding of its implications on respiratory health.