Histomorphometric Evaluation of the Small Coronary Arteries in Rats Exposed to Industrial Noise

Abstract

Morphological changes induced by industrial noise (IN) have been experimentally observed in several organs. Histological observations of the coronary arteries showed prominent perivascular tissue and fibrosis among IN-exposed rats. The effects on the small arteries are unknown. Objective: To evaluate the histomorphometric changes induced by IN on rat heart small arteries. Methods: Twenty Wistar rats exposed to IN during a maximum period of seven months and 20 age-matched controls were studied. Hearts were transversely sectioned from ventricular apex to atria and a mid-ventricular fragment was selected for analysis. The histological images were obtained with an optical microscope using 400× magnifications. A total of 634 arterial vessels (298 IN-exposed and 336 controls) were selected. The mean lumen-to-vessel wall (L/W) and mean vessel wall-to-perivascular tissue (W/P) ratios were calculated using image J software. Results: There were no differences between exposed and control animals in their L/W ratios (p = 0.687) and time variations in this ratio were non-significant (p = 0.110). In contrast, exposed animals showed lower W/P ratios than control animals (p < 0.001), with significant time variations (p = 0.004). Conclusions: Industrial noise induced an increase in the perivascular tissue of rat small coronary arteries, with significant development of periarterial fibrosis.

Infrasound induces coronary perivascular fibrosis in rats

“…In humans, sleep disturbance is associated with a proinflammatory state [41]. As previously mentioned, the common finding in the noise experiments conducted by our group was the perivascular and myocardial fibrotic development in the absence of inflammatory cells [20][21][22][23]. In the present study, we included a group of IFS-exposed animals treated with dexamethasone, a synthetic glucocorticoid member with immunosuppressive potency of about 20-30 times that of hydrocortisone and 4-5 times of prednisone [42,43].…”

“…Previous work from our group, in Wistar rats, investigated the histomorphometric changes in the large and small coronary arteries induced by high-intensity industrial noise within a wide spectrum of wavelengths that included LFN, this last characterized by large sound pressure amplitude ≥90 dB and low-frequency bands of ≤500 Hz [20,21]. The exposure time ranged from 1 to 7 months.…”

“…Considering that animals also possess inherent specific sound frequencies in certain tissues and organs [16], it is important to assess the morphological and biological effects induced by noise with different wavelengths in distinct animal models. So far, we have focused our investigation on the effects of large pressure amplitude noise within a wide spectrum of wavelengths, from the industrial to LFN and IFS, and with different exposure times, from 1 to several months [20][21][22][23]. The common finding was an abnormal deposition of collagen in the extracellular matrix (ECM), regardless of the characteristics of the noise stimulus other than pressure amplitude.…”

“…The cardiovascular system of rodents is sensitive to LFN [17][18][19]. We previously documented the development of perivascular fibrosis around the coronary arteries (from small to large caliber) of rats exposed to industrial noise [20,21]. We also found a significant fibrotic development in ventricular myocardium among rats submitted to LFN [22,23].…”

Role of moxifloxacin-dexamethasone in cardiac histomorphometric findings among Wistar rats from infected mothers

“…In this research, the histomorphometric measurements were performed using the Image J 1.51, Java 1.8.0_101 (64-bit) digital image analysis software. This program is widely used in scientific research involving quantification and analysis of images [5][6][7][8][9][10] , with programming platform based on the Java language. In a systematic way, all the photomicrographs were processed according to the same algorithm.…”