Chronic exposure of rats to occupational textile noise causes cytological changes in adrenal cortex

Abstract

Chronic exposure to industrial noise and its effects on biological systems. Occupational exposure to noise may result in health disorders. Our aim was to evaluate the effects of chronic exposure to high-intensity noise of textile industry cotton rooms on the adrenal morphology. The environmental noise of a cotton-mill room from a large textile factory of Northern Portugal was recorded and reproduced by an adopted electroacoustic setup in a sound-insulated animal room where the rats were housed. The sounds were reproduced at the original levels of approximately 92 dB, which was achieved by equalization and distribution of sound output in the room. Wistar rats were submitted to noise exposure, in the same time schedule as employed in textile plants. After one, three, five, and seven months, the adrenals were collected and analyzed by light microscopy. Analyzed by multivariate analysis of variance and post hoc Bonferroni correction for multiple comparisons of the means between the groups. Noise exposure induced time-dependent changes in adrenal cortex, with decrease of zona fasciculata (ZF) and increase of zona reticularis volumes, together with a significant depletion of lipid droplet density in ZF cells of exposed rats, in comparison to control rats. Chronic exposure of rats to textile industry noise triggers cytological changes in the adrenals that suggest the existence of a sustained stress response.

Morphological changes of adrenal gland and heart tissue after varying duration of noise exposure in adult rat

“…However, there was an increase in the thickness of the zona reticularis without cellular disorganization. Our findings were similar to the work of Oliveira et al [11] showing that chronic exposure to industrial noise triggers cytological changes in the adrenal gland, and then a depletion of lipid droplet in zona fasciculata cells and an increase in the volume of the zona reticularis.…”

“…The noise-induced changes were located in the adrenal cortex zone, [11,12] which is the most sensitive area to adrenocorticotropic hormone stimulation, known to increase during stress conditions that activate the HPA axis. [13] Recent study demonstrated that exposure to long-term noise (3 month) for different intensities 70 and 85 dB(A) affected various parameters of the endocrine glands.…”

“…Noise exposure induced time-dependent changes in the adrenal cortex that suggest the existence of a sustained stress response. [11] The duration of exposure to noise is thus a factor of harm. In fact, even a lowintensity noise can be annoying.…”

“…It allows editing noise on multiple tracks and is accompanied by various filters and effects (noise reduction, equalizer, increased frequencies, compression, amplification…). The noise level generated by the software was set at 70 dB(A) to an octave-band noise (8)(9)(10)(11)(12)(13)(14)(15)(16) by the use of two loudspeakers installed at a distance of 10 cm to each cage. The noise level was monitored using an Integrating Sound Level Meter with Class 1 accuracy-type 2238 Bruel and Kjaer.…”

How and why environmental noise impacts animals: an integrative, mechanistic review

“…Although the damage did not appear to become more severe over time, it did become more widespread. Oliveira et al. (2009), who also studied the effects of noise on rats, found time‐dependent physical changes in the adrenal cortex, including a decrease in ZF volume and an increase ZR volume.…”