Effects of noise stress on thyroid stimulating hormone in adult rats

Objective: To determine the effect of noise stress on thyroid stimulating hormone in adult rats. Study Design: Laboratory-based experimental study. Place and Duration of Study: Department of Anatomy, Army Medical College, Rawalpindi in collaboration with National Institute of Health, Islamabad, from Jan to Dec 2020. Methodology: A total of 30 adult Sprague Dawley rats were distributed into three groups as ten rats/group. Group A served as the control group, rats in group B were exposed to 100 dB noise for continuous 4 hours/day for four months, and the rats in group C were exposed to 100 dB noise for continuous 6 hours/day for four months. At the end of the study, serum samples were collected from the rats’ tail veins. Thyroid-stimulating hormone levels were compared among the groups. Results: At the start of the study, mean serum thyroid stimulating hormone level of control group A rats was 0.34 ± 0.15 µIU/ml. Mean serum thyroid stimulating hormone level of experimental groups B and C rats at the start of the study was 0.46 ± 0.18 µIU/ml and 0.41 ± 0.14 µIU/ml, respectively Mean serum thyroid stimulating hormone of rats did not differ statistically significantly between the group p=0.26, By the end of study mean serum thyroid stimulating hormone level of control group A rats was 0.6 ± 0.2 µIU/ml. Mean serum thyroid stimulating hormone levels of experimental groups B and C rats at the end of the study were 1.32 ± 0.35 µIU/ml and 1.86 ± 0.67 µIU/ml, respectively, Mean serum thyroid stimulating hormone of rats differed significantly between the groups p<0.001. Conclusion: Loud noise exposure can lead to an increased level of mean serum thyroid stimulating hormone levels in adult rats.