ABSTRACT
Due to the high prevalence of noise and vibration exposure in most industries, this study aimed to investigate the effects of simultaneous exposure to noise and vibration on sex hormone levels and fertility capacity in rats, as well as the protective effects of the hydroalcoholic extract of cinnamon. In this experimental study, 64 adult male rats were randomly divided into 8 groups, control, noise (N), cinnamon (C), noise + cinnamon (NC), vibration (V), vibration + cinnamon (VC), noise + vibration (NV) and groups Noise + Vibration + Cinnamon (NVC). Groups C, NC, VC and NVC received a 75 mg/kg dose of cinnamon extract by gavage. The rats of groups N and NC, V and VC and NV and NVC were each exposed to noise at 100 dB (700-5700 Hz), vibration acceleration of 1 m/s2 rms (frequency range of 4-8 Hz), and simultaneously exposed to vibration and noise for 8 hours continuously every night (23:00-7:00) for 50 consecutive nights. Next, a blood sample was taken from the lateral tail vein and the levels of LH, FSH and testosterone were measured with ELISA kits. Each male rat was caged with 3 female rats for one week. The pregnant rats were kept until all of the rat pups were born. Then the fertility capacity, the total number of births, the live births and the birth weight of the rat pups were analyzed with the software SPSS. In the N and NV groups, compared to the control group, a significant decrease in LH and testosterone levels, the number of births and the birth weight was observed (p < 0.05). A significant decrease in testosterone levels, number of births and birth weight was observed in Group V compared to the control group (p < 0.05). In addition, significant increases in LH, FSH and testosterone levels and in birth weight were observed in group C compared to the control group (p < 0.05). Significant increases in FSH and testosterone levels, birth weight, and the number of births were noted in the NVC group compared to the NV group (p < 0.05). Based on the results of this study, cinnamon extract could alleviate the destructive effects of noise and vibration (both individually and in combination) on levels of sex hormones (LH, FSH, and testosterone), the number of births, and birth weight.
