Assessment of the Toxicological Effects of Mercury in Aqueous Stockfish Extract on Reproductive Hormones in Male Albino Rats
Ijeoma Jacinta Nwagbara *
Department of Medical Laboratory Sciences, Faculty of Health Sciences and Technology, University of Nigeria Enugu Campus, Enugu, Nigeria.
Obi-Ezeani Chikaodili Nwando
Department of Medical Laboratory Sciences, Faculty of Health Sciences and Technology, Chukwuemeka Odumegwu Ojukwu University Igbariam Campus, Anambra State, Nigeria.
Eugenia Obiageli Nnoruka
Department of Medical Laboratory Sciences, Faculty of Health Sciences and Technology, Chukwuemeka Odumegwu Ojukwu University Igbariam Campus, Anambra State, Nigeria.
Augustine Chijioke Nwuko
Department of Medical Laboratory Sciences, Faculty of Health Sciences and Technology, University of Nigeria Enugu Campus, Enugu, Nigeria.
Chukwugozie N. Okwuosa
Department of Medical Laboratory Sciences, Faculty of Health Sciences and Technology, University of Nigeria Enugu Campus, Enugu, Nigeria.
Peter U. Achukwu
Department of Medical Laboratory Sciences, Faculty of Health Sciences and Technology, University of Nigeria Enugu Campus, Enugu, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Mercury contamination in fish products remains a concern because of its potential endocrine-disrupting effects. This study assessed the toxicological effects of aqueous stockfish-derived mercury on reproductive hormonal profiles in male albino rats. Twenty-five adult male albino rats (Rattus norvegicus) weighing 180–210 g were randomly allocated into five groups (n = 5). The control group received distilled water, while the treatment groups received graded oral doses of aqueous stockfish extract (250–1000 mg/kg body weight) for 30 days. The aqueous stockfish extract contained 0.043 ± 0.018 mg/L mercury. Mercury concentrations in the extract and blood samples were determined using atomic absorption spectrophotometry. Serum follicle-stimulating hormone (FSH), luteinising hormone (LH), and testosterone were measured using ELISA and chemiluminescence immunoassay techniques, while testicular tissues were examined after haematoxylin and eosin staining. Blood mercury levels increased dose-dependently from 0.024 ± 0.005 µg/L in the control group to 0.053 ± 0.011 µg/L in the highest-dose group. LH showed a significant positive correlation with mercury exposure (r = 0.586, p = 0.002), while testosterone increased markedly. FSH remained relatively unchanged. Histological examination showed normal seminiferous tubule architecture at lower doses, with mild structural alterations at the highest dose. These findings indicate that stockfish-derived mercury exposure may affect the hypothalamic–pituitary–gonadal axis and produce early testicular structural changes in male albino rats.
Keywords: Mercury toxicity, stockfish, dietary exposure, male albino rats, Rattus norvegicus, reproductive hormones, luteinising hormone, follicle-stimulating hormone, testosterone, endocrine disruption, bioaccumulation