Ameliorating effect of melatonin on mercuric chloride-induced neurotoxicity in rats

Eman S Said; Radwa M Ahmed; Rehab A Mohammed; Enas M Morsi; Mohamed H Elmahdi; Hassan S Elsayed; Rania H Mahmoud; Eman H Nadwa

doi:10.1016/j.heliyon.2021.e07485

Ameliorating effect of melatonin on mercuric chloride-induced neurotoxicity in rats

Heliyon. 2021 Jul 6;7(7):e07485. doi: 10.1016/j.heliyon.2021.e07485. eCollection 2021 Jul.

Authors

Eman S Said^{1

2}, Radwa M Ahmed³, Rehab A Mohammed⁴, Enas M Morsi⁵, Mohamed H Elmahdi⁶, Hassan S Elsayed⁷, Rania H Mahmoud⁷, Eman H Nadwa^{8

9}

Affiliations

¹ Department of Clinical Pharmacology, Faculty of Medicine, Fayoum University, Fayoum, Egypt.
² Department of Pharmacology and Toxicology, College of Pharmacy, Qassim University, Saudi Arabia.
³ Department of Anatomy and Embryology, Faculty of Medicine, Fayoum University, Egypt.
⁴ Department of Medical Physiology, Faculty of Medicine, Fayoum University, Egypt.
⁵ Department of Forensic Medicine and Clinical Toxicology, Faculty of Medicine, Fayoum University, Egypt.
⁶ Department of Pathology, Faculty of Medicine, Fayoum University, Egypt.
⁷ Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Fayoum University, Egypt.
⁸ Department of Pharmacology and Therapeutics, College of Medicine, Jouf University, Sakaka, Saudi Arabia.
⁹ Department of Medical Pharmacology, Faculty of Medicine, Cairo University, Giza, Egypt.

Abstract

Mercury is a highly toxic metal. It induces its toxicity via production of reactive oxygen species. Brain tissues are more susceptible to oxidative damage. Melatonin and its metabolites are free radical scavengers. The aim of this work is to elucidate the neuroprotective effect of melatonin on mercuric chloride-induced neurotoxicity in rats. Fifty male albino rats were used and divided into five groups. Group I acts as normal control. Group II (LD HgCl₂) received mercuric chloride at a dose of 2 mg/kg. Group III (HD HgCl₂) received HgCl₂ at a dose of 4 mg/kg. Rats in group IV (LD HgCl₂ +MLT) received HgCl₂ 2 mg/kg + Melatonin 5 mg/kg. Rats in group V (HD HgCl₂+MLT) received HgCl₂ 4 mg/kg + Melatonin5 mg/kg. This study revealed that mercuric chloride decreased the activity of superoxide dismutase, catalase and glutathione peroxidase enzymes and increased malondialdehyde levels. Toxicity of mercuric chloride lead to upregulation of the gene expression level vascular endothelial growth factor. HgCl₂ induced fragmentation of rough endoplasmic reticulum, ballooning of Golgi apparatus, nuclear and cytoplasmic degeneration of pyramidal neurones of rat cerebral cortex. This neuronal damage caused by HgCl₂ was significantly improved by melatonin.

Keywords: Cerebral cortex; Melatonin; Mercuric chloride; Neurotoxicity; Oxidative stress.