Neuroprotective Effects of Eleveted Dose Vitamin A on the Hippocampus of Adult Male Wistar Rats Exposed to Toxic Doses of Methamphetamine
Ezejindu Damian Nnabuihe
Department of Anatomy, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Joshua Izuchukwu Abugu
*
Department of Anatomy, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria and Department of Human Anatomy, Fculty of Basic Medical Sciences, State University of Medical and Applied Sciences, Igbo-Eno, Enugu State, Nigeria.
Enemuo Ijeoma
Department of Anatomy, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Okeke Somadina Nnamdi
Department of Anatomy, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
K. Ogbuokiri Doris
Department of Anatomy, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Okeke Henry Kachikwuru
Department of Anatomy, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Ekoh Augustine Alobu
Department of Anatomy, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Benedict Nzube Obinwa
Department of Anatomy, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Chinyere Elizabeth Eze
Department of Anatomy, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Nwaefulu Kester Eluemunor
Department of Physiology, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Sobanke A. Omolara
Department of Physiology, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Chidinma Ifeyinwa Mmaju
Department of Physiology, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Okafor Anulika Jacinta
Department of Physiology, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Chuka-Onwuokwu Ngozi Cynthia
Department of Physiology, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Ejiogu Ikedichukwu Chibueze
Department of Biochemistry, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Nwoko Sebastine Okechukwu
Department of Biochemistry, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Wuraola Serah Nnaemeka
Department of Biochemistry, Faculty of Basic Medical Sciences, Nnamdi Azikiwe University, Nnewi Campus, Anambra State, Nigeria.
Ebi Victory Chinecherem
Department of Medicine, College of Medicine, University of Calabar, Cross River State, Nigeria.
Agu Augustine Uchenna
Department of Anatomy, Faculty of Basic Medical Sciences, University of Nigeria, Enugu Campus, Enugu State, Nigeria.
Ugwu Augustus Uchenna
Department of Anatomy, Faculty of Basic Medical Sciences, University of Nigeria, Enugu Campus, Enugu State, Nigeria.
Nwodo Ndubuisi Francis
Department of Human Anatomy, Faculty of Basic Medical Sciences, Madonna University, Rivers State, Nigeria.
Elemuo Chukwuebuka Stanley
Department of Anatomy, Chukwuemeka Odumegwu Ojukwu University, Uli Campus, Anambra State, Nigeria.
Agbai Johnson Ukwa
Department of Human Anatomy, Faculty of Basic Medical Sciences, Abia State University, Uturu, Abia State, Nigeria.
Muorah Chinecherem Onyekachi
Department of Nursing Science, Christopher University, Ogun State, Nigeria.
Ozoemena Chiadikobi Lawrence
Department of Human Anatomy, Fculty of Basic Medical Sciences, State University of Medical and Applied Sciences, Igbo-Eno, Enugu State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Methamphetamine overstimulates brain regions such as the striatum and hippocampus by increasing neurotransmitter activity, thereby causing neurotoxicity, whereas vitamin A may help protect neurons through anti-inflammatory and neuroprotective effects. This study investigated the neuroprotective effects of an elevated dose of vitamin A on the hippocampus of adult male Wistar rats exposed to toxic doses of methamphetamine (METH). Twenty adult male rats were randomly divided into four groups (n = 5): Group A (control) received feed and water only; Group B received METH at 5 mg/kg at 3-hour intervals within 12 hours; Group C received vitamin A only (2.5 mg/kg); and Group D received the combined treatment of METH (5 mg/kg at 3-hour intervals within 12 hours) and vitamin A (2.5 mg/kg) for 28 days. After the final administration, the animals were sedated and sacrificed; their brains were harvested, fixed in 10% neutral formol saline, and processed for histological examination using haematoxylin and eosin (H&E) staining. Body-weight analysis revealed weight loss in methamphetamine-intoxicated Wistar rats. Methamphetamine increased MDA levels and reduced GSH and SOD levels, indicating oxidative stress. Hippocampus-dependent cognitive performance assessed using the Morris water maze indicated impaired learning after methamphetamine exposure, whereas vitamin A improved cognition and antioxidant status. Histological analysis revealed better-preserved hippocampal architecture in the vitamin A-treated groups than in the METH-only group. Overall, vitamin A provided partial neuroprotection against METH-induced hippocampal toxicity but did not completely reverse the damage.
Keywords: Methamphetamine, vitamin A, retinoic acid, hippocampus, neurotoxicity, oxidative stress, Morris water maze, neuroprotection