The Effects of Sodium Metabisulfite on the Hippocampus and Prefrontal Cortex in Wistar Rats: A Cognitive, Neurochemical, and Histological Study

Background: This study investigates the potential effect of sub-chronic exposure to sodium metabisulfite (NaMBS) on the hippocampus and prefrontal cortex of female Wistar rats.  Methods: A total of ۲۴ adolescent female Wistar rats were randomly divided into four groups (۶ rats each) as follows: Group ۱ (control) received ۰.۵ mL of normal saline; group ۲ was administered by ۱۰۰ mg/kg of NaMBS; group ۳ was issued by ۳۰۰ mg/kg of NaMBS; group ۴ received ۵۰۰ mg/kg of NaMBS. The route of administration was oral for ۲۸ days. After completing the administration phase, the Y-maze test was conducted. Subsequently, the rats were euthanized, and tissue samples from the prefrontal cortex and hippocampus were collected for biochemical assays, precisely measuring malondialdehyde (MDA) and acetylcholinesterase (AChE) levels, as well as histological studies, such as hematoxylin and eosin, and glial fibrillary acidic protein (GFAP). Meanwhile, the neuronal count was done.  Results: The learning and memory functions of rats in the treated and control groups were similar (number of alternations: P>۰.۰۵). The group treated with ۵۰۰ mg/kg NaMBS presented indications of neurodegeneration in CA۱ of the hippocampus and high glial fibrillary acidic protein-immunoreactivity but had no noticeable effects on layer II/III of the prefrontal cortex. Regardless of the dosage of NaMBS, malondialdehyde level was the same (P>۰.۰۵) for all groups; however, in the group that received ۵۰۰ mg/kg NaMBS, the acetylcholinesterase level was significantly reduced (P˂۰.۰۵).  Conclusion: This study revealed that while NaMBS can lead to neurodegeneration in the hippocampus of Wistar rats at ۵۰۰ mg/kg, the prefrontal cortex remains resilient and spatial memory is unaffected, but a decrease in acetylcholinesterase activity raises cognitive concerns, emphasizing the need for cautious consideration of its use.

Keywords:

Sodium metabisulfite , Hippocampus , Prefrontal cortex , Neurodegeneration , Acetylcholinesterase , Cognition