The effect of acute and chronic formaldehyde exposure on learning and memory in male and female rats

Abstract

Aim: Formaldehyde is a chemical that lies behind the various systemical failures in organism. Many products that people use contain formaldehyde. Owing to its tissue fixative properties, scientists who work in life sciences are exposed to this substance more than others. Several studies have shown that formaldehyde affects the CA1 and CA3 regions of the hippocampus, which play crucial roles in memory consolidation. In this study, we aimed to investigate anxiety levels and indicate the short and long term effects of formaldehyde and sex-related differences by exposing formaldehyde to male and female rats.

Materials and methods: Formaldehyde (10 mg/kg) was administered intraperitoneally for 7 days for acute exposure and 30 days for chronic exposure. Cognitive assessment was performed using fear conditioning, elevated plus maze, and Morris water maze tests. TUNEL staining was used to identify apoptosis in the brains obtained after decapitation.

Results: Exposure to intraperitoneal formaldehyde does not impair learning and memory in acute and chronic periods and has no effect on depression or anxiety. After acute exposure, apoptosis was observed in the hippocampal CA1 and CA3 regions in males. When the cognitive test results were examined, no differences were found between the experimental and control groups. There was also no significant difference between males and females.

Keywords: Learning and memory; fear conditioning; formaldehyde; hippocampus; morris water maze; plus maze.