Abstract
Background: The hippocampus is well-known for its role in memory processing and learning and for its ability of neurogenesis. Any factors that influence neurogenesis in the hippocampus might lead to subsequent memory and learning deficiencies. Light is one of the factors that exerts powerful effects on the hippocampus structure and function. In addition, there might be sexual dimorphism in neurogenesis following certain interventions. Due to the importance of neurogenesis, the effects of the light-dark cycle and sex-dependent differences on memory and learning deficiency in humans need to be determined. Objectives: This study investigated possible sex-dependent neurogenesis due to changes in the light-dark cycle in the hippocampus of adult rats that received two months of total light deprivation (2mTLD). Patients and Methods: Forty male and female adult Wistar rats randomly sorted into four groups were used in this study. Total light deprivation for two months (TLD) was done. TLD started one week prenatally and continued for seven more weeks. To study possible sexual differences in neurogenesis male and female rats were separated from the first day of TLD. Nissl staining, bromodeoxyuridine immunohistochemistry (BrdU IHC) and the Morris Water Maze (MWM) were used to study cell density, neurogenesis in dentate gyrus (DG), and spatial memory, respectively. The results were subjected to statistical analysis and presented as mean ± SD. P < 0.05 was considered significant. Results: BrdU IHC showed a significant decrease in neurogenesis following TLD in both sexes showing more severity in male rats than in female rats. Results of Nissl staining and MWM also confirmed the BrdU findings. Regarding sexual dimorphism, our data showed no significant sex differences in the DG area of the hippocampus. Conclusions: Sex-dependent reduction in neurogenesis following TLD could be one of the reasons for sex-dependent differences of cognitive disorders under the same the conditions.
Published Version
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