Investigation of bdnf and trkb genes expression in the presence and lack of fish oil treatment in male rats hippocampus region following memory damage caused rem sleep deprivation

Mohammad Fallahi,1,* Mohammad nasehi,2 Pegah ghoraeiyan,3

1. Department of Genetics, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.
2. Department of Genetics, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.
3. Department of Genetics, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.

Abstract

Introduction

Sleep which is known as one of the most vital needs among creatures includes many biological processes of living organisms, both at the cellular and molecular level as well as the clinical level. sleep is composing of two distinct: rapid eye movements phase (rem) and non-rapid eye movement (nrem) which have unique features with the ability to adjust by separate neural centers. sleep plays a key role in memory processing by using the rem phase which is important to generate memories and also learning as a part of the sleep cycle. in other hands, sleep deprivation which is known as one of the most serious problems in developed countries, causes many disorders, especially abnormalities of consciousness and memory. the prevalence of sleep deprivation among mid-class people increase dramatically. brain and its different nuclei and segments are the only major player in learning and producing memory. it has been argued that the most important nucleus which is responsible for the process of memorizing in the brain is called “hippocampus”. the hippocampus is a complex structure in the brain which is located deep inside the temporal lobe. many genes have their own proteins which are responsible for memory creation. one of them is the gene-derived brain-derived neurotrophic factor (bdnf), which increases the transmission efficiency of the stimulant and enhances the synaptic plasticity that supports memory and cognition. the trkb gene, which is the coding for the bdnf protein receptor, also plays a vital role in the process of memory formation. it is believed that the activation of the pathway of bdnf-trkb and the expression of their genes to enhance the learning and memory of the hippocampus is required. nowadays, the significance of using seafood in health is clear to everyone. marine foods are rich in unsaturated fatty acids of the omega family. fish oil is, also, known to have high levels of omega-3, an unsaturated fatty acid, which is worked as a developer of the central nervous system. human studies have shown that high levels of omega3-s are associated with an increase in the amount of gray matter in the brain, especially in the hippocampal nucleus and brain regions. it plays a key role in the formation and consolidation of memory and learning. the effect of these unsaturated fatty acids on the change in the expression of different genes at different tissues has also been proven.

Methods

In this study, we investigated the effect of fish oil on changes in bdnf gene expression (neuronal factor gene) and its receptor gene (trk-b) in the hippocampus of wistar male rats by using real-time pcr technique. in this research, rats were divided into five groups. which included: control (healthy rats), sham (under stress), sham was treated by fish oil, deprived of rem sleep and deprived rem sleep-treated by fish oil. then, the rna was extracted from the tissue of the hippocampus and from that cdna was made. real-time pcr reaction was performed for each cdna sample. finally, the gene expression was analyzed using genex software.

Results

The findings showed that the expression of bdnf gene in sham, sham-treated by fish oil, and rem sleep-deprived groups were not significantly different from the control group. but the expression of the bdnf gene in the deprived of rem sleep treated by fish oil group increased compared with the rem sleep-deprived group. in trk-b gene, there was no significant difference between sham and sham-treated by fish oil groups with the control group. but the comparison between the deprived rem sleep group and control group showed a significant decrease in trk-b gene expression in deprived rem sleep group compared to the control group. also, trk-b showed a significant increase in deprived rem sleep treated by fish oil group compared with the deprived rem sleep group. from this study, it can be concluded that rem sleep deprivation decreases the expression of the bdnf receptor gene, the trk-b gene. but stress has no effect on the expression of this gene.

Conclusion

It can also be concluded that fish oil contributes to the improvement of neuronal and memory damage by affecting cellular and molecular mechanisms and increasing the expression of bdnf and trk-b genes in rem sleep deprived rats.

Keywords

Sleep deprivation, memory, hippocampus, fish oil, rat