Related Experiment Video
Updated: May 7, 2026
An Adipocyte Cell Culture Model to Study the Impact of Protein and Micro-RNA Modulation on Adipocyte Function
Published on: May 4, 2021
Differential expression of rat hippocampal microRNAs in two rat models of chronic pain
Yoko Hori1, Gentaro Goto, Masae Arai-Iwasaki
1Department of Anesthesiology and Pain Medicine, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan.
Abstract:
The two most common forms of chronic pain are inflammatory pain and neuropathic pain. Nevertheless, the underlying mechanisms of these pain conditions and their therapeutic responses are poorly understood. MicroRNAs (miRNAs) negatively regulate cell genes, and thus control cell proliferation, inflammation and metabolism. In the present study, we examined gene expression in the hippocampus of rats in two models of chronic pain. In addition, we used the left hindpaw procedure to identify differences in the bilateral hippocampus. We divided the rats into the 4 following groups: the group with chronic constriction injury (CCI), the sham-operated group, the group injected with complete Freund's adjuvant (CFA) and the group injected with normal saline. miRNA expression profiles were analyzed using TaqMan low-density array (TLDA). We observed 54 miRNAs (22.7%) in the rats with CCI rats that were differentially expressed, including 7 miRNAs that were downregulated compared with the sham-operated rats. In the CFA-injected rats, 40 miRNAs (16.8%) were differentially expressed, including 8 miRNAs that were downregulated compared with the normal saline-injected rats. Pearson's correlation co-efficient for all detected miRNAs in the rat hippocampus failed to identify differences between the hippocampi bilaterally. An unsupervised cluster analysis produced separate clusters between the control and experimental groups. In this study, we demonstrate the differential expression of hippocampal miRNAs in two rat models of chronic pain; however, no significant differences were observed bilaterally in hippocampal miRNA expression. Further research is required to determine the correlation among miRNAs, messenger RNAs (mRNAs) and proteins.
Insights
This study reveals altered microRNA (miRNA) expression in the rat hippocampus in chronic pain models. While significant changes were found, no bilateral differences in hippocampal miRNA expression were observed.
Area of Science:
- Neuroscience
- Molecular Biology
- Pain Research
Background:
- Chronic pain, encompassing inflammatory and neuropathic types, presents complex mechanisms and therapeutic challenges.
- MicroRNAs (miRNAs) are key regulators of gene expression, influencing cellular processes like proliferation, inflammation, and metabolism.
- Understanding miRNA roles in chronic pain is crucial for developing effective treatments.
Purpose of the Study:
- To investigate differential microRNA (miRNA) expression in the rat hippocampus in response to two chronic pain models.
- To identify potential differences in miRNA expression between the bilateral hippocampi in these pain models.
Main Methods:
- Two established rat models of chronic pain were utilized: chronic constriction injury (CCI) and complete Freund's adjuvant (CFA) injection.
- miRNA expression profiles in the hippocampus were analyzed using TaqMan low-density array (TLDA).
- Comparative analyses were performed between experimental groups (CCI, CFA) and their respective sham/saline controls.
Main Results:
- Differential expression of 54 miRNAs (22.7%) was observed in the CCI model, with 7 downregulated compared to sham controls.
- Differential expression of 40 miRNAs (16.8%) was noted in the CFA model, with 8 downregulated compared to saline controls.
- No significant bilateral differences in hippocampal miRNA expression were detected between the left and right hippocampi in either pain model.
Conclusions:
- Hippocampal miRNA expression is significantly altered in rat models of chronic inflammatory and neuropathic pain.
- Despite observed differential expression, no lateralization of hippocampal miRNA changes was found in these models.
- Further investigation is needed to elucidate the relationships between miRNAs, mRNAs, and proteins in chronic pain pathophysiology.
