Pain Perception Modulates Synaptic and Somatic Plasticity in the Dentate Gyrus of Rats

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BackgroundDespite extensive research on the link between pain experience and neural processes, the influences of intermittent sub-chronic pain on the hippocampal plasticity are less clear.In this work, we investigated at long-term plastic alterations in synaptic connections and neuronal function in rats with dentin erosion. MethodsExperiments were carried out on control and the rats with dentin erosion.The dentin hypersensitivity test was used to assess the behavioral reaction of rats by injecting of cold or warmish water.The short-term and the long-term plasticity of the dentate gyrus area were induced by electrical stimulation of the perforant pathway.The expressions of certain neurodegeneration-related genes were assessed by quantitative real-time PCR.Western blot was used to measure the expression of key proteins associated with neuronal plasticity. ResultsExposure of teeth to acetic solution caused molar tooth lesions with increased motor reaction when stimulated with cold water.These rats expressed facilitated short-term synaptic depression, post-tetanic potentiation and long-term potentiation.The PSEN2-mRNA levels significantly elevated in the rats exposed to painful stimuli, compared to the rats exposed to painless stimuli.There was no significant difference in MAPT-mRNA, JNK-mRNA, and BACE1-mRNA.Pain perception prevented down regulation of ERK1/2 phosphorylation by dentin erosion. DiscussionThe present study suggests a link between peripheral nociceptive information and neuronal plasticity in the dentate gyrus.The simultaneous presence of increased PSEN2 expression and facilitated plasticity in pain-perceived rats requires further investigation into the role of pain in the development of neurodegenerative alterations.