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Updated: Apr 23, 2026
Mechanical Conflict-Avoidance Assay to Measure Pain Behavior in Mice
Published on: February 18, 2022
Repeated amphetamine treatment alters spinal magnetic resonance signals and pain sensitivity in mice
Bing-Hsuan Lei1, Jyh-Horng Chen2, Hsiang-Shu Yin3
1Interdisciplinary MRI/MRS Lab, Graduate Institute of Electrical Engineering, National Taiwan University, Taiwan, ROC; National Taiwan University Molecular Imaging Center, Taiwan, ROC.
Abstract:
Manganese-enhanced magnetic resonance imaging (MEMRI) has been extensively used in studying the structural and functional features of the central nervous system (CNS). Divalent manganese ion (Mn(2+)) not only enhances MRI contrast, but also enters cells via voltage-gated calcium channels or ionotropic glutamate receptors, which represents an index of neural activities. In the current mouse model, following the repeated amphetamine (Amph) treatment, a reduction of reactivity to thermal pain stimulus was noticed. Since the spinal dorsal horn is the first relay station for pain transmission in CNS, we examined the changes of neural activity in the dorsal spinal cord, particularly the superficial dorsal horn, by analyzing manganese-enhanced T1-weighted MR images (T1WIs). Our data revealed a temporal correlation between reduced pain sensitivity and increased MEMR signals in the spinal dorsal horn subsequent to repeated Amph treatments.
Insights
Repeated amphetamine (Amph) treatment in mice reduced pain sensitivity. Manganese-enhanced MRI revealed increased neural activity in the spinal dorsal horn, correlating with this reduced pain response.
Area of Science:
- Neuroscience
- Pain research
- Magnetic Resonance Imaging
Background:
- Manganese-enhanced magnetic resonance imaging (MEMRI) visualizes central nervous system (CNS) structure and function.
- Manganese ions (Mn(2+)) act as MRI contrast agents and enter cells, indicating neural activity.
- Repeated amphetamine (Amph) administration in mice leads to decreased sensitivity to thermal pain stimuli.
Purpose of the Study:
- To investigate changes in neural activity within the spinal dorsal horn following repeated amphetamine treatment.
- To correlate alterations in pain sensitivity with MEMRI signals in the CNS.
Main Methods:
- Manganese-enhanced T1-weighted MR images (T1WIs) were analyzed in a mouse model.
- Neural activity was assessed in the dorsal spinal cord, specifically the superficial dorsal horn.
- Mice underwent repeated amphetamine treatments to induce changes in pain perception.
Main Results:
- A reduction in reactivity to thermal pain stimuli was observed after repeated amphetamine exposure.
- Increased MEMRI signals were detected in the spinal dorsal horn.
- A temporal correlation was found between diminished pain sensitivity and heightened MEMR signals.
Conclusions:
- Repeated amphetamine treatment alters neural activity in the spinal dorsal horn.
- MEMRI can detect functional changes in the spinal cord related to altered pain perception.
- The spinal dorsal horn plays a crucial role in mediating amphetamine-induced changes in pain sensitivity.
