FMRP acts as a key messenger for visceral pain modulation

Area of Science:

• Neuroscience
• Pain Research
• Genetics

Background:

• Visceral pain is a common symptom linked to mechanical stretch, spasm, ischemia, and inflammation.
• Fragile X syndrome (FXS), caused by FMRP deficiency, is associated with intellectual disabilities and self-injurious behaviors, suggesting potential nociceptive deficits.
• The specific role of FMRP in visceral pain regulation remains largely unexplored.

Purpose of the Study:

• To investigate the role of fragile X mental retardation protein (FMRP) in the central nervous system's processing of visceral pain.
• To elucidate the molecular mechanisms underlying FMRP's involvement in pain sensitization and modulation.

Main Methods:

• Utilized FMR1 knockout (KO) mice and SH-SY5Y neuroblastoma cells for in vitro and in vivo studies.
• Administered zymosan to induce visceral pain and inflammation, assessing behavioral responses and neuronal activity in the anterior cingulate cortex (ACC).
• Measured glutamate release, postsynaptic potentials, adenylyl cyclase 1 (AC1) activity, and NMDA GluN2B receptor expression.

Main Results:

• FMR1 KO mice exhibited reduced sensitivity to zymosan-induced visceral pain compared to wild-type (WT) mice.
• Zymosan treatment led to decreased presynaptic glutamate release and postsynaptic responses in the ACC of FMR1 KO mice.
• Upregulation of AC1 and NMDA GluN2B receptors in the ACC following zymosan was attenuated in FMR1 KO mice, with increased FMRP levels observed in WT mice.

Conclusions:

• FMRP is essential for the proper upregulation of NMDA GluN2B receptors and AC1 in response to visceral pain stimuli.
• A positive feedback loop involving GluN2B, AC1, and FMRP plays a significant role in modulating visceral pain.
• These findings highlight FMRP as a potential therapeutic target for visceral pain conditions, particularly in the context of FXS.