Induction of transcription factor AP2 mRNA expression in rat primary afferent neurons during acute inflammation

Area of Science:

• Neuroscience
• Molecular Biology
• Pain Research

Background:

• Peripheral nerve injury and inflammation trigger complex cellular responses in sensory neurons.
• Immediate early genes (IEGs) are rapidly activated following cellular stimulation and play a role in long-term changes in gene expression.
• Dorsal root ganglion (DRG) neurons are primary sensory neurons involved in transmitting pain and other sensory information.

Purpose of the Study:

• To investigate the expression of immediate early gene mRNAs in DRG neurons after peripheral adjuvant injection.
• To identify specific IEGs involved in the early transcriptional response to peripheral inflammation.
• To explore the potential role of AP-2 transcription factor in initiating neuropeptide gene expression in DRG neurons.

Main Methods:

• In situ hybridization was used to examine mRNA expression in DRG neurons.
• Peripheral adjuvant injection was administered to induce an inflammatory response.
• Expression levels of several IEGs, including NGFI-A, NGFI-B, c-jun, jun D, jun B, and AP-2, were quantified.

Main Results:

• Neuronal expression of NGFI-A, NGFI-B, c-jun, jun D, and jun B mRNAs was undetectable or unchanged after adjuvant injection.
• AP-2 mRNA was expressed in most DRG neurons in control conditions.
• AP-2 mRNA levels significantly increased 1 hour after adjuvant injection (217% of control) and returned to baseline by 2 hours.

Conclusions:

• AP-2 mRNA expression is rapidly and transiently upregulated in DRG neurons following peripheral adjuvant injection.
• AP-2 may be a key component of the early transcriptional response that leads to neuropeptide gene expression in DRG neurons.
• This study identifies AP-2 as a potential early marker and mediator in the neuroinflammatory response within the DRG.