POMC mediates orofacial hyperalgesia under hypoestrogenic conditions

Area of Science:

• Neuroscience
• Endocrinology
• Pain Research

Background:

• Estrogen influences sensory neuron excitability and pain perception.
• Pro-opiomelanocortin (POMC) is a key regulator of pain response, highly expressed in the trigeminal ganglion (TG).
• Hypoestrogenic states can alter pain sensitivity, particularly in women.

Purpose of the Study:

• To investigate the link between trigeminal ganglion POMC and orofacial allodynia in hypoestrogenic rats.
• To elucidate the regulatory mechanism of estrogen on POMC expression and function in the TG.
• To determine the role of estrogen receptor alpha (ERα) in mediating these effects.

Main Methods:

• Ovariectomized rat model to induce hypoestrogenism.
• Gene and protein expression analysis of POMC in the TG.
• Overexpression of POMC in the TG to assess pain reversal.
• Administration of selective estrogen receptor agonists to the TG.
• Chromatin Cleavage and Tagging (CUT&Tag) and dual-luciferase assays to study promoter activity.
• Protein binding assays.

Main Results:

• Hypoestrogenism significantly decreased POMC expression in the TG at both gene and protein levels.
• Overexpression of POMC in the TG reversed pain hyperalgesia in ovariectomized rats.
• Estradiol (E2) in the TG regulates POMC expression via ERα.
• ERα positively regulates the POMC promoter, but may inhibit its activity.
• ERα also regulates POMC protein biological activity in the TG.

Conclusions:

• Estrogen receptor alpha (ERα) in the trigeminal ganglion plays a dual role in regulating POMC.
• ERα inhibits POMC gene expression by affecting POMC promoter activity.
• ERα also modulates POMC protein activity through direct binding.
• This dual regulation contributes to decreased orofacial mechanical pain threshold and allodynia in hypoestrogenic states.