Neurogastroenterology and motility · 2026
Proopiomelanocortin (POMC)-β-Endorphin System in the Rat Colon: Expression, Up Regulation by Stress, and Correlation With Stress-Induced Visceral Analgesia.
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Yuan Pu-Qing, Larauche Muriel, Wu Vincent, Taché Yvette
Аннотация
BACKGROUND: The pituitary proopiomelanocortin (POMC)-β-endorphin (β-END) system is activated by hypothalamic corticotropin-releasing factor (CRF) signaling and stress. We investigated whether this pathway is also expressed in the rat colon, regulated by peripheral CRF and stress, and correlated with stress-induced visceral analgesia.
METHODS: POMC and the prohormone convertases PC1/3 and PC2 transcripts were assessed by RT-PCR, and POMC and β-END localization was examined by immunohistochemistry in the proximal and distal colon of naïve adult male Sprague-Dawley rats. Proximal colonic POMC mRNA was quantified by real-time quantitative PCR 1 h after intraperitoneal injection of CRF (10 μg/kg) or saline and on day 11 after assessing visceromotor responses (VMRs) to colorectal distension (CRD) using a non-invasive method in rats subjected to repeated water avoidance stress (rWAS) (1 h/day for 10 days) or control handling. The correlation between POMC gene expression and VMRs was evaluated.
RESULTS: POMC, PC1/3, and PC2 transcripts were detected in the proximal and distal colon. POMC- and β-END-immunoreactive cells are localized in the lamina propria and enteric plexuses. CRF increased POMC mRNA expression by 2.5-fold. rWAS decreased VMRs to CRD in a pressure-dependent manner, with a reduction of up to 52% at 60 mmHg, and increased POMC expression 10-fold compared with controls; POMC expression was inversely correlated with cumulative VMRs (r = -0.655, p = 0.034).
CONCLUSIONS: POMC-β-END system expression in the rat colonic enteric plexus, together with CRF/stress-induced upregulation of POMC and its correlation with analgesic responses to CRD, suggests a possible relevance in modulating visceral pain.
METHODS: POMC and the prohormone convertases PC1/3 and PC2 transcripts were assessed by RT-PCR, and POMC and β-END localization was examined by immunohistochemistry in the proximal and distal colon of naïve adult male Sprague-Dawley rats. Proximal colonic POMC mRNA was quantified by real-time quantitative PCR 1 h after intraperitoneal injection of CRF (10 μg/kg) or saline and on day 11 after assessing visceromotor responses (VMRs) to colorectal distension (CRD) using a non-invasive method in rats subjected to repeated water avoidance stress (rWAS) (1 h/day for 10 days) or control handling. The correlation between POMC gene expression and VMRs was evaluated.
RESULTS: POMC, PC1/3, and PC2 transcripts were detected in the proximal and distal colon. POMC- and β-END-immunoreactive cells are localized in the lamina propria and enteric plexuses. CRF increased POMC mRNA expression by 2.5-fold. rWAS decreased VMRs to CRD in a pressure-dependent manner, with a reduction of up to 52% at 60 mmHg, and increased POMC expression 10-fold compared with controls; POMC expression was inversely correlated with cumulative VMRs (r = -0.655, p = 0.034).
CONCLUSIONS: POMC-β-END system expression in the rat colonic enteric plexus, together with CRF/stress-induced upregulation of POMC and its correlation with analgesic responses to CRD, suggests a possible relevance in modulating visceral pain.