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5-HT2B receptors modulate visceral hypersensitivity in a stress-sensitive animal model of brain-gut axis dysfunction

2009; Wiley; Volume: 22; Issue: 5 Linguagem: Inglês

10.1111/j.1365-2982.2009.01432.x

1365-2982

Siobhain M. O’Mahony, David C. Bulmer, Anne-Marie Coelho, Patrick Fitzgerald, Cheryl M. Bongiovanni, K. Lee, W. Winchester, Timothy G. Dinan, John F. Cryan,

Music Therapy and Health

Background Irritable bowel syndrome (IBS) is associated with an enhanced perception to visceral stimuli and exaggerated stress response. The serotonergic neurotransmitter system has been strongly implicated as a key player in the manifestation of IBS symptomatology including visceral hypersensitivity. However the role of 5-HT2B receptors in visceral pain, although speculated, is currently unclear. Thus we assessed the impact of a selective 5-HT2B receptor antagonist, RS-127445, on visceral hypersensitivity in a model of brain gut axis dysfunction the Wistar Kyoto (WKY) rat. Methods Colorectal distension (CRD) was used to assess the visceral sensitivity of the WKY rat compared to normosensitive Sprague Dawley (SD) rats. Once we verified the visceral sensitivity of the WKY rat we assessed the efficacy of RS-127445 in pain signalling from the colorectum. We administered the compound peripherally (i.p.) and centrally (i.c.v.) in order to ascertain the site of action of RS 127445. Behavioural responses to colorectal distention were then monitored. Key Results The WKY rats were more viscerally hypersensitive than the SD as previously shown. RS-127445 (5 mg kg−1, i.p.) significantly reversed visceral hypersensitivity in WKY animals. Moreover, when administered intracerebroventricularly RS-127445 (100 nM) also decreased the number of pain behaviours during noxious CRD in the WKY animals. Conclusions & Inferences Taken together, blockade of 5-HT2B receptors offers an exciting novel therapeutic target for pain relief in stress-related gastrointestinal disorders such as IBS.