5-HT3 receptor signaling in serotonin transporter-knockout rats: a female sex-specific animal model of visceral hypersensitivity | Zendy

Nadine C. El-Ayache | Zendy; James J. Galligan | Zendy

Open Access

5-HT₃ receptor signaling in serotonin transporter-knockout rats: a female sex-specific animal model of visceral hypersensitivity

Author(s) -

Nadine C. El-Ayache,

James J. Galligan

Publication year - 2018

Publication title -

ajp gastrointestinal and liver physiology

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 1.644

H-Index - 169

eISSN - 1522-1547

pISSN - 0193-1857

DOI - 10.1152/ajpgi.00131.2018

Subject(s) - medicine , serotonin transporter , endocrinology , agonist , serotonin , 5 ht receptor , irritable bowel syndrome , visceral pain , receptor , receptor antagonist , antagonist , nociception

The irritable bowel syndrome (IBS) is a functional gastrointestinal motor and visceral sensation disorder that is more common in women than men. Female serotonin transporter (SERT)-gene knockout (KO) rats exhibit hypersensitivity to colorectal balloon distention (CRD) that mimics colonic hypersensitivity occurring in female IBS patients. Alosetron (5-HT 3 receptor antagonist) is used to treat diarrhea-predominant IBS in female patients. Other 5-HT 3 receptor antagonists are ineffective at treating IBS symptoms. The visceromotor response (VMR) to CRD in SERT-KO and wild-type (WT) rats was measured following subcutaneous (sc), intracerobroventricular (icv), or intrathecal (it) treatment with 5-HT 3 receptor antagonists and an agonist. Alosetron (sc) and granisetron (antagonists) caused a paradoxical increase in the VMR to CRD in SERT-KO female rats. Alosetron (sc) increased the VMR to CRD in WT male rats. Alosetron (it) increased the VMR to CRD in SERT-KO female rats only, and the 5-HT 3 receptor agonist SR-52772 increased the VMR to CRD in SERT-KO male rats. Depletion of spinal 5-HT using 5,7-dihydroxytryptamine prevented the increase in VMR to CRD in SERT-KO female and male rats treated it with alosetron and SR-52772, respectively. Alosetron (icv) did not affect the VMR to CRD in WT or KO female rats, but it increased the VMR in male SERT-KO but not WT male rats. These data suggest that 5-HT 3 receptor signaling at the dorsal spinal cord mediates visceral hypersensitivity in female SERT-KO rats. Such differences could facilitate development of sex-specific drug treatments for visceral pain. NEW & NOTEWORTHY We studied a model of female sex-specific visceral hypersensitivity using rats that had a loss of function of the serotonin transporter (SERT) caused by gene truncation. Female SERT-KO rats exhibited visceral hypersensitivity in response to colorectal balloon distention. We found that increased 5-HT signaling at dorsal spine 5-HT 3 receptors was responsible for visceral hypersensitivity in female but not male SERT-KO rats.

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