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Effects of the peripherally acting NK 3 receptor antagonist, SB‐235375, on intestinal and somatic nociceptive responses and on intestinal motility in anaesthetized rats
Author(s) -
Shafton A. D.,
Bogeski G.,
Kitchener P. D.,
Lewis V. A.,
Sanger G. J.,
Furness J. B.
Publication year - 2004
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1111/j.1365-2982.2004.00501.x
Subject(s) - nociception , distension , motility , medicine , barostat , endocrinology , visceral pain , spinal cord , anesthesia , receptor , biology , genetics , psychiatry
We investigated the effects of the selective NK 3 tachykinin receptor antagonist, SB‐235375, on noxious signalling from gut and skin and on intestinal motility in anaesthetized rats. We also measured penetrance into brain and spinal cord. Nociceptive responses in reaction to colorectal distension and skin pinch were assessed by recording the electromyogram (EMG) from the external oblique muscle (a visceromotor response). Motility was measured by recording intraluminal pressure waves during changes in baseline pressure in the jejunum. Colorectal compliance was assessed by measuring luminal pressure change during isovolumic distension. SB‐235375 (20 mg kg −1 , by i.v. bolus) reduced the EMG response to colorectal distension by over 90%. The reduction was slow at onset, peaked at about 60 min, and lasted for over 2 h. Responses to noxious skin pinch were unchanged. Amplitudes of propulsive waves in the jejunum were slightly reduced, but their frequency of occurrence was unchanged. SB‐235375 decreased colorectal compliance by 5–10%. There was undetectable penetration of i.v. SB‐235375 into brain or spinal cord. We conclude that SB‐235375 acts peripherally to substantially reduce nociceptive signalling from colorectum without affecting noxious signalling from skin and with little effect on intestinal motility.