title: An animal model to assess aversion to intra-oral capsaicin: increased threshold in mice lacking substance p.
abstract: Despite the widespread consumption of products containing chemicals that irritate the oral mucosa, little is known about the underlying neural mechanisms nor is there a corresponding animal model of oral irritation. We have developed a rodent model to assess aversion to capsaicin in drinking water, using a paired preference paradigm. This method was used to test the hypothesis that the neuromodulator substance P (SP) plays a role in the detection of intra-oral capsaicin. 'Knockout' (KO) mice completely lacking SP and neurokinin A due to a disruption of the preprotachykinin A gene and a matched population of wild-type (WT) mice had free access to two drinking bottles, one containing water and the other capsaicin at various concentrations. Both KO and WT mice showed a concentration-dependent aversion to capsaicin. KO mice consumed significantly more capsaicin than WT at a single near threshold (1.65 microM) concentration, indicating that SP plays a limited role in the detection and rejection of oral irritants.
authors: Section of Neurobiology, Physiology and Behavior, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, USA.
authors: C T
authors: CT
authors: Simons
authors: J M
authors: JM
authors: Dessirier
authors: S L
authors: SL
authors: Jinks
authors: E
authors: E
authors: Carstens
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002211:Capsaicin / Q000008:administration & dosage* / Q000737:chemistry; D004361:Drug Tolerance / Q000502:physiology; D007509:Irritants / Q000008:administration & dosage / Q000737:chemistry; D051379:Mice; D020297:Mice, Congenic; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout / Q000235:genetics* / Q000502:physiology; D023421:Models, Animal; D015288:Neurokinin A / Q000096:biosynthesis / Q000235:genetics*; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics; D013045:Species Specificity; D013373:Substance P / Q000096:biosynthesis / Q000235:genetics*; D015320:Tachykinins / Q000096:biosynthesis / Q000235:genetics; D013652:Taste Threshold / Q000502:physiology*
chemical_list: D007509:Irritants; D011498:Protein Precursors; D015320:Tachykinins; C044206:preprotachykinin; D013373:Substance P; D015288:Neurokinin A; D002211:Capsaicin