Localization of the beta(beta)3-adrenoceptor in the human gastrointestinal tract: an immunohistochemical study.
BACKGROUND
Activation of human and non-human colonic beta(beta)3-adrenoceptors causes smooth muscle relaxation. beta3-Adrenoceptor agonists protect against experimental indomethacin-induced jejunal ulceration. The mechanism of protection may involve spasmolytic/vasodilatory agonist activity. The precise localization of beta3-adrenoceptors in the human gut is not known.


OBJECTIVE
To localize the beta3-adrenoceptor within the human gastrointestinal tract using the immunohistochemical technique.


METHODS
Human beta3-adrenoceptors were immuno-localized in paraffin sections of human oesophagus (OS), stomach (ST), duodenum (DU), ileum (IL), sigmoid colon (SC), rectum (R) and gall-bladder (GB) using the rabbit polyclonal antibody anti-P12. Staining was graded , ++, + and 0. Immunostaining of SC was also done with pre-incubation of anti-P12 with P12 peptide. Western blotting of anti-P12 on human and murine IL and SC isolated membrane proteins was performed.


RESULTS
All epithelia, vascular endothelial cells and ganglia scored 0. Smooth muscle of the vasculature, muscularis propria, muscularis mucosae and mucosa was graded, respectively, as follows; OS ( , , ,-), ST (++, , ++, ++), DU (++, , , +), IL (++, ++, ++, +), SC ( , ++, ++, ++), R (++, ++, +, +), GB ( , , -, 0). Pre-incubation of anti-P12 with P12 peptide almost abolished SC smooth muscle positivity. Western blot analysis using anti-P12 on human, but not murine, IL and SC membrane proteins revealed a single 5 5 kDa band, a size consistent with the predicted size of a partially glycosylated form of the human beta3-adrenoceptor.


CONCLUSIONS
This immunohistochemical study has localized the beta3-adrenoceptor to vascular and nonvascular smooth muscle in the human gastrointestinal tract. These findings support a role for the beta3-adrenoceptor in the control of blood flow and motility in the human gastrointestinal tract.
Anthony
A
A
Inflammatory Bowel Disease Study Group, University Department of Histopathology, Royal Free Hospital School of Medicine, London, UK.
Schepelmann
S
S
Guillaume
J L
JL
Strosberg
A D
AD
Dhillon
A P
AP
Pounder
R E
RE
Wakefield
A J
AJ
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000737:chemistry; D015153:Blotting, Western; D003106:Colon / Q000033:anatomy & histology / Q000378:metabolism; D004064:Digestive System / Q000033:anatomy & histology / Q000378:metabolism*; D005704:Gallbladder / Q000033:anatomy & histology / Q000378:metabolism; D006801:Humans; D007082:Ileum / Q000033:anatomy & histology / Q000378:metabolism; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000033:anatomy & histology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D022702:Receptors, Adrenergic, beta-3
D000906:Antibodies; D011943:Receptors, Adrenergic, beta; D022702:Receptors, Adrenergic, beta-3