Intestinal anaphylaxis induces fos immunoreactivity in the
myenteric plexus of the rat small intestine.
Miampamba, M., D. T. M. Tan, M. R. Oliver, K. A. Sharkey, and R. B.
Scott.
Gastrointestinal and Neuroscience Research Groups, Faculty of
Medicine, The University of Calgary, Calgary, Alberta, Canada. T2N
4N1
APStracts 3:0193G, 1996.
Fos immunohistochemistry was used to identify myenteric neurons
activated as a consequence of intestinal anaphylaxis in Hooded-Lister
rats sensitized to egg albumin (EA, 10 [mu]g, i.p.). Following
incubation in test solutions, or after in vivo challenge, jejunal
tissues were processed for immunohistochemistry with an anti-Fos
antibody (1:500, TF161). The neuronal identity of the Fos labelled
nuclei was confirmed by double labelling with neuron specific enolase
(1:1000, NSE). In in vitro studies, exposure of control tissue to 50
mM K+ Krebs' EA (2 X 10-5 M) solutions significantly increased Fos
-immunoreactivity in the myenteric plexus, while a basal level of Fos
was seen in control tissue incubated in Krebs' solution, sham
-sensitized tissue exposed to bovine serum albumin (2 X 10-5 M BSA) or
EA, and sensitized tissue exposed to BSA. Pretreatment of sensitized
tissue with doxantrazole (10-4 M) markedly reduced Fos
-immunoreactivity observed after EA exposure. In in vivo studies,
there was negligible Fos-immunoreactivity in the myenteric plexus of
control, sham-sensitized or sensitized rats challenged with saline. A
low level of Fos was seen in neurons of sham-sensitized rats
challenged with BSA or EA, and in sensitized rats challenged with
BSA. Significantly greater levels of Fos were observed in the
myenteric plexus of sensitized animals challenged with EA, even after
pretreatment with capsaicin (125 mg/kg). These results suggest a role
for myenteric neurons in intestinal anaphylaxis. In sensitized rats,
activation of myenteric neurons is dependent upon antigen-induced
mast cell activation, and occurs independently of capsaicin-sensitive
afferent nerves.
Received 30 October 1995; accepted in final form 29 August 1996.
APS Manuscript Number G471-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996