Distribution and colocalization of NADPH-diaphorase activity, nitric oxide synthase immunoreactivity, and VIP immunoreactivity in the newly hatched chicken gut.
BACKGROUND
The distribution and colocalization of nitric oxide synthase and NADPH-diaphorase have been investigated quite extensively in the mammalian gut; however, no such study has been undertaken in the avian gut. In the present report, we have therefore studied the distribution and coexpression of nitric oxide synthase (NOS), NADPH-diaphorase, and vasoactive intestinal polypeptide (VIP) in enteric neurons of the newly hatched chicken gut.


METHODS
Immunohistochemical methods were used to detect NOS immunoreactivity (NOS-IR) and VIP immunoreactivity (VIP-IR). NADPH-diaphorase activity was detected using a histochemical technique.


RESULTS
Neurons expressing NADPH-diaphorase activity, NOS-IR, and VIP-IR were detected in both the myenteric and submucous plexus of all regions of the gastrointestinal tract examined. All NADPH-diaphorase positive neurons were also NOS-IR and all NOS-IR neurons were NADPH-diaphorase positive, in both plexuses, indicating that NADPH-diaphorase can be used as a marker for NOS containing neurons in the chicken gut. The majority of VIP-IR neurons also expressed NADPH-diaphorase activity. Only few neurons that expressed NADPH-diaphorase activity did not express VIP-IR. The proportion of VIP immunopositive neurons that were NADPH-diaphorase negative increased anally and these neurons were more prominent in the submucous than the myenteric plexus ganglia. NADPH-diaphorase positive, NOS-IR, and VIP-IR nerve fibres were detected in the circular muscle, but very few, if any, were present in the longitudinal muscle. VIP-IR, but not NOS-IR or NADPH-diaphorase activity, was detected in mucosal fibres, in contrast to the situation in the mammalian gut.


CONCLUSIONS
These results indicate that in birds, as in mammals, nitric oxide may play a role in the neural control of the gut musculature, but that it is unlikely to be involved in the nervous control of mucosal activity.
Department of Anatomy and Developmental Biology, University College London, United Kingdom.
C
C
Balaskas
M J
MJ
Saffrey
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G
Burnstock
D000818:Animals; D002645:Chickens / Q000378:metabolism*; D004064:Digestive System / Q000294:innervation*; D017615:Enteric Nervous System / Q000737:chemistry* / Q000201:enzymology; D007150:Immunohistochemistry; D009130:Muscle, Smooth / Q000294:innervation; D009197:Myenteric Plexus / Q000737:chemistry / Q000201:enzymology; D009252:NADPH Dehydrogenase / Q000032:analysis*; D009474:Neurons / Q000737:chemistry* / Q000201:enzymology; D019001:Nitric Oxide Synthase / Q000032:analysis*; D011531:Proventriculus / Q000294:innervation; D014660:Vasoactive Intestinal Peptide / Q000032:analysis*
D014660:Vasoactive Intestinal Peptide; D019001:Nitric Oxide Synthase; D009252:NADPH Dehydrogenase