Pattern of distribution and co-localization of NOS and ATP in the myenteric plexus of human fetal stomach and intestine

The pattern of distribution and co-localization of nitric oxide synthase (N OS) and quinacrine fluorescence (indicative of vesicular adenosine 5'-triph osphate, ATP), and co-localization of NADPH-diaphorase (NADPH-d) activity a nd NOS-immunoreactivity in the myenteric plexus of pre-term human fetal (6- 17 weeks of gestation) stomach and small intestine was examined using immun ohistochemical and histochemical techniques. In all stages of gestation inv estigated, NOS-immunoreactive and NADPH-d-reactive myenteric neurons and ne rve fibres were seen in the fetal intestine and stomach. However, in fetuse s of 6-10 weeks of gestation, only 15% of the NADPH-d-positive myenteric ne urons were NOS-immunoreactive, whereas a 100% co-localization was found in samples of 12-17 weeks of gestation. Quinacrine fluorescent myenteric neuro ns and nerve fibres were found only in the fetal intestine of 12-17 weeks o f gestation, of which 25% of the NADPH-d-positive-myenteric neurons in thes e samples were quinacrine fluorescent. These findings demonstrate the prese nce and colocalization of markers for nitric oxide (NO)- and ATP-utilizing myenteric neurons and nerve fibres in the early stages of gestation, sugges ting possible co-transmitter and/or trophic roles of ATP and NO in the proc ess of development and maturity of human myenteric neurons. In addition, th e fact that only a small percentage of NADPH-d-reactive myenteric neurons e xpress NOS immunoreactivity at 6-10 weeks of gestation confirms that NADPH- d-reactivity does not always represent NOS activity. NeuroReport 11:5-8 (C) 2000 Lippincott Williams & Wilkins.