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Neurogastroenterol Motil. 2010 Aug;22(8):909-18, e236-7. doi: 10.1111/j.1365-2982.2010.01508.x. Epub 2010 May 13.

Inhibitory neuromuscular transmission to ileal longitudinal muscle predominates in neonatal guinea pigs.

Author information

  • 1Department of Chemistry, Michigan State University, East Lansing, MI, USA.

Abstract

BACKGROUND:

Inhibitory neurotransmission to the longitudinal muscle is more prominent in the neonatal than in the adult guinea pig ileum.

METHODS:

Inhibitory neuromuscular transmission was investigated using in vitro ileal longitudinal muscle myenteric plexus (LMMP) preparations made from neonatal (< or =48 h postnatal) and adult ( approximately 4 weeks postnatal) guinea pigs.

KEY RESULTS:

Amperometric measurements of nicotine-induced nitric oxide (NO) release (measured as an oxidation current) from myenteric ganglia revealed larger currents in neonatal (379 +/- 24 pA) vs adult (119 +/- 39 pA, P < 0.05) tissues. Nicotine-induced oxidation currents were blocked by the nitric oxide synthase (NOS) inhibitor, nitro-l-arginine (NLA, 100 micromol L(-1)). Nicotine-induced, NLA-sensitive oxidation currents could be detected in the tertiary plexus of neonatal but not adult tissues. Immunohistochemistry demonstrated stronger NOS immunoreactivity in neonatal compared with adult myenteric ganglia. Western blot studies revealed higher levels of NOS in neonatal compared with adult LMMP. Cell counts revealed that the total number of myenteric neurons in the small intestine was greater in adults than in neonatal guinea pigs, however, the ratio of NOS : Calbindin neurons was significantly higher in neonatal compared with adult tissues.

CONCLUSIONS & INFERENCES:

Nitric oxide signaling to the longitudinal muscle is stronger in neonatal compared with adult guinea pig ileum. Nitric oxide synthase-containing neurons are diluted postnatally by cholinergic and other, as yet unidentified neuronal subtypes.

PMID:
20482699
[PubMed - indexed for MEDLINE]
PMCID:
PMC2911488
Free PMC Article

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