Expression of corticotropin releasing factor (CRF) in the enteric nervous system of the jejunum of sheep

Corticotropin releasing factor (CRF), a 41-amino acid neuropeptide widely distributed in the mammalian central nervous system, has been shown to infl uence several gastrointestinal functions. Recent studies show that CRF released locally from enteric nerves may also underlie alterations in gut function. In this study, immunohistochemisty was applied to demonstrate the presence of CRF in the jejunum of sheep. Using double immunohistochemical staining the co-localization of CRF with vasoactive intestinal peptide (VIP), galanin, tyrosine hydroxylase (TH), neuropeptide Y (NPY) and substance P (SP) was evaluated. Th e presence of CRF was detected in myenteric neurons (3.6 ± 0.9%) as well as in submucous neurons (10.5 ± 1.2%). In the ovine jejunum diff erent numbers of CRF-expressing nerve fi bres were detected in myenteric ganglia, submucous ganglia, circular smooth muscle layer, lamina muscularis mucosae and between mucosal glands. None of the CRF-positive enteric neurons and CRF-positive nerve fi bres exhibited the presence of TH. CRF-immunoreactive (IR) myenteric neurons widely co-expressed VIP and/or NPY. A minor population of CRF-IR myenteric neurons additionally co-stored SP. Galanin was not present in CRF-IR myenteric neurons. Th e presence of VIP was observed in the vast majority of CRF-positive submucous neurons. Moderate numbers of CRF-IR sumbucous neurons co-expressing galanin or NPY were also found. Th e presence of SP in CRF-positive submucous neurons was noted only incidentally. In the circular smooth muscle layer CRF-IR/VIP-IR, CRF-IR/NPY-IR as well as CRF-IR/SP-IR nerve fi bres were present. In the mucosal layer of the ovine jejunum CRF-IR nerve fi bres co-stored additionally VIP, galanin, NPY or SP. Th is present study provides for the fi rst time evidence that CRF present in diff erent subclasses of enteric neurons may infl uence certain activities of the ovine jejunum. Co-localization studies indicate that VIP, galanin, SP and NPY functionally co-operate with CRF in the jejunum of the sheep.