EXPRESSION OF MESSENGER-RNA FOR VASOACTIVE-INTESTINAL-PEPTIDE IN RAT SMALL-INTESTINE

Transplantation of small intestine is a neural model that permits stud ies of expression of the neuropeptide, vasoactive intestinal peptide; following extrinsic denervation, transection of intrinsic neural pathw ays, and an ischemic interval. Tissue levels of vasoactive intestinal peptide were examined at 3 months in ileum from a sham operation, in i leum after resection of proximal small intestine, in ileum after resec tion of proximal small intestine and extrinsic denervation, in ileum a fter resection of proximal small intestine and 30 min of ischemia, and in ileum obtained 3 months after ileal isografting in Lewis-to-Lewis combinations. Vasoactive intestinal peptide levels were increased in t ransplanted rat ileum, resection controls, denervation controls, and i schemic controls compared to sham-operated ileum (pANOVA < 0.01). The increased levels of this peptide were highest in denervation controls and lowest in ischemic controls. Northern blot analysis using rat vaso active intestinal peptide cDNA identified a single 1.7-kb transcript i n normal and transplanted rat ileum. The density of vasoactive intesti nal peptide transcripts was increased in transplanted ileum (8450 +/- 540) compared to normal ileum (5790 +/- 620) (P < 0.01), and the ratio of this transcript to glyceraldehyde-3-phosphate dehydrogenase densit y units was also increased in transplanted ileum (0.81 +/- 0.08) compa red to normal ileum (0.40 +/- 0.07; P < 0.01). Enhanced transcriptiona l regulation was the likely mechanism for increased tissue vasoactive intestinal peptide. The increased tissue levels appeared to be a respo nse to extrinsic denervation and transection of intrinsic neural pathw ays, while an ischemic interval appeared to decrease tissue levels of the peptide.