Faculty Collaboration Database

Fractionated irradiation alters enteric neuroendocrine products. Dig Dis Sci 1995 Aug;40(8):1691-702

Date

08/01/1995

Pubmed ID

7544259

DOI

10.1007/BF02212690

Scopus ID

2-s2.0-0029151167 (requires institutional sign-in at Scopus site)   31 Citations

Abstract

Radiation profoundly alters the contractile activity of the small intestine and colon. We hypothesized that some motor changes of the gut might be secondary to impaired neural input to smooth muscle or abnormal release of gut endocrine peptides. The density of products within peptidergic and cholinergic nerves and gut endocrine cells was estimated in six normal controls and six dogs who had received 1500 cGy in six equal fractions of 250 cGy. Choline acetyltransferase, acetylcholinesterase, vasoactive intestinal peptide (VIP), substance P, peptide YY (PYY), and motilin were measured in tissue specimens divided into mucosal-submucosal (MS) and muscularis externa (ME) layers. Tissue samples were obtained from the duodenum, jejunum, ileum, and proximal and distal colon. In addition, serum levels of motilin and PYY were determined before and during the administration of 1500 cGy in four separate dogs instrumented to record upper gut contractile activity. Intrinsic cholinergic activity as estimated by choline acetyltransferase activity was unchanged, while acetylcholinesterase activity increased in the MS layers of distal small bowel and colon. VIP was increased in the MS layers of jejunum and proximal colon as well as in the ME layers the jejunum and ileum. By contrast, substance P increased in the jejunal and proximal colonic MS layers and in the ME layers of the jejunum and ileum. Duodenal and jejunal motilin levels markedly decreased after radiation exposure, while serum motilin levels continued to cycle at a decreased peak level with migrating motor complexes. Colonic PYY remained unchanged but serum PYY levels decreased after irradiation. Increased neuronal synthesis and inhibition of neurotransmitter release are potential explanations for elevated tissue concentrations of VIP, substance P, and acetylcholinesterase. There appeared to be differences in the sensitivity of gut endocrine cells to irradiation. Changes in gut regulatory peptides and cholinergic enzyme activity occur with fractionated doses of abdominal irradiation, while the same schedule of irradiation produces striking changes in the canine small intestinal and colonic motor activity. It is therefore likely that alterations of contractile events may be produced by changes in gut neuroendocrine products.

Author List

Otterson MF, Koch TR, Zhang Z, Leming SC, Moulder JE

Author

Mary F. Otterson MD Professor in the Surgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Acetylcholinesterase
Animals
Choline O-Acetyltransferase
Cholinergic Fibers
Colon
Dogs
Gastrointestinal Hormones
Histocytochemistry
Intestinal Mucosa
Intestine, Small
Intestines
Motilin
Neuropeptides
Peptide YY
Peptides
Radioimmunoassay
Spectrophotometry
Substance P
Vasoactive Intestinal Peptide