AJP - Gastrointestinal and Liver Physiology, Vol 267, Issue 2 180-G186, Copyright © 1994 by American Physiological Society
Effect of aging on neurotensin-stimulated growth of rat small intestine
B. M. Evers, M. Izukura, S. Rajaraman, D. Parekh, K. Thakore, K. Yoshinaga, T. Uchida, C. M. Townsend Jr and J. C. Thompson
Department of Surgery, University of Texas Medical Branch, Galveston 77555.
The proliferative activity of gut mucosa is altered with aging; the
potential for the aged gut to respond to trophic stimuli is not known. The
purpose of this study was to determine whether there are age-related
differences in the effects of the trophic gut peptide neurotensin (NT) on
the structure and function of small bowel mucosa. NT (300 micrograms/kg) or
saline (control) was injected subcutaneously at 8-h intervals for 5 days in
rats of two age groups, young (2 mo) and aged (24 mo). On day 6, rats were
killed, and the gut mucosa (proximal and distal small bowel) was scraped,
weighed, and analyzed for DNA, RNA, and protein content and for
disaccharidase (sucrase and maltase) activity. In a second experiment, the
groups of rats and the protocol for NT administration were identical;
however, when the rats were killed, the distal gut was removed for
histological evaluation of crypt and villus length (mm) and density (no./cm
gut segment) and bromodeoxyuridine immunohistochemistry. NT produced
significant increases in mucosal growth (wt, DNA, RNA, and protein) in both
age groups when compared with age-matched controls; the increase of growth
measurements was the greatest in the small bowel mucosa of the aged rats.
In addition, NT increased crypt density in both groups; only the aged group
treated with NT demonstrated increases in crypt depth and villus height.
Specific activities of sucrase and maltase did not change with NT treatment
in either of the age groups. We conclude that the proliferative potential
of small bowel mucosa is maintained with aging in response to
administration of NT.(ABSTRACT TRUNCATED AT 250 WORDS)
