ISSN:
1432-119X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary In order to test the influence of thyroid hormones on small intestine function, adult female Wistar rats were injected daily with either 100 μg/100 g body weight tetraiodothyronine or placebo. After 12 days, jejunal segments were removed and processed for morphometric analysis of mucosal architecture and quantitative histochemical determinations of the apparent Km- and Vmax-values of lactase/β-glucosidase and neutral α-glucosidase at constant basal and apical measuring positions along the villi. The villus-crypt-architecture was the same in both experimental groups. At the cellular levels, however, application of tetraiodothyronine resulted in a marked decrease in the apparent Vmax of lactase/β-glucosidase at both villus positions, maintaining the normal activity gradient along the villi. In comparison with the controls, a less pronounced but significant reduction in activity was also demonstrated for the neutral α-glucosidase. Substrate affinity, however, was only increased for this enzyme, the apparent Km of lactase/β-glucosidase not being affected by the hormone. The results indicate a direct effect of tetraiodothyronine on jejunal brush border disaccharidases of the rat. The alternative mechanism, an effect mediated by an altered enterocyte turnover is unlikely to occur.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00493141
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