Angiotensin-(1-7) Influences Tryptophan Absorption in the Rat and Mouse Intestine
Journal Title: Journal of Advances in Medicine and Medical Research - Year 2017, Vol 19, Issue 4
Abstract
Aim: Components of the renin-angiotensin system are involved in absorption and regulate both fluid and electrolyte transport in the intestinal epithelium. The angiotensin-converting enzyme 2 (ACE2) is a major Angiotensin-(1-7)-forming enzyme, and a key regulator of the homeostasis of dietary tryptophan (Trp). The aim of the present study was to investigate the physiological role of the Ang-(1-7)/Mas pathway in the intestinal tryptophan absorption. Place and Duration of Study: Departamento de Fisiologia e Biofísica. Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil. July 2014-August-2015. Methodology: Two models of Mas receptor inhibition were used: treatments, in rats, with the specific Mas receptor inhibitor, the A-779, and Mas receptor knockout (KO) mice; Ang-(1-7) or Ang-(1-7) + A-779 were injected prior Trp infusion. Male Wistar rats (n = 5 in each goup), wild-type (WT) FVB/N mice and Mas (KO) FVB/N mice (n = 4-8 in each group) were anesthetized, and submitted to midline laparotomy to expose, and isolate jejunal loop. Tyrode’s solution (pH 8) containing tryptophan (0. 25 mg%) was infused (0.5 mL and 0.15 min-1 for rats and mice, respectively) into the jejunal loop and samples were taken at 10-min intervals during the 40-min experiment. Results: Tryptophan absorption was determined by the difference between influx and efflux. Ang-(1-7) increased tryptophan absorption in comparison to the control group (0.13 ± 0.03 vs. 0.23 ± 0.0 mg%, P = .01). ACE2 activity in the effluent of jejunal perfusion, and the expression of ACE2 in the tissue of the small intestine were higher in the group that received Ang-(1-7) compared to the control (13.6 ± 1.5 vs. 50.5 ± 4.1 and 0.14 ± 0.0 vs. 0.38 ± 0.05, (P = .001, and P =.003, respectively). Moreover, the effect of Ang-(1-7) on tryptophan absorption was blunted in Mas KO mice, in comparison to WT (9.8 ± 2.6 vs.1.7 ± 3.0). Conclusions: The results of the present study indicate that Ang-(1-7) increases jejunal tryptophan absorption in rats and these changes are associated with increases in ACE2 activity and expression. In Mas KO mice, these actions were blunted. The findings suggest a new mechanism that is dependent on Ang-(1-7)/Mas by which ACE2 modulates tryptophan intestinal absorption.
Authors and Affiliations
Elizabeth L. Borges, Patrícia B. Lima, Antônio A. B. Peluso, Walkyria O. Sampaio, Jamil S. de Oliveira, Marilene L. de Oliveira, Gisele M. Etelvino, Rafael T. Ruoccolo, Anderson J. Ferreira, Robson A. S. Santos
Keywords
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- EP ID EP311440
- DOI 10.9734/BJMMR/2017/30329
- Views 83
- Downloads 0
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