Exercise-induced stimulation of murine macrophage phagocytosis may
be mediated by thyroxine.
Forner, M. A., C. Barriga, and E. Ortega.
Department of Physiology (Animal Physiology), Faculty of Science,
University of Extremadura, 06071 Badajoz, Spain
APStracts 2:0484A, 1995.
The present study was designed to test the hypothesis that changes in
plasma concentrations of hormones may be responsible for the
exercise-induced macrophage phagocytic stimulation. The effect of 30
minutes incubation of macrophages with plasma from mice previously
exposed to swimming until exhaustion (with or without previous
training) was studied, and the results showed a similar stimulation
of the phagocytic capacity (attachment and ingestion) of these cells
to that found in previous studies after exercise. Also, changes in
plasma concentration of both thyroxine (T4) and triiodothyronine (T3)
after exercise were measured, and their effect on phagocytic capacity
after in vitro incubation with peritoneal macrophages investigated.
Results indicated that, after exercise, plasma concentrations of T3
and T4 increased. Incubation of peritoneal macrophages for 30 minutes
with a concentration of T3 similar to that observed in the plasma
immediately after exercise (1.5 ng x ml-1) induced no modifications
in the phagocytic capacity. However, a physiological concentration of
T4 after exercise (75 ng x ml-1) stimulated the phagocytic capacity
of peritoneal macrophages. In addition, a 10000-fold greater
concentration of these thyroid hormones did not modify the macrophage
function. It is concluded that physiological concentration of
thyroxine may be a mediator of the stimulation of the phagocytic
function of macrophages induced by exercise.
Received 22 May 1995; accepted in final form 27 October 1995.
APS Manuscript Number A539-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95