TY - JOUR
T1 - Short- and long-term effects of testosterone on diaphragm in castrated and normal male rats
AU - Prezant, David J.
AU - Karwa, Manoj L.
AU - Kim, Helen H.
AU - Maggiore, Diane
AU - Chung, Virginia
AU - Valentine, David E.
PY - 1997/1
Y1 - 1997/1
N2 - The effects of short- and long-term testosterone absence or treatment on the diaphragm were studied in castrated and sexually normal male rats. Compared with control rats (untreated normal males), testosterone absence or treatment did not significantly affect costal weight. In untreated castrated males, there were significant decreases in specific forces, type II fiber cross-sectional area, and myosin heavy chain (MHC) isoform 2B after 2.5 wk. In castrated males that received testosterone, there were significant increases in specific forces, type II total fiber proportional area, and relative expression of all adult diaphragm fast MHC isoforms (MHC-2(all)) after 2.5 wk. In normal males that received testosterone, the only significant finding was an increase in MHC-2B after 2.5 wk. Across all groups, there was close correlation between increases in maximum tetanic forces and MHC-2(all). Changes in diaphragm function and composition were closely related to changes in serum testosterone levels at 2.5 wk. The lack of significant change in diaphragm function at 10 wk occurred despite changes in serum testosterone levels and diaphragm composition similar to those at 2.5 wk. These findings support our hypothesis that the effects of testosterone are dependent on basal circulating androgen levels and study duration.
AB - The effects of short- and long-term testosterone absence or treatment on the diaphragm were studied in castrated and sexually normal male rats. Compared with control rats (untreated normal males), testosterone absence or treatment did not significantly affect costal weight. In untreated castrated males, there were significant decreases in specific forces, type II fiber cross-sectional area, and myosin heavy chain (MHC) isoform 2B after 2.5 wk. In castrated males that received testosterone, there were significant increases in specific forces, type II total fiber proportional area, and relative expression of all adult diaphragm fast MHC isoforms (MHC-2(all)) after 2.5 wk. In normal males that received testosterone, the only significant finding was an increase in MHC-2B after 2.5 wk. Across all groups, there was close correlation between increases in maximum tetanic forces and MHC-2(all). Changes in diaphragm function and composition were closely related to changes in serum testosterone levels at 2.5 wk. The lack of significant change in diaphragm function at 10 wk occurred despite changes in serum testosterone levels and diaphragm composition similar to those at 2.5 wk. These findings support our hypothesis that the effects of testosterone are dependent on basal circulating androgen levels and study duration.
KW - anabolic steroids and sexual status
KW - myosin heavy chain isoforms
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U2 - 10.1152/jappl.1997.82.1.134
DO - 10.1152/jappl.1997.82.1.134
M3 - Article
C2 - 9029208
AN - SCOPUS:0031033943
SN - 8750-7587
VL - 82
SP - 134
EP - 143
JO - Journal of applied physiology
JF - Journal of applied physiology
IS - 1
ER -