Abstract
Background and Purpose. Administration of glucocorticoids results in atrophy and contractile dysfunction in the rat diaphragm. Anabolic steroids may be useful in preventing atrophy and contractile dysfunction. The purpose of this study was to assess the effects of simultaneous administration of testosterone and glucocorticoids on morphological and contractile properties of the rat diaphragm. Subjects. Eighty-eight adult female Sprague-Dawley rats were divided into 1 of 4 groups: a control group that was given sham injections for 13 days (CONT group, n=23), a group that was given prednisolone injections (0.5 mg/100 g) for 10 days (PRED group, n=23), a group that was given testosterone injections (0.5 mg/100 g) for 13 days (TEST group, n=18), and a group that was given a combination of prednisolone and testosterone injections (0.5 mg/100 g) for 10 and 13 days, respectively (COMBO group, n=23). Methods. The animals were weighed daily, and drug doses were adjusted to changes in body mass. Twenty-four hours following the final injection, animals were weighed and sacrificed and the diaphragm was removed and weighed. A small strip of diaphragm was attached to a force transducer to determine normalized maximal isometric tetanic tension (PO). Results. Body weights in the PRED group were decreased by 26% as compared with body weights in the CONT group, and body weights in the COMBO group were decreased by 11% as compared with body weights in the CONT group. Diaphragm weights in the PRED and COMBO groups were decreased by 22% and 12%, respectively, as compared with diaphragm weights in the CONT group. Normalized maximal isometric tetanic tension was decreased by 11% in the PRED group as compared with PO in both the CONT and TEST groups and was decreased by 13% as compared with PO in the COMBO group. There was no difference in PO among the CONT, TEST, and COMBO groups. Discussion and Conclusion. The results support the hypothesis that simultaneous administration of testosterone with glucocorticoids would prevent a decrease in PO. The results indicate that simultaneous administration of testosterone with glucocorticoids prevented the loss in body weight and partially attenuated the loss in diaphragm weight that is commonly observed when glucocorticoids are given alone. These data support the notion that testosterone may be useful in the prevention of glucocorticoid-induced atrophy.
Mechanisms of contractile dysfunction in the senescent rat diaphragm / by David S. Criswell.
