title: Receptor-mediated suppression of cardiac heat-shock protein 72 expression by testosterone in male rat heart.
abstract: The impact of testosterone on cardiac expression of heat-shock protein 72 (HSP72) remains to be elucidated. Male Sprague Dawley rats 10 wk of age (adult) were castrated. Four weeks later, testosterone (10 mg/kg, ip) was administered as a single dose, followed by the application of hyperthermia (HT) (43 C) at 6 h after testosterone administration. Twenty-four hours later, each heart was isolated. Cardiomyocytes were prepared from 3- to 5-d-old Wistar rats and male Sprague Dawley rats 10 wk of age. Testosterone (0.1-10 microM) was added to the medium, followed by the application of HT (42 C). Twenty-four hours later, cells were collected. We observed the following: 1) Exogenous testosterone suppressed HT-induced HSP72 expression, but castration alone had no influence. 2) HT resulted in better reperfusion-induced cardiac performance in castrated rats comparable with sham-operated rats, which was inhibited by testosterone. The number of apoptotic cells after ischemia/reperfusion was also increased by testosterone. 3) HT-induced HSP72 expression in cultured cardiomyocytes was suppressed by testosterone. 4) HT resulted in less damage to cells, including apoptosis, in response to hypoxia/reoxygenation, which was inhibited by testosterone. 5) Flutamide, a testosterone receptor blocker, cancelled the suppressive effects of testosterone on HSP72 expression. 6) The HT-induced increase in heat-shock factor 1 activity to bind to heat-shock element DNA was suppressed by testosterone, and this was reversed by flutamide. Our results indicate that testosterone potentially has inhibitory effects on cardiac HSP72 expression by modulating transcription, through testosterone receptor-mediated genomic mechanisms.
authors: Department of Internal Medicine, Faculty of Medicine, Oita University, 1-1 Idaigaoka, Hasama, Oita 879-5593, Japan.
authors: Hiroaki
authors: H
authors: Kohno
authors: Naohiko
authors: N
authors: Takahashi
authors: Tetsuji
authors: T
authors: Shinohara
authors: Tatsuhiko
authors: T
authors: Ooie
authors: Kunio
authors: K
authors: Yufu
authors: Mikiko
authors: M
authors: Nakagawa
authors: Hidetoshi
authors: H
authors: Yonemochi
authors: Masahide
authors: M
authors: Hara
authors: Tetsunori
authors: T
authors: Saikawa
authors: Hironobu
authors: H
authors: Yoshimatsu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002369:Castration; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005485:Flutamide / Q000494:pharmacology; D050884:HSP72 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006321:Heart / Q000187:drug effects / Q000503:physiopathology; D006358:Hot Temperature; D020287:In Situ Nick-End Labeling; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000188:drug therapy; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D013739:Testosterone / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors; D014162:Transfection
chemical_list: D050884:HSP72 Heat-Shock Proteins; D034741:RNA, Small Interfering; D013739:Testosterone; D005485:Flutamide; D004247:DNA