Estrogenic regulation of HSP90 kD synthesis in rat urinary bladder

The role of heat shock protein (HSP90 kD) has been investigated in regard t o its association with steroid receptors. HSP90 kD may play a role in stero id receptor stabilization and activation. Oophorectomized Sprague-Dawley ra ts (n = 25) were placed into five groups and injected subcutaneously with 3 0 mug beta -estradiol 17-benzoate in sesame oil, with one group injected wi th carrier oil (control). After estrogen administration, the rats were kill ed, and their bladders removed for immunostaining, immunoblotting and enzym e-linked immunosorbent assay (ELISA). Immunoblot analysis demonstrated a 90 -kD band in bladder homogenates, even in the absence of estrogen. However, the bands were more intense 12 and 24 h after administering estrogen. ELISA showed significant differences in HSP90 kD synthesis as early as 6 h compa red to controls (P < 0.05). After 48 h the estrogen-treated rats and contro ls were identical. The above results were confirmed by immunostaining for H SP90 kD. HSP90 kD synthesis in the rat urinary bladder is under estrogenic regulation. These findings may be relevant in the etiology and pathobiology of interstitial cystitis and menopausal voiding dysfunctions since the bla dder is enriched with estrogenic receptors and is under estrogenic influenc e.