Expression of sex hormone-binding globulin (SHBG) in human granulosa-lutein cells.

Sex hormone-binding globulin (SHBG) was classically thought to be a plasma steroid-carrying protein of hepatic origin, but recently, locally produced, membrane-bound SHBG has been shown to influence cell functions in several steroid-responsive tissues. In the ovary, SHBG is known to be present in the follicular fluid, but information about a possible intracellular presence of SHBG in this organ is still very scarce. In this study the presence of SHBG was assessed by immunohistochemistry in human granulosa-lutein cells (GLC) collected by follicle puncture for in vitro fertilization. SHBG was detected in the cytoplasm of GLC before and after in vitro culture for up to 96 h. The presence of full-length SHBG messenger RNA was demonstrated in GLC by reverse transcription-polymerase chain reaction (RT-PCR) in both cultured and uncultured cells. These results demonstrate a local synthesis of SHBG in GLC and raise the question of the physiological significance of these findings in follicular physiology.