Gene Expression in Endocrine Tissues
(T515) GENE EXPRESSION OF GLUCOCORTICOID RECEPTOR AND 11 -HSD IN BOVINE FOLLICLE AND CORPUS LUTEUM.
Tetsuka, Masa1, Nishimoto, Hiromi1, Yamamoto, Sawa2, Hamano, Seizo2, 1 Obihiro University of Agriculture & Veterinary Medicine, Obihiro, Japan2 Livestock Improvement Association of Japan Inc, Tokyo, Japan
ABSTRACT- Glucocorticoid (Gluc), a C21 steroid that is produced exclusively in adrenal cortex, acts as a modulator of physiological functions in several organs including the ovary. The magnitude of Gluc action in a target organ is determined by levels of glucocorticoid receptor (GR) and active Gluc (i.e. free cortisol). Recently we demonstrated that two 11bHSDs that mediate conversion between active and inactive Gluc, namely reductive 11-HSD type1 (11HSD1) and oxidative 11-HSD type2 (11HSD2), were expressed in the bovine ovary. In the present study we examined gene expression pattern of GR as well as 11HSD1 and 2 in granulose cells (GC), theca interna (TI) and corpus luteum (CL). Ovaries were obtained from Holstein x Japanese Black F1 cattle at a local slaughterhouse. Follicular fluid (FF) was aspirated from each follicle and GC and TI were harvested. Follicles were classified into five groups based on the diameter, ratio of E2:P4 in FF, stage of CL and the relationship between dominant and subordinate follicles: i.e. preovulatory dominant follicle (POD); E2 active dominant follicle (EAD); E2 inactive dominant follicle (EID); small follicle accompanied with EID (ASF); and small follicle with EAD or POD (SSF). Levels of mRNA encoding GR, 11HSD1 and 2 were quantified by a real-time PCR. GR and 11HSD1 mRNA were detected in both GC and TI while 11HSD2 mRNA was not detected in GC except that in EID. The expression of GR was higher in TI than GC with no appreciable difference was observed among follicular classes. The expression of 11HSD1 was higher in GC than TI with the expression much higher in dominant follicles (POD, EAD, EID) compared with small follicles. All three genes were detected in CL. The expression of GR was comparably low in stage I then increased 5 folds in stage II-IV CL. 11HSD1 mRNA was expressed at similar levels in stage I-III then decreased sharply in stage IV CL. The expression of 11HSD2 was highest in stage I then gradually decreased as CL aged. In conclusion, genes mediating Gluc action and metabolism are expressed in the bovine follicle and CL and they are regulated in stage and tissue specific manners. (Supported by a JSPS grant 16580237)
KEY WORDS: glucocorticoid, receptor, 11-HSD, ovary