PARENT SESSION
Hormone Receptors

ANDROGEN RECEPTOR mRNA EXPRESSION IN BOVINE OVARIAN FOLLICLES.

Hampton, James¹, Manikkam, Mohan¹, Lubahn, Dennis¹, Smith, Michael¹, Garverick, H. Allen¹, ¹

ABSTRACT- Previous studies have shown that androgen receptor (AR) is expressed in granulosa cells of healthy, growing ovarian follicles in rats and primates. However, AR expression in the bovine ovary has not been examined. Therefore, using RT–PCR amplification, we cloned and sequenced a 346–base pair segment of the hormone–binding domain of the bovine AR cDNA from total bovine liver mRNA. This segment shared 100, 99, and 96 % sequence homology with bovine, ovine, and human AR, respectively. Using a ribonuclease protection assay, we detected AR expression in total RNA from bovine ovarian cortex. Expression (absence or presence) of AR mRNA was detected by in situ hybridization using cryosections of bovine ovarian cortex collected from a local abattoir. Follicles (n = 32) were classified as follows: type 1 (1 layer of flattened granulosa cells), type 2 (1 to 1.5 layers of cuboidal granulosa cells), type 3 (2 to 3 layers of granulosa cells), type 4 (4 to 6 layers of cuboidal granulosa cells and formation of thecal layer), and type 5 (> 6 layers of cuboidal granulosa cells, defined thecal layer, and antrum formation). Frequency of AR mRNA expression increased (P < 0.001) as follicles entered the growing pool. Expression of AR mRNA was absent in type 1 follicles (n = 8), while present in the granulosa of 41 % of type 2 follicles (n = 12). In type 3, 4, and 5 follicles, AR mRNA expression was present in granulosa of 100 % of follicles examined (n = 4, 4, and 4, respectively) and was significantly greater than type 1 follicles (P = 0.002). These data provide the first evidence of AR mRNA expression in bovine follicles and suggest that AR mRNA increases as follicles develop from the primordial to later stages of development.

KEY WORDS: androgen receptor, follicle, ovary