Oestrogen and Progesterone Receptor Gene Expression in Canine Oocytes and Cumulus Cells Throughout the Oestrous Cycle

• Published in: Reproduction in domestic animals Vol. 44; no. s2; pp. 239 - 242
• Main Authors: Gonçalves, JSA, Vannucchi, CI, Braga, FC, Paula-Lopes, FF, Milazzotto, MP, Assumpção, MEOA, Visintin, JA
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.07.2009; Blackwell Publishing Ltd
• Subjects: Animal reproduction; Animals; Cellular biology; Cumulus Cells - metabolism; Dogs; Dogs - physiology; Estrous Cycle - physiology; Female; Gene expression; Gene Expression Regulation - physiology; Hormones; Oocytes - metabolism; Receptors, Estrogen - metabolism; Receptors, Progesterone - metabolism; Veterinary medicine
• ISSN: 0936-6768; 1439-0531
• DOI: 10.1111/j.1439-0531.2009.01422.x

The aim of this research was to analyze oestrogen receptor-α (ERα), ERβ and progesterone receptor (PR) gene expression in the canine oocyte and cumulus cells throughout the oestrous cycle. Ovaries from 38 bitches were recovered after ovariohysterectomy and sliced. The phase of the oestrous cycle was determined by vaginal cytology, vaginoscopy and serum hormonal measurements. Oocytes were mechanically denuded by repeated pipetting. For each phase of the cycle, a sample was composed by a pool of 50 oocytes (sample number: prooestrus = 3, oestrus = 8, dioestrus = 5 and anoestrus = 5) or a pool of cumulus cells (prooestrus = 4, oestrus = 7, dioestrus = 4 and anoestrus = 6). Oocyte and cumulus cells' total RNA was isolated and reverse transcription was conducted to perform real-time PCR. Oestrogen receptor-α was expressed throughout the cycle in the oocyte (33.33%, 25.0%, 20.0% and 60.0% for prooestrus, oestrus, dioestrus and anoestrus, respectively) and cumulus cells (50.0%, 47.14%, 25.0% and 66.67% for prooestrus, oestrus, dioestrus and anoestrus, respectively). In the oocyte, the ERβ was also expressed in all phases of the cycle (33.33%, 50.0%, 20.0% and 60.0% for prooestrus, oestrus, dioestrus and anoestrus, respectively), whereas in cumulus cells, ERβ was only expressed during prooestrus (50%) and oestrus (14.29%). Interestingly, while the oocyte PR was not detected in any phase of the cycle, this receptor was expressed during prooestrus (50%), oestrus (42.86%) and anoestrus (16.67%) in cumulus cells. In conclusion, canine oocytes express ERα and ERβ throughout the oestrous cycle, however, there is a lack of PR expression in all these phases. Moreover, in cumulus cells, only ERα was expressed throughout the oestrous cycle.