Cloning of equine prostaglandin dehydrogenase and its gonadotropin-dependent regulation in theca and mural granulosa cells of equine preovulatory follicles during the ovulatory process.

This research studies the regulation of a certain enzyme (prostaglandin dehydrogenase or PGDH) that plays a significant role in ovulation in horses. The researchers marked this study as the first to report the particular way the PGDH enzyme is regulated in horses during the ovulation process, emphasizing the unique mechanisms compared to primates.

Study Objectives and Methodology

• The main goal of this study is to understand how the PGDH enzyme is structured in horses, and how it is regulated during the process of ovulation, specifically when prompted by the hormone human chorionic gonadotropin (hCG).
• Using techniques like reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE), the researchers were able to derive the full structure of the equine (horse) PGDH.
• The researchers also utilized a semi-quantitative approach using RT-PCR in combination with a Southern blot, a method to detect specific sequences within a DNA sample, in order to study PGDH regulation in follicles after hCG injection.
• The production and regulation of the PGDH enzyme were observed at different time intervals post-hCG.

Key Findings

• The research indicates that the expression of PGDH in horses was initially low, increased at 12 and 24 hours post-hCG, and then decreased at 36 hours post-hCG. This shift in enzyme expression was marked by two distinct increases, referred to as a biphasic pattern.
• Presentation of PGDH was observed to be different in mural granulosa cells and theca cells within the ovulating follicles.
• Immunohistochemistry and immunoblotting techniques were used to confirm the expression of the PGHD protein in both cell types after the administration of hCG.
• High levels of PGDH mRNA were found in the corpus luteum and other non-ovarian tissues, excluding kidney, muscle, brain, and heart.

Significance of Research

• The research presents the first study to depict the gonadotropin-dependent control of PGDH during ovulation in a non-primate species — in this case, horses.
• The increased expression of PGDH was found to be different in horses compared to primates. While in primates it followed a monophasic pattern and was limited to granulosa cells, in horses it followed a biphasic pattern and was reported in both theca and mural granulosa cells.
• The observed species-specific variations in the regulation of PGDH during ovulation may lead to more targeted and effective treatments in equine reproductive health.