Inhibin localization in equine granulosa-theca cell tumours and inhibin forms in tumour fluid.

The study looks at the production of inhibin, a hormone, in granulosa-theca cell tumors in horses and compares the types and levels of inhibin in both healthy and diseased horses.

Objective of the Study

• The research aimed to investigate the production of inhibin, specifically the alpha- and betaA-subunits, in granulosa-theca cell tumours (GTCT) in horses.
• It intended to differentiate the alpha- and betaA-subunits of inhibin in tumour fluid from GTCT and normal equine follicular fluid (eFF).
• The study also sought to determine if dimeric inhibin is present in the blood plasma and tumour fluid of horses with GTCT.

Methodology

• Plasma, tumour fluid and tumour tissue were collected from six horses afflicted with GTCT.
• For comparison purposes, plasma and eFF were also gathered from four healthy horses undergoing normal reproductive cycles.
• An immunohistochemical examination was performed on the GTCT tumour sections to identify inhibin alpha- and betaA-subunit production in the tumour cells.

Results & Findings

• The examination revealed strong production of both the inhibin alpha- and betaA-subunits in the granulosa cells and polyhedral-shaped cells within the thecal-stromal layer of the tumor.
• Interestingly, the presence of these polyhedral-shaped cells was found to be related to the concentration of testosterone in the tumour fluid.
• Alpha-subunit forms of lower molecular weight were less abundant in the tumor fluid than in the eFF.
• In contrast, the amounts of betaA-subunit forms were similar in the tumor fluid and eFF.
• Noticeably, concentrations of betaA were found to be increased in the blood plasma of horses with GTCT, compared to the control group (normal horses).
• In conclusion, the findings suggest the alpha-subunit forms are less evident in the GTCT fluid when compared with eFF and that levels of betaA are higher in the plasma of GTCT-afflicted horses compared with control plasma.