Zebra chorionic gonadotropin: partial purification and characterization.

The research paper focuses on the isolation and characterization of zebra chorionic gonadotropin (zCG), a hormone found in zebra during pregnancy. The results suggested that zCG behaves like luteinizing hormone (LH) and is immunologically comparable to equine CG but does not compete for follicle stimulating hormone (FSH) receptors unlike equine CG and LH, making it more similar to donkey CG and LH and zebra LH.

Purification and concentration of zCG

• In this study, sera from six samples of pregnant zebras were analyzed and found to have chorionic gonadotropin levels comparable to that of the mare. Notably, these levels were usually higher in the first trimester than in the second trimester.
• The team used methods previously used for the purification of horse and donkey chorionic gonadotropin to fractionate a pool of sera, yielding a concentration of zebra chorionic gonadotropin.
• Analysis through High Performance Liquid Chromatography suggested that the zCG content was about 7%, and the molecular size of zCG was found to be smaller than equine CG, greater than ovine LH, and similar to equine LH.

Testing and comparisons of zCG

• zCG was tested using multiple assays, namely radioimmunoassay for LH and eCG, radioreceptor assays for LH and FSH, and the rat testis Leydig cell assay for LH.
• The investigations examined zCG in comparison with horse and donkey chorionic gonadotropin, as well as horse and zebra LH.
• The preliminary results showed that zCG is bioactive and acts as an LH. It was also found to be immunologically similar to eCG, eLH, donkey CG, and zLH, i.e., it can evoke similar immune responses as these hormones.
• Importantly, unlike eCG and eLH, which have high levels of intrinsic FSH activity, zCG was found to compete for LH receptors, but not FSH receptors. This distinguishes it from horse and donkey CG and makes it more similar to donkey and zebra LH.

Implications of the findings

• All these findings suggest that zCG works more like the luteinizing hormone (LH) and is less similar to the follicle-stimulating hormone (FSH).
• This research contributes to the broader understanding of hormone action, providing important insights into the role of CG during pregnancy in different species.