Partial purification and characterization of rhinoceros gonadotropins, growth hormone, and prolactin: comparison with the horse and sheep.

This research study focuses on the isolation and partial purification of certain hormones from the pituitary gland of the rhinoceros, also determining their responses to different assays. The hormones studied included luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), and prolactin (PRL). Findings show a low FSH activity in LH and marked differences between the pituitary FSH fraction in black and white rhinoceros.

Methods Used in the Study

• The pituitary glands from a Black Rhinoceros and a White Rhinoceros were homogenized and then extracted at a pH of 9.5. Following this, the extracts went through a number of purification procedures, including salt fractionation, pH fractionation, and ion-exchange chromatography. This resulted in partially purified fractions of LH, FSH, GH, and PRL.
• The presence and characteristics of LH were confirmed through different tests including a rat Leydig cell assay and radioimmunoassay (RIA) using a monoclonal antibody against bovine LH. Both tests showed LH’s presence and enabled comparison with equine LH.
• The FSH activity in the LH fraction was studied using an FSH RIA and a calf testis radioreceptor assay (RRA). Results showed very low FSH activity.
• The presence of GH and PRL was confirmed using SDS-PAGE and Western blotting. The results showed one immunoreactive GH band and multiple immunoreactive PRL bands. Additional testing with Concanavalin A-Sepharose showed that some of the PRL bands are glycosylated.

Significant Findings

• The research confirmed the presence of the four hormones in the rhinoceros pituitary gland and was able to partially purify them for further assessment and comparison.
• The LH fraction showed low FSH activity, indicating that the rhinoceros LH does not possess the high intrinsic FSH activity commonly found in equine LH.
• There were marked distinctions in FSH fractions between the Black and White Rhinoceros, with no detectable FSH activity in the White Rhino’s FSH fraction and apparent activity in the Black Rhino’s.
• The detected presence of GH and PRL contributes to the broader knowledge of rhinoceros endocrinology, with the detection of multiple PRL bands, and some being glycosylated, indicating complexity in the function of this hormone in rhinoceros.

Implications of the Study

• This research contributes to the field of endocrinology by providing valuable information about hormone production in rhinoceros, a species about which little reproductive endocrinology is known.
• The insights gained from the study could be beneficial in efforts to conserve and breed endangered rhinoceros species in the future, providing more understanding about their reproductive processes.
• This study could also offer better comparability between different species, facilitating broader understanding between equine and rhinoceros endocrinology, and potentially providing useful insights for comparative endocrinology.