Chemical, biological and immunological properties of pituitary gonadotropins from the donkey (Equus asinus): comparison with the horse (Equus caballus).

The research provides a comparative analysis between the hormonal substances from donkeys and horses and it investigates their chemical, biological, and immunological properties. It reveals that these substances have remarkably different degrees of activity and content levels.

Research Methodology

• The researchers used nearly 200 donkey pituitaries to derive purified form of donkey gonadotropins (dLH and dFSH)
• The purification process used was the same as the one previously used for equine gonadotropins
• The researchers conducted multiple assays and tests to examine chemical, biological, and immunological properties of the isolated gonadotropins

Chemical Properties

• dLH and dFSH were found to be similar to eLH and eFSH in terms of their fractionation behavior and glycoprotein nature
• Two forms of the dFSH molecule were detected, identical to eFSH
• Carbohydrate and sialic acid content of the two dFSH preparations was similar to that of eFSH
• Donkey LH was chemically different from Equine LH as it had significantly less total carbohydrate and sialic acid
• A slightly higher content of tyrosine, an amino acid, was noted in the donkey gonadotropins

Immunological Properties

• In a heterologous FSH radioimmunoassay (RIA), dFSH preparations exhibited equal to or double the activity as compared to the eFSH preparations
• On the contrary, in homologous RIAs for eCG, eFSH and eLH, both the dLH and dFSH were considerably less active

Biological Properties

• As far as the potency is concerned, both dFSH preparations showed equal potency with eFSH
• In the Sertoli cell assay for cAMP (FSH assay) and the Leydig cell assay for testosterone (LH assay), both dFSH and dLH exhibited more activity than their equine counterparts
• In both rat and equine testis FSH homologous radioreceptor assays, dFSH preparations were found to be equal to and more potent than eFSH
• In contrast, dLH was 10-fold less active than eLH in the equine LH homologous radioreceptor assay

Conclusive Findings

• eLH has similarities with eCG as both possess both LH and FSH activity
• In contrast, dLH behaves more like donkey chorionic gonadotropin (dCG) which has a low level of FSH activity
• dLH was found to have little intrinsic FSH or inhibitory activity, and the observed FSH activity was likely due to contamination