Influence of foetal genotype on the follicle-stimulating hormone:luteinizing hormone ratio of pregnant mare serum gonadotrophin.

The research investigates how the genetic makeup of a foetus influences the ratio of follicle-stimulating hormone (FSH) to luteinizing hormone (LH) in the serum of pregnant mares. It found that the ratio varies significantly between different species; the ratio in horses was approximately 1:1, while in donkeys it was considerably lower.

Methodology

• To carry out this research, the scientists utilized Rat testicular radioreceptor assays – analytical procedures that specifically detect and measure the levels of FSH and LH hormones.
• The scientists examined pregnant mare serum gonadotrophin (PMSG) produced from the pregnant females of horses, donkeys, mules and hinnies.
• This investigation included assessing the hormone ratio in PMSG both from in vivo (inside the body) and in vitro (outside the body in a controlled environment) production by the conceptuses (early stages of foetal development).

Findings

• The results show that the genotype – the set of genes characteristic of the foetus – significantly influences the FSH:LH ratio in PMSG.
• Specifically, the hormone ratio in horses was around 1:1, suggesting an equal presence of FSH and LH hormones. However, the ratio in donkeys was significantly lower (0.2), indicating a dominance of LH over FSH.
• Interestingly, the hybrid species – mules and hinnies – presented a PMSG hormone ratio approximately halfway between those of horses and donkeys.

Implications

• The variability of the FSH:LH ratio based on the foetus’ genotype implies that species-specific signalling mechanisms might be at work in hormone production, potentially impacting reproductive strategies employed by different species.
• The research may have significant implications in terms of understanding species-specific reproductive physiology and potentially influence breeding and conservation strategies for these animal species.