Use of push-pull perfusion techniques in studies of gonadotrophin-releasing hormone secretion in mares.

This research article explores the use of push-pull perfusion techniques to study secretion patterns of Gonadotrophin-Releasing Hormone (GnRH) in different stages of sexual cycle in Pony mares. The study finds that GnRH secretion varies with the stage within the estrous cycle, with the highest secretion occurring during oestrus.

Understanding the Experiment

• The study is concentrated on the use of push-pull perfusion – a technique that allows for the collection and analysis of fluid from a localized area – in order to understand how GnRH secretion varies during different stages of the sexual cycle in Pony mares.
• In the technique, a dual-chambered tube is inserted into the hypothalamus region of the mare’s brain. Artificial cerebrospinal fluid is then flowed through the inner tube and drawn out from the outer tube. This constant flow allows the researchers to track the secretion of GnRH.
• The sampling process was run for 10-15 hours at intervals of every 10 minutes and the perfused fluid samples were acidified, stored and later analyzed through radioimmunoassay.
• Blood samples were simultaneously taken from the jugular vein of the horses for assessing the levels of LH or Luteinizing Hormone.

Sampling and Results

• The study was conducted on a total of nineteen mares, with each one representing anoestrus (non-breeding phase), transition (period between breeding and non-breeding), dioestrus (receptive to mating but non-ovulating), and oestrus stages (breeding or heat phase).
• The study found the secretion of GnRH to be the least during anoestrus, slightly increasing during the transitional phase and the most during the oestrus phase.
• In terms of secretory episodes, these were significantly higher during the oestrus phase as compared to anoestrus and transitional phases.
• Although there were no major differences within the groups with respect to the number of secretory peaks or the interval between peaks, the mean rate of secretion was found to be significantly different among the groups.

Conclusion

• The study concluded that GnRH secretion is increased in early transition, a phenomenon that was hypothesized to occur in response to an increase in FSH (Follicle-stimulating hormone) secretion.
• However, a corresponding increase in LH (Luteinizing Hormone) was not observed.