Effect of the GnRH Agonist, Deslorelin, on the Prolactin Axis

Gonadotropin-releasing hormone (GnRH) agonists have become increasingly important as anti-fertility agents in the veterinary field over the past decade, proving a successful alternative to surgical sterilization in domestic and captive animals. Although previous GnRH agonists used in reproductive management demonstrated several shortcomings, deslorelin, a relatively new GnRH agonist, has overcome many of these problems and has successfully suppressed reproduction in numerous species, including domestic dogs, cats, wild canids, felids and cattle. Approximately 135-day old Sprague-Dawley rats were used. Animals received 1 of 2 treatments for 6 weeks: a 1.1mg deslorelin implant alone or a sham implant insertion. Both the percentage of prolactin cells and the total number of cells differed insignificantly between treatment groups (P>0.05). These results disagree with our hypothesis that the known decrease in FSH-immunoreactive cells during treatment would affect the lactotrope population. It is possible, however, that lactotropes depend on LH rather than FSH cells. Thus, further research into the relationship between lactotropes and gonadotropes during treatment with GnRH agonists is required.