Eliminating Hormones With Orally Active Gonadotropin-releasing Hormone Antagonists

Provocative tests with Kisspeptin-10 and GnRH set the scene for determining social status and environmental impacts on reproductive capacity in male African lions (Panthera leo)

Understanding the hypothalamic factors regulating reproduction facilitates maximising the reproductive success of breeding programmes and in the management and conservation of threatened species, including African lions. To provide insight into the physiology and pathophysiology of the hypothalamic-pituitary-gonadal reproductive axis in lions, we studied the luteinising hormone (LH) and steroid hormone responses to gonadotropin-releasing hormone (GnRH) and its upstream regulator, kisspeptin. Six young (13.3 ± 1.7 months, 56.2 ± 4.3 kg) and four adult (40.2 ± 1.4 months, 174 ± 6 kg) male lions (Ukutula Conservation Centre, South Africa) were used in this study. Lions were immobilised with a combination of medetomidine and ketamine and an intravenous catheter was placed in a jugular, cephalic or medial saphenous vein for blood sampling at 10-min intervals for 220 min. The ten-amino acid kisspeptin which has full intrinsic activity (KP-10, 1 µg/kg) and GnRH (1 µg/kg) were administered intravenously to study their effects on LH and steroid hormone plasma concentrations, measured subsequently by ELISA and liquid chromatography tandem mass spectrometry (LC-MS/MS), respectively. Basal LH levels were similarly low between the age groups, but testosterone and its precursor levels were higher in the adult animals. Adult lions showed a significant LH response to KP-10 (10-fold) and GnRH (11-fold) administration (p < 0.05 and P < 0.001, respectively) whereas in young lions LH increased significantly only in response to GnRH. In adults alone, testosterone and its precursors steadily increased in response to KP-10, with no significant further increase in response to GnRH. Plasma levels of glucocorticoids in response to KP-10 remained unchanged. We suggest that provocative testing of LH and steroid stimulation with kisspeptin provides a new and sensitive tool for determining reproductive status and possibly an index of exposure to stress, environmental insults such as disease, endocrine disruptors and nutritional status. 272 words.

Short-term administration of oral relugolix before single-port laparoscopic-assisted vaginal hysterectomy for symptomatic uterine myomas: A retrospective comparative study with leuprorelin injection

AIM

To investigate the efficacy of short-term administration of relugolix, a novel orally active gonadotropin-releasing hormone (GnRH) antagonist, before single-port laparoscopic-assisted vaginal hysterectomy (LAVH) for symptomatic uterine myomas, retrospectively compared with injection of leuprorelin, a GnRH agonist.

METHODS

A retrospective comparative study of each 35 women with symptomatic myomas in the relugolix and leuprorelin groups.

RESULTS

Before administration of relugolix and leuprorelin, the median uterine volume did not differ significantly between the two groups (p = 0.53). Median uterine volume change from baseline after short-term administration of relugolix and leuprorelin did not differ significantly (p = 0.17). Surgical duration (p = 0.84) and estimated blood loss (p = 0.48) were not different between the two groups. According to a patient questionnaire, the side effects of the drugs were not different between the two groups (p = 0.27). When patients were was asked if they wanted to have either of these drugs again, some relugolix users preferred leuprorelin due to concern about forgetting daily medication, while some leuprorelin users preferred relugolix to avoid pain at injection.

CONCLUSION

Oral relugolix medication or leuprorelin injection administered before single-port LAVH for uterine myomas yielded an equivalent reduction of uterine volume and perioperative outcomes with no significant adverse events. Patient preference for either oral daily relugolix or a monthly injection of leuprorelin could be considered when preoperative management is determined.