Continuous human metastin 45-54 infusion desensitizes G protein-coupled receptor 54-induced gonadotropin-releasing hormone release monitored indirectly in the juvenile male Rhesus monkey (Macaca mulatta): a finding with therapeutic implications.
Seminara. Stephanie B SB; Dipietro. Meloni J MJ; Ramaswamy. Suresh S; Crowley. William F WF; Plant. Tony M TM
Key Findings
- A bolus of kisspeptin‑10 spikes LH, but continuous infusion leads to rapid GPR54 desensitization and LH suppression.
- GnRH and NMDA still trigger LH after desensitization, confirming the downstream pathway remains functional.
- Continuous kisspeptin exposure could be repurposed to reversibly suppress gonadal steroids for conditions like precocious puberty or hormone‑dependent cancers.
Practical Outcomes
- For DIY hormone tinkering, this means you should use short, intermittent kisspeptin doses if you want to boost testosterone, not a steady infusion. Continuous high‑dose kisspeptin might be explored as a way to temporarily lower sex hormones, but it requires IV delivery and careful monitoring, so it isn’t a ready‑to‑use protocol for most enthusiasts.
Summary
In monkeys, a single dose of kisspeptin-10 (metastin 45‑54) quickly raises LH, but keeping the peptide flowing continuously makes the receptor stop working, causing LH to crash. The downstream hormone system still works, so the drop is due to the receptor itself becoming desensitized. This shows that continuous kisspeptin can shut down the reproductive hormone axis, similar to how GnRH drugs are used clinically.
Abstract
The effect of continuous administration of the C-terminal fragment of metastin, the ligand for the G protein-coupled receptor, GPR54, on GnRH-induced LH secretion was examined in three agonadal, juvenile male monkeys whose responsiveness to GnRH was heightened by pretreatment with a chronic pulsatile iv infusion of synthetic GnRH. After bolus injection of 10 microg human (hu) metastin 45-54 (equivalent to kisspeptin 112-121), the GPR54 agonist was infused continuously at a dose of 100 microg/h and elicited a brisk LH response for approximately 3 h. This rise was then followed by a precipitous drop in LH despite continuous exposure of GPR54 to metastin 45-54. On d 4, during the final 3 h of the infusion, single boluses of hu metastin 45-54 (10 microg), N-methyl-DL-aspartic acid (NMDA) (10 mg/kg) and GnRH (0.3 microg) were administered to interrogate each element of the metastin-GPR54-GnRH-GnRH receptor cascade. Although the NMDA and GnRH boluses were able to elicit LH pulses, that of hu metastin 45-54 was not, demonstrating functional integrity of GnRH neurons (NMDA) and GnRH receptors (NMDA and GnRH) but desensitization of GPR54. The desensitization of GPR54 by continuous hu metastin 45-54 administration has therapeutic implications for a variety of conditions currently being treated by GnRH and its analogs, including restoration of fertility in patients with abnormal GnRH secretion (i.e. idiopathic hypogonadotropic hypogonadism and hypothalamic amenorrhea) and selective, reversible suppression of the pituitary-gonadal axis to achieve suppression of gonadal steroids (i.e. precocious puberty, endometriosis, uterine fibroids, and prostate cancer).
Study Information
pubmed
2006
2006-02-09T00:00:00.000Z
10.1210/en.2005-1550