Kisspeptin

What is kisspeptin?

Kisspeptin is a signaling peptide, encoded by the KISS1 gene, that binds the KISS1R receptor on GnRH neurons and acts as an upstream switch for the reproductive hormone axis.

The full peptide is kisspeptin-54 (54 amino acids). Shorter fragments keep the same core activity, and the most studied short form is kisspeptin-10, the 10 amino acid sequence at the C-terminal end. Both bind the same receptor and set off the same chain of hormone signaling. Human research began with kisspeptin-54, which raised LH, FSH, and testosterone in men (Dhillo et al., 2005), then moved to kisspeptin-10, which was characterized as a potent LH stimulator (George et al., 2011).

How does kisspeptin raise testosterone?

Kisspeptin stimulates GnRH neurons, which drives the pituitary to release LH and FSH, and LH then signals the testes to make testosterone.

This is the hypothalamic-pituitary-gonadal (HPG) axis, and kisspeptin sits above it as an early trigger:

1. Kisspeptin binds KISS1R on GnRH neurons. 2. GnRH is released and travels to the pituitary. 3. The pituitary releases LH and FSH. 4. LH signals the testes to produce testosterone.

Human studies map this out at each step. Kisspeptin-10 given by IV bolus produced a potent LH response and increased LH pulse frequency in healthy men (George et al., 2011). Kisspeptin-54 by IV infusion raised LH, FSH, and testosterone in healthy men (Dhillo et al., 2005). The effect also held in a clinical group: men with type 2 diabetes and mild biochemical hypogonadism showed increased LH and testosterone after kisspeptin-10 (George et al., 2013).

What does the research report for kisspeptin dosing?

Human kisspeptin studies used intravenous administration (bolus and infusion) in controlled settings, and there is no established oral or standardized at-home protocol.

The table below summarizes what the published human trials administered and reported. It is a record of research, not a protocol to follow.

The source papers report the exact per-kilogram amounts and infusion rates. These were research settings using intravenous delivery under monitoring. This page does not provide a dose to use, and any personal protocol belongs with a qualified clinician.

What is kisspeptin's half-life and how long does it act?

After an intravenous bolus, kisspeptin-10's LH-stimulating action is rapid and short-lived, on the order of minutes (George et al., 2011).

Because the response starts and fades quickly, the studies that mapped LH pulse frequency relied on repeated bolus or continuous infusion (George et al., 2011). Kisspeptin-54 was studied mainly by infusion, which sustained exposure long enough to raise LH, FSH, and testosterone (Dhillo et al., 2005). Precise plasma half-life values for each fragment are not well detailed in this small human literature, so the practical point is that the action is brief and dosing in the trials was intravenous.

Kisspeptin-10 vs kisspeptin-54: what is the difference?

Both fragments activate KISS1R and stimulate the HPG axis; kisspeptin-54 is the longer parent peptide studied by IV infusion, while kisspeptin-10 is the short C-terminal fragment shown to be a potent LH stimulator by IV bolus.

What are the side effects and safety signals?

In the published human studies, intravenous kisspeptin was generally well tolerated at the doses tested, but sample sizes were small and long-term safety data are limited (Dhillo et al., 2005; George et al., 2011).

The human evidence base for kisspeptin is early. It comes from short, controlled studies in modest numbers of participants, using intravenous administration. There is no large, long-term safety dataset, no oral formulation with human outcome data, and no standardized subcutaneous protocol in this literature. Anyone considering kisspeptin should treat it as a research compound and route questions about personal use to a qualified clinician.

How is kisspeptin different from PT-141 (bremelanotide)?

Kisspeptin acts on the HPG axis to influence LH, FSH, and testosterone, while PT-141 is a melanocortin receptor agonist studied for sexual desire rather than upstream hormone signaling.

The two work through different systems and should not be treated as interchangeable. PT-141 (bremelanotide) research reported nausea as a common side effect, a tolerability signal that does not map to the kisspeptin pathway. For the mechanism, trial data, and side-effect profile of that compound, see the PT-141 hub.