Kisspeptin

Kisspeptin is a naturally occurring neuropeptide encoded by the KISS1 gene that acts as the master regulator of the hypothalamic-pituitary-gonadal (HPG) axis. By binding to GPR54 receptors in the hypothalamus it triggers a powerful pulse of GnRH, which in turn drives LH and FSH release, stimulating endogenous testosterone and estradiol production. It is used clinically to restore suppressed HPG axis function and is being studied extensively for male and female hypogonadism, IVF protocols, and as an alternative to exogenous LH in fertility treatment.

• Restores suppressed LH/FSH and testosterone after anabolic steroid or TRT use
• Stimulates endogenous testosterone production without directly suppressing the HPG axis
• Improves sperm count and motility in hypogonadotropic hypogonadism
• Drives ovulation in anovulatory women — clinical IVF trigger
• Elevates libido and sexual arousal (psychosexual effects studied in humans)
• May improve mood, motivation, and energy via downstream testosterone effects
• Alternative or adjunct to hCG/gonadorelin for PCT or HPG axis recovery

• Hot flashes / flushing (dose-dependent)
• Mild nausea
• Headache
• Transient hypotension with IV dosing
• Tachyphylaxis (desensitization) with continuous infusion — must use pulsatile dosing
• Potential gonadotropin hyperstimulation with very high doses

Dhillo et al. (JCEM 2005) — first human study showing IV KP-54 raises LH. Jayasena et al. (Clinical Endocrinology) demonstrated SubQ KP-54 sustained LH and testosterone elevation. Multiple clinical trials ongoing for male infertility (hypogonadotropic hypogonadism) and as an IVF ovulation trigger replacing hCG.