Kisspeptin-10 kept LH up for 12 days in healthy men

The main takeaway is that intermittent under-the-skin (subcutaneous) infusions kept the reproductive signal going, while continuous infusion did not. The study first tested single 8-hour infusions at doses from 1.25 to 10.0 nmol per kilogram per hour in seven healthy men. Luteinizing hormone, follicle-stimulating hormone, and testosterone all rose in a dose-dependent pattern compared with salt-water placebo ¹. A second part placed four men on a continuous 180 nmol per hour infusion for five days. Testosterone remained elevated, but LH and FSH fell back to levels that were not meaningfully different from placebo, which fits the known pattern of receptor desensitization. Desensitization means the cells stop responding as strongly when the signal never turns off ¹.

Then the key experiment ran seven men through 12 days of eight-hour infusions at 150 nmol per hour, with 16 hours off each day. LH on day 1 was 1.68 units above the placebo pattern; on day 12 it was still 1.14 units above, and the difference was unlikely to be chance (p=0.003) ¹. After the 12 days, a follow-up 1 nmol/kg bolus still produced a gonadotropin rise, meaning the receptor had not gone silent. The study measured LH, FSH, and testosterone, not fertility outcomes, so it cannot answer whether the pattern changes fertility ¹.

Comparing by duration helps. In short-term studies, a continuous 24-hour intravenous (IV) infusion of Kisspeptin-10 in healthy men raised LH roughly five- to eight-fold, with a partial decline after the first spike ². The new acute subcutaneous data show the same quick, dose-dependent rise ¹. The mid-term picture changed: in the new study, five days of continuous infusion led LH and FSH back toward placebo even though testosterone stayed slightly elevated ¹. That matches earlier primate and human work showing that constant drive can desensitize the kisspeptin receptor ².

By the long-term comparison, the new 12-day intermittent schedule is the longest controlled evidence so far that an on-and-off pattern can keep the receptor responsive. Daily infusions with 16 hours off kept LH clearly above placebo at day 12, and a bolus at the end still worked ¹. Previous human use of Kisspeptin-10 was mostly single or short infusions, so this extends the timeline considerably ¹. The sample is small, and the study was not designed to test long-term safety.

A separate 2026 study compared Kisspeptin-10 with two longer kisspeptin forms, KP-14 and KP-13, in mice and pancreatic beta cells. Beta cells are the cells in the pancreas that make insulin. The takeaway is that Kisspeptin-10 breaks down quickly, and its metabolic effects are mixed: it raised short-term glucose and reduced food intake, but it worsened the body's glucose tolerance, which is the ability to clear sugar from the blood ⁴.

In plasma, KP-14 resisted breakdown, while KP-10 and KP-13 lost part of their N-terminal end (the beginning segment of the peptide chain). KP-13 could break down into KP-10, which complicates comparisons ⁴. In a beta-cell line and isolated mouse islets, kisspeptins had modest direct effects on insulin release. KP-13 was the most effective at making beta cells multiply and protecting them from inflammatory damage, outperforming exenatide, a diabetes drug used as a reference ⁴. Kisspeptin-10 was not the standout for insulin release or beta-cell survival.

After a single acute dose in healthy mice, all three kisspeptin forms raised circulating glucose. KP-14 and Kisspeptin-10 made glucose tolerance worse, while KP-13 did not ⁴. On appetite, all isoforms suppressed food intake, and Kisspeptin-10 caused the strongest feeding inhibition in this comparison ⁴. This is one of the first direct side-by-side metabolic comparisons, but it is mouse and cell work, not human data.

Another new rat study looked at what happens when Kisspeptin-10 is given during pregnancy to mothers with hypothyroidism, a low thyroid state. Hypothyroidism in pregnancy can restrict fetal growth and is linked to later heart risks. When pregnant Wistar rats had hypothyroidism induced by propylthiouracil, their offspring had smaller hearts, slower heart muscle cell division, and disrupted markers for cell death and blood vessel growth ⁵. Giving Kisspeptin-10 starting on gestational day 8 partially rescued several of those changes: offspring gained more weight after birth, heart muscle cell division returned toward normal, and markers like Vegf and Ang2 improved ⁵.

However, Kisspeptin-10 also increased two stress-related markers in fetal hearts, 8-OHdG for oxidative stress and Grp78 for endoplasmic reticulum stress. One of those, Chop, was lower later in offspring ⁵. The study authors describe the effect as partial rescue, not a clean fix. This is a rat model, and it is not evidence that Kisspeptin-10 should be used in pregnancy.

Across the three new studies, the marker pattern splits into three time frames and three species.

The table shows why the human result is narrow but meaningful. It answers a receptor-desensitization question that had blocked longer protocols before, while the metabolic and cardiac findings are still in animals. Neither animal study was designed to predict human outcomes.

The human 12-day study was not designed to test whether the LH pattern leads to better fertility or sustained testosterone in a way that matters clinically. The sample was small, and there was no long-term follow-up. The mouse and rat studies were also not designed to predict human metabolic or developmental effects. We do not know whether Kisspeptin-10's food-intake suppression in mice would appear in humans, or whether the cardiac rescue in hypothyroid rats has any parallel in people. Future work would need longer intermittent protocols and direct comparison with longer-lasting kisspeptin forms, because the new human study only compared Kisspeptin-10 with placebo ¹.