Kisspeptin helps connect the brain with the reproductive system. Its story began with cancer research, before revealing a central role in puberty, fertility and sexual signaling.

In 1996, Jeong Hyung Lee, Danny Welch and colleagues at Penn State in Hershey, Pennsylvania, reported the KISS1 gene. The name nodded to Hershey's chocolate kisses. Researchers were studying how cancer spreads, not searching for a fertility hormone.

In 2001, teams identified kisspeptins as signals for a receptor now called KISS1R. In 2003, human genetic studies linked disruptions in that receptor to absent or delayed puberty.

Kisspeptin is a family of peptides, including forms with ten and fifty-four amino acids. In the brain, it stimulates neurons that release gonadotropin-releasing hormone. That signal prompts the pituitary to release hormones that regulate the ovaries and testes.

This makes kisspeptin an important coordinator of reproductive hormone signaling, rather than a replacement for testosterone or estrogen.

At Imperial College London, Waljit Dhillo and colleagues explored its therapeutic potential. A 2014 study in fifty-three women showed that kisspeptin-fifty-four could trigger egg maturation during IVF treatment. Fertilization, pregnancies and live births followed.

Later placebo-controlled studies in women and men with distressing low sexual desire found changes in sexual brain processing. The men's study also found increased physical arousal.

These findings connect reproductive hormones with the brain circuits involved in sexual responses. They establish promising research directions; they do not establish a lasting treatment benefit.

Nearly thirty years after the original gene report, kisspeptin research spans puberty, fertility and sexual health, revealing how one signaling system links the brain with reproduction.

World Peptide Foundation. Peptides in 2. Every experience matters.