RFRP-3

Where it comes from

Made in

The dorsomedial hypothalamus

Sent out by

Stress, through glucocorticoids; the seasons, through melatonin; falls before the LH surge

Acts on

• GnRH neurons and kisspeptin neurons
• Pituitary gonadotrophs
• Gonads directly

What it does

• Inhibits GnRH neurons and LH release, the opposite of kisspeptin ¹
• Carries stress and season into the reproductive axis ³
• Reduces sexual motivation in rodents

In medicine

• No medicine. In the one human study an infusion lowered overall LH output in five postmenopausal women without changing the LH pulses, and in four men it did not blunt kisspeptin-driven LH ²
• It is not measured in people, and no assay for it is offered: the human work gave the peptide rather than measured it ²

Beyond the body’s own use

• It is studied as a non-steroidal route to suppress reproduction, and as the signal that carries stress and the seasons into the reproductive axis; nothing has gone beyond that single-dose human infusion ²
• Nothing containing it is approved or obtainable outside the laboratory
• The gap between species is the problem. In birds and seasonal mammals gonadotropin-inhibitory hormone has clear effects on reproduction; in people a dose that worked in animals barely moved LH, so whether humans use this brake at all is unsettled ¹²