Testosterone made by your own testis

Given to men, kisspeptin-10 raised LH sharply within thirty minutes and, held on across a long enough window, raised testosterone from about 16.6 to 24.0 nanomoles per litre. The important part is where that testosterone came from: the man's own testis, driven by his own pituitary, with the whole chain intact. That is the opposite of giving testosterone from outside, which switches the chain off and shrinks it. In men with type 2 diabetes and low testosterone the same response worked, which showed their fault lay above the testis.