The pulse generator

Reproductive hormones are not released in a steady stream, they come in pulses, and the rhythm carries as much information as the amount. The pulse is generated by KNDy neurons in the arcuate nucleus, which carry kisspeptin, neurokinin B and dynorphin together and use the second to excite each other and the third to switch themselves off, producing a regular beat. Given to men, kisspeptin-10 raised LH pulse frequency from about 0.7 to 1.0 pulses an hour and roughly tripled the size of each burst. Faster, bigger pulses are what the testis reads as an instruction to make testosterone.