KNDyNeuronen

KNDy neurons are a population of neurons located in the arcuate nucleus of the hypothalamus in mammals. The name KNDy reflects their core neurochemical signature: kisspeptin, neurokinin B (NKB), and dynorphin A. These neurons coexpress all three peptides and are interconnected within a feedback network that is thought to drive the pulsatile secretion of gonadotropin-releasing hormone (GnRH).

The neurochemical interactions within the KNDy network form the basis of their proposed pulsatile mechanism. Neurokinin B acts on NK3 receptors on neighboring KNDy neurons to promote activity and kisspeptin release. Dynorphin A provides inhibitory feedback through kappa opioid receptors, helping to terminate the pulse. Kisspeptin released from KNDy neurons then acts directly on GnRH neurons, stimulating GnRH release and thereby triggering pulses of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary. The activity of KNDy neurons is modulated by sex steroids, contributing to estrogen-mediated regulation of GnRH pulse frequency and amplitude.

Functionally, the KNDy network is considered central to the generation of GnRH pulses that govern reproductive function. This includes roles in puberty onset, the maintenance of adult reproductive cycles, and the modulation of GnRH secretion in response to hormonal feedback. The model is supported by evidence from rodent and primate studies showing coexpression of the three peptides and coordinated activity influencing GnRH dynamics.

Research on KNDy neurons continues to explore their exact connectivity, regulatory mechanisms, and potential involvement in reproductive disorders. They are often discussed in the context of kisspeptin signaling and broader hypothalamic control of reproduction.