Journal of Endocrinology

Schematic and proposed model for the metabolic regulation and coordination of the leptin-mediated reproductive and nutritional axes. Leptin, insulin, and IGF1 are shown as the most critical circulatory factors that act on hypothalamic and other brain networks to regulate food intake and GnRH secretion. The pathway, rich in redundancies, depicts the various direct and indirect inputs that converge on GnRH neurons. The crosstalks of the reproductive and nutritional axes are represented by the projections of the AgRP/NPY and POMC neurons to the KNDy neurons and by the AgRP/NPY neurons onto GnRH neurons. The first-order leptin responsive neurons in the PMV and other hypothalamic areas are denoted with a thick green arrow to highlight their essential reproductive function and the release of the NO neurotransmitter. Ligands and receptors are shown on each set of neurons and green/red arrows represent stimulatory and inhibitory effects respectively. The postulated elusive leptin intermediate neurons are denoted with a question mark. Acronyms in the figure are the same as in the text.