Figure 1 The adult neuroendocrine axes Figure 1 | The adult neuroendocrine axes. Neuroendocrine systems are the final common pathway for the central control of neurohormone secretion. As such, they are subject to a complex array of excitatory and inhibitory trans-synaptic inputs that modulate their activity. Magnocellular neurons (blue) of the hypothalamo–neurohypophyseal system release oxytocin and vasopressin directly into the general circulation. Parvicellular neurons (green) of the hypothalamo–antehypophyseal system project to the median eminence of the hypothalamus, where they make contact with the pericapillary space bordering the pituitary portal blood vessels. Following their release into the pituitary portal system, neurohormones travel to the pituitary to stimulate the synthesis and secretion of pituitary hormones. Blood-borne pituitary hormones act on target glands — including the gonads, the thyroid gland and the adrenal gland — to regulate their function. TSH-releasing hormone is secreted from the cell bodies of parvicellular neurons in the paraventricular nucleus107,108, while parvicellular neurons in the preoptic region secrete gonadotropin-releasing hormone (GnRH; abundant GnRH cell bodies can also be found in the tuberal region of the hypothalamus in primates)134,135. Cell bodies of parvicellular neurons expressing dopamine, growth hormone-releasing hormone and somatostatin are also located in the tuberal region of the hypothalamus, including the arcuate nucleus of the hypothalamus92. Clasadonte, J. & Prevot, V. (2017) The special relationship: glia–neuron interactions in the neuroendocrine hypothalamus Nat. Rev. Endocrinol. doi:10.1038/nrendo.2017.124