The reasoning: two routes, layered feedback
| Hypothalamic nucleus | Hormone | Target |
|---|---|---|
| Paraventricular (parvocellular) | CRH, TRH (also AVP co‑secreted with CRH) | corticotrophs, thyrotrophs |
| Arcuate | GHRH, dopamine (PIH), kisspeptin | somatotrophs; lactotrophs; GnRH neurons |
| Preoptic / mediobasal | GnRH (pulsatile) | gonadotrophs |
| Periventricular | somatostatin (GHIH) | somatotrophs, thyrotrophs |
| Supraoptic/paraventricular (magnocellular) | AVP, oxytocin | posterior pituitary (axonal) |