Conflicting reports exist regarding the effect of ATP in vasopressin- and oxytocin-containing neurons from supraoptic nucleus (SON). Using calcium imaging on hypothalamic neurons of rat brain slices we demonstrated that a substantial proportion of SON neurons respond to ATP application with increase in intracellular calcium. Using electrophysiological measurements we found that 80 % of SON neurons respond to stimulation with extracellular ATP by potentiation of GABAergic and glutamatergic synaptic transmission indicating that both oxytocin and vasopressin neurons express P2XR on their presynaptic terminals. To characterize the ATP-responsiveness of identified oxytocin and in vasopressin SON neurons, we are employing whole-cell patch-clamp electrophysiology on genetically identified oxytocin and vasopressin neurons in transgenic rat model expressing a vasopressin-enhanced green fluorescent protein fusion gene and an OT-monomeric red fluorescent protein 1 fusion transgene.