In contractile skeletal and heart myocytes and secretory cells, Ca2+-induced Ca2+ release (CICR) from the ryanodine receptor Ca2+-releasing channels is one of the major mechanisms of increasing intracellular free Ca2+ concentration1. Cyclic ADP-ribose (cADPR) is a co-activator of CICR, modulating ryanodine receptors in the microsomes2. cADPR is synthesised from beta-NAD+ by ADP-ribosyl cyclases, such as CD383. Recently, we showed that CD38 is essential for the secretion of oxytocin, but not vasopressin, from hypothalamic neurons into the brain and from their nerve endings in the posterior pituitary into the bloodstream in vivo 4. Furthermore, the release of oxytocin from isolated pituitary preparations was enhanced by extracellular application of cADPR, indicating that the mechanism of OT secretion involves cADPR-ryanodine receptor-mediated Ca2+ mobilisation from intracellular stores4. Therefore, in the field of neuroscience, there is increasing interest regarding whether CICR is utilised in release of a particular neurotransmitter or neuropeptide in a distinct brain region. Here, we describe a simple method to determine the usage of CICR in a given synapse by extracellular application of cADPR or beta-NAD+-related compounds5,6 — in our case, oxytocin in the isolated hypothalamus and pituitary.