Endocrine Abstracts

Arginine vasopressin (AVP) and oxytocin (OXT) are neuropeptides produced in hypothalamic nuclei and released into circulation from axon terminals projecting to the posterior pituitary. A disrupted hypothalamic-pituitary axis caused by inflammation, tumours, or head trauma can cause AVP deficiency, also known as central diabetes insipidus (cDI), a condition characterised by polyuria and consecutive polydipsia. Once diagnosed, desmopressin, a selective AVP receptor 2 agonist, is prescribed to overcome cDI symptoms. Despite treatment with desmopressin, patients often report residual psychological symptoms such as heightened anxiety levels, difficulties describing or expressing emotions, and depressed mood, leading to a reduced quality of life. Due to the anatomical proximity, a disrupted AVP system leading to cDI could also disturb the OXT system leading to OXT deficiency. The central oxytocinergic system is key in regulating socio-emotional functioning, including attachment and pair bonding, fear extinction, and emotion recognition. Therefore, increased psychopathological findings in patients with cDI may be caused — at least partially — by an additional OXT deficiency. However, OXT deficiency has never been proven and established as a disease entity. Few studies attempted to measure OXT in these patients and mainly focused on basal measurements delivering inconclusive results. Notably, similar to other pituitary hormones, single basal levels are unreliable in identifying a deficiency in this context and no standard provocation test for OXT has been established. Using an innovative provocation test with MDMA (‘ecstasy’), our new data clearly indicate an OXT deficiency in patients with cDI, laying the groundwork for a new hypothalamic-pituitary entity. An important question, however, is whether this deficiency is related to alterations or dysfunctions in socio-emotional behaviour, which needs to be investigated in further interventional studies.