In contrast to experiments by injecting into the PVN, injecting the non‐retrograde Cre‐carrying virus into the OVLT directly confirmed that OSR1 and SPAK deficiency in the OVLT produced partial central diabetes insipidus phenotypes featured by relative polyuria and urine hypotonicity that persisted in water restriction, and impaired AVP release in response to water restriction (Figure 5B–F). Here, STK39 is linked to Central diabetes insipidus.