GPR39 and depressive symptom measurement: The direct link between these findings and other characteristics of Gpr39-KO mice remains to be established, but it is plausible, given the role of zinc and magnesium in disease areas [13,14,15,16,17,18,19] in which GPR39 is increasingly investigated (e.g., neurovascular diseases, cardiovascular diseases, bone diseases, CNS diseases such as depression, epilepsy, etc. [6,7,8,9,10,11,12]).