Using immunohistochemistry to label brain slices (ex vivo) with collagen IV, a specific marker of BVs, together with a specific antibody against AQP-4, which is localized to the endfeet of astrocytes surrounding BVs (Papadopoulos and Verkman, 2013), we revealed that in the PFC of HAB rats the BVs showed a 60% reduction in coverage by AQP-4-IR endfeet with respect to NAB rats, similar to the finding in MDD patients [Figure 1; NAB, 0.16 ± 0.04, N = 8; HAB, 0.06 ± 0.02, N = 7; Student’s t-test, t(1,13) = 2.198, ∗p < 0.05]. The gene discussed is AQP4; the disease is major depressive disorder.