Fig. 1: Chronic icv OXT infusion increases anxiety in male rats.

A Schematic of the chronic OXT (cOXT) infusion paradigm (created with BioRender.com). Osmotic minipumps (flow rate 0.25 µl/h, infusion duration 14 days) were filled with vehicle (VEH), 4 or 40 µM OXT, corresponding to 1 and 10 ng/h of OXT release rates, respectively, subcutaneously implanted and connected to the lateral ventricle of rats via polyethylene tubing. Day 1 marks the start of infusions. After 13 days, rats were mildly stressed by exposure to the elevated platform (EPF) for 5 min, and tested in the light-dark box (LDB) on day 14. Brain samples were collected immediately after LDB exposure. B cOXT decreased the time spent in the light box in a dose-dependent manner. Shown is the percentage of time spent in the lit box (LB). Data are represented as mean ± SEM. F(2;50) = 10.131; p < 0.001; Holm-Sidak *p < 0.001 vs VEH; n(VEH) = 15, n(1 ng/h, 10 ng/h) = 18. C Representative heat maps of rat location in the LDB; treatments as described in B. D Acute bilateral infusion of OXT (acOXT; 20 µM, 0.01nmol/0.5 µl per side) into the paraventricular nucleus (PVN) reduced anxiety-related behavior. Male rats were tested in the LDB or elevated plus-maze (EPM) 10 min after infusion, and 24 h after EPF exposure. Shown is the percentage of time spent in the LB or open arm (OA). Data are represented as mean ± SEM. One-tailed Student’s t test, p < 0.01, df = 6; n(VEH) = 4, n(acOXT) = 4. E Representative heat maps of rat location in the LDB and EPM after intra-PVN VEH or acOXT treatment.