Figure 2.
Changes in the OT system of the PVN and NAc in response to separation and altered passive stress-coping following manipulations of OTR in the NAc shell.
Top: Decreased OT mRNA expression in the PVN and decreased OTR binding in the NAc shell after 3-day separation from the pair bonded female partner, but not from the male sibling. Numbers of animals included in the statistics were female paired = 7; separated = 6; sibling paired = 6; separated = 5.
Middle: Separation from the female partner increased floating in the forced swim test, indicative of passive stress-coping, in male prairie voles chronically infused with vehicle bilaterally into the NAc shell. Activating OTR by synthetic OT in the NAc shell abolished the increased passive stress-coping after separation. Blocking OTR by a specific OTR antagonist (OTR-A) increased passive stress-coping in the non-separated males. Floating was higher in both OTR-A treated groups compared to the corresponding OT-treated males. Passive stress-coping of male prairie voles treated with OT or OTR-A outside the NAc shell (“miss”; infusion site is depicted by the tips of black arrows in schematic drawing (Paxinos and Watson, 1998)) did not differ from vehicle-treated controls. Numbers of animals included in the statistics were vehicle = 6/5; OT = 7/9; OTR-A = 11/6 (paired/separated); miss = 1.
Bottom: The viral vector expressing the shRNA targeting the prairie vole OTR resulted in a significant reduction in OTR binding in the NAc shell, but not caudate putamen (CP) or prefrontal cortex (PFC), compared to the scrambled control viral vector. Knock-down of OTR in male prairie voles increased passive stress-coping on day 10 of cohabitation with a female. Numbers of animals included in the statistics were scrambled sequence = 8; OTR shRNA = 7.
Data are expressed as mean + sem. ** p < 0.01, * p < 0.05 vs corresponding control group (top: female paired; middle: vehicle-treated; bottom: scrambled-treated); ## p = 0.01 vs corresponding female-paired group; ++ p≤0.01 vs corresponding OT-treated group.