Fig. 3

Activation of PVN OXT neurons enhance long-term SRM. A Schematic representation of the experimental design. B Schematic representation of viral injection and CNO administration. Three weeks after stereotaxic injection of AAV₅-mOXT-hM3D(Gq)-mCherry into the PVN, mice were subjected to three-chamber paradigm test and long-term SRM retention was tested 7 days after the initial interaction. Mice were bilaterally injected with either vehicle (Veh) or CNO into dCA2 20 min before the initial interaction. Representative images showing the co-expression of hM3D(Gq)-mCherry and OXT immunoreactivity in the PVN. Scale bar represents 50 μm. C Top, schematic representation of the three-chamber sociability test. Bottom left, time spent by the subject mouse in sniffing directed at the wire cage containing the juvenile stimulus mouse or the empty wire cage. hM3D(Gq)/Veh and hM3D(Gq)/CNO subject mice spent significantly more time interacting with the wire cage containing the juvenile stimulus mouse than the empty wire cage. Bottom right, discrimination index (stimulus minus empty) was similar among groups in the sociability test. D Top, schematic representation of the three-chamber social novelty preference test. Bottom left, time spent by the subject mouse in sniffing directed at the wire cage containing a familiar mouse or a novel 1 mouse, 10 min after the sociability test. hM3D(Gq)/Veh and hM3D(Gq)/CNO subject mice spent significantly more time sniffing the cage containing the novel mouse than the familiar mouse. Bottom right, discrimination index (novel 1 minus familiar) was comparable among groups in the social novelty preference test. E Top, schematic representation of the three-chamber long-term SRM test. Bottom, time spent by the subject mouse in sniffing directed at the wire cage containing a familiar mouse or a novel 2 mouse, 7 days after the initial interaction. hM3D(Gq)/Veh and hM3D(Gq)/CNO subject mice spent significantly more time sniffing the cage containing the novel mouse than the familiar mouse. Bottom right, discrimination index (novel 2 minus familiar) of hM3D(Gq)/CNO subject mice was significantly higher than those of hM3D(Gq)/Veh subject mice in 7-day long-term SRM test. The total number of animal examined is indicated by n in parenthesis. Error bars represent the SEM; **P < 0.01, *** P < 0.001