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Fig. 8 | Journal of Biomedical Science

Fig. 8

From: A dorsal CA2 to ventral CA1 circuit contributes to oxytocinergic modulation of long-term social recognition memory

Fig. 8

Activation of dCA2-to-vCA1 projections rescues long-term SRM deficit in Oxtr−/− mice. A Schematic representation of the experimental design. B Schematic representation of viral injection and CNO administration. Three weeks after stereotaxic injection of AAV5-hSyn-DIO-hM3D(Gq)-mCherry or AAV5-hSyn-DIO-mCherry into the dCA2 of Oxtr−/− mice, mice were subjected to three-chamber paradigm test and long-term SRM retention was tested 7 days after the initial interaction. Oxtr−/− mice were bilaterally administered of CNO into vCA1 20 min before the initial interaction. Representative images showing the co-expression of hM3D(Gq)-mCherry and STEP immunoreactivity in dCA2 pyramidal neurons of Oxtr−/− mice. Scale bar represents 50 μm. mCherry signals of axonal projections were observed in vCA1. Scale bar represents 100 μm. NeuN neuronal nuclear protein, SO stratum oriens, SP stratum pyramidale, SR stratum radiatum. 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. Both mCherry/CNO and hM3D(Gq)/CNO Oxtr−/− 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) were similar between mCherry/CNO and hM3D(Gq)/CNO Oxtr−/− mice 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. Both mCherry/CNO and hM3D(Gq)/CNO Oxtr−/− 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 between mCherry/CNO and hM3D(Gq)/CNO Oxtr−/− mice 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)/CNO, but not mCherry/CNO, Oxtr−/− 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 Oxtr−/− mice was significantly higher than mCherry/CNO Oxtr−/− 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 < 0.05, **P < 0.01, ***P < 0.001

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