Enriched environment reduces pyramidal neuron excitability in the anterior cingulate cortex to alleviate restraint stress-induced anxiety-like behaviors in mice

doi:10.12122/j.issn.1673-4254.2025.05.08

Abstract

Abstract:

Objective To investigate the mechanism by which the pyramidal neurons of the anterior cingulate cortex (ACC) modulate the effects of enriched environment (EE) for relieving anxiety-like behaviors in mice. Methods C57BL/6J mice were randomly divided into control group, restraint stress (RS) group, and RS+EE group (n=8). The mice in the latter two groups were subjected to RS for 2 h daily for 3 days, and those in RS+EE group were housed in an EE during modeling. Anxiety-like behaviors of the mice were evaluated using the elevated plus-maze tests (EPM) and open field test (OFT). Changes in c-Fos expression in the ACC of the mice were detected with immunofluorescence assay, and pyramidal neuron excitability in the ACC (Pyn^ACC) was measured using patch-clamp technique. The miniature excitatory and inhibitory postsynaptic currents (mEPSC and mIPSC, respectively) were analyzed to assess synaptic transmission changes. Results Behavioral tests showed obvious anxiety-like behaviors in RS mice, and such behavioral changes were significantly improved in RS+EE mice. Immunofluorescence staining revealed significantly increased c-Fos expression in the ACC in RS mice but lowered c-Fos expression in RS+EE group. Compared with the control mice, the RS mice showed increased action potential firing rate of Pyn^ACC, which was significantly reduced in RS+EE group. Compared with the RS mice, the RS+EE mice showed also decreased frequency of mEPSCs of Pyn^ACC, but the amplitude exhibited no significant changes. No obvious changes in the frequency or amplitude of mIPSCs were observed in RS+EE mice. Conclusion EE reduces excitability of Pyn^ACC to alleviate anxiety-like behaviors induced by RS in mice.

Key words: enriched environment, anterior cingulate cortex, pyramidal neuron, anxiety, excitability

Changfeng CHEN, Qin FANG, Yinhuan GAO, Liecheng WANG, Lei CHEN. Enriched environment reduces pyramidal neuron excitability in the anterior cingulate cortex to alleviate restraint stress-induced anxiety-like behaviors in mice[J]. Journal of Southern Medical University, 2025, 45(5): 962-968.

Figures/Tables 4

Fig.1 Enriched environment (EE) alleviates anxiety-like behaviors induced by restraint stress (RS) in mice. A: Heatmaps of 5-minute walking paths in the 3 groups in elevated plus-maze (EPM) tests. B: Time spent in open arms. C: Entries in open arms. D: Total distance in EPM tests. E: Heatmaps of 5-minute walking paths in the 3 groups in open field test (OFT). F: Entries in the central area. G: Time in the central area in OFT. *P<0.05, **P<0.01 (n=8).

Fig.2 EE prevents the high c-Fos expression of the ACC induced by RS. A: The location of ACC in the brain atlas (Bregma 0.02 mm). B: The original diagram of c-Fos expression in ACC from each group. Scale bar=100 μm. C: Statistical graphs of c-Fos expression in each group. CON: n=3, RS: n=4, RS+EE: n=4. **P<0.01, ***P<0.001.

Fig.3 EE attenuates RS-induced increases in action potentials of PynACC. A: Representative image of a PynACC under whole-cell recording (Scale bar=100 μm). B: Groups of typical sequential spikes. C: Quantification of the numbers of spikes with different stimuli. CON: 10 cells from 4 mice; RS: 11 cells from 4 mice; RS+EE: 10 cells from 3 mice. *P<0.05, **P<0.01.

Fig.4 EE attenuates RS-induced increase of mEPSC frequency of PynACC. A: Representative traces of mEPSCs of PynACC. B: Cumulative plots of inter-event interval of mEPSC. C: Statistical results of mEPSC frequency. D: Cumulative plots of amplitude of mEPSC. E: Statistical results of mEPSC amplitude. CON: 12 cells from 4 mice; RS: 13 cells from 3 mice; RS+EE: 14 cells from 3 mice. F: Representative traces of mIPSCs of PynACC. G: Cumulative plots of inter-event interval of mIPSC. H: Statistical results of mIPSC frequency. I: Cumulative plots of amplitude of mIPSC. J: Statistical results of mIPSC amplitude. CON: 12 cells from 4 mice; RS: 11 cells from 4 mice; RS+EE: 11 cells from 3 mice. *P<0.05.

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