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Yanjiong Chen
Department of Immunology and Pathogenic Biology, College of Basic Medicine, Xi'an Jiaotong University Health Science Center
Corresponding Author
ORCiD: https://orcid.org/0000-0001-8510-6004
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This work is licensed under a CC BY 4.0 License. Read Full License
Background: Nucleus accumbens (NAc) inflammation is implicated in the development and progression of depression but the underlying mechanism remains largely unclear. We previously reported that dopamine D3 receptor (D3R) expressed in the NAc strongly correlated with inflammation-related depression. The objective of the present study is to determine the exact mechanism of D3R in the NAc inflammation relevant depression.
Methods: Bilateral NAc injection of Lipopolysaccharide (LPS)-induced NAc inflammation mouse model was used to explore the relationship between NAc inflammation and depressive-like behaviors. Either conditional knockout of D3R in the NAc in the adult mice or restoration of D3R expression in the NAc in D3R mutant mice was applied to investigate the effects of D3R in the NAc on depressive disorders. The exact molecular mechanism of D3R in the NAc inflammation-induced depressive-like phenotype was ascertained by in vivo and in vitro studies.
Results: NAc inflammation induced by intra-NAc LPS triggered a series of depressive-like disorders, and the interaction of D3R and microglia activation involved in the NAc inflammation-induced depressive-like phenotype. We observed that selective knock-down of D3R in the NAc elicited the depressive-like behaviors, but re-expression of D3R in the NAc alleviated the depressive-like behaviors established by D3R mutation. Finally, D3R in the NAc mediated microglial polarization to M1 phenotype mainly through Akt signaling pathway.
Conclusions: These findings provide direct evidence that not only NAc inflammation but also down-regulation of D3R in the NAc has a role in regulation the initiation and development of depression, and indicate that D3R negatively regulated microglial M1 polarization mainly via Akt signaling pathway that may be involved in the NAc inflammation and thereby depressive-like behaviors.
Keywords
NAc inflammation, D3R, microglia polarization, Akt signaling pathway, depression
Figure 1
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Figure 6
This is a list of supplementary files associated with this preprint. Click to download.
- SFig.1.tif
D3R inhibition aggravates pro-inflammatory cytokines production in vitro and in vivo study. (a-e) In results of cytokine levels produced by LPS, the pro-inflammatory cytokines expression of TNF-α，IL-1β and IL-6 were increased significantly compared to control group, and inhibition in D3R aggravated pro-inflammatory cytokines production stimulated by LPS compared to that of LPS treatment alone; but anti-inflammatory molecules IL-10 and arginase-1 expression did not show any differences in the cultured BV-2 microglial cells among different treatment groups (n=6/group). (f-j) In cultured primary microglial cells, D3R deficiency significantly increased the pro-inflammatory cytokines TNF-α, IL-1β and IL-6 but did not affect anti-inflammatory molecules IL-10 and arginase-1 expression, compared to WT mice following LPS challenge (n=4/group). The data are presented as the mean±SEM. One-way ANOVA followed by LSD’s multiple comparisons post hoc test were used to assess significant differences. *p＜0.05, **p＜0.01, ***p＜0.001, ns: no significance.
- SFig.2.tif
D3R inhibition did not change inflammatory cytokine levels in IL-4 treatment-induced microglial M2 phenotype. (a-c) In the cultured BV-2 cells, IL-4 treatment obviously decreased pro-inflammatory cytokines TNF-α, IL-1β and IL-6, but D3R inhibition did not affect pro-inflammatory cytokines expression following IL-4 stimulus compared to IL-4 treatment alone (n=6/group). (d-e) In the cultured BV-2 cells, IL-4 treatment elevated anti-inflammatory cytokines production, while co-treatment of IL-4 and D3R inhibition did not find any changes in anti-inflammatory cytokine levels compared to IL-4 treatment alone (n=6/group). The data are presented as the mean±SEM. One-way ANOVA followed by LSD’s multiple comparisons post hoc test were used to assess significant differences. *p＜0.05, **p＜0.01, ***p＜0.001, ns: no significance.
- SFig.3.tif
The roles of JNK and Akt signaling pathway in microglia activation after D3R inhibition. (a) Representative data for SP600125 (80 uM and 160 uM) and MK2206 (20 uM and 40 uM) treatments in microglial M1 phenotype induced by LPS challenge in BV-2 cells.
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A new preprint design is coming!
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This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research
Yanjiong Chen
Department of Immunology and Pathogenic Biology, College of Basic Medicine, Xi'an Jiaotong University Health Science Center
Corresponding Author
ORCiD: https://orcid.org/0000-0001-8510-6004
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 07 May, 2021
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: Nucleus accumbens (NAc) inflammation is implicated in the development and progression of depression but the underlying mechanism remains largely unclear. We previously reported that dopamine D3 receptor (D3R) expressed in the NAc strongly correlated with inflammation-related depression. The objective of the present study is to determine the exact mechanism of D3R in the NAc inflammation relevant depression.
Methods: Bilateral NAc injection of Lipopolysaccharide (LPS)-induced NAc inflammation mouse model was used to explore the relationship between NAc inflammation and depressive-like behaviors. Either conditional knockout of D3R in the NAc in the adult mice or restoration of D3R expression in the NAc in D3R mutant mice was applied to investigate the effects of D3R in the NAc on depressive disorders. The exact molecular mechanism of D3R in the NAc inflammation-induced depressive-like phenotype was ascertained by in vivo and in vitro studies.
Results: NAc inflammation induced by intra-NAc LPS triggered a series of depressive-like disorders, and the interaction of D3R and microglia activation involved in the NAc inflammation-induced depressive-like phenotype. We observed that selective knock-down of D3R in the NAc elicited the depressive-like behaviors, but re-expression of D3R in the NAc alleviated the depressive-like behaviors established by D3R mutation. Finally, D3R in the NAc mediated microglial polarization to M1 phenotype mainly through Akt signaling pathway.
Conclusions: These findings provide direct evidence that not only NAc inflammation but also down-regulation of D3R in the NAc has a role in regulation the initiation and development of depression, and indicate that D3R negatively regulated microglial M1 polarization mainly via Akt signaling pathway that may be involved in the NAc inflammation and thereby depressive-like behaviors.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
This is a list of supplementary files associated with this preprint. Click to download.
- SFig.1.tif
D3R inhibition aggravates pro-inflammatory cytokines production in vitro and in vivo study. (a-e) In results of cytokine levels produced by LPS, the pro-inflammatory cytokines expression of TNF-α，IL-1β and IL-6 were increased significantly compared to control group, and inhibition in D3R aggravated pro-inflammatory cytokines production stimulated by LPS compared to that of LPS treatment alone; but anti-inflammatory molecules IL-10 and arginase-1 expression did not show any differences in the cultured BV-2 microglial cells among different treatment groups (n=6/group). (f-j) In cultured primary microglial cells, D3R deficiency significantly increased the pro-inflammatory cytokines TNF-α, IL-1β and IL-6 but did not affect anti-inflammatory molecules IL-10 and arginase-1 expression, compared to WT mice following LPS challenge (n=4/group). The data are presented as the mean±SEM. One-way ANOVA followed by LSD’s multiple comparisons post hoc test were used to assess significant differences. *p＜0.05, **p＜0.01, ***p＜0.001, ns: no significance.
- SFig.2.tif
D3R inhibition did not change inflammatory cytokine levels in IL-4 treatment-induced microglial M2 phenotype. (a-c) In the cultured BV-2 cells, IL-4 treatment obviously decreased pro-inflammatory cytokines TNF-α, IL-1β and IL-6, but D3R inhibition did not affect pro-inflammatory cytokines expression following IL-4 stimulus compared to IL-4 treatment alone (n=6/group). (d-e) In the cultured BV-2 cells, IL-4 treatment elevated anti-inflammatory cytokines production, while co-treatment of IL-4 and D3R inhibition did not find any changes in anti-inflammatory cytokine levels compared to IL-4 treatment alone (n=6/group). The data are presented as the mean±SEM. One-way ANOVA followed by LSD’s multiple comparisons post hoc test were used to assess significant differences. *p＜0.05, **p＜0.01, ***p＜0.001, ns: no significance.
- SFig.3.tif
The roles of JNK and Akt signaling pathway in microglia activation after D3R inhibition. (a) Representative data for SP600125 (80 uM and 160 uM) and MK2206 (20 uM and 40 uM) treatments in microglial M1 phenotype induced by LPS challenge in BV-2 cells.
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