Stanniocalcin-1 Overexpression Prevents Depression-Like Behaviors Through Inhibition of the ROS/NF-κB Signaling Pathway

Abstract

Background: Depression is a burdensome psychiatric disorder presenting with disordered inflammation and neural plasticity. We conducted this study with an aim to explore the effect of stanniocalcin-1 (STC1) on inflammation and neuron injury in rats with depression-like behaviors. Methods: A model of depression-like behaviors was established in Wistar rats by stress stimulation. Adeno-associated virus (AAV)-packaged STC1 overexpression sequence or siRNA against STC1 was introduced into rats to enhance or silence the STC1 expression. Moreover, we measured pro-inflammatory and anti-inflammatory proteins, superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) and reactive oxygen species (ROS) production. An in vitro model was induced in hippocampal neurons by CORT to explore the effect of STC1 on the neuron viability, toxicity and apoptosis. RT-qPCR and Western blot assay were employed to determine the expression of STC1 and nuclear factor κB (NF-κB) signaling pathway-related genes. Results: STC1 was under-expressed in the hippocampus of rats with depression-like behaviors, while its overexpression could reduce the depression-like behaviors in the stress-stimulated rats. Furthermore, overexpression of STC1 resulted in enhanced neural plasticity, reduced release of pro-inflammatory proteins, elevated SOD and CAT and diminished MDA level in the hippocampus of rats with depression-like behaviors. Overexpressed STC1 blocked the ROS/NF-κB signaling pathway, thereby enhancing the viability of CORT-treated neurons while repressing their toxicity and apoptosis. Conclusion: Collectively, overexpression of STC1 inhibits inflammation and protects neuron injury in rats with depression-like behaviors by inactivating the ROS/NF-κB signaling pathway.

Keywords: NF-κB; depression; inflammation; neural plasticity; reactive oxygen species; stanniocalcin-1.

Figure 1

A rat model of depression-like behaviors is successfully established. (A) weight of rats with depression-like behaviors. (B) sucrose preference in rats with depression-like behaviors. (C) total movement distance and cumulative immobility time of rats with depression-like behaviors in the forced-swimming test and tail suspension experiment. (D) latency time of food foraging of rats with depression-like behaviors. (E) 5-HT, BDNF, and ACTH levels in the serum of rats with depression-like behaviors. (F) IL-1β, IL-6, TNF-α, hs-CRP, and IFN-γ levels in serum of rats with depression-like behaviors. (G) numbers of BrdU- and Nestin-positive cells in the hippocampus of rats with depression-like behaviors. (H) The percentage of TUNEL-positive cells in the hippocampus of rats with depression-like behaviors. *p < 0.05. n = 8.

Figure 2

STC1 is underexpressed while ROS/NF-κB signaling pathway is activated in enhances rats with depression-like behaviors. (A) STC1 and NF-κB p65 mRNA expression in the hippocampal tissues of rats with depression-like behaviors determined by RT-qPCR. (B) STC1 and NF-κB p65 protein expression in the hippocampal tissues of rats with depression-like behaviors measured by Western blot assay. (C) Quantitative analysis of STC1 and NF-κB p65 protein expression. (D) ROS production in the hippocampal tissues of rats with depression-like behaviors. (E) SOD, CAT, and MDA levels in hippocampal tissues of rats with depression-like behaviors. *p < 0.05. n = 8.

Figure 3

STC1 overexpression reduces the toxicity and apoptosis of hippocampal neurons induced by CORT. (A) STC1 mRNA expression in hippocampal neurons induced by CORT determined by RT-qPCR. (B) STC1 protein expression in hippocampal neurons induced by CORT measured by Western blot assay. (C) viability of hippocampal neurons induced by CORT. (D) LDH activity in hippocampal neurons induced by CORT. (E) apoptosis of hippocampal neurons induced by CORT. *p < 0.05 vs. neurons treated with oe-NC. Cell experiment was repeated 3 times.

Figure 4

STC1 overexpression inhibits the ROS/NF-κB signaling pathway. (A) ROS production in hippocampal neurons induced by CORT. (B) SOD and CAT activity in hippocampal neurons induced by CORT. (C) MDA level in hippocampal neurons induced by CORT. (D) NF-κB p65 mRNA expression in hippocampal neurons induced by CORT determined by RT-qPCR. (E) NF-κB p65 protein expression in hippocampal neurons induced by CORT measured by Western blot assay. *p < 0.05 vs. neurons treated with oe-NC. Cell experiment was repeated 3 times.

Figure 5

STC1 overexpression inhibits the ROS/NF-κB signaling pathway to repress toxicity and apoptosis of hippocampal neurons induced by CORT. (A) STC1 mRNA expression in hippocampal neurons induced by CORT determined by RT-qPCR after different treatments. (B) ROS production in hippocampal neurons induced by CORT after different treatments. (C) SOD and CAT activity in hippocampal neurons induced by CORT after different treatments. (D) MDA level in hippocampal neurons induced by CORT after different treatments. (E) NF-κB p65 mRNA expression in hippocampal neurons induced by CORT determined by RT-qPCR after different treatments. (F) NF-κB p65 protein expression in hippocampal neurons induced by CORT measured by Western blot assay after different treatments. (G) viability of hippocampal neurons induced by CORT after different treatments. (H) LDH activity in hippocampal neurons induced by CORT after different treatments. (I) apoptosis of hippocampal neurons induced by CORT after different treatments. *p < 0.05 vs. neurons treated with si-NC + DMSO. ^#p < 0.05 vs. neurons treated with si-NC + NAC. ^&p < 0.05 vs. neurons treated with si-NC + BAY117082. Cell experiment was repeated 3 times.

Figure 6

STC1 overexpression reduces depression-like behaviors. (A) STC1 and NF-κB p65 mRNA expression in the hippocampal tissues of rats with depression-like behaviors determined by RT-qPCR. (B) STC1 and NF-κB p65 protein expression in the hippocampal tissues of rats with depression-like behaviors measured by Western blot assay. (C) ROS production in the hippocampal tissues of rats with depression-like behaviors. (D) SOD, CAT, and MDA levels in the hippocampal tissues of rats with depression-like behaviors. (E) weight of rats with depression-like behaviors. (F) sucrose preference in rats with depression-like behaviors. (G) total movement distance and cumulative immobility time of rats with depression-like behaviors in the forced-swimming test and tail suspension experiment. (H) latency time of food foraging of rats with depression-like behaviors. (I) 5-HT, BDNF, and ACTH levels in the serum of rats with depression-like behaviors. (J) IL-1β, IL-6, TNF-α, hs-CRP, and IFN-γ levels in serum of rats with depression-like behaviors. (K) expression of neural plasticity-related genes (BDNF, GIUR1 and GFAP) and S100β determined by RT-qPCR. (L) expression of neural plasticity-related proteins (BDNF, GIUR1 and GFAP) and S100β measured by Western blot assay. (M) numbers of BrdU- and Nestin-positive cells in the hippocampus of rats with depression-like behaviors. (N) percentage of TUNEL-positive cells in the hippocampus of rats with depression-like behaviors. *p < 0.05 vs. stress-stimulated rats treated with oe-NC. n = 8.