Dan-Dan Xu, Zhi-Qi Hou, Ya-Yun Xu, Jun Liang, Ye-Jun Gao, Chen Zhang, Fan Guo, Dan-Dan Huang, Jin-Fang Ge, Qing-Rong Xia
{"title":"Potential Role of Bmal1 in Lipopolysaccharide-Induced Depression-Like Behavior and its Associated","authors":"Dan-Dan Xu, Zhi-Qi Hou, Ya-Yun Xu, Jun Liang, Ye-Jun Gao, Chen Zhang, Fan Guo, Dan-Dan Huang, Jin-Fang Ge, Qing-Rong Xia","doi":"10.1007/s11481-024-10103-3","DOIUrl":null,"url":null,"abstract":"<p>Inflammation plays an important role in the pathogenesis of depression; however, the underlying mechanisms remain unclear. Apart from the disordered circadian rhythm in animal models and patients with depression, dysfunction of clock genes has been reported to be involved with the progress of inflammation. This study aimed to investigate the role of circadian clock genes, especially brain and muscle ARNT-like 1 (Bmal1), in the linkage between inflammation and depression. Lipopolysaccharide (LPS)-challenged rats and BV2 cells were used in the present study. Four intraperitoneal LPS injections of 0.5 mg/kg were administered once every other day to the rats, and BV2 cells were challenged with LPS for 24 h at the working concentration of 1 mg/L, with or without the suppression of Bmal1 via small interfering RNA. The results showed that LPS could successfully induce depression-like behaviors and an “inflammatory storm” in rats, as indicated by the increased immobility time in the forced swimming test and the decreased saccharin preference index in the saccharin preference test, together with hyperactivity of the hypothalamic–pituitary–adrenal axis, hyperactivation of astrocyte and microglia, and increased peripheral and central abundance of tumor necrosis factor-α, interleukin 6, and C-reactive protein. Moreover, the protein expression levels of brain-derived neurotrophic factor, triggering receptor expressed on myeloid cells 1, Copine6, and Synaptotagmin1 (Syt-1) decreased in the hippocampus and hypothalamus, whereas the expression of triggering receptor expressed on myeloid cells 2 increased. Interestingly, the fluctuation of temperature and serum concentration of melatonin and corticosterone was significantly different between the groups. Furthermore, protein expression levels of the circadian locomotor output cycles kaput, cryptochrome 2, and period 2 was significantly reduced in the hippocampus of LPS-challenged rats, whereas Bmal1 expression was significantly increased in the hippocampus but decreased in the hypothalamus, where it was co-located with neurons, microglia, and astrocytes. Consistently, apart from the reduced cell viability and increased phagocytic ability, LPS-challenged BV2 cells presented a similar trend with the changed protein expression in the hippocampus of the LPS model rats. However, the pathological changes in BV2 cells induced by LPS were reversed after the suppression of Bmal1. These results indicated that LPS could induce depression-like pathological changes, and the underlying mechanism might be partly associated with the imbalanced expression of Bmal1 and its regulated dysfunction of the circadian rhythm.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>\n<p><b>Conclusions</b> In conclusion, our results indicated that LPS could induce depression-like behaviors and an “inflammatory storm” in vivo, activate microglia in vitro, together with a disruption of synaptic plasticity and circadian rhythm. This mechanism may be involved in the imbalanced expression of Bmal1. Our results can help uncover a novel clock-immunological mechanism of neuroinflammation-induced depression and shed light on the development of new effective pharmacotherapies for depression</p>","PeriodicalId":16500,"journal":{"name":"Journal of Neuroimmune Pharmacology","volume":null,"pages":null},"PeriodicalIF":5.2000,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Neuroimmune Pharmacology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1007/s11481-024-10103-3","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"NEUROSCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Inflammation plays an important role in the pathogenesis of depression; however, the underlying mechanisms remain unclear. Apart from the disordered circadian rhythm in animal models and patients with depression, dysfunction of clock genes has been reported to be involved with the progress of inflammation. This study aimed to investigate the role of circadian clock genes, especially brain and muscle ARNT-like 1 (Bmal1), in the linkage between inflammation and depression. Lipopolysaccharide (LPS)-challenged rats and BV2 cells were used in the present study. Four intraperitoneal LPS injections of 0.5 mg/kg were administered once every other day to the rats, and BV2 cells were challenged with LPS for 24 h at the working concentration of 1 mg/L, with or without the suppression of Bmal1 via small interfering RNA. The results showed that LPS could successfully induce depression-like behaviors and an “inflammatory storm” in rats, as indicated by the increased immobility time in the forced swimming test and the decreased saccharin preference index in the saccharin preference test, together with hyperactivity of the hypothalamic–pituitary–adrenal axis, hyperactivation of astrocyte and microglia, and increased peripheral and central abundance of tumor necrosis factor-α, interleukin 6, and C-reactive protein. Moreover, the protein expression levels of brain-derived neurotrophic factor, triggering receptor expressed on myeloid cells 1, Copine6, and Synaptotagmin1 (Syt-1) decreased in the hippocampus and hypothalamus, whereas the expression of triggering receptor expressed on myeloid cells 2 increased. Interestingly, the fluctuation of temperature and serum concentration of melatonin and corticosterone was significantly different between the groups. Furthermore, protein expression levels of the circadian locomotor output cycles kaput, cryptochrome 2, and period 2 was significantly reduced in the hippocampus of LPS-challenged rats, whereas Bmal1 expression was significantly increased in the hippocampus but decreased in the hypothalamus, where it was co-located with neurons, microglia, and astrocytes. Consistently, apart from the reduced cell viability and increased phagocytic ability, LPS-challenged BV2 cells presented a similar trend with the changed protein expression in the hippocampus of the LPS model rats. However, the pathological changes in BV2 cells induced by LPS were reversed after the suppression of Bmal1. These results indicated that LPS could induce depression-like pathological changes, and the underlying mechanism might be partly associated with the imbalanced expression of Bmal1 and its regulated dysfunction of the circadian rhythm.
Graphical Abstract
Conclusions In conclusion, our results indicated that LPS could induce depression-like behaviors and an “inflammatory storm” in vivo, activate microglia in vitro, together with a disruption of synaptic plasticity and circadian rhythm. This mechanism may be involved in the imbalanced expression of Bmal1. Our results can help uncover a novel clock-immunological mechanism of neuroinflammation-induced depression and shed light on the development of new effective pharmacotherapies for depression
期刊介绍:
The aims of the Journal of Neuroimmune Pharmacology are to promote the dissemination, interest, and exchange of new and important discoveries for the pharmacology and immunology of the nervous system. The aims parallel that of the Society on NeuroImmune Pharmacology by increasing the fundamental understanding of neurologic and neuropsychiatric disorders affected by the immune system or vice versa and towards pharmacologic measures that lead, either to a better understanding of disease mechanisms, or by improving disease outcomes. The scope of JNIP includes all primary works and reviews into the etiology, prevention, and treatment of neuroimmune and nervous system diseases affected by disordered immunity. Original studies serving to define neuroimmune modulation of environmental or endogenous cues such as toxins and drugs of abuse, hormones, and cytokines are welcome. JNIP will serve as a reliable source of interdisciplinary information bridging the fields of pharmacology, immunology, and neuroscience.