Latent Sex Differences in CaMKII-nNOS Signaling That Underlie Antidepressant-Like Effects of Yueju-Ganmaidazao Decoction in the Hippocampus.

Ying Yin,Shiyu Qian,Yifan Chen,Wenda Xue,Dongdong Sun,Yongfei Yu,Yan Sun,Wei Wang,Jia Han,Xinlang Yu,Lanying Liu,Yuqiao Li,Zhangjie Wu,Rui Ge,Haoxin Wu,Jianqing Li

doi:10.3389/fnbeh.2021.640258

Abstract

Previous studies have demonstrated that Yueju-Ganmaidazao (YG) decoction induces rapid antidepressant-like effects, and the antidepressant response is mostly dependent on the suppression of nitric oxide-cyclic guanosine monophosphate signaling in male mice. This study aimed to investigate the sex difference mediated by calcium/calmodulin-dependent protein kinase II (CaMKII)-neuronal nitric oxide synthase (nNOS) signaling involved in the antidepressant-like effect of YG in mice. We found that the immobility times in the tail suspension test (TST) were found to be decreased after the single injection of YG in male and female mice with the same dosage. Additionally, chronic administration for 4 days of subthreshold dosage of YG and escitalopram (ES) also significantly decreased the immobility time in mice of both sexes. Chronic subthreshold dosage of YG and ES in LPS-treated mice and in chronic unpredictable stress (CUS) mice both decreased the immobility time, which was increased by stress. Meanwhile, in CUS-treated mice, sucrose preference test, forced swimming test, and open field test were applied to further confirm the antidepressant-like effects of YG and ES. Moreover, CUS significantly decreased the expression of nNOS and CaMKII, and both YG and ES could enhance the expression in the hippocampus of female mice, which was opposite to that in male mice, while endothelial nitric oxide synthase expression was not affected by stress or drug treatment neither in male mice nor in female mice. Finally, subthreshold dosage of YG combined with 7-nitroindazole (nNOS inhibitor) induced the antidepressant-like effects both in female and in male mice, while the single use of YG or 7-NI did not display any effect. However, pretreatment with KN-93 (CaMKII inhibitor) only blocked the antidepressant-like effect of high-dosage YG in female mice. Meanwhile, in CUS mice, chronic stress caused NR1 overexpression and inhibited cAMP response element binding protein action, which were both reversed by YG and ES in male and female mice, implying that YG and ES produced the same antidepressant-like effect in mice of both sexes. The study revealed that chronic treatment with a subthreshold dose of YG also produced antidepressant-like effects in female mice, and these effects depended on the regulation of the CaMKII-nNOS signaling pathway.

Highlights

Depression is one of the most common mental disorders that is associated with high morbidity and mortality, and it affects more than 350 million people in the world (Menard et al, 2016)
We measured the expression of neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) in the hippocampus of mice, and the results showed that the depressive-like behaviors in both sexes were significantly improved when compared with the CUS group, and in male mice, YG and ES decreased the expression of nNOS, but the eNOS expression did not change significantly
calmodulin-dependent protein kinase II (CaMKII) phosphorylates at Ser741 could lead to a reduction of nNOS activity by blocking the binding of Ca2+/CaM (Song et al, 2004; Takata et al, 2020). nNOS is a calcium-dependent enzyme, and we find that nNOS requires downstream of CaMKII signaling in both sexes, and the results are similar to those reported by Stein et al (2015)

Summary

Introduction

Depression is one of the most common mental disorders that is associated with high morbidity and mortality, and it affects more than 350 million people in the world (Menard et al, 2016). Women are more likely to suffer from anxiety disorders, while men are more likely to suffer from substance-use disorders, suggesting that there are some differences in the mechanisms of depression between the sexes. Evidence suggests that the sex-dependent differences have been observed in the antidepressant-like effects of ketamine, which are believed to modulate the NMDA signaling in the brain, and potentially indicates that there is a different underlying pathology between men and women (Carrier and Kabbaj, 2013; Franceschelli et al, 2015). We designed this study to search for clues underlying the sex differences in depression in the response to antidepressants

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