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Published on: October 27, 2020
Takeda G Protein-Coupled Receptor 5 Orchestrates Anxiolysis by Enhancing Anterior Paraventricular Thalamic Nucleus
Shanshan Hu1, Shuyun Xing1, Weijun Huang1
1Department of Pharmacology, College of Pharmacy, China Pharmaceutical University, Nanjing, China.
Background:
The pathogenesis of anxiety disorders remains elusive, underscoring the urgent need for novel therapeutic targets. In this study, we investigated the role of TGR5 (Takeda G protein-coupled receptor 5) in anxiety and its underlying molecular and neural circuit mechanisms.
Methods:
Open field, elevated plus maze, and novelty suppressed feeding tests were used to assess anxiety-like behaviors. Immunofluorescence, Western blot, and RNAscope in situ hybridization were used to characterize TGR5 expression. Adeno-associated virus vectors carrying Cre-dependent double-floxed inverted open-reading frame (DIO) sequence were injected into the anterior paraventricular thalamic nucleus (aPVT) of vGlut2-Cre mice for TGR5 bidirectional modulation. Fiber photometry and chemogenetic manipulations were used to assess neuronal activity along with behaviors. In vitro electrophysiology recordings were used to assess neuronal excitability and ICav3.1. Channelrhodopsin-2-assisted circuit mapping was used to explain neural circuits and synaptic mechanisms.
Results:
Chronic restraint stress (CRS) selectively downregulated TGR5 expression in aPVT glutamatergic neurons. TGR5 overexpression in aPVT glutamatergic neurons alleviated anxiety-like behaviors in CRS mice, while knockdown combined with subthreshold stress exacerbated anxiety phenotypes. Mechanistically, TGR5 activation enhanced aPVT glutamatergic neuronal excitability via the cAMP (cyclic adenosine monophosphate)/PKA (protein kinase A)/Cav3.1 pathway. TGR5 activation enhanced presynaptic glutamate release probability in the monosynaptic projection from the aPVT to the medial prefrontal cortex and restored the excitation-inhibition balance in the bed nucleus of the stria terminalis through direct efferent and indirect local circuit modulation under CRS, thereby contributing to emotional homeostasis.
Conclusions:
Our findings establish TGR5 as a pivotal regulator of anxiety, providing a crucial experimental foundation for novel therapeutics and a deeper understanding of anxiety disorders.
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