Elsevier

Biological Psychiatry

Volume 85, Issue 3, 1 February 2019, Pages 214-225
Biological Psychiatry

Archival Report
SAR405, a Highly Specific VPS34 Inhibitor, Disrupts Auditory Fear Memory Consolidation of Mice via Facilitation of Inhibitory Neurotransmission in Basolateral Amygdala

https://doi.org/10.1016/j.biopsych.2018.07.026Get rights and content

Abstract

Background

Autophagy has been demonstrated to play an important role in memory deficits as well as the degradation of neurotransmitter receptors. SAR405 is a newly discovered inhibitor that can specifically inhibit vacuolar sorting protein 34 and prevent autophagosome biogenesis. However, the effects of SAR405 on memory processes remain largely unknown.

Methods

Western blotting, immunofluorescence, and transmission electron microscopy were used to assess the level of autophagy after fear conditioning and SAR405 treatment. Behavioral tests, biotinylation assay, electrophysiology, and co-immunoprecipitation were used to unravel the mechanisms of SAR405 in memory consolidation.

Results

SAR405 infusion into the basolateral amygdala impaired long-term memory through autophagy inhibition. Furthermore, the trafficking of gamma-aminobutyric acid type A receptors (GABAARs) following fear conditioning was disrupted by SAR405, and the decreased frequency and amplitude of miniature inhibitory postsynaptic currents induced by fear conditioning were also reversed by SAR405, suggesting that SAR405 disrupted memory consolidation through blockade of the downregulated inhibitory neurotransmission in basolateral amygdala. GABAAR-associated protein (GABARAP) and its interaction with GABAAR γ2 subunit were found to be upregulated after fear conditioning, and SAR405 could suppress this increased interaction. Moreover, disruption of the GABARAP-GABAAR binding by a trans-activating transcriptional activator–GABARAP inhibitory peptide blocked the decrease in surface expression of GABAARs and attenuated long-term memory.

Conclusions

The present study suggests that SAR405 can prevent the memory consolidation via intervening autophagy and GABAAR trafficking and has a potential therapeutic value for disorders characterized by exaggerated fear memories, such as posttraumatic stress disorder.

Section snippets

Animals

Male C57BL/6 mice used in the present study were obtained from Hunan Silaike Jingda Laboratory Animal Corporation Ltd (Changsha, China). They were maintained on a 12-hour light/dark cycle at a constant temperature (22 ± 2°C) and humidity of 50 ± 10% with food and water available ad libitum. Five mice were housed in a cage, and mice 8 to 11 weeks of age were used in the experiment. All experimental procedures were approved by the Animal Welfare Committee of Huazhong University of Science and

Infusion of SAR405 Into BLA Impairs Long-Term Memory and Inhibits Autophagy Induced by Auditory Fear Conditioning

First, we explored whether SAR405 had an effect on auditory fear conditioning. Mice implanted with a bilateral guide cannula aimed at the BLA were administered with SAR405 (1 μM) after recovering from surgery, as shown in Figure 1A. These mice were subjected to auditory fear conditioning 24 hours after administration. Fear memory was evaluated by measuring the percentage of freezing behavior at 3 hours (short-term memory [STM]) and 24 hours (long-term memory [LTM]) after training to investigate

Discussion

The present study demonstrated that SAR405, as a specific autophagy inhibitor, impaired memory consolidation through blocking the autophagy-dependent downregulation of the surface GABAAR γ2 subunit, and the increased GABARAP-GABAAR binding was required for autophagic degradation of surface GABAARs (Figure 6). These observations uncovered a novel role of autophagy pathway in learning and memory, and propose SAR405 as a new candidate for prevention of psychiatric disorders with altered fear

Acknowledgments and Disclosures

This work was supported by Foundation for Innovative Research Groups of National Natural Science Foundation of China Grant No. 81721005 to (J-GC and FW); National Basic Research Program of China Grant No. 2014CB744601 (to FW); National Natural Science Foundation of China Grant Nos. 81471377 (to FW), 81671438 (to FW), 81473198 (to J-GC), 81673414 (to J-GC); Program for Changjiang Scholars and Innovative Research Team in University Grant No. IRT13016 (to J-GC); and the Program for Huazhong

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    KL and H-SC contributed equally to this work.

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