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Year : 2021  |  Volume : 17  |  Issue : 74  |  Page : 327-333  

Paeoniflorin prevents depression like behavior in rats by suppressing mitophagy mediated nod like receptor protein 3 inflammasome signaling

1 College of Traditional Chinese Medicine, North China University of Science and Technology, Tangshan, China
2 Basic Medical Sciences, Shaanxi University of Chinese Medicine, Xianyang, China

Date of Submission06-Mar-2020
Date of Decision05-May-2020
Date of Acceptance16-Feb-2021
Date of Web Publication12-Jul-2021

Correspondence Address:
Yongxue Zhou
Shiji Ave., Xi'an-Xianyang New Ecomic Zone, Shaanxi Province, 712046
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/pm.pm_85_20

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Background: The pathogenesis of depression is related to the NOD-like receptor protein 3 (NLRP3) inflammasome activation and low level of mitophagy. In traditional Chinese medicine, Paeonia lactiflora Pall is a common herb as a possible treatment for depression. As a main and active constituent of P. lactiflora Pall, paeoniflorin (PF)'s mechanisms of antidepression effects are not evidently unstated. Therefore, this study intended to explore whether PF can prevent depression-like behavior by conquering NLRP3 inflammasome activation and whether PF prevents NLRP3 inflammasome activation via upregulating mitophagy. Materials and Methods: Ten of a total of 50 rats were selected randomly as the control group. After establishment of the chronic unpredictable mild stress (CUMS) model, CUMS rats were randomly divided into four groups: CUMS group, fluoxetine hydrochloride group, PF group, and PF + cyclosporine A group. After 3 weeks of drug involvement, behavioral tests were measured. The protein expressions of PINK-1, Parkin, Beclin-1, LC3B, NLRP3, apoptosis-associated speck-like protein containing CARD (ASC), caspase-1 p20, interleukin-1β (IL-1β), and IL-18 were spotted with Western Blot method. Results: PF upturned stress persuaded behavioral changes and PF treatment augmented sucrose consumption rates (P < 0.01) in sucrose preference test and reduced the immobility time (P < 0.01) in forced swimming test of CUMS rats. PF also improved the levels of mitophagy-related proteins PINK-1, Parkin, Beclin-1, and LC3B (P < 0.01) in the hippocampus. Moreover, PF decreased the levels of NLRP3 inflammasome-related proteins (NLRP3, ASC, caspase-1 p20 antibody, IL-1β, and IL-18 [P < 0.01]) tempted by stress. Conclusion: PF advances depression in CUMS rats, reduced the inflammatory injury in the hippocampus of CUMS rats. Hence, based on those facts, NLRP3 inflammasome activation is accomplished by inhibiting its effect on mitophagy.

Keywords: Antidepressant-like activity, depression, mitophagy, NOD-like receptor protein 3 inflammasome, paeoniflorin

How to cite this article:
Wang M, Yan S, Kong J, Zhou Y, Xie P. Paeoniflorin prevents depression like behavior in rats by suppressing mitophagy mediated nod like receptor protein 3 inflammasome signaling. Phcog Mag 2021;17:327-33

How to cite this URL:
Wang M, Yan S, Kong J, Zhou Y, Xie P. Paeoniflorin prevents depression like behavior in rats by suppressing mitophagy mediated nod like receptor protein 3 inflammasome signaling. Phcog Mag [serial online] 2021 [cited 2022 Dec 7];17:327-33. Available from: http://www.phcog.com/text.asp?2021/17/74/327/321264


  • Paeoniflorin employs antidepressant-like effects in chronic unpredictable mild stress rats and thus expands rats' behaviors
  • Paeoniflorin not only improves the activity of mitophagy but also prevents the NOD-like receptor protein 3 inflammasome activation in the hippocampus of chronic unpredictable mild stress rats. Thus, paeoniflorin hinders NOD-like receptor protein 3 inflammasome activation in depression context by modifiable mitophagy.

Abbreviations used: ASC: Apoptosis-associated speck-like protein containing CARD; CUMS: Chronic unpredictable mild stress; CYC-A: Cyclosporine A; FLU-HCl: Fluoxetine hydrochloride; FST: Forced swimming test; IL-1β: Interleukin-1β; NLRP3: NOD-like receptor protein 3; PF: Paeoniflorin; SPT: Sucrose preference test.

   Introduction Top

Depression represents a wide range of mental illnesses with multifactorial psychopathologies. It is one of the most common mental ailments and a major public health problem in the modern society.[1] Although many treatments are available for depression, more than 30% of patients with depression do not effect reasonable recovery.[2] Therefore, the development of safer and effective drugs for this illness is highly obligatory.

In a recent report, it has been familiar that depression is strongly associated with inflammation.[3] NOD-like receptor protein 3 (NLRP3) inflammasome activation activates inflammation and depression.[4] It has been specified that the components of NLRP3 inflammasome in the serum of depressed rats were augmented. Application of NLRP3 inflammasome inhibitor reduced Interleukin-1β (IL-1β) levels in the serum and hippocampus tissues and lessened the depression-associated behaviors in rats.[5],[6] NLRP3 gene knockout mice did not demonstrate depressive behavior under chronic stress.[7] As a downstream effector of NLRP3 inflammasome, IL-1 β can precisely imitate the activation level of NLRP3 inflammasome. IL-1 β composes the first step of pro-inflammatory response to psychological stress and when unduly produced, it causes cell injury in stress-related diseases comprising depression.[8] It was found that patients with severe depression and suicidal tendencies have severe neuroinflammatory responses, IL-1 β is augmented in their frontal cortex.[9] Therefore, the NLRP3 inflammasome may be a key mark to the treatment of depression.

Mitophagy is a kind of autophagy in which damaged mitochondria are familiar by the autophagosomes to the lysosomes for degradation.[10] Mitophagy destroys damaged mitochondria and inhibits NLRP3 inflammasome activation via mitochondrial reactive oxygen species (mtROS) and mitochondrial DNA (mtDNA). In this way, mitophagy defends cells against damage.[11],[12] There is an indication that the mitophagy level is reduced in the hippocampus of depressed rats and some antidepression drugs could improve mitophagy expressively.[13],[14]

In traditional Chinese medicine, Paeonia lactiflora Pall has the function of “shuganjieyu.” Paeoniflorin (PF), a monoterpene glycoside compound (the main active component of P. lactiflora Pall), is frequently used to treat depressive-like disorder.[15] For instance, PF eased cell injury caused by depression-related neurotoxicity.[16] An earlier study displayed that PF reduced the serum level of inflammatory mediators such as IL-1 β, tumor necrosis factor-α, and IL-6 and decreased the expression of neuroinflammatory factors in the prefrontal cortex, ventral hippocampus, and amygdala.[17] A study on menopause-induced depression showed that application of PF at a dose of 10 mg/kg diminished the stress hormone levels.[18] The anti-inflammatory effect of PF in the nervous system has also been detected in many models of neuroinflammation.[17],[19] However, whether PF moves the NLRP3 inflammasome and mitophagy remains indescribable.

In this study, chronic unpredictable mild stress (CUMS) rats were employed as a depression model. PF was used as an intervention for CUMS rats. Fluoxetine hydrochloride (FLU-HCl) was used as a positive control drug for CUMS rats. Cyclosporine A (CYC-A), a mitophagy inhibitor, was employed combined with PF. Levels of the proteins (PINK-1, Parkin, Beclin-1, and LC3B) related to mitophagy and proteins (NLRP3, apoptosis-associated speck-like protein containing CARD [ASC], caspase-1 p20, IL-1 β, and IL-18) related to NLRP3 inflammasome in the hippocampus were distinguished.

   Materials and Methods Top

Reagents and antibodies

PF (CAS No. 23180-57-6, purity was higher than 98%) was purchased from Chenguang Biotechnology Co. Ltd., Baoji, China. FLU-HCl (CAS No. 56296-78-7) was purchased from Sigma-Aldrich Co. Ltd., USA. CYC-A (CAS No. z130495) was procured from National Institutes for Food and Drug Control (Beijing, China). BCA Protein Assay Kit (Cat # PC 0020) was obtained from Solarbio Science and Technology Co. Ltd., Beijing, China. β-actin antibody was bought from Bioss Biotechnology Co. Ltd., Beijing, China. Anti-TMS1 (ASC, ab175449), anti-caspase-1 (ab1872), anti-NLRP3 (ab214185), anti-IL-18 (ab191860), anti-IL-1 β (ab9722), anti-PINK-1 (ab23707), anti-Parkin (ab77924), anti-LC3B1/2 (ab48934), anti-SQSTM1/p62 (ab91526), and anti-Beclin-1 (ab62557) antibodies were acquired from Abcam Biotechnology Co. Ltd., Cambridge, UK.

Model and treatment


Seventy male SD rats (180 ± 20 g) were provided by the Animal Centre of Xi'an Jiaotong University (P. R. China, Certificate No. SCXK [Shan] 2017-003). Animals were accommodated at the conservative dwelling unit under standard conditions (a controlled room temperature [25°C ± 2°C], relative humidity [65% ± 10%], and 12 h light/dark cycle). This research was permitted by the Animal Ethics Committee of Shaanxi University of Traditional Chinese Medicine. The experimental design is revealed in [Figure 1].
Figure 1: The experimental design. The chronic unpredictable mild stress protocol lasted for 6 weeks, during which rats were stimulated by a variety of mild stressors. After chronic unpredictable mild stress procedure for 3 weeks, drugs for rats in each group were administered. Sucrose preference test and forced swimming test were implemented at the final stage of animal experiments

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Chronic unpredictable mild stress model

After 5 days of adaptation, the rats were given sucrose drinking training and sucrose preference rate baseline test. In the first 24 h, the rats were given two bottles of 1% sucrose solution (500 mL). In the second 24 h, the rats were given 1 bottle of 1% sucrose solution (500 mL) and 1 bottle of water (500 mL). Additional, baseline assessment of sucrose preference (SP) of rats was verified. After water prohibition for 24 h, the rats were given 1% sucrose solution and 1 bottle of water. After calculating the SP rate, the rats with low sucrose intake (SP < 0.5, SP = weight of sucrose solution intake/weight of total intake) were detached to prevent low-level sweetness in rats from distressing the results. Each rat was exposed to 1 stressor per day for 3 weeks except those in the control group (n = 10). The CUMS modeling method was achieved as described earlier.[20] A series of stressors in the CUMS group comprised swimming in cold water (4°C) for 5 min, cage tilting at a 45° angle (12 h), overnight lighting for 36 h, wet pad for 15 h (per 100 g sawdust with 200 mL water), food deprivation for 24 h, clamping tail for 5 min (tail of rats were clamped gently for 5 times, 50s each time), water deprivation for 24 h, crowding for 3 h (every eight rats were located in a small cage with a size of 25 cm × 15 cm × 13 cm), cage shaking for 5 min (each cage was shaken to the extent that rats could not stand), and vinegar stimulation for 24 h (20 mL vinegar was scattered in each cage). All stressors were pragmatic randomly and continuously at any time of the day and were given 1 or 2 times within the CUMS procedure. SP and weight were planned after CUMS treatment again. When the rats in the control and model group had noteworthy differences in SP, the CUMS model was measured effective.

Grouping and treatment

After the CUMS model was recognized successfully, the SP of rats was tested again and sucrose predilections of each rat before and after modeling were likened. Rats which botched during the modeling steps were detached from the experiment. Successfully stressed rats with reliable weight and SP were aimlessly divided into four groups: CUMS group (n = 10), FLU-HCl group (n = 10), PF group (n = 10), and PF + CYC-A group (n = 10). Rats in the control group, CUMS group, FLU-HCl group, and PF group received intraperitoneal (i. p.) injection of 0.9% sodium chloride (10 mL/kg) every day. Rats in PF + CYC-A group received i. p. injection of CYC-A (10 mg/kg) every day. Rats in the control group and CUMS group received intragastric (i. g.) administration of 0.9% sodium chloride (10 mL/kg) every day. Rats in the FLU-HCl group received i. g. administration of FLU-HCl (10 mg/kg) every day and rats in PF group and PF + CYC-A group received i. g. administration of PF (10 mg/kg) every day. Rats in each group were interfered at 10 a. m. for 3 weeks. During the treatments, all the rats excluding those in the control group continued to receive stressors.

Behavioral tests

After 3-weeks' treatment, behavioral tests were accomplished. Behavioral tests involved sucrose consumption test and forced swimming test (FST). To evade that one behavioral test might have restricted with behavior in the subsequent test, the behavioral tests were carried out at an interval of 2 days. FST was carried out at 3 pm and SP test (SPT) was achieved at 8 pm. In our study, SPT was performed weekly. On the day of behavior test, drug interferences were still carried out on rats.

Sucrose preference test

SPT is often used to measure the anhedonia behaviors of rodents.[21] To remove the effect of circadian rhythm on water drinking in rats, the test was achieved at night (8 p. m.) in a quiet room with controlled temperature (25°C ± 2°C) and relative humidity (65% ± 10%). Before SPT, the rats were deprived of food and water for 24 h. Then, the rats were given 200 mL water and 200 mL 1% sucrose solution for 1 h. In the middle of SPT, the bottle position was transformed. Before and after SPT, the drinking tubes were assessed to calculate SP.[22] The SP percentage was designed according to the following formula: SP = weight of sucrose solution intake/weight of total intake. When the SP of rats in the CUMS group was decreased compared with control group, which represented the anhedonia of rats, indicating the CUMS depression model was effective.[23]

Forced swimming test

The rats were placed in a glass cylinder with a size of 20 cm (diameter) ×40 cm (height), filled with water to a 30 cm depth. In this test, the rats were mandatory to swim in a glass cylinder for 6 min. The duration of immobility was logged during the last 4 min. For each test, water with a controlled temperature (24°C ± 1°C) was substituted for each rat. After the test, the rats were dehydrated and placed in a thermostat for 5 min.

Western blot analysis

After treatments and behavioral tests, the rats were surrendered for Western blot tissue collection. After saline infusion, the rats were anatomized and decapitated immediately on ice. Hippocampus tissues were carefully isolated on the ice and preserved at −80°C. Hippocampus tissues (100 mg) were evaluated, placed in a centrifugal tube, and homogenized by 1 mL hippocampus tissue lysis buffer solution. After incubation on ice for 30 min (the protein was blended every 10 min), the protein supernatants were centrifuged with a high-speed centrifuge (12,000 g, 4°C) for 15 min. BCA assay kit was employed to assess protein concentrations. After the addition of protein sample buffer, the proteins were denatured in water (100°C) for 5 min, then separated by SDS-PAGE gel electrophoresis and transferred to a 0.45 μm polyvinylidene fluoride membrane. The membrane was congested in TBST containing 5% skimmed milk for 2 h at room temperature and then incubated with primary antibodies for 10 h at 4°C. After washing four times (5 min each time), the membrane was protected with an anti-rabbit secondary antibody (room temperature for 2 h). Finally, the membrane was imagined by the chemiluminescence detection system.

Data analysis

Data were presented as mean ± standard deviation and analyzed by ANOVA. Dunnett's t-test and LSD t-test were also used. Statistical differences between the groups were measured significant when the probability level of P < 0.05.

   Results Top

Paeoniflorin improves the stress state of chronic unpredictable mild stress rats

After CUMS model was recognized, the rats were in a state of depression such as clustering, weight loss, appetite loss, hair loss, irritability, and low spirits. PF could suggestively advance the state of depression of rats.

Paeoniflorin increases sucrose consumption rate

As shown in [Figure 2]a, the baseline of SP for rats was confirmed before the establishment of CUMS, there was no alteration in SP rate among the five groups. After 3-week modeling, sucrose consumption rates for CUMS rats were diminished when compared with the control group [P < 0.01 [Figure 2]b]. After FLU or PF treatment for 1 week, 2 weeks, and 3 weeks, the sucrose consumption rates were augmented [P < 0.01, [Figure 2]c, [Figure 2]d, [Figure 2]e]. In addition, after PF treatment for 2 and 3 weeks, rats in the PF group showed a significant surge in the sucrose consumption rate as compared with those in the PF + CYC-A group [P < 0.05, [Figure 2]d and [Figure 2]e].
Figure 2: Sucrose preference rate. Before modeling, there was no difference in sucrose preference test among all groups (a). After 3-week chronic unpredictable mild stress procedure (b), **P < 0.01 indicates comparison with control group. After 1-week treatments (c). **P < 0.01 indicates comparison with control group, ^^P < 0.01 indicates comparison with the chronic unpredictable mild stress group, ##P < 0.01 indicates comparison with chronic unpredictable mild stress group. After 2- and 3-week treatments (d and e). **P < 0.01 indicates comparison with control group, ^^P < 0.01 and ##P < 0.01 indicate comparison with chronic unpredictable mild stress group, +P < 0.05 indicates comparison with PF group

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Paeoniflorin decreases immobility time in forced swimming test

In CUMS group, the immobility time of rats was suggestively greater than the control group [P < 0.01, [Figure 3]]. In contrast, the immobility time of rats in FLU group and PF group was strikingly reduced after 3-week treatment [P < 0.01 [Figure 3]]. As expected, PF treatment abridged the immobility time compared with PF + CYC-A treatment [P < 0.01, [Figure 3]].
Figure 3: Immobility time of forced swimming test. After 3 weeks of treatments, the immobility time of rats during forced swimming was tested. **P < 0.01 indicates comparison with the control group, ^^P < 0.01 and ##P < 0.01 indicate comparison with the chronic unpredictable mild stress group, +P < 0.05 indicates comparison with the PF group

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Paeoniflorin increases the level of mitophagy

The expressions of mitophagy-related proteins PINK-1, Parkin, Beclin-1, and LC3B in hippocampal tissues are exposed in [Figure 4]a, [Figure 4]b, [Figure 4]c, [Figure 4]d. The CUMS procedure reduced the protein expression of PINK-1 [P < 0.01, [Figure 4]a], Parkin [P < 0.01, [Figure 4]b], Beclin-1 [P < 0.01, [Figure 4]c], and LC3B [P < 0.01, [Figure 4]d]. PF competently augmented the levels of these proteins [P < 0.01, [Figure 4]a, [Figure 4]b, [Figure 4]c, [Figure 4]d]. Application of mitophagy inhibitor, CYC-A, eliminated the effects of PF on the protein expression, as showed by the importantly reduced protein expression [P < 0.01, [Figure 4]a, [Figure 4]b, [Figure 4]c, [Figure 4]d].
Figure 4: The level of mitophagy. After 3 weeks of treatments, the expressions of PINK-1 (a), Parkin (b), Beclin-1 (c), and LC3B (d) of rats were tested. **P < 0.01 indicates comparison with the control group, ^^P < 0.01 and ##P < 0.01 indicate comparison with the chronic unpredictable mild stress group, ++P < 0.01 indicates comparison with the PF group

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Paeoniflorin blocks activation of NOD-like receptor protein 3 inflammasome

The expressions of proteins involved in NLRP3 inflammasome activation are shown in [Figure 5]a, [Figure 5]b, [Figure 5]c. The result shows that the CUMS procedure improved NLRP3 [P < 0.01, [Figure 5]a], ASC [P < 0.01, [Figure 5]b], and caspase-1 p20 [P < 0.01, [Figure 5]c] in the hippocampus. PF or FLU-HCl treatment reduced these proteins in CUMS rats [P < 0.01, [Figure 5]a, [Figure 5]b, [Figure 5]c]. Application of mitophagy inhibitor, CYC-A, expressively augmented the expression levels of NLRP3 [P < 0.01, [Figure 5]a], ASC [P < 0.01, [Figure 5]b], and caspase-1p20 [P < 0.01, [Figure 5]c].
Figure 5: NOD-like receptor protein 3 inflammasome activation. After 3 weeks of treatments, the expression of NOD-like receptor protein 3 (a), Apoptosis-associated speck-like protein containing CARD (b), and Caspase-1 p20 (c) of rats were tested. **P < 0.01 indicates comparison with the control group, ^^P < 0.01 and ##P < 0.01 indicate comparison with the chronic unpredictable mild stress group, ++P < 0.01 indicates comparison with the PF group

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Paeoniflorin decreases the levels of interleukin-1 β and interleukin-18

Variations in protein levels of IL-1 β and IL-18 in the hippocampus of rats are shown in [Figure 6]a and [Figure 6]b. Reliably, the CUMS procedure augmented the protein levels of IL-1β [P < 0.01, [Figure 6]a] and IL-18 [P < 0.01, [Figure 6]b] suggestively, which were diminished by PF [P < 0.01, P < 0.01, [Figure 6]a and [Figure 6]b] and FLU-HCl treatment [P < 0.01, [Figure 6]a and [Figure 6]b]. Application of mitophagy inhibitor, CYC-A, meaningfully augmented the levels of IL-1β [P < 0.01, [Figure 6]a] and IL-18 [P < 0.01, [Figure 6]b].
Figure 6: Analysis of pro-inflammatory cytokines. After 3 weeks of treatments, the expression of IL-1 β (a) and IL-18 (b) of rats were tested. **P < 0.01 indicates comparison with the control group, ^^P < 0.01 and ##P < 0.01 indicate comparison with the chronic unpredictable mild stress group, ++P < 0.01 indicates comparison with the PF group

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   Discussion Top

Depression designates a group of mental disorders with multifactorial psychopathologies. CUMS is demarcated as a chronic impulsive mild stress-induced depression model, which is a typical modeling method for depression. The etiology and pathological mechanism of CUMS model are similar to those of human depression.[24] Thus, this work purposes to study the mechanism of depression.[25] PF is a major essential of the root part of P. lactiflora Pall and has several biological activities.[26] The antidepressant-like effects of PF have been reported earlier.[27] There were indications recommended that the antidepressant mechanisms of PF are thoroughly related to its inhibition of neuroinflammatory response.[17],[19] Thus, we explored the pharmacological mechanism of PF and examined whether NLRP3 inflammasome and mitophagy mediate the antidepressant-like effects of PF.

SPT is frequently employed to measure the state of absence of delight. FST is often used to evaluate the success of depression models as well as the effectiveness of antidepressant agents.[28] After CUMS procedure, FST established that rats precisely replicated the depressive state. The depressive state of rats was recognized in the decrease of sucrose consumption in SPT and the increase of immobility time in FST. Application of PF upturned the stress-induced behavioral changes, demonstrating that PF exerts antidepressant effects.

Inflammation is concerned in depression pathologic process. Studies have shown that chronic stress and systemic inflammation happen in CUMS rats.[29] NLRP3 inflammasome activation has been detected in the hippocampus of depressed mice and NLRP3 inflammasome intercedes depression through neuroinflammation.[8] The antidepressant effect of fluoxetine was linked to its inhibition of the NLRP3 inflammasome.[30] NLRP3 inflammasome is composed of NLRP3, ASC, and procaspase-1. After NLRP3 inflammasome activation, procaspase-1 is cleaved into mature caspase-1 through MAPK and NF-kappa B signaling pathways and the pro-IL-1 β and pro-IL-18 are cleaved into mature IL-1 β and IL-18.[31]

In this study, the protein levels of NLRP3, ASC, caspase-1 p20, IL-1 β, and IL-18 in the hippocampus of rats were augmented after the CUMS procedure, representing incidence of a notable inflammatory injury in the hippocampus. Particularly, the stress-induced inflammation injury was improved by treatment with PF or FLU-HCl, signifying that PF employs antidepressant effects by inhibiting NLRP3 inflammasome activation.

Accumulating evidence proposes that mitochondria are convoluted in the NLRP3 inflammasome activation.[32] The release or acquaintance of mitochondrial ROS and DNA after mitochondrial injury causes the assembly of the NLRP3 inflammasome activation.[33] Thus, the oxidation of mtDNA activates NLRP3 inflammasome.[34] Mitophagy abolishes damaged mitochondria and averts mtROS and mtDNA from being released into the cytoplasm, thereby limiting the NLRP3 inflammasome activation.[35] Stimulating macrophages knockout genes LC3B or Beclin-1 with ATP, resulted in an increase in damaged mitochondria and activation of NLRP3 inflammasome.[36] Mitophagy prevents the NLRP3 inflammasome activation.[37] PINK-1-Parkin pathway is a key regulator of mitophagy. Protein kinase (PINK-1) is amalgamated in the cytoplasm, after which it enters the mitochondria through the molecular channel of the mitochondrial membrane. It is finally degraded by proteolytic enzymes in the mitochondria.[38] Mitochondrial injury leads to the accumulation of PINK-1 on extracorporeal membrane of mitochondria. Parkin, an E3 ubiquitin-protein ligase, is activated by PINK-1. This ligase can ubiquitinate dented mitochondrial membrane proteins, which interact with signal junction proteins and autophagy-related proteins on the phagocytic membrane. In this way, it pledges the phagocytosis and finally reduces damaged mitochondria.[39],[40]

In this study, the levels of PINK-1, Parkin, Beclin-1, and LC3B proteins in the hippocampus of rats were reduced after the CUMS procedure, representing that the level of mitophagy was diminished in the hippocampus. The level of mitophagy in the hippocampus was augmented after treatment with PF or FLU-HCl, signifying that the PF antidepressant consequence may comprise enhancement of mitophagy. We also found that the mitophagy inhibitor, CYC-A, could partially deteriorate the downregulation effect of PF on NLRP3 inflammasome activation, thereby blocking the antidepressant effects of PF.

   Conclusion Top

PF improves depressive symptoms in CUMS rats. This is accomplished by inhibiting the NLRP3 inflammasome activation. In addition, it averts inflammation temperately by enhancing mitophagy.


The authors thank the Science and Technology Coordinated Innovation Project of Shaanxi Province for the funding.

Financial support and sponsorship

This study was supported by the Science and Technology Coordinated Innovation Project of Shaanxi Province, China [2016TTC-S-1-7].

Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]


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