VGluT2 neuron subtypes in the paraventricular thalamic nucleus regulate depression in paraquat-induced Parkinson's disease.

Parkinson's disease (PD) is a prevalent neurodegenerative disease and approximately one third of patients with PD are estimated to experience depression. Paraquat (PQ) is the most widely used herbicide worldwide and PQ exposure is reported to induce PD with depression. However, the specific brain region and neural networks underlying the etiology of depression in PD, especially in the PQ-induced model, have not yet been elucidated. Here, we report that the VGluT2-positive glutamatergic neurons in the paraventricular thalamic nucleus (PVT) promote depression in the PQ-induced PD mouse model. Our results show that PVTVGluT2 neurons are activated by PQ and their activation increases the susceptibility to depression in PD mice. Conversely, inhibition of PVTVGluT2 neurons reversed the depressive-behavioral changes induced by PQ. Similar to the effects of intervention the soma of PVTVGluT2 neurons, stimulation of their projections into the central amygdaloid nucleus (CeA) also strongly influenced depression in PD mice. PQ induced malfunctioning of the glutamate system and changes in the dendritic and synaptic morphology in the CeA through its role on PVTVGluT2 neuronal activation. In summary, our results demonstrate that PVTVGluT2 neurons are key neuronal subtypes for depression in PQ-induced PD and promote depression processes through the PVTVGluT2-CeA pathway.

Neurorotective Effect of Chaihu Jia Longgu Mulitang on Parkinson's Disease with Depression Model Rats and Its Mechanism Based on AMPK/mTOR Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo observe the protective effect of Chaihu Jia Longgu Mulitang （CLMT） on dopaminergic neurons in Parkinson's disease with depression （PDD） model rats， and to explore the mechanism based on adenosine monophosphate-activated protein kinase/mammalian target of rapamycin （AMPK/mTOR） signaling pathway. MethodAmong the 80 male SD rats， 10 were randomly selected as normal group and the rest were treated with long-term low-dose subcutaneous injection of rotenone in the neck and back combined with chronic unpredictable mild stress （CUMS） to establish PDD rat model. The successfully modeled PDD rats were randomly divided into model group， western medicine group （madopar 0.032 g·kg-1+fluoxetine hydrochloride 0.002 g·kg-1）， CLMT low-dose， medium-dose and high-dose groups （5， 10 and 20 g·kg-1）， 10 rats in each group. Normal group and model group were administrated with the same amount of normal saline by gavage for 4 consecutive weeks. Behavioral changes of rats in each group were evaluated by open field test and pole climbing test. The content of dopamine （DA） and 5-hydroxytryptamine （5-HT） in cerebrospinal fluid was determined by high performance liquid chromatography （HPCL）. The pathological changes of dopaminergic neurons in substantia nigra of rats were observed by hematoxylin-eosin （HE） staining. The positive expression of tyrosine hydroxylase （TH） and expression of α-synuclein in substantia nigra were detected by immunohistochemistry （IHC） and immunofluorescence （IF）， repsectively. The protein expression of microtubule-associated protein 1 light chain 3 （LC3）， adenosine monophosphate-activated protein kinase （AMPK）， phosphorylated AMPK （p-AMPK）， mammalian target of rapamycin （mTOR） and phosphorylated mTOR （p-mTOR） was detected by Western blot. ResultCompared with the conditions in normal group， the total horizontal distance and the activity time in the central region in open field test and the content of DA and 5-HT in cerebrospinal fluid were decreased （P<0.05， P<0.01）， and the time of pole climbing was shortened （P<0.01）， with increased score （P<0.01） in model group. Compared with model group， CLMT high-dose group and western medicine group increased the total horizontal distance and activity time in the central region and the content of DA and 5-HT （P<0.05， P<0.01）， and extended the time of climbing pole （P<0.05）， with decreased score （P<0.05， P<0.01）. Compared with those in normal group， the number of dopaminergic neurons in the substantia nigra was reduced， with narrowed and loosely arranged cell body. The fluorescence expression of α-synuclein was enhanced （P<0.01）， and the positive expression of TH was decreased （P<0.01） in model group. Compared with model group， CLMT high-dose group and western medicine group showed elevated number of dopaminergic neurons in the substantia nigra， with enlarged cell body， and decreased fluorescence expression of α-synuclein， and enhanced the positive expression of TH （P<0.05， P<0.01）. Compared with normal group， model group had lowered expression of LC3Ⅱ/Ⅰ， p-AMPK/AMPK in striatum （P<0.05， P<0.01） and increased expression of p-mTOR/mTOR （P<0.01）. Compared with those in model group， LC3Ⅱ/Ⅰ and p-AMPK/AMPK expression were increased （P<0.05， P<0.01） and p-mTOR /mTOR expression was decreased （P<0.01） in CLMT high-dose group and western medicine group. ConclusionCLMT exerts a neuroprotective effect by inhibiting rotenone neurotoxicity. It enhances the level of DA， and thus improves the depression condition in rats with Parkinson's disease. The underlying mechanism may be related to the regulation of AMPK/mTOR signaling pathway， activation of autophagy， and promotion of degrading α-synuclein.

Development and Validation of a Plasma FAM19A5 and MRI-Based Radiomics Model for Prediction of Parkinson's Disease and Parkinson's Disease With Depression.

Background: Prediction and early diagnosis of Parkinson's disease (PD) and Parkinson's disease with depression (PDD) are essential for the clinical management of PD. Objectives: The present study aimed to develop a plasma Family with sequence similarity 19, member A5 (FAM19A5) and MRI-based radiomics nomogram to predict PD and PDD. Methods: The study involved 176 PD patients and 181 healthy controls (HC). Sandwich enzyme-linked immunosorbent assay (ELISA) was used to measure FAM19A5 concentration in the plasma samples collected from all participants. For enrolled subjects, MRI data were collected from 164 individuals (82 in the PD group and 82 in the HC group). The bilateral amygdala, head of the caudate nucleus, putamen, and substantia nigra, and red nucleus were manually labeled on the MR images. Radiomics features of the labeled regions were extracted. Further, machine learning methods were applied to shrink the feature size and build a predictive radiomics signature. The resulting radiomics signature was combined with plasma FAM19A5 concentration and other risk factors to establish logistic regression models for the prediction of PD and PDD. Results: The plasma FAM19A5 levels (2.456 ± 0.517) were recorded to be significantly higher in the PD group as compared to the HC group (2.23 ± 0.457) (P < 0.001). Importantly, the plasma FAM19A5 levels were also significantly higher in the PDD subgroup (2.577 ± 0.408) as compared to the non-depressive subgroup (2.406 ± 0.549) (P = 0.045 < 0.05). The model based on the combination of plasma FAM19A5 and radiomics signature showed excellent predictive validity for PD and PDD, with AUCs of 0.913 (95% CI: 0.861-0.955) and 0.937 (95% CI: 0.845-0.970), respectively. Conclusion: Altogether, the present study reported the development of nomograms incorporating radiomics signature, plasma FAM19A5, and clinical risk factors, which might serve as potential tools for early prediction of PD and PDD in clinical settings.

Effect of Chaigan Jieyou Decoction on Hippocampal Neurons and Brain-derived Neurotrophic Factor Expression in Rats of Parkinson’s Disease with Depression / 广州中医药大学学报

Objective To investigate the effect of Chaigan Jieyou Decoction on hippocampal neurons and the expression of hippocampal brain-derived neurotrophic factor(BDNF)in rats of Parkinson’s disease with depression (PDD). Methods Twenty-four adult male SD rats were randomly divided into 4 groups, namely normal group, model group, Chaigan Jieyou Decoction group and Fluoxetine group, 6 rats in each group. Except for the normal group, the rats in the other groups were fed solitarily. After the establishment of PDD model, the model group, Chaigan Jieyou Decoction group and Fluoxetine group were given intragastric administration of distilled water 2.0 mL, Chaigan Jieyou Decoction 8 g·kg-1, Fluoxetine 1.8 mg·kg-1 for one day respectively, once a day. The treatment covered 21 continuous days. The hippocampal neuron damage and the expression of BDNF in hippocampal tissues were detected by Nissl’s staining and immunohistochemistry, respectively. Results Compared with the normal group, model group had obvious morphological damage of the hippocampal neurons, while Chaigan Jieyou Decoction and fluoxetine could relieve the damage, showing certain protection of hippocampal neurons. Compared with the normal group, BDNF positive staining area, integral optical density (IOD), and mean optical density(MOD) of the hippocampus in the model group were significantly decreased (P<0.01). Compared with the model group, BDNF positive staining area, integral optical density and mean optical density in Chaigan Jieyou Decoction group and fluoxetine group were significantly increased(P<0.05 or P<0.01). Conclusion Chaigan Jieyou Decoction has an effect on the relief of the damage of neurons and the increase of expression of BDNF in hippocampus of rats with PDD, which probably contributes to one of its therapeutic mechanisms.

Discussion of mechanisms of rats with depression in Parkinson′s disease treated with Chaigan Jieyou decoction / 实用医学杂志

Objective To build rat models and observe changes of behavior and monoamine of PDD. Methods The rats were injected with 6-OHDA and accepted CUMS for the establishment of PDD model , so as to assess its behavior changes and detect brain tissue monoamine contents by ELISA. Results Significant behavioral and monoamine abnormalities can be observed in model rats. Behavioral and monoamine improvement can be observed after treated with Chaigan Jieyou. Conclusion The PDD model can be established by 6-OHDA and CUMS. Chaigan Jieyou decoction may reach therapeutic purposes by increasing monoamine contents.