Rhynchophylline Attenuates Tourette Syndrome via BDNF/NF-κB Pathway In Vivo and In Vitro

The effects of Shaoma Zhijing granules and its main components on Tourette syndrome

BACKGROUND

Tourette syndrome (TS) represents a neurodevelopmental disorder characterized by an uncertain etiology and influencing factors. Frequently, it co-occurs with conditions such as attention deficit hyperactivity disorder, obsessive-compulsive disorder, and sleep disturbances, which have garnered substantial attention from the research community in recent years. Clinical trials have demonstrated that Shaoma Zhijing Granules (SMZJG, 5-ling granule, also known as TSupport or T92 under U.S. development), a traditional Chinese medicine compound, is an effective treatment for TS.

PURPOSE

To conduct scientometric analysis on developing trends, research countries and institutions, current status, hot spots of TS and discuss the underlying mechanisms of SMZJG and its main components on TS. The aim is to provide valuable reference for ongoing clinical and basic research on TS and SMZJG.

STUDY DESIGN & METHODS

Using Tourette syndrome, SMZJG and its main components along with their synonyms as keywords, we conducted a comprehensive search across major scientific databases including the Web of Science Core Collection, PubMed and China National Knowledge Infrastructure (CNKI) databases. A total of 5952 references and 99 patents were obtained. Among these, 5039 articles and reviews, as well as 54 patents were analyzed by Citespace and VOSviewer software.

RESULTS

The available evidence indicates that the SMZJG's components likely exert their mechanisms in treating TS by regulating the dopaminergic pathway system, neurotransmitter imbalances, reducing neuroinflammation, promoting the repair of nerve damage and improving sleep disorders.

CONCLUSION

This comprehensive analysis lays the foundation for an extensive exploration of the feasibility and clinical applications of SMZJG in TS treatment.

The inflammatory injury in the striatal microglia-dopaminergic-neuron crosstalk involved in Tourette syndrome development

Background

Tourette syndrome (TS) is associated with immunological dysfunction. The DA system is closely related to TS development, or behavioral stereotypes. Previous evidence suggested that hyper-M1-polarized microglia may exist in the brains of TS individuals. However, the role of microglia in TS and their interaction with dopaminergic neurons is unclear. In this study, we applied iminodipropionitrile (IDPN) to establish a TS model and focused on the inflammatory injury in the striatal microglia-dopaminergic-neuron crosstalk.

Methods

Male Sprague-Dawley rats were intraperitoneally injected with IDPN for seven consecutive days. Stereotypic behavior was observed to verify the TS model. Striatal microglia activation was evaluated based on different markers and expressions of inflammatory factors. The striatal dopaminergic neurons were purified and co-cultured with different microglia groups, and dopamine-associated markers were assessed.

Results

First, there was pathological damage to striatal dopaminergic neurons in TS rats, as indicated by decreased expression of TH, DAT, and PITX3. Next, the TS group showed a trend of increased Iba-1 positive cells and elevated levels of inflammatory factors TNF-α and IL-6, as well as an enhanced M1-polarization marker (iNOS) and an attenuated M2-polarization marker (Arg-1). Finally, in the co-culture experiment, IL-4-treated microglia could upregulate the expression of TH, DAT, and PITX3 in striatal dopaminergic neurons vs LPS-treated microglia. Similarly, the TS group (microglia from TS rats) caused a decreased expression of TH, DAT, and PITX3 compared with the Sham group (microglia from control rats) in the dopaminergic neurons.

Conclusion

In the striatum of TS rats, microglia activation is M1 hyperpolarized, which transmits inflammatory injury to striatal dopaminergic neurons and disrupts normal dopamine signaling.

Regulation of inflammation by VEGF/BDNF signaling in mouse retinal Müller glial cells exposed to high glucose

The inflammatory changes seem to play an important role in the development of diabetic retinopathy (DR). Anti-VEGF therapy has been testified to inhibit inflammation in animal models of diabetes, but the detailed mechanisms during this process are not yet clear. Müller glial cells (MGCs) in the mammalian retina are deeply involved in DR, while the BDNF overexpression reduces inflammation in diabetic mice. In this research, we aimed to explore the relationship between VEGF and BDNF in mouse retinal MGCs during inflammation of diabetes. We examined the expression of glutamine-synthetase (GS), glial fibrillary acidic protein (GFAP), vascular-endothelial growth factor (VEGF), interleukin-1beta (IL-1β), and tumor necrosis factor-alpha (TNF-α) at different time points after mouse retinal MGCs exposed to high glucose (25 mM). We also explored changes in the expression of brain-derived neurotrophic factor (BDNF), nuclear factor kappa B (NF-κB), IL-1β, and TNF-α in MGCs after treatments with anti-VEGF, VEGF siRNA, BDNF siRNA, BDNF recombination protein, and NF-κB inhibitor. In mouse retinal MGCs exposed to high glucose, BDNF was increased after treatments with anti-VEGF or VEGF siRNA. BDNF was decreased in MGCs from VEGF overexpressed mice. Moreover, the expressions of NF-κB, IL-1β, and TNF-α changed with BDNF: NF-κB, IL-1β, and TNF-α were increased after treatments with BDNF siRNA; NF-κB, IL-1β, and TNF-α were decreased after treatments with BDNF recombination protein. VEGF may regulate cytokines (IL-1β and TNF-α) by BDNF/NF-κB signaling pathway. The regulation of the VEGF/BDNF/NF-κB signaling pathway may be a significant therapeutic strategy for DR.

Neuroinflammation in a Rat Model of Tourette Syndrome

Objective

Tourette syndrome (TS) is a group of childhood-onset chronic neuropsychiatric disorders characterized by tics, i.e., repetitive, sudden, and involuntary movements or vocalizations, which is often associated with various psychopathological and/or behavioral comorbidities, including attention deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), anxiety, depression, and sleep disorders and have a worse prognosis. The mechanism of TS is still not clear. The relationship between immune activation, neuroinflammation, and neuropsychiatric disorders has attracted much attention in the past two decades. To explore the underlying mechanism in TS, the relationship between neuroinflammation and behavioral alterations in TS rats was investigated in this study.

Methods

A total of 36 Sprague-Dawley male rats were divided into three groups randomly as follows: the TS, control (CON), and drug intervention groups. The TS rat group was treated with haloperidol (Hal) (the TS + Hal group). The TS rat model was established using 3,3-iminodipropionitrile (IDPN), which is a well-known animal model of TS. The behavioral syndromes, brain tissue cytokines, like interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-α), and microglial activation of the three groups were assessed.

Results

The behavioral scores of rats in the TS group and the TS + Hal group were higher than those in the CON group (P < 0.05), but the scores of behavioral tests in the TS + Hal group were lower than those in the TS group (P < 0.05). The levels of IL-6 and TNF-α in the rat brain tissue were significantly higher in the TS group than in the CON group (P < 0.05), while no significant differences were found between the CON group and the TS + Hal group (P > 0.05). The microglia was significantly activated in the TS group and slightly activated in the TS + Hal group, which was considerably less than that in the TS group.

Conclusion

The IDPN-induced TS rats had significant neuroinflammation in the brain, and the interaction between dopamine (DA) dysregulation and immune dysfunction may play a vital role in the pathogenic mechanisms of TS.

Neuroprotective Effects of Rhynchophylline Against Aβ1-42-Induced Oxidative Stress, Neurodegeneration, and Memory Impairment Via Nrf2-ARE Activation

Extensive studies have shown that oxidative stress is a crucial pathogenic factor in Alzheimer's disease (AD). Nuclear factor E2-related factor 2 (Nrf2) is a master cytoprotective regulator against oxidative stress, and thus represents an attractive therapeutic target in AD. The goal of our study is to investigate the contribution of Nrf2 in Rhynchophylline (Rhy)-induced neuroprotection in AD. The data showed that intraperitoneal administration of Rhy (10 or 20 mg/kg) could ameliorate Aβ1-42-induced cognitive impairment, evidenced by performance improvement in memory tests. The result of Antioxidant response element (ARE)-luciferase activity assay indicated that Rhy treatment improved ARE promoter activity. The results of reactive oxygen species (ROS), malondialdehyde (MDA) and glutathione (GSH) assessment in the frontal cortex and hippocampus showed that Rhy treatment could attenuate Aβ1-42-induced oxidative stress to some extent, evidenced by reversion of these cytokines compared to Aβ1-42 + Veh group. Rhy treatment also restored expression of Nrf2 and its downstream protein heme oxygenase-1 (HO-1), NAD(P)H/quinone oxidoreductase 1 (NOQ1), and recombinant glutamate cysteine ligase, modifier subunit (GCLM) in the frontal cortex and hippocampus of Aβ1-42-treated mice. In addition, to investigate whether activation of Nrf2-mediated pathway is responsible for the neuroprotection of Rhy, Nrf2 siRNA was used in human neuroblastoma cells (SH-SY5Y). Interestingly, the results showed that the protective effects of Rhy, including anti-oxidative, anti-apoptosis and elevation of Nrf2 and its downstream proteins, were abolished in Nrf2 siRNA-transfected cells. These findings indicate that Rhynchophylline is protective against Aβ1-42-induced neurotoxicity via Nrf2-ARE activation, and suggest that Rhy may serve as a potential candidate and promising Nrf2 activator for management of AD.

Cellular Effects of Rhynchophylline and Relevance to Sleep Regulation

Uncaria rhynchophylla is a plant highly used in the traditional Chinese and Japanese medicines. It has numerous health benefits, which are often attributed to its alkaloid components. Recent studies in humans show that drugs containing Uncaria ameliorate sleep quality and increase sleep time, both in physiological and pathological conditions. Rhynchophylline (Rhy) is one of the principal alkaloids in Uncaria species. Although treatment with Rhy alone has not been tested in humans, observations in rodents show that Rhy increases sleep time. However, the mechanisms by which Rhy could modulate sleep have not been comprehensively described. In this review, we are highlighting cellular pathways that are shown to be targeted by Rhy and which are also known for their implications in the regulation of wakefulness and sleep. We conclude that Rhy can impact sleep through mechanisms involving ion channels, N-methyl-d-aspartate (NMDA) receptors, tyrosine kinase receptors, extracellular signal-regulated kinases (ERK)/mitogen-activated protein kinases (MAPK), phosphoinositide 3-kinase (PI3K)/RAC serine/threonine-protein kinase (AKT), and nuclear factor-kappa B (NF-κB) pathways. In modulating multiple cellular responses, Rhy impacts neuronal communication in a way that could have substantial effects on sleep phenotypes. Thus, understanding the mechanisms of action of Rhy will have implications for sleep pharmacology.

Suppression of autophagy through JAK2/STAT3 contributes to the therapeutic action of rhynchophylline on asthma

Background

Asthma is a chronic inflammatory disease characterized by airway remodeling and inflammation. Rhynchophylline is a kind of indole alkaloid isolated from Uncaria rhynchophylla. Here we investigated the effect of rhynchophylline on autophagy in asthma.

Methods

A mice model of asthma was established by ovalbumin challenge. Histopathological changes were assessed by hematoxylin-eosin staining, periodic acid-schiff staining and Masson staining. The levels of IgE in serum, interleukin-6 and interleukin-13 in bronchoalveolar lavage fluid, as well as the activities of superoxide dismutase and catalase in lung tissues were detected. The expression of autophagy-related genes and Janus kinase (JAK) 2/ signal transducer and activator of transcription (STAT) 3 signal was detected by western blot and immunofluorescence. Airway smooth muscle cells (ASMCs) were isolated, and the effect rhynchophylline on autophagy in ASMCs was explored.

Results

Our data showed that rhynchophylline treatment alleviated inflammation, airway remodeling, and oxidative stress in asthma. In addition, autophagy, which was implicated in asthma, was suppressed by rhynchophylline with decreased level of autophagy-related proteins. Furthermore, rhynchophylline suppressed the JAK2/STAT3 signaling pathway, which was activated in asthma. In vitro study showed that rhynchophylline suppressed ASMC autophagy through suppressing the activation of JAK2/STAT3 signal.

Conclusions

Our study demonstrated that rhynchophylline can alleviate asthma through suppressing autophagy in asthma, and that JAK2/STAT3 signal was involved in this effect of rhynchophylline. This study indicates that rhynchophylline may become a promising drug for the treatment of asthma.

Recent research progress of Uncaria spp. based on alkaloids: phytochemistry, pharmacology and structural chemistry

Medicinal plants are well-known in affording clinically useful agents, with rich medicinal values by combining with disease targets through various mechanisms. Plant secondary metabolites as lead compounds lay the foundation for the discovery and development of new drugs in disease treatment. Genus Uncaria from Rubiaceae family is a significant plant source of active alkaloids, with anti-hypertensive, sedative, anti-Alzheimer's disease, anti-drug addiction and anti-inflammatory effects. This review summarizes and discuss the research progress of Uncaria based on alkaloids in the past 15 years, mainly in the past 5 years, including biosynthesis, phytochemistry, pharmacology and structural chemistry. Among, focusing on representative compounds rhynchophylline and isorhynchophylline, the pharmacological activities surrounding the central nervous system and cardiovascular system are described in detail. On the basis of case studies, this article provides a brief overview of the synthesis and analogues of representative compounds types. In summary, this review provides an early basis for further searching for new targets and activities, discussing the mechanisms of pharmacological activity and studying the structure-activity relationships of active molecules.