Studying CNS effects of Traditional Chinese Medicine using zebrafish models

Acute toxicology on Danio rerio embryo and adult from Chinese traditional medicine preparation Danggui Shaoyao san

ETHNOPHARMACOLOGICAL RELEVANCE

Although the Traditional Chinese Medicine (TCM) prescription of Danggui Shaoyao San (DSS) presents substantial clinical efficacy and promising clinical prospects, the safety of DSS and its extracts have been inadequately investigated. The larva-adult duality of the zebrafish model offers a more efficient approach for evaluating the safety of herbal preparations in the fields of toxicology and pharmacology.

AIM OF THE STUDY

To investigate the acute toxicity of the extract derived from Danggui Shaoyao San, a traditional Chinese medicine preparation, on both Danio rerio embryos and adult organisms.

MATERIALS AND METHODS

The components of DSS were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The hatching rate of Danio rerio juveniles with different concentrations of DSS was calculated and the morphological changes of juveniles after administration were observed through a microscope. The behavioral trajectory of the adult fish was recorded by the observation tower of the automated Danio rerio analysis system, and DSS's effects on the behavior was analyzed. The pathological changes of Danio rerio gills, livers, kidneys, intestines and spermaries were examined using HE staining.

RESULTS

Compared with the control group, 25, 50 and 100 mg/L of DSS did not elicit any significant impacts on the hatching rate and morphology. Both 200 mg/L and the propylene glycol 2% reduced the hatching rate and caused the morphological teratogenic changes of the juvenile fish. The dosage of DSS below 100 mg/L had no discernible effect on the behavior of the adult fish, whereas the application of propylene glycol 2% was found to stimulate the adult fish, resulting in a notable increase in high-speed movement distance. 100 mg/L DSS group was not observed to cause any noticeable damage to the gills, livers, intestines and spermaries of Danio rerio, only mild nephrotoxicity was detected. The propylene glycol 2% group was found to result in pathological changes such as hyperplasia of epithelial cells on secondary lamellae, liver cell outline loss or atypia, tubal disorganization, goblet cell hypertrophy and irregularly arranged spermatozoa.

CONCLUSION

A viable approach for conducting toxicological studies on TCM preparations was developed and tested in this research. The findings showed that Danggui Shaoyao San has minimal acute toxicity to embryos and adult organisms at concentrations up to 100 mg/L. These results indicate that Danggui Shaoyao San is a safe TCM preparation.

Salidroside Ameliorates Ischemia-Induced Neuronal Injury through AMPK Dependent and Independent Pathways to Maintain Mitochondrial Quality Control

Salidroside, an active ingredient in Rhodiola rosea, has potent protective activity against cerebral ischemia. However, the mechanisms underlying its pharmacological actions are poorly understood. In this study, we employed a mouse middle cerebral artery occlusion (MCAO) and cellular oxygen and glucose deprivation (OGD) models to test the hypothesis that salidroside may restore mitochondrial quality control in neurons by modulating the relevant signaling. The results indicated that salidroside mitigated almost 40% the ischemia-induced brain infarct volumes in mice and the OGD-decreased viability of neurons to ameliorate the mitochondrial functions. Furthermore, salidroside treatment alleviated the OGD- or ischemia-induced imbalance of mitochondrial fission and fusion, mitophagy and promoted mitochondrial biogenesis in neurons by attenuating the AMPK activity. Moreover, salidroside alleviated 50% the OGD-promoted mitochondrial calcium fluorescence intensity and 5% mitochondria-associated membrane (MAM) area by down-regulating GRP75 expression independent of the AMPK signaling. Finally, similar findings were achieved in primary mouse neurons. Collectively, these data indicate that salidroside effectively restores the mitochondria dynamics, facilitates mitochondrial biogenesis by attenuating the AMPK signaling, and maintains calcium homeostasis in neurons independent of the AMPK activity.

Effect of aerobic exercise as a treatment on type 2 diabetes mellitus with depression-like behavior zebrafish

BACKGROUND

Depression is the most known complication of type 2 diabetes mellitus (T2DM). Aerobic exercise improves glycemic control in T2DM, although the underlying mechanisms of comorbid depression-like behaviors in T2DM have not yet been fully elucidated.

METHODS

120 zebrafish were randomly assigned to four groups: Control, T2DM, T2DM + metformin, and T2DM + aerobic exercise. Then, all animals except the control group were fed with high glucose fairy shrimp (~40 g/kg/day) and exposed reserpine (40 μg/ml for 20 min) for 10 days. Here, behavioral tests were used for model verification. Following the verification, all groups were treated as before. Additionally, the T2DM + metformin group received metformin (~10.6 mg/kg/day) at the same time, while the T2DM + aerobic exercise group received aerobic exercise 30 min/day. Finally, blood glucose and behavioral tests, as well as protein and molecular levels were determined at Day 11 and 12.

RESULTS

Aerobic exercise alleviated depressive-like behavior and enhanced the levels of antidepressant biomarkers (NE, 5-HIAA) in zebrafish after 10 consecutive days of exercise. Additionally, 10 consecutive days of aerobic exercise decreased the levels of inflammatory biomarkers (IFN-γ, IL-1, IL-4) and depressive biomarkers (cortisol). Meanwhile, it also aided in the reduction of CD11b, IL-6, IL-6R, and caspase-3 expression to combat the neuroinflammation induced by T2DM, mediated the BDNF-TrkB pathway, and increased Bcl-2/Bax levels.

CONCLUSION

Given the remarkable similarity in neurochemistry between humans and zebrafish, this study supports the effectiveness of aerobic exercise as clinical guidance in preventing and treating T2DM complicated with depression.

Future Directions for the Discovery of Natural Product-Derived Immunomodulating Drugs

Drug discovery from natural sources is going through a renaissance, having spent many decades in the shadow of synthetic molecule drug discovery, despite the fact that natural product-derived compounds occupy a much greater chemical space than those created through synthetic chemistry methods. With this new era comes new possibilities, not least the novel targets that have emerged in recent times and the development of state-of-the-art technologies that can be applied to drug discovery from natural sources. Although progress has been made with some immunomodulating drugs, there remains a pressing need for new agents that can be used to treat the wide variety of conditions that arise from disruption, or over-activation, of the immune system; natural products may therefore be key in filling this gap. Recognising that, at present, there is no authoritative article that details the current state-of-the-art of the immunomodulatory activity of natural products, this in-depth review has arisen from a joint effort between the International Union of Basic and Clinical Pharmacology (IUPHAR) Natural Products and Immunopharmacology, with contributions from a Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation number of world-leading researchers in the field of natural product drug discovery, to provide a "position statement" on what natural products has to offer in the search for new immunomodulatory argents. To this end, we provide a historical look at previous discoveries of naturally occurring immunomodulators, present a picture of the current status of the field and provide insight into the future opportunities and challenges for the discovery of new drugs to treat immune-related diseases.

Progress in using zebrafish as a toxicological model for traditional Chinese medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has been applied for more than 2000 years. However, modern basic research on the safety of TCMs is limited. Establishing safety evaluation technology in line with the characteristics of TCM and conducting large-scale basic toxicity research are keys to comprehensively understand the toxicity of TCMs. In recent years, zebrafish has been used as a model organism for toxicity assessment and is increasingly utilized for toxicity research of TCMs. Yet, a comprehensive review in using zebrafish as a toxicological model for TCMs is lacked.

AIM OF THE STUDY

We aim to summarize the progress and limitation in toxicity evaluation of TCMs using zebrafish and put forward the future research ideas.

MATERIALS AND METHODS

The scientific databases, including Springer, Science Direct, Wiley, Pubmed and China Knowledge Resource Integrated (CNKI) were searched using the key words of zebrafish, toxicology, traditional Chinese medicine, acute toxicity, liver injury, cardiotoxicity, kidney toxicity, developmental toxicity, neurotoxicity, gastrointestinal irritation, immunotoxicity, ototoxicity, and osteotoxicity.

RESULTS

Zebrafish assays are low experimental cost and short cycle, easily achieving high-throughput toxicity screening, and exemption from ethical legislation up to 5 dpf. It has been widely used to evaluate the acute toxicity, liver toxicity, cardiotoxicity, nephrotoxicity, developmental toxicity, neurotoxicity, gastrointestinal irritation, immunotoxicity, and ototoxicity caused by TCMs, although some physiological difference limited its application.

CONCLUSIONS

Zebrafish is a powerful model for TCMs toxicity evaluation, but it is not flawless. The toxicity testing criterion and high throughput assays are urgent to be established. This review provides references for future studies.

Exploring CNS effects of American traditional medicines using zebrafish models

Although American traditional medicine (ATM) has been practiced for millennia, its complex multi-target mechanisms of therapeutic action remain poorly understood. Animal models are widely used to elucidate the therapeutic effects of various ATMs, including their modulation of brain and behavior. Complementing rodent models, the zebrafish (Danio rerio) is a promising novel organism in translational neuroscience and neuropharmacology research. Here, we emphasize the growing value of zebrafish for testing neurotropic effects of ATMs and outline future directions of research in this field. We also demonstrate the developing utility of zebrafish as complementary models for probing CNS mechanisms of ATM action and their potential to treat brain disorders.

Zebrafish as a tool for the discovery of anticonvulsant compounds from botanical constituents

Epilepsy affects about 65 million people in the world, which makes this disease a public health problem. In addition to the incidence of recurrent seizures, this neurological condition also culminates in cognitive, psychological, behavioral, and social consequences to the patients. Epilepsy treatment is based on the use of drugs that aim to inhibit repetitive neuronal discharges, and consequently, the recurrence of seizures. However, despite the large number of antiepileptic drugs currently available, about 30-40% of patients with epilepsy do not respond satisfactorily to treatments. Therefore, the investigation of new therapeutic alternatives for epilepsy becomes relevant, especially the search for new compounds with anticonvulsant properties. The therapeutic potential of plant-derived bioactive compounds has been a target for alternative treatments for epilepsy. The use of animal models for drug screening, such as zebrafish, contributes to a better understanding of the mechanisms involved in seizures and for investigating methods and alternative treatments to decrease seizure incidence. The sensitivity of zebrafish to chemoconvulsants and its use in genetic approaches reinforces the contribution of this animal to epilepsy research. Moreover, we summarize advances in zebrafish-based studies that focus on plant-derived bioactive compounds with potential antiseizure properties, contributing to the screening of new drugs for epilepsy treatment.

Unconventional anxiety pharmacology in zebrafish: Drugs beyond traditional anxiogenic and anxiolytic spectra

Anxiety is the most prevalent brain disorder and a common cause of human disability. Animal models are critical for understanding anxiety pathogenesis and its pharmacotherapy. The zebrafish (Danio rerio) is increasingly utilized as a powerful model organism in anxiety research and anxiolytic drug screening. High similarity between human, rodent and zebrafish molecular targets implies shared signaling pathways involved in anxiety pathogenesis. However, mounting evidence shows that zebrafish behavior can be modulated by drugs beyond conventional anxiolytics or anxiogenics. Furthermore, these effects may differ from human and/or rodent responses, as such 'unconventional' drugs may affect zebrafish behavior despite having no such profiles (or exerting opposite effects) in humans or rodents. Here, we discuss the effects of several putative unconventional anxiotropic drugs (aspirin, lysergic acid diethylamide (LSD), nicotine, naloxone and naltrexone) and their potential mechanisms of action in zebrafish. Emphasizing the growing utility of zebrafish models in CNS drug discovery, such unconventional anxiety pharmacology may provide important, evolutionarily relevant insights into complex regulation of anxiety in biological systems. Albeit seemingly complicating direct translation from zebrafish into clinical phenotypes, this knowledge may instead foster the development of novel CNS drugs, eventually facilitating innovative treatment of patients based on novel 'unconventional' targets identified in fish models.

The use of zebrafish as a non-traditional model organism in translational pain research: the knowns and the unknowns

The ability of the nervous system to detect a wide range of noxious stimuli is crucial to avoid life-threatening injury and to trigger protective behavioral and physiological responses. Pain represents a complex phenomenon, including nociception associated with cognitive and emotional processing. Animal experimental models have been developed to understand the mechanisms involved in pain response, as well as to discover novel pharmacological and non-pharmacological anti-pain therapies. Due to the genetic tractability, similar physiology, low cost, and rich behavioral repertoire, the zebrafish (Danio rerio) has been considered a powerful aquatic model for modeling pain responses. Here, we summarize the molecular machinery of zebrafish to recognize painful stimuli, as well as emphasize how zebrafish-based pain models have been successfully used to understand specific molecular, physiological, and behavioral changes following different algogens and/or noxious stimuli (e.g., acetic acid, formalin, histamine, Complete Freund's Adjuvant, cinnamaldehyde, allyl isothiocyanate, and fin clipping). We also discuss recent advances in zebrafish-based studies and outline the potential advantages and limitations of the existing models to examine the mechanisms underlying pain responses from an evolutionary and translational perspective. Finally, we outline how zebrafish models can represent emergent tools to explore pain behaviors and pain-related mood disorders, as well as to facilitate analgesic therapy screening in translational pain research.