An Adrenalectomy Mouse Model Reflecting Clinical Features for Chronic Fatigue Syndrome

Models of Congenital Adrenal Hyperplasia for Gene Therapies Testing

The adrenal glands are important endocrine organs that play a major role in the stress response. Some adrenal glands abnormalities are treated with hormone replacement therapy, which does not address physiological requirements. Modern technologies make it possible to develop gene therapy drugs that can completely cure diseases caused by mutations in specific genes. Congenital adrenal hyperplasia (CAH) is an example of such a potentially treatable monogenic disease. CAH is an autosomal recessive inherited disease with an overall incidence of 1:9500–1:20,000 newborns. To date, there are several promising drugs for CAH gene therapy. At the same time, it remains unclear how new approaches can be tested, as there are no models for this disease. The present review focuses on modern models for inherited adrenal gland insufficiency and their detailed characterization. In addition, the advantages and disadvantages of various pathological models are discussed, and ways of further development are suggested.

Improvement Effects of Myelophil on Symptoms of Chronic Fatigue Syndrome in a Reserpine-Induced Mouse Model

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is associated with various symptoms, such as depression, pain, and fatigue. To date, the pathological mechanisms and therapeutics remain uncertain. The purpose of this study was to investigate the effect of myelophil (MYP), composed of Astragali Radix and Salviaemiltiorrhizae Radix, on depression, pain, and fatigue behaviors and its underlying mechanisms. Reserpine (2 mg/kg for 10 days, intraperitoneally) induced depression, pain, and fatigue behaviors in mice. MYP treatment (100 mg/kg for 10 days, intragastrically) significantly improved depression behaviors, mechanical and thermal hypersensitivity, and fatigue behavior. MYP treatment regulated the expression of c-Fos, 5-HT1A/B receptors, and transforming growth factor β (TGF-β) in the brain, especially in the motor cortex, hippocampus, and nucleus of the solitary tract. MYP treatment decreased ionized calcium binding adapter molecule 1 (Iba1) expression in the hippocampus and increased tyrosine hydroxylase (TH) expression and the levels of dopamine and serotonin in the striatum. MYP treatment altered inflammatory and anti-oxidative-related mRNA expression in the spleen and liver. In conclusion, MYP was effective in recovering major symptoms of ME/CFS and was associated with the regulation of dopaminergic and serotonergic pathways and TGF-β expression in the brain, as well as anti-inflammatory and anti-oxidant mechanisms in internal organs.

Mechanistic insights into the anti-depressant effect of emodin: an integrated systems pharmacology study and experimental validation

Depression is a complex neuropsychiatric disease involved multiple targets and signaling pathways. Systems pharmacology studies could potentially present a comprehensive molecular mechanism to delineate the anti-depressant effect of emodin (EMO). In this study, we investigated the anti-depressant effects of EMO in the chronic unpredictable mild stress (CUMS) rat model of depression and gained insights into the underlying mechanisms using systems pharmacology and molecular simulation analysis. Forty-three potential targets of EMO for treatment of depression were obtained. GO biological process analysis suggested that the biological functions of these targets mainly involve the regulation of reactive oxygen species metabolic process, response to lipopolysaccharide, regulation of inflammatory response, etc. KEGG pathway enrichment analysis showed that the PI3K-Akt signaling pathway, insulin resistance, IL-17 signaling pathway were the most significantly enriched signaling pathways. The molecular docking analysis revealed that EMO might have a strong combination with ESR1, AKT1 and GSK3B. Immunohistochemical staining and Western blotting showed that 2 weeks' EMO treatment (80 mg/kg/day) reduced depression related microglial activation, neuroinflammation and altered PI3K-Akt signaling pathway. Our findings provide a systemic pharmacology basis for the anti-depressant effects of EMO.

Exogenous Transforming Growth Factor-β in Brain-Induced Symptoms of Central Fatigue and Suppressed Dopamine Production in Mice

Myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS) is one of the most refractory diseases in humans and is characterized by severe central fatigue accompanied with various symptoms that affect daily life, such as impaired memory, depression, and somatic pain. However, the etiology and pathophysiological mechanisms of CFS remain unknown. To investigate the pathophysiological role of transforming growth factor (TGF)-β1, we injected a cytokine into the lateral ventricle of a C57BL/6 mouse. The intracranial injection of TGF-β1 increased the immobility duration in a forced swimming test (FST) and time spent at the closed arm in elevated plus maze (EPM) analysis. The mice injected with TGF-β1 into their brain showed increased sensitivity to pain in a von Frey test, and had a decreased retention time on rotarod and latency time in a bright box in a passive avoidance test. In addition, the serum levels of muscle fatigue biomarkers, lactate dehydrogenase (LDH) and creatine kinase (CK), were significantly increased after administration of TGF-β1. Intracranial injection of TGF-β1 significantly reduced the production of tyrosine hydroxylase (TH) in the ventral tegmental area, accompanied by a decreased level of dopamine in the striatum. The suppression of TH expression by TGF-β1 was confirmed in the human neuroblastoma cell line, SH-SY5Y. These results, which show that TGF-β1 induced fatigue-like behaviors by suppressing dopamine production, suggest that TGF-β1 plays a critical role in the development of central fatigue and is, therefore, a potential therapeutic target of the disease.

Differences in fatigue-like behavior in the lipopolysaccharide and poly I:C inflammatory animal models

Central fatigue is a condition associated with impairment of the central nervous system often leading to the manifestation of a range of debilitating symptoms. Fatigue can be a consequence of systemic inflammation following an infection. Administration of lipopolysaccharide (LPS) and polyriboinosinic:polyribocytidlic (poly I:C) to animals can induce systemic inflammation by mimicking a bacterial or viral infection respectively and therefore have been used as models of fatigue. We evaluated a range of phenotypic behaviors exhibited in the LPS and poly I:C animal models to assess whether they adequately replicate fatigue symptomology in humans. In addition to standard observation- and intervention-based behavioral assessments, we used powerful in-cage monitoring technology to quantify rodent behavior without external interference. LPS and poly I:C treated Sprague Dawley rats displayed 'sickness behaviors' of elevated temperature, weight loss and reduced activity in the open field test and with in-cage monitoring within 24 h post-treatment, but only LPS-treated rats displayed these behaviors beyond these acute timepoints. Once sickness behavior diminished, LPS-treated rats exhibited an increase in reward-seeking and motivation behaviors. Overall, these results suggest that the LPS animal model produces an extensive and sustained fatigue-like phenotype, whereas the poly I:C model only produced acute effects. Our results suggest that the LPS animal model is a more suitable candidate for further studies on central fatigue-like behavior.