Among the popular animal models of Parkinson's disease (PD) commonly used in research are those that employ neurotoxins, especially 1-methyl- 4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP). This neurotoxin exerts it neurotoxicity by causing a barrage of insults, such as oxidative stress, mitochondrial apoptosis, inflammation, excitotoxicity, and formation of inclusion bodies acting singly and in concert, ultimately leading to dopaminergic neuronal damage in the substantia nigra pars compacta and striatum. The selective neurotoxicity induced by MPTP in the nigrostriatal dopaminergic neurons of the mouse brain has led to new perspectives on PD. For decades, the MPTP-induced mouse model of PD has been the gold standard in PD research even though it does not fully recapitulate PD symptomatology, but it does have the advantages of simplicity, practicability, affordability, and fewer ethical considerations and greater clinical correlation than those of other toxin models of PD. The model has rejuvenated PD research and opened new frontiers in the quest for more novel therapeutic and adjuvant agents for PD. Hence, this review summarizes the role of MPTP in producing Parkinson-like symptoms in mice and the experimental role of the MPTP-induced mouse model. We discussed recent developments of more promising PD therapeutics to enrich our existing knowledge about this neurotoxin using this model.
To date, plants have been the major source of anticancer drugs. Boldine is a natural alkaloid commonly found in the leaves and bark of Peumus boldus. In this study, we found that boldine potently inhibited the viability of the human invasive breast cancer cell lines, MDA-MB-231 (48-hour IC₅₀ 46.5±3.1 μg/mL) and MDA-MB-468 (48-hour IC₅₀ 50.8±2.7 μg/mL). Boldine had a cytotoxic effect and induced apoptosis in breast cancer cells as indicated by a higher amount of lactate dehydrogenase released, membrane permeability, and DNA fragmentation. In addition, we demonstrated that boldine induced cell cycle arrest at G2/M phase. The anticancer mechanism is associated with disruption of the mitochondrial membrane potential and release of cytochrome c in MDA-MB-231. Boldine selectively induced activation of caspase-9 and caspase-3/7, but not caspase-8. We also found that boldine could inhibit nuclear factor kappa B activation, a key molecule in tumor progression and metastasis. In addition, protein array and Western blotting analysis showed that treatment with boldine resulted in downregulation of Bcl-2 and heat shock protein 70 and upregulation of Bax in the MDA-MB-231 cell line. An acute toxicity study in rats revealed that boldine at a dose of 100 mg/kg body weight was well tolerated. Moreover, intraperitoneal injection of boldine (50 or 100 mg/kg) significantly reduced tumor size in an animal model of breast cancer. Our results suggest that boldine is a potentially useful agent for the treatment of breast cancer.
Preventing osteoporotic fractures in millions of individuals may significantly reduce the associated morbidity and health-care expenditures incurred. As such, the search for newer anti-osteoporotic agents has been ongoing for years. Genetic studies have proven that the secreted protein sclerostin is one of the main culprits, which negatively regulates the bone formation. Recently, sclerostin-neutralizing monoclonal antibodies (Scl-Ab) in rodent studies have shown positive effects on bone homeostasis. An extensive search of the literature was performed in the BIOSIS, Cinahl, EMBASE, Pub- Med, Web of Science and Cochrane Library databases to evaluate the published murine studies on the effects of Scl-Ab on the bone metabolism and histomorphometric parameters. Our systematic review depicts a significant association between Scl-Ab administration and improvement in bone formation, bone density, bone volume and trabecular thickness.
Osteoporosis may cause bone fracture even under slight trauma. Osteoporotic fracture has become a major public health problem but until today, the treatments available are not satisfactory. Many pre-clinical testings on animals were done to find new agents that can be sourced from natural products and synthetic drugs for osteoporotic fracture healing. Animal models are more appropriate for fracture healing study than human subject due to several reasons including the ethical issues involved. The bones of rodents are similar to human in term of their morphological change and response to therapy. Small rodents such as rats and mice are suitable animal models for fracture healing studies as they have a similar bone remodeling system to human. To date, there is no specific guideline to carry out fracture healing studies in animal models for the evaluation of new agents. This paper highlights the protocols of various fracture and fixation methods for experimental osteoporotic fracture healing using rodent models.
Alpinia conchigera Griff. (Zingiberaceae), locally known to the Malays as "lengkuas ranting", is native to Peninsular Malaysia. The Malays traditionally used it to treat infection and rashes, and as a health drink. This study evaluated the analgesic and anti-inflammatory activities of the ethanol extract of A. conchigera rhizomes in mice and rats, respectively. The analgesic activity was elucidated using the acetic acid-induced writhing test, hot plate test, and formalin test, while the anti-inflammatory activity was determined using carrageenan-induced paw edema. The extract (30, 100, and 300 mg/kg) given intraperitoneally (i.p.) exhibited antinociceptive and anti-inflammatory activities in all tests used. The range of percentage of analgesia obtained for all doses of extract in the writhing test was 50-92%, and in the early and late phases of the formalin test was 25-62% and 63-98%, respectively. In addition, naloxone (5 mg/kg) given subcutaneously (s.c.) was found to reverse the extract (300 mg/kg)-induced antinociceptive activity in the writhing, hot plate, and formalin tests. Based on the results obtained, it can be concluded that the ethanol extract of A. conchigera rhizomes possessed a peripheral and central antinociceptive activity that was mediated, in part, via the opioid receptor, as well as anti-inflammatory activity.
Plasmodium knowlesi is a malaria parasite of Old World monkeys and is infectious to humans. In this study Macaca fascicularis was used as a model to understand the host response to P. knowlesi using parasitological and haematological parameters. Three M. fascicularis of either sex were experimentally infected with P. knowlesi erythrocytic parasites from humans. The pre-patent period for P. knowlesi infection in M. fascicularis ranged from seven to 14 days. The parasitemia observed was 13,686-24,202 parasites per microL of blood for asexual stage and 88-264 parasites per microL of blood for sexual stage. Periodicity analysis adopted from microfilaria periodicity technique of asexual stage showed that the parasitemia peak at 17:39h while the sexual stage peaked at 02:36 h. Mathematical analysis of the data indicates that P. knowlesi gametocytes tend to display periodicity with a peak (24:00-06:00) that coincides with the peak biting activity (19:00-06:00) of the local vector, Anopheles latens. The morphology of P. knowlesi resembled P. falciparum in early trophozoite and P. malariae in late trophozoite. However, it may be distinguishable by observing the appliqué appearance of the cytoplasm and the chromatin lying inside the ring. Haematological analysis on macaques with knowlesi malaria showed clinical manifestations of hypoglycaemia, anaemia and hyperbilirubinemia. Gross examination of spleen and liver showed malaria pigments deposition in both organs.
We describe a model of Enterovirus 71 encephalomyelitis in 2-week-old mice that shares many features with the human central nervous system (CNS) disease. Mice were infected via oral and parenteral routes with a murine-adapted virus strain originally from a fatal human case. The mice succumbed to infection after 2 to 5 days. Vacuolated and normal-appearing CNS neurons showed viral RNA and antigens and virions by in situ hybridization, immunohistochemistry, and electron microscopy; inflammation was minimal. The most numerous infected neurons were in anterior horns, motor trigeminal nuclei, and brainstem reticular formation; fewer neurons in the red nucleus, lateral cerebellar nucleus, other cranial nerve nuclei, motor cortex, hypothalamus, and thalamus were infected. Other CNS regions, dorsal root, and autonomic ganglia were spared. Intramuscular-inoculated mice killed 24 to 36 hours postinfection had viral RNA and antigens in ipsilateral lumbar anterior horn cells and adjacent axons. Upper cord motor neurons, brainstem, and contralateral motor cortex neurons were infected from 48-72 hours. Viral RNA and antigens were abundant in skeletal muscle and adjacent tissues but not in other organs. The distinct, stereotypic viral distribution in this model suggests that the virus enters the CNS via peripheral motor nerves after skeletal muscle infection, and spread within the CNS involves motor and other neural pathways. This model may be useful for further studies on pathogenesis and for testing therapies.
Wilson's disease (WD), also known as hepatoleticular degeneration (HLD), is a rare autosomal recessive genetic disorder of copper metabolism, which causes copper to accumulate in body tissues. In this study, rats fed with copper-laden diet are used to render the clinical manifestations of WD, and their copper toxicity-induced organ lesions are studied. To investigate metabolic behaviors of 'decoppering' process, penicillamine (PA) was used for treating copper-laden rats as this chelating agent could eliminate excess copper through the urine. To date, there has been limited metabolomics study on WD, while metabolic impacts of copper accumulation and PA administration have yet to be established.
Number of ligations made in the chronic constriction injury (CCI) neuropathic pain model has raised serious concerns. We compared behavioural responses, nerve morphology and expression of pain marker, c-fos among CCI models developed with one, two, three and four ligations. The numbers of ligation(s) on sciatic nerve shows no significant difference in displaying mechanical and cold allodynia, and mechanical and thermal hyperalgesia throughout 84 days. All groups underwent similar levels of nerve degeneration post-surgery. Similar c-fos level in brain cingulate cortex, parafascicular nuclei and amygdala were observed in all CCI models compared to sham-operated group. Therefore, number of ligations does not impact intensity of pain symptoms, pathogenesis and neuronal activation. A single ligation is sufficient to develop neuropathic pain, in contrast to the established model of four ligations. This study dissects and characterises the CCI model, ascertaining a more uniform animal model to surrogate actual neuropathic pain condition.
Despite being widely used for treating cancer, chemotherapy is accompanied by numerous adverse effects as a result of systemic distribution and nonspecific interactions of the drugs with healthy tissues, eventually leading to therapeutic inefficacy and chemoresistance. Cyclophosphamide (Cyp) as one of the chemotherapeutic pro-drugs is activated in liver and used to treat breast cancer in high dose and in combination with other drugs. In an attempt to reduce the off-target effects and enhance the therapeutic efficacy, pH-sensitive carbonate apatite nanoparticles that had predominantly and size-dependently been localized in liver following intravenous administration, were employed to electrostatically immobilize Cyp and purposely deliver it to the liver for activation. Cyp-loaded particles formed by simple 30 min incubation at 37ºC of the DMEM (pH 7.4) medium containing CaCl2 and Cyp, enhanced in vitro cytotoxicity at different degrees depending on the cell types. The size of the particles could be tightly controlled by the amount of CaCl2 required to prepare the particles and thus the bio-distribution pattern inside different organs of the body. Unlike the small particles (~ 200 nm), the large size particles (~ 600 nm) which were more efficiently accumulated in liver, significantly reduced the tumor volume following intravenous injection in 4T1-induced murine breast cancer model at a very low dose (0.17 mg/Kg) of the drug initially added for complex formation, thus shedding light on the potential applications of the Cyp-loaded nano-formulations in the treatment of breast cancer.
Coxsackievirus A16 (CV-A16) is one of the major causes of mild and self-limiting hand-foot-and-mouth disease (HFMD) in young children, which may occasionally leads to serious neurological complications. In this study, we had developed a novel, consistent, orally infected CV-A16 HFMD hamster model with encephalomyelitis. Four groups of 7-day-old hamsters in a kinetic study were orally infected with mouse-adapted CV-A16 strains and sacrificed at 1-4 days post infection (dpi), respectively. Tissues were studied by light microscopy, immunohistochemistry to detect viral antigens, in situ hybridization to detect viral RNA, and by viral titration. In a separate transmission experiment, orally infected index hamsters were housed together with contact hamsters to investigate oral and fecal viral shedding by virus culture and reverse transcription polymerase chain reaction (RT-PCR). At severe infection/death endpoints, index and contact hamster infection were also histopathologically analyzed. In the kinetic study, infected hamsters developed signs of infection at 4 dpi. Viral antigens/RNA were localized to brainstem (medulla/pons; reticular formation and motor trigeminal nucleus) and spinal cord anterior horn neurons, oral squamous epithelia and epidermis from 3 to 4 dpi. Salivary and lacrimal glands, myocardium, brown adipose tissue, intestinal smooth muscle, and skeletal muscle infection was also demonstrated. Viremia at 1 dpi and increasing viral titers in various tissues were observed from 2 dpi. In the transmission study, all contact hamsters developed disease 3-5 days later than index hamsters, but demonstrated similar histopathological findings at endpoint. Viral culture and RT-PCR positive oral washes and feces confirmed viral shedding. Our hamster model, orally infected by the natural route for human infection, confirmed CV-A16 neurotropism and demonstrated squamous epitheliotropism reminiscent of HFMD, attributes not found in other animal models. It should be useful to investigate neuropathogenesis, model person-to-person transmission, and for testing antiviral drugs and vaccines.
A predominantly pig-to-human zoonotic infection caused by the novel Nipah virus emerged recently to cause severe morbidity and mortality in both animals and man. Human autopsy studies showed the pathogenesis to be related to systemic vasculitis that led to widespread thrombotic occlusion and microinfarction in most major organs especially in the central nervous system. There was also evidence of extravascular parenchymal infection, particularly near damaged vessels (Wong KT, Shieh WJ, Kumar S, Norain K, Abdullah W, Guarner J, Goldsmith CS, Chua KB, Lam SK, Tan CT, Goh KJ, Chong HT, Jusoh R, Rollin PE, Ksiazek TG, Zaki SR, Nipah Virus Pathology Working Group: Nipah virus infection: Pathology and pathogenesis of an emerging paramyxoviral zoonosis. Am J Pathol 2002, 161:2153-2167). We describe here a golden hamster (Mesocricetus auratus) model that appears to reproduce the pathology and pathogenesis of acute human Nipah infection. Hamsters infected by intranasal or intraperitoneal routes died within 9 to 29 days or 5 to 9 days, respectively. Pathological lesions were most severe and extensive in the hamster brain. Vasculitis, thrombosis, and more rarely, multinucleated endothelial syncytia, were found in blood vessels of multiple organs. Viral antigen and RNA were localized in both vascular and extravascular tissues including neurons, lung, kidney, and spleen, as demonstrated by immunohistochemistry and in situ hybridization, respectively. Paramyxoviral-type nucleocapsids were identified in neurons and in vessel walls. At the terminal stage of infection, virus and/or viral RNA could be recovered from most solid organs and urine, but not from serum. The golden hamster is proposed as a suitable model for further studies including pathogenesis studies, anti-viral drug testing, and vaccine development against acute Nipah infection.
Henipaviruses are implicated in severe and frequently fatal pneumonia and encephalitis in humans. There are no approved vaccines or treatments available for human use, and testing of candidates requires the use of well-characterized animal models that mimic human disease. We performed a comprehensive and statistically-powered evaluation of the African green monkey model to define parameters critical to disease progression and the extent to which they correlate with human disease. African green monkeys were inoculated by the intratracheal route with 2.5 × 10(4) plaque forming units of the Malaysia strain of Nipah virus. Physiological data captured using telemetry implants and assessed in conjunction with clinical pathology were consistent with shock, and histopathology confirmed widespread tissue involvement associated with systemic vasculitis in animals that succumbed to acute disease. In addition, relapse encephalitis was identified in 100% of animals that survived beyond the acute disease phase. Our data suggest that disease progression in the African green monkey is comparable to the variable outcome of Nipah virus infection in humans.
Animal models, particularly rodents, are major translational models for evaluating novel anticancer therapeutics. In this review, different types of nanostructure-based photosensitizers that have advanced into the in vivo evaluation stage for the photodynamic therapy (PDT) of cancer are described. This article focuses on the in vivo efficacies of the nanostructures as delivery agents and as energy transducers for photosensitizers in animal models. These materials are useful in overcoming solubility issues, lack of tumor specificity, and access to tumors deep in healthy tissue. At the end of this article, the opportunities made possible by these multiplexed nanostructure-based systems are summarized, as well as the considerable challenges associated with obtaining regulatory approval for such materials. The following questions are also addressed: (1) Is there a pressing demand for more nanoparticle materials? (2) What is the prognosis for regulatory approval of nanoparticles to be used in the clinic?
BACKGROUND: Environmental enrichment (EE) exposure is known to influence the structural changes in the neuronal network of hippocampus. In the present study, we evaluated the effects of EE exposure on the streptozotocin (STZ)-induced diabetic and stressed rat hippocampus.
METHODS: Male albino rats of Wistar strain (4-5 weeks old) were grouped into normal control (NC), vehicle control (VC), diabetes (DI), diabetes + stress (DI + S), diabetes + EE (DI + E), and diabetes + stress + EE (DI + S + E) groups (n = 8 in each group). Rats were exposed to stress and EE after inducing diabetes with STZ (40 mg/kg). Rats were sacrificed on Day 30 and brain sections were processed for cresyl violet staining to quantify the number of surviving neurons in the CA1, CA3, and dentate hilus (DH) regions of hippocampus.
RESULTS: A significant (p < 0.001) decrease in the number of survived neurons was noticed in DI (CA1, 34.06 ± 3.2; CA3, 36.1 ± 3.62; DH, 9.83 ± 2.02) as well as DI + S (CA1, 14.03 ± 3.12; CA3, 20.27 ± 4.09; DH, 6.4 ± 1.21) group rats compared to NC rats (CA1, 53.64 ± 2.96; CA3, 62.1 ± 3.34; DH, 21.11 ± 1.03). A significant (p < 0.001) increase in the number of survived neurons was observed in DI + E (CA1, 42.3 ± 3.66; CA3, 46.73 ± 4.74; DH, 17.03 ± 2.19) and DI + S + E (CA1, 29.69 ± 4.47; CA3, 36.73 ± 3.89; DH, 12.23 ± 2.36) group rats compared to DI and DI + S groups, respectively.
CONCLUSIONS: EE exposure significantly reduced the amount of neuronal damage caused by complications of diabetes and stress to the neurons of hippocampus.
Dopamine (DA) is one of the key neurotransmitters in the striatum, which is functionally important for a variety of cognitive and motor behaviours. It is known that the striatum is vulnerable to damage from traumatic brain injury (TBI). However, a therapeutic approach has not yet been established to treat TBI. Hence, the present work aimed to evaluate the ability of Normobaric hyperoxia treatment (NBOT) to recover dopaminergic neurons following a fluid percussion injury (FPI) as a TBI experimental animal model. To examine this, mice were divided into four groups: (i) Control, (ii) Sham, (iii) FPI and (iv) FPI+NBOT. Mice were anesthetized and surgically prepared for FPI in the striatum and immediate exposure to NBOT at various time points (3, 6, 12 and 24 h). Dopamine levels were then estimated post injury by utilizing a commercially available ELISA method specific to DA. We found that DA levels were significantly reduced at 3 h, but there was no reduction at 6, 12 and 24 h in FPI groups when compared to the control and sham groups. Subjects receiving NBOT showed consistent increased DA levels at each time point when compared with Sham and FPI groups. These results suggest that FPI may alter DA levels at the early post-TBI stages but not in later stages. While DA levels increased in 6, 12 and 24 h in the FPI groups, NBOT could be used to accelerate the prevention of early dopaminergic neuronal damage following FPI injury and improve DA levels consistently.
Honey is widely used in folk medicine to treat cough, fever, and inflammation. In this study, the effect of aerosolised honey on airway tissues in a rabbit model of ovalbumin (OVA)-induced asthma was investigated. The ability of honey to act either as a rescuing agent in alleviating asthma-related symptoms or as a preventive agent to preclude the occurrence of asthma was also assessed.
Wounds with full-thickness skin loss are commonly managed by skin grafting. In the absence of a graft, reepithelialization is imperfect and leads to increased scar formation. Biomaterials can alter wound healing so that it produces more regenerative tissue and fewer scars. This current study use the new chitosan based biomaterial in full-thickness wound with impaired healing on rat model. Wounds were evaluated after being treated with a chitosan dermal substitute, a chitosan skin substitute, or duoderm CGF. Wounds treated with the chitosan skin substitute showed the most re-epithelialization (33.2 ± 2.8%), longest epithelial tongue (1.62 ± 0.13 mm), and shortest migratory tongue distance (7.11 ± 0.25 mm). The scar size of wounds treated with the chitosan dermal substitute (0.13 ± 0.02 cm) and chitosan skin substitute (0.16 ± 0.05 cm) were significantly decreased (P < 0.05) compared with duoderm (0.45 ± 0.11 cm). Human leukocyte antigen (HLA) expression on days 7, 14, and 21 revealed the presence of human hair follicle stem cells and fibroblasts that were incorporated into and surviving in the irradiated wound. We have proven that a chitosan dermal substitute and chitosan skin substitute are suitable for wound healing in full-thickness wounds that are impaired due to radiation.