Parkinson’s disease model in zebrafish using intraperitoneal MPTP injection

IntroductionParkinson’s disease (PD) is the second most common neurodegenerative disease that severely affects the quality of life of patients and their family members. Exposure to 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been shown to reflect behavioral, molecular, and proteomic features of PD. This study aimed to assess the protocol for inducing PD following MPTP injection in adult zebrafish.MethodsFish were injected with 100 μg/g of MPTP intraperitoneally once or twice and then assessed on days 1 to 30 post-injection.ResultsBetween one-time and two-time injections, there was no significant difference in most locomotor parameters, expressions of tyrosine hydroxylase-2 (th2) and dopamine transporter (dat) genes, and dopaminergic neurons (tyrosine hydroxylase positive, TH+ cells) counts. However, caspase-3 levels significantly differed between one- and two-time injections on the day 1 assessment.DiscussionOver a 30-day period, the parameters showed significant differences in swimming speed, total distance traveled, tyrosine hydroxylase-1 (th1) and dat gene expressions, caspase-3 and glutathione protein levels, and TH+ cell counts. Days 3 and 5 showed the most changes compared to the control. In conclusion, a one-time injection of MPTP with delayed assessment on days 3 to 5 is a good PD model for animal studies

Neuroprotective effects of Neurotrophin-3 in MPTP-induced zebrafish Parkinson’s disease model

Introduction: Neurotrophin-3 (NT3) is a neuroprotective growth factor that induces the development, maintenance and survival of neurons. This study aims to localize NT3-expressing cells in the adult zebrafish brain and examine the role of NT3 in a zebrafish Parkinson’s disease (PD) model.Methods: Cellular localization of NT3 in adult zebrafish brains was conducted using in situ hybridization. Subsequently, adult zebrafish were injected intraperitoneally with 100 μg/g of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and treated with 400 ng/g body weight of recombinant NT3 (rNT3) via intracranial injection 24 h following MPTP injection. The fish were assessed for neurobehavioral, gene expression, immunohistology, and protein analysis on days 3, 5 and 10 post-MPTP injection.Results: Our findings showed that NT3 was extensively expressed throughout the adult zebrafish brain in neurons. Administration of rNT3 has significantly improved locomotor activity, with upregulation of th1, dat, ntf3 and bdnf gene expressions compared to MPTP-induced zebrafish. Dopaminergic neurons were also significantly increased in the zebrafish brain following rNT3 treatment. ELISA analysis reported raised GST and decreased caspase-3 levels on day 3 of assessment. The trophic changes of rNT3, however, decline as the assessment day progresses.Conclusion: This study is the first to examine the role of NT3 in the adult zebrafish PD model. NT3 has remarkable trophic effects in the zebrafish PD model. However, further study is needed to examine the dosage requirements and long-term effects of NT3 in PD

Targeting dopamine transporter to ameliorate cognitive deficits in Alzheimer's disease

Alzheimer's disease (AD) is characterized by the pathologic deposition of amyloid and neurofibrillary tangles in the brain, leading to neuronal damage and defective synapses. These changes manifest as abnormalities in cognition and behavior. The functional deficits are also attributed to abnormalities in multiple neurotransmitter systems contributing to neuronal dysfunction. One such important system is the dopaminergic system. It plays a crucial role in modulating movement, cognition, and behavior while connecting various brain areas and influencing other neurotransmitter systems, making it relevant in neurodegenerative disorders like AD and Parkinson's disease (PD). Considering its significance, the dopaminergic system has emerged as a promising target for alleviating movement and cognitive deficits in PD and AD, respectively. Extensive research has been conducted on dopaminergic neurons, receptors, and dopamine levels as critical factors in cognition and memory in AD. However, the exact nature of movement abnormalities and other features of extrapyramidal symptoms are not fully understood yet in AD. Recently, a previously overlooked element of the dopaminergic system, the dopamine transporter, has shown significant promise as a more effective target for enhancing cognition while addressing dopaminergic system dysfunction in AD

Oral administration of tocotrienol ameliorates lead-induced toxicity in the rat brain

The occurrence of severe lead (Pb) poisoning has risen in certain countries. There is increasing evidence that chronic lead exposure disturbs the prooxidant: antioxidant balance in the brain tissue and alters brain histology. The present study observed the antioxidant effect of tocotrienol-rich fraction (TRF) on brain tissues of the experimental rats following lead poisoning. Eighteen (n=18) male Sprague-Dawley rats, 6-weeks old, were randomly divided into control (CTRL) group and experimental groups; fed with 0.2% w/v lead acetate, as PB2 group; and fed with 0.2% w/v lead acetate and daily TRF supplementation (200 mg/kg body weight) as PB2T group. The experiment was conducted for 30 days. At the end of the study, the brain tissues were harvested and histopathological changes of the hippocampal region were observed. Biochemical findings such as brain lead, TRF and malondialdehyde (MDA) levels, and erythrocyte superoxide dismutase (SOD) activity were determined. It was observed that atypical apoptotic-like and disorganized neurons were present in the hippocampal region of the untreated PB2 group compared to PB2T group. Biochemical parameters showed a significant decrease (p 0.05) was obtained for MDA level, there was a significant increase (p < 0.05) in the erythrocyte SOD activity in PB2T compared to PB2 and CTRL. Supplementation with TRF improved histopathological changes in the brain tissues caused by lead exposure in drinking water by reducing lead accumulation in the brain of experimental rats

Comparable Benefits of Stingless Bee Honey and Caffeic Acid in Mitigating the Negative Effects of Metabolic Syndrome on the Brain

There is mounting evidence that metabolic syndrome (MetS) contributes to the development of neurodegenerative disorders such as Alzheimer’s disease. Honey, which has been used for generations, is high in antioxidants and has been demonstrated to benefit the brain and mental health by reducing oxidative stress and boosting cognitive outcomes. Honey from the stingless bees of Heterotrigona itama has been found to have higher phenolic content compared to other types of honeys. The aim of this study is to investigate the effects of stingless bee honey (SBH) supplementation and to compare it with a pure form of antioxidant, caffeic acid (CA), on MetS parameters and inflammatory markers in the brains of MetS-induced rats. A total of 32 male Wistar rats were divided equally into groups of control, high-carbohydrate high-fructose (HCHF) diet (MetS), HCHF + SBH supplemented (1 g/kg) (SBH), and HCHF + CA supplemented (10 mg/kg) (CA) groups. The total duration for SBH and CA supplementation was eight weeks. The HCHF diet was found to promote hypertension, hyperglycemia, and hypertriglyceridemia, and to increase brain TNF-α levels. Supplementation with SBH and CA significantly reversed (p < 0.05) the hyperglycemic and hypertensive effects of the HCHF diet. Although both supplemented groups showed no significant changes to serum HDL or TG, SBH significantly reduced (p < 0.05) brain TNF-α levels and increased (p < 0.05) brain BDNF levels. Immunohistochemistry investigations of neurogenesis (EdU) and apoptosis (TUNEL) on the cornu Ammonis 1 (CA1) and dentate gyrus (DG) areas of the hippocampus showed no changes with SBH and CA supplementation compared to the control. These findings suggest that SBH and CA have the potential to mitigate HCHF-induced MetS effects and possess neuroprotective abilities

Preventive effects of Polygonum minus essential oil on cisplatin-induced hepatotoxicity in sprague dawley rats

Cisplatin is a chemotherapeutic agent widely used in treating various types of cancer. However, its usage is restricted due to the adverse hepatoxicity, as seen in approximately 36% of cancer patients receiving cisplatin treatment. Polygonum minus essential oil has high antioxidant capacity, and is enriched with terpenoids and phenolic compounds. The objective of this study was to investigate effects of P. minus essential oil (PmEO) supplementation on cisplatin-induced hepatotoxicity in rats. Male rats were divided into seven different groups, namely: control (C), cisplatin-induced (CP), positive control with β-caryophyllene 150 mg/kg (BCP), PmEO 100 mg/kg (PmEO100CP), PmEO 200 mg/kg (PmEO200CP), PmEO 400 mg/kg (PmEO400CP) and PmEO 400 mg/kg alone (PmEO400). PmEO and BCP was given orally for 14 days prior to a single dose cisplatin (10 mg/kg) injection on day 15 and rats were sacrificed on day 18. Liver enzymes, histology, ultrastructural morphology and oxidative stress markers such as glutathione, glutathione peroxidase, catalase, superoxide dismutase and malondialdehyde were assayed. Compared to controls, levels of transaminase enzymes, serum bilirubin and oxidative stress were all increased in CP, PmEO200CP and PmEO400CP groups. However, only PmEO100CP and BCP groups reduced these increases in level of transaminase enzymes and oxidative stress compared to CP group. On both light microscopic and ultrastructural examination, CP and PmEO400CP groups showed hepatotoxicity, exhibited by cytoplasmic vacuolation, congested blood sinusoids and increased number of Kupffer cells. However, these changes were minimized in the PmEO100CP group. Therefore, we concluded that PmEO given at 100 mg/kg has preventive effect against cisplatin-induced hepatotoxicity in rats

Polygonum minus essential oil modulates cisplatin-induced hepatotoxicity through inflammatory and apoptotic pathways

Oxidative stress, inflammation and apoptosis are thought as primary mediators of cisplatin-induced hepatotoxicity. The objective of this study was to determine the protective effect of Polygonum minus essential oil in cisplatin-induced hepatotoxicity. A total of forty-two male rats were randomly divided into seven groups: control, cisplatin, β-caryophyllene 150 mg/kg (BCP), PmEO 100 mg/kg + cisplatin (PmEO100CP), PmEO 200 mg/kg + cisplatin (PmEO200CP), PmEO 400 mg/kg + cisplatin (PmEO400CP) and PmEO 400 mg/kg (PmEO400). Rats in the BCP, PmEO100CP, PmEO200CP, PmEO400CP and PmEO400 group received respective treatment orally for 14 consecutive days prior to cisplatin injection. All animals except for those in the control group and PmEO400 were administered with a single dose of cisplatin (10 mg/kg) intraperitoneally on day 15 and all animals were sacrificed on day 18. PmEO100CP pretreatment protected against cisplatin-induced hepatotoxicity by decreasing CYP2E1 and indicators of oxidative stress including malondialdehyde, 8-OHdG and protein carbonyl which was accompanied by increased antioxidant status (glutathione, glutathione peroxidase, superoxide dismutase and catalase) as compared to cisplatin group. PmEO100CP pretreatment also modulated changes in liver inflammatory markers (TNF-α, IL-1α, IL-1β, IL-6 and IL-10). PmEO100CP administration also notably reduced cisplatin-induced apoptosis significantly as compared to cisplatin group. In conclusion, our results suggested that P. minus essential oil at a dose of 100 mg/kg may protect against cisplatin-induced hepatotoxicity possibly via inhibition of oxidative stress, inflammation and apoptosis

Imagineering anatomy assessment amidst Covid-19: turning obstacles into achievements

A well-designed assessment has beneficial impacts on students’ learning and competency attainment. Failure in obtaining psychomotor learning competency, lack of understanding of assessment principles among instructors, unoptimized information and technology facilities, and difficulties in ensuring the integrity of online examination are among the threats to validity of online anatomy assessment during the COVID-19 pandemic. To ensure the validity of anatomy assessment during the pandemic, it is important to adopt several educational principles into the assessment design. We solidify the input discussed in the Malaysian Anatomical Association webinar 2021, on the challenges of anatomy online assessment and proposed six solutions to the challenges, namely adopting the programmatic assessment design, conducting small group in-person high stake examination, modifying assessment policy, utilizing question bank software, upgrading ICT facilities, and offering the ICT training to the students and instructors. It is envisioned that anatomy assessment are future ready are adaptive to change

The effect of type, duration and intensity of exercise on inflammatory markers CRP, IL-6 and IL-18 in metabolic syndrome patients : a systematic review

Metabolic syndrome (MetS) has become a major clinical challenge worldwide due to rise of urbanisation, surplus energy intake, increasing obesity and sedentary lifestyle. C-reactive protein (CRP), interleukin-6 (IL-6) and interleukin-18 (IL-18) are associated with MetS. We performed a systematic review to investigate the effects of exercise on these markers in MetS patients and therefore to determine the best exercise regime for them. We searched Medline (Pubmed and Ovid), Scopus and CINAHL databases. The searches were standardized by using the same search strategy which included the terms such as ‘metabolic syndrome’, ‘CRP’, ‘IL-6’, ‘IL-18’ and ‘exercise’. Only clinical human studies published from Jan 2007 to May 2018 were included. A total of 11 clinical trials (466 participants) were selected. Majority of the studies were randomized controlled studies (90.9%). All studies showed a decrease in serum levels of the biomarkers. However, not all were statistically significant. The main type of exercise in most of the studies was aerobic. Aerobic-resistance exercise was more effective rather than aerobic alone, but aerobic exercise was the only effective as a sole intervention. Aerobic exercise showed promising role as the main lifestyle intervention in MetS. It is concluded that patients with MetS should have combined aerobic-resistance exercise

Neuroprotective effect of metallothionein

Non-mammalian vertebrates such as teleosts have the ability to regenerate brain parts after injury. Previously, we identified significant up-regulation of metallothionein (MT) in the zebrafish brain after brain injury. MT is a relatively small molecular weight peptide rich in cysteine (Cys), and is thought to maintain essential metal homeostasis, heavy metal detoxification and provides protection against oxidative stress. Studies in mammalian models have demonstrated changes of MT expression in several neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. Hence, this study was designed to investigate the distribution of MT and its possible neuroprotective effect in mechanical and neurotoxin-induced brain injury in the adult zebrafish. The thesis has three experimental chapters with three main objectives as described in below. In objective 1, we localized two MT homologous genes (mt2 and smtb) and their receptor gene (lrp2a) in the brain of zebrafish to investigate their functions by in situ hybridization (ISH). ISH showed mt2, smtb and lrp2a are expressed in different parts of the brain, especially near to the ventricular surface of the brain, most of which are cell proliferating regions. Double-labelling staining further confirmed that mt2-, smtb- and lrp2a-mRNA are expressed in neurons and not in astrocytes, and some cells are co-localized with a cell proliferating marker protein. These results suggest possible role of MTs in neurogenesis, or protection of new born cells in the brain of zebrafish. In objective 2, we assessed the expression of mt2, smtb and lrp2a, and the effect of exogenous MT (human MT2 peptide, hMT2) in the zebrafish following mechanical brain injury to the telencephalon. Upon brain injury, mt2 and smtb expression were up-regulated and remained high until 4 day post-injury (dpi), however, lrp2a expression were down-regulated. ISH revealed increased number of mt2 and smtb mRNA expressing cells in the injured telencephalon at 4-dpi. Exogenous administration of hMT2 up-regulated mt2 expression and increased the number of proliferating cells but reduced apoptotic cells. This effect was blocked by administration of antibody against hMT2. These results demonstrated neuroprotective effect of MT following mechanical brain injury in the zebrafish. In objective 3, we examined the role of MT in a neurotoxin-induced brain injury. Fish were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to induce degeneration and death of the dopaminergic cell. MPTP administration reduced the total numbers of dopaminergic neurons and the locomotor activity as seen in Parkinson’s disease. Intracranial MPTP administration up-regulated mt2, smtb, lrp2a and dopamine related genes (th1 and th2) expression at day 14 post-injection, which were attenuated by hMT2 treatment. Furthermore, hMT2 treatment induced reduction of dopaminergic neuronal loss and recovery of locomotor activity, suggesting the protective effect of MT against MPTP-induced brain injury. In conclusion, I have presented the possible role of zebrafish MTs in neuronal proliferation in the brain. The up-regulation of mt2 and smtb genes following mechanical and neurotoxin-induced brain injury suggest neuroprotective roles of MTs. Furthermore, administration of exogenous MT successfully promoted recovery of brain injury. Our findings suggest that MT plays an important role in strong neuroregenerative capability of non-mammalian vertebrate brain, which provides a novel insight into the MT as a novel therapeutic target for human brain injury