Anatomy and Histology

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Browsing Anatomy and Histology by browse.metadata.advisor "Chellan, Nireshni"

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    Beta secretase regulation and inflammation in pancreatic β-cells: the potential role of Rooibos
    (Stellenbosch : Stellenbosch University, 2018-12) Burger, Joleen; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Anatomy and Histology.; Chellan, Nireshni; Lopes, John; Muller, Christo J.F.
    Introduction Chronic, low-grade inflammation is a hallmark of insulin resistance (IR) and underlies pancreatic β-cell failure and the development of type 2 diabetes (T2D), a disease characterized by a reduction in β-cell functional mass. However, therapeutics that directly protect β-cells from stressors, such as inflammation and oxidative stress, are limited. Amylin, a neuro-hormone, is co-secreted with insulin, therefore hyperinsulinemia often coincides with hyper secretion of amylin. Increased secretion of amylin is associated amyloid deposition which have detrimental effects on β-cell function. In pancreatic islets, β-secretase (BACE) modulates the deposition of cytotoxic islet amyloid, an initiator of intra-islet inflammation and oxidative stress, making BACE inhibition a therapeutic target. Insights into mechanisms involved in islet inflammation and the associated effect(s) of BACE, may reveal an opportunity to develop novel therapeutics to protect and preserve β-cells in T2D. In addition to their antidiabetic properties, aspalathin (Asp), Z-2-(β-D-glucopyranosyloxy)-3-phenylpropenoic acid (PPAG), and an unfermented Rooibos extract (GRT) may have anti-inflammatory effects in β-cells and may additionally modulate BACE activity. Aim To determine if GRT or two of its most bioactive polyphenols have BACE inhibition activity and can reduce pro-inflammatory effects in rat insulinoma (INS1) pancreatic β-cells. Methods A model of moderate inflammation was established in INS1 cells using a cytokine cocktail, containing tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interferon-γ (IFN-γ). Rat insulinoma cell viability, function, and oxidative stress was measured in response to the cytokine cocktail and exposure to Asp, PPAG, and GRT by quantifying cellular adenosine triphosphate (ATP) production, cell death via apoptosis and necrosis, proliferation rate, insulin/amylin secretion and content, reactive oxygen species (ROS) production and nitrate (NO2-) generation. Beta secretase inhibition profiling of GRT, Asp, and PPAG was assessed using fluorescence resonance energy transfer (FRET) in a purified enzyme assay, followed by kinetically assessing BACE activity in vitro. Results The cytokine cocktail induced a state of moderate inflammation after 24 hours, mainly through IL-1β. High concentrations of Asp (1000 μM) and moreso, GRT (1 mg/ml), showed a trend towards BACE inhibition compared to controls (56.20% ± 2.05, p<0.0001 and 39.80% ± 0.55, p<0.0001), but reduced mitochondrial dehydrogenase activity in inflamed INS1 cells (19.02% ± 2.98, p<0.0001; 36.88% ± 1.53, p<0.0001), while PPAG showed no measurable effect. Lower concentrations of Asp (0.1–10 μM), PPAG (0.1–10 μM), and GRT (0.0001-0.01 mg/ml) may have a protective effect on inflamed pancreatic β-cells as an increase, albeit not significant, in overall cell viability and function was observed, with a concomitant decrease in oxidative stress after 24 hours (97.66% ± 3.5, p<0.66; 95.54% ± 5.61, p<0.52; 96.80% ± 3.67, p<0.55).
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    The effects of Rooibos (Aspalathus linearis) supplementation on the pancreas, liver, and kidney of male Wistar rats following antiretroviral treatment
    (Stellenbosch : Stellenbosch University, 2017-12-05) Pereira, Daniella Lagoa; Kotzé, Sanet Henriette; Chellan, Nireshni; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences. Division Anatomy and Histology.
    ENGLISH ABSTRACT : The health burden of human immunodeficiency virus (HIV) has improved with the introduction of antiretroviral therapy (ART). Near perfect adherence to ART is needed to ensure the maximum benefits of the drugs. Adherence is compromised by side effects and adverse drug reactions (ADRs) which may, in part, be due to drug induced oxidative stress. Rooibos (Aspalathus linearis) is a shrub-like bush native to South Africa and is cultivated primarily as an herbal tea. Rooibos contains various polyphenols that add to its overall antioxidant capabilities. Aspalathin, the most abundant polyphenol present in rooibos, has shown potent antioxidant capabilities in vitro, providing an attractive model for therapy. The following study questions whether the histological observable effects of ART can be attenuated with the introduction of rooibos tea in vivo. The study aimed to assess the effects of combination ART, and rooibos tea on the histology of the pancreas, liver, and kidney in a HIV-negative rat model. Rats (n=40) were subcatogorised into four groups namely: control (C), control ART (C-ART), control rooibos (C-R), and experimental (ART+R) groups. The C-ART and ART+R groups were administered a dose of combination ART consisting of 200 mg Emtricitabine (EMT), 600 mg Efavirenz (FTC) and 300 mg Tenofovir (TDF). A 2% (w/v) rooibos tea solution was administered ad libitum to C+R and ART+R groups. Samples of rooibos tea were analysed using liquid chromatography-mass spectrometry techniques to determine whether rats received the same concentrations of polyphenols throughout the investigation. Samples from the pancreas, liver, and kidney underwent standard histological processing. Routine haematoxylin and eosin stains and appropriate immunohistochemical and tinctorial techniques were conducted. Detailed morphometric measurements on pancreatic islet size, number and percentage of α and β-cells were performed. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were evaluated to test liver function. Changes in size of the glomerular corpuscle, glomeruli and proximal convoluted tubules (PCT) in the kidney were measured. Organ architecture, cellular structure and associated pathology were analysed in each organ, scored, and confirmed by a histopathologist. The size and number of pancreatic islets and the percentage of α and β-cells did not vary significantly from the control group. Serum AST and ALT levels did not vary significantly from controls indicating normal liver function. Glomerular corpuscle, glomeruli and PCT size remained constant compared to controls. No overt histopathology was present indicative of ART induced pancreatic toxicity, hepatotoxicity or nephrotoxicity. The results indicated no major changes between the various tea solutions indicating that the rats received similar concentrations of rooibos polyphenols throughout the week. The study maintains that ART, when given to rats, does not cause significant changes to organ histomorphometry. While rooibos tea administration did not worsen, or improve organ histomorphometry.
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    A histomorphometric study of the effect of Afriplex GRT(TM) on the pancreas, liver and kidney of rats fed a high-fat diet
    (Stellenbosch : Stellenbosch University, 2018-12) Layman, Jodie; Kotze, Sanet; Chellan, Nireshni; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Biomedical Sciences: Anatomy and Histology.
    ENGLISH ABSTRACT: Obesity causes a wide range of disorders including insulin resistance, hepatic steatosis as well as renal glomerular and tubular pathology. These disorders are typically associated with oxidative stress and inflammation. Rooibos, Aspalathus linearis, is a South African plant which has antioxidative, anti-inflammatory, antilipidemic, and antihyperglycemic properties as shown in vivo and in vitro. Afriplex GRT™ is an unfermented green rooibos extract which is postulated to have enhanced effects compared to fermented rooibos, mostly due to its high aspalathin content. The present study aimed to determine the ameliorative effects of Afriplex GRT™ on the histomorphometry of the pancreas liver and kidney in a diet-induced obese rat model. Male Wistar rats (N=28) were randomly sorted into four study groups (n=7) namely, control (C), GRT fed control (GRT), high-fat diet (HFD) and HFD supplemented with GRT (HFDGRT). Animals were either fed a control feed or a HFD which contained fat, cholesterol and fructose. Animals in the GRT and HFD-GRT groups were supplemented with Afriplex GRT™ at a concentration of 60 mg per kg body mass per day. Body mass, and pancreatic, liver and kidney mass were determined after which samples were processed to wax. Tissues were sectioned at 4 – 5 µm in thickness and stained using haematoxylin and eosin for analysis by a histopathologist. Immunohistochemistry using anti-insulin and anti-glucagon double antibody labelling was performed on the pancreas. Other staining techniques included Masson’s trichrome, Gordon and Sweet’s reticulin impregnation and periodic acid Schiff. Additionally, frozen sections of the liver and pancreas were stained using Oil red O for lipid infiltration. Morphometric techniques included area, diameter, radii, point counting and ratios. Body mass significantly decreased in the HFD-GRT group compared to the HFD group. Pancreas and kidney mass decreased significantly in the HFD-GRT group compared to the Cgroup, however liver mass significantly increased in both HFD groups. Islet area and β-cell area significantly decreased in the HFD-GRT group compared to all three control groups however, a greater number of islets was observed. Hepatic steatosis and liver pathology were reduced in the HFD-GRT group compared to the HFD group. Renal space and the proximal convoluted tubules were decreased in the HFD-GRT compared to C-group as indicated by trends. Additionally, a trend was observed in the arcuate artery media to lumen ratio which was increased in the GRT group compared to the HFD group. Similar to the present study, a decrease in body mass has been observed with fermented rooibos and its polyphenols in HFD-fed animals. In the HFD-GRT group, increased islets per section area and smaller islet areas are associated with increased insulin secretion, which suggests improved glucose tolerance. This study suggests that Afriplex GRT™ may effectively reduce hepatic steatosis, an effect previously seen in studies on fermented rooibos and rooibos polyphenols. More in-depth studies on the effects of Afriplex GRT™ in the kidney are needed, potentially for a longer study period. Therefore, Afriplex GRT™ has observable ameliorative effects on the histomorphology of the liver and the pancreas; the effects on the kidney requires further investigation.