Organ-Specific Toxicity

Cardiotoxicity Screening

Assay Description

The cardiotoxicity screening model uses adult zebrafish to evaluate the effects of chemical exposure on heart rate, rhythm, and overall cardiovascular health.

Testing Method: Adult zebrafish are exposed to the toxic substance, and their heart rate, rhythm, and blood circulation are monitored using video recording and advanced imaging techniques.

Pathology

Heart Morphology: Inspection for heart abnormalities such as ventricular arrhythmias, myocardial infarction, or hypertrophy.
Vascular Integrity: Monitoring of blood vessel development and integrity, looking for signs of vessel leakage or hemorrhage.

Biomarkers

Troponin I and T: Released into the bloodstream after myocardial injury, indicating cardiotoxicity.
BNP (B-type natriuretic peptide): Elevated levels signify heart failure or cardiovascular strain.
C-Reactive Protein (CRP): Elevated CRP indicates inflammation or stress in the cardiovascular system.

Screening Endpoints

Heart Rate: Decreased or irregular heart rate under exposure.
Rhythm Abnormalities: Tachycardia, bradycardia, arrhythmia, or irregular heartbeat patterns.
Vascular Leakage: Observable leakage or impaired blood flow in capillaries and major arteries.

Neurotoxicity Screening

Assay Description

The neurotoxicity model focuses on assessing the potential neurotoxic effects of substances on the nervous system. This includes both behavioral changes (motor function) and pathological changes in the central nervous system (CNS) of zebrafish.

Testing Method: Zebrafish embryos and larvae are exposed to the compound, and subsequent motor responses, locomotor activity, and brain development are monitored.

Pathology

Neural Defects: Morphological examination of the brain and spinal cord for structural defects, neuronal degeneration, or abnormal axon growth.
Behavioral Assays: Analysis of motor function, including spontaneous movement, response to stimuli, and locomotor activity in a controlled environment.

Biomarkers

Neurotransmitter Levels: Measurement of dopamine, serotonin, and acetylcholine levels to assess neurochemical disruptions.
Synaptic Proteins: Monitoring of synaptic markers (e.g., synaptophysin, PSD-95) to evaluate neurotoxicity at the synaptic level.
Neuroinflammatory Markers: Elevated levels of glial fibrillary acidic protein (GFAP) indicating neuroinflammation.

Screening Endpoints

Behavioral Changes: Altered movement patterns, reduced response to external stimuli, or abnormal swimming behavior.
Motor Function: Impaired coordination and balance, tested using assays like the "swim test" or touch-evoked response.
Neural Development: Abnormal neural tube closure or brain size, abnormal neuronal patterning.

Hepatotoxicity Screening

Assay Description

The Hepatotoxicity Assay leverages the transparency and rapid development of zebrafish embryos/larvae to evaluate liver toxicity induced by chemical compounds, drugs, or environmental toxins. This assay assesses hepatic function, structure, and biomarker expression to detect potential hepatotoxic effects.

Testing Method: Zebrafish embryos are exposed to different concentrations of the test compound starting from 6 hours post-fertilization (hpf).
Observations are conducted at 24, 48, and 72 hpf to assess liver morphology, size, and functionality.
Chemical exposure is continued until 5 days post-fertilization (dpf) to monitor subchronic hepatotoxic effects.

Pathology

Liver Morphology: Evaluation of liver size and shape under a stereomicroscope. Assessment of liver pigmentation, transparency, and structural integrity.
Histopathology: Hematoxylin and eosin (H&E) staining to identify hepatocyte necrosis, steatosis, and fibrosis. Oil Red O staining to detect lipid accumulation indicating steatosis.

Biomarkers

Enzymatic Markers: Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST) as indicators of liver injury.
Gene Expression Analysis: Upregulation of Cytochrome P450 enzymes (e.g., CYP1A, CYP2D6). Expression of apoptotic genes such as caspase-3, bax, and bcl-2.
Oxidative Stress Markers: Reactive Oxygen Species (ROS) and Malondialdehyde (MDA) levels to detect oxidative damage.

Screening Endpoints

Liver Morphology Analysis: Observable structural changes such as hepatomegaly or atrophy.
Lipid Accumulation: Lipid vacuole formation indicating steatosis.
Enzyme Activity Assays: Elevated ALT and AST levels indicating hepatocellular damage.
Apoptosis Detection: Increased expression of caspase-3 and other apoptotic markers.
ROS Assay: Increased ROS levels indicating oxidative stress.

Nephrotoxicity Screening

Assay Description

The Nephrotoxicity Assay assesses kidney structure and function in zebrafish embryos/larvae exposed to potential nephrotoxic compounds. This model evaluates renal morphological changes, glomerular filtration, and marker expression related to kidney injury.

Testing Method: Zebrafish embryos are exposed to test compounds at 24 hpf to 5 dpf.
Fluorescent dyes such as BODIPY FL and Dextran-FITC are used to monitor renal function and nephron integrity.
Live imaging is performed at 48, 72, and 96 hpf to assess glomerular filtration and tubular function.

Pathology

Kidney Morphology: Visualization of pronephros and mesonephros under fluorescence microscopy. Assessment of renal tubule structure, swelling, and cyst formation.
Histopathology: PAS staining to evaluate glomerular integrity. H&E staining to detect tubular necrosis and fibrosis.

Biomarkers

Kidney Injury Markers: Upregulation of Kim-1 and NGAL as indicators of renal tubular damage.
Oxidative Stress Markers: Elevated ROS and MDA levels indicating oxidative damage to renal tissues.
Apoptotic Markers: Activation of caspase-3 and bax genes as indicators of renal cell apoptosis.

Screening Endpoints

Renal Morphology Analysis: Observation of tubular dilation, cyst formation, and glomerular swelling.
Glomerular Filtration Assay: Monitoring filtration rate using fluorescently labeled dextran.
ROS Analysis: Quantification of oxidative stress levels in renal tissue.
Apoptosis Detection: Increased caspase-3 expression in kidney tissue.
Kidney Function Assessment: Detection of proteinuria and hematuria using urinalysis.