Related Experiment Video
Updated: Feb 25, 2026
A Plate-Based Assay for the Measurement of Endogenous Monoamine Release in Acute Brain Slices
Published on: August 11, 2021
A Renal Clearable Probe for In Vivo Monoamine Oxidase (MAO) Detection
Marcia Domínguez1,2, David Azorín-Soriano1,3, Araceli Lérida-Viso1,2,3,4
1Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, Valencia, Spain.
Abstract:
Hyperactivation of monoamine oxidase enzymes (MAO) is associated with uncontrolled production of neurotoxic compounds such as reactive oxygen species, whose accumulation is linked to neurodegenerative, chronic, and age-related diseases. Although chromo-fluorogenic probes for detecting and quantifying MAO activity have been reported, non-invasive methods for monitoring MAO overexpression in vivo remain elusive. Here, we report a renal-clearable fluorogenic probe based on the cyanine-7 fluorophore (Cy7-MAO) for in vivo detection of MAO overexpression through a simple measurement of the fluorescence in urine. The probe incorporates sulfonic acid moieties for renal clearance and a propylamino group as a MAO substrate. Upon administration, Cy7-MAO is hydrolysed at the site by MAO, releasing a highly emissive Cy7 fluorophore, which is excreted in urine and quantified by fluorescence. Cy7-MAO is validated in vitro using HepG2 liver human cells, which express elevated MAO levels. We further demonstrate the in vivo applicability of Cy7-MAO for MAO activity monitoring in aged mice, which show significantly higher urine fluorescence than young mice, consistent with an elevated MAO activity in older animals. These findings support Cy7-MAO as a tool for longitudinal assessment of MAO activity in vivo, providing a novel approach to study MAO-related pathologies.
Insights
A new urine-detectable probe, Cy7-MAO, allows non-invasive monitoring of monoamine oxidase (MAO) enzyme activity in vivo. This breakthrough aids in studying MAO-related diseases and aging processes.
Area of Science:
- Biomedical Engineering
- Biochemistry
- Medical Imaging
Background:
- Hyperactivation of monoamine oxidase (MAO) enzymes contributes to neurotoxic compound production, linked to neurodegenerative and age-related diseases.
- Current methods for MAO detection are often invasive, limiting in vivo monitoring.
- Non-invasive tools are needed to track MAO overexpression and its pathological implications.
Purpose of the Study:
- To develop a novel, renal-clearable fluorogenic probe for non-invasive in vivo detection of MAO activity.
- To establish a simple method for quantifying MAO overexpression by measuring urine fluorescence.
- To validate the probe's utility in cell models and aged animal studies.
Main Methods:
- Design and synthesis of a cyanine-7 (Cy7) based fluorogenic probe (Cy7-MAO) with sulfonic acid groups for renal clearance and a propylamino MAO substrate.
- In vitro validation using HepG2 liver cells with elevated MAO levels.
- In vivo testing in young and aged mice to assess MAO activity via urine fluorescence measurement.
Main Results:
- The Cy7-MAO probe successfully detected MAO activity in vitro.
- Administration of Cy7-MAO led to MAO-mediated hydrolysis, releasing a fluorescent Cy7 signal excreted in urine.
- Aged mice exhibited significantly higher urine fluorescence compared to young mice, indicating elevated MAO activity.
Conclusions:
- Cy7-MAO serves as an effective tool for the longitudinal, non-invasive assessment of MAO activity in vivo.
- This probe offers a novel approach for studying MAO-related pathologies and aging.
- Urine fluorescence measurement provides a simple and accessible method for MAO activity monitoring.
More Related Videos
11:01Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase
Published on: November 23, 2016
13:35A Convenient Method for Extraction and Analysis with High-Pressure Liquid Chromatography of Catecholamine Neurotransmitters and Their Metabolites
Published on: March 1, 2018