Aminopeptidases: Development Of A Potential Diagnostic Method To Identify Prenatal Alcohol Exposure

Background: Foetal Alcohol Spectrum Disorders (FASD) diagnosis without

maternal confirmation has led to difficulties in accurate diagnosis for healthcare

professionals. Despite several studies on the effects of alcohol and its metabolites

on the developing foetus, animal studies have failed to identify the exact neuronal

mechanism of the damage responsible for deficits in cognitive function. A potential

biomarker that can be rapidly obtained, cost-effective and non-invasive can be a

steppingstone in identification of prenatal alcohol exposure (PAE) in all stages of

life.

Aim of the study: (1) To investigate Renin Angiotensin System (RAS) activities

and expression in a mouse model of PAE. (2) To identify urinary and serum RAS

aminopeptidases (IRAP, ApN, ApB and ApA) in a healthy population and in

individuals with an independent FASD diagnosis. (3) To explore how confounding

factors affect serum and urinary aminopeptidases.

Methods: RAS aminopeptidases activity and expression were measured in whole

brain, heart, kidney and uteri of 33 C57BL/6J mice. Urine was collected from

healthy participants and urine and serum were collected from children

independently diagnosed with FASD. Enzyme assays, Western blot analysis and

Immunohistochemical (IHC) detection by Immunofluorescence were used to

measure the rate of activity, expression and localities of aminopeptidases.

Results: (1) PAE causes significant changes in aminopeptidases rate of activity

and expression in a mouse model of PAE. (2) There are demonstrable differences

in urinary and serum aminopeptidase activities between FASD and non-FASD

children. (3) Aminopeptidases are altered by changes in hormonal status in

humans.

Conclusion: Using a mouse model of PAE, this study has identified a potential

mechanism, involving Angiotensin IV receptor binding, by which PAE causes

defects in cognitive function. In animals, IRAP is known to be involved in learning,

memory, cognition and emotional processing; drugs targeted at IRAP open-up

possibilities of potential therapies for FASD. Knowledge of factors affecting

aminopeptidases in human urine and serum can lead to their possible use as

biomarkers to identify PAE. This would allow early and reliable diagnosis and early

targeted therapeutic intervention for individuals with FASD.