Cannabinoid Modulation of Monoamine Levels in Mouse Brain: Unveiling Neurochemical Dynamics through an Innovative High-performance Liquid Chromatography-Fluorescence Detection Bioanalysis

Abstract

Homeostasis of monoaminergic pathways is compromised in aging and neurodegenerative/neurological diseases such as Alzheimer’s disease and depression. On the other hand, their modulation has also been linked to the mechanism of action of several drugs. Therefore, monitoring the levels of noradrenaline (NA), adrenaline (AD), dopamine (DA), and serotonin (5-HT), as well as those of tryptophan (TRYP), the precursor of 5-HT, and DA metabolites, namely 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), is fundamental for assessing disease severity and progression. This work aimed to develop and validate the first High-Performance Liquid Chromatography (HPLC) coupled with fluorescence detector (FLD) method that simultaneously and accurately quantifies NA, AD, DA, DOPAC, HVA, 5-HT and TRYP in mouse brain and prefrontal cortex (PFC) matrices. Previous sample preparation by protein precipitation was required to extract the compounds. Calibration curves were plotted using the background subtraction approach to reduce the interference of the endogenous analytes. Intra and inter-day accuracy and precision were within the ranges defined by ICH (The International Council for Harmonisation) guideline for bioanalytical method validation. Following validation, the impact of cannabidiol (CBD), cannabigerol (CBG), and cannabidivarin (CBDV) was explored in mice brains post-administration, revealing significant alterations in specific neurotransmitter levels upon cannabinoid exposure and shedding light on the complex modulation of neurochemical dynamics by cannabinoids. This research highlights the fit-for-purpose of the HPLC-FLD method and provides insights into potential mechanisms underlying phytocannabinoid actions in the central nervous system (CNS).