Efflux Transporters in Rat Placenta and Developing Brain: Transcriptomic and Functional Response to Paracetamol

Abstract

Adenosine triphosphate binding cassette (ABC) transporters transfer lipid-soluble molecules across cellular interfaces either directly or after enzymatic metabolism. RNAseq analysis identified transcripts for ABC transporters and enzymes in rat E19, P5 and adult brain and choroid plexus and E19 placenta. Their functional capacity to efflux small molecules was studied by quantitative analysis of paracetamol (acetaminophen) and its metabolites using liquid scintillation counting, autoradiography and ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Animals were treated acutely (30min) and chronically (5 days, twice daily) with paracetamol (15mg/kg) to investigate ability of brain and placenta barriers to regulate ABC transport functionality during extended treatment. Results indicated that transcripts of many efflux-associated ABC transporters were higher in adult brain and choroid plexus than at earlier ages. Chronic treatment upregulated certain transcripts only in adult brain and altered concentrations of paracetamol metabolites in circulation of pregnant dams. Combination of changes to metabolites and transport system transcripts may explain observed changes in paracetamol entry into adult and fetal brains. Analysis of lower paracetamol dosing (3.75mg/kg) indicated dose-dependent changes in paracetamol metabolism. Transcripts of ABC transporters and enzymes at key barriers responsible for molecular transport into the developing brain showed alterations in paracetamol pharmacokinetics in pregnancy following different treatment regimens.

Entry of the antipsychotic drug, olanzapine, into the developing rat brain in mono- and combination therapies

“…On the other hand, co-treatment with paracetamol decreased olanzapine entry into the fetal CSF, suggesting competition for the same influx transporter(s). The observed increased olanzapine entry into the fetal brain following combination with fellow Pgp substrates digoxin and lamotrigine, is consistent with our previous findings of lower expression of abcb1a (pgp) in fetal rats compared to adult animals (Ek et al, 2010;Koehn et al, 2021), implying less capacity of the fetal brain to efflux Pgp substrates.…”

“…The placentas in both species are haemochorial; although there are some morphological differences, and are much more similar than many other species that are used for developmental studies (Ek et al, 2010;Studdert et al, 2020;Møllgård et al, 2017). Of particular importance is the similarity of cellular distribution of ABC efflux transporters in rat and human placenta and brain barriers (Ek et al, 2010;Saunders & Dziegielewska, 2020;Koehn et al, 2021).…”

Multi-omics approach reveals dysregulated genes during hESCs neuronal differentiation exposure to paracetamol

“…We also compared our data to previously published studies using the webtool ( hescneuroparacet ). In a rat model of foetal paracetamol exposure (95), dysregulation in specific ABC efflux transporters and related enzymes was found after chronic treatment of the mothers in E19 foetal brain and choroid plexus. In our model of paracetamol exposure, we also identified differential expression of the relevant genes ABCA1, ABCC5, ABCD3 and GSTM 3.…”