Open AccessExpression of the cholinergic signal‐transduction pathway components during embryonic rat heart development
Author(s) -
Franco Diego,
Moorman Antoon F.M.,
Lamers Wouter H.
Publication year - 1997
Publication title -
the anatomical record
Language(s) - English
Resource type - Journals
eISSN - 1097-0185
pISSN - 0003-276X
DOI - 10.1002/(sici)1097-0185(199705)248:1<110::aid-ar13>3.0.co;2-s
Subject(s) - choline acetyltransferase , muscarinic acetylcholine receptor , acetylcholinesterase , cholinergic , biology , acetylcholine , signal transduction , messenger rna , heart development , embryonic heart , acetylcholine receptor , gene isoform , microbiology and biotechnology , embryonic stem cell , medicine , endocrinology , receptor , enzyme , biochemistry , gene
Background Previous studies showed that acetylcholinesterase (AChE) activity is present in the downstream (arterial) part of the embryonic chick and rat heart, but its functional significance was unclear. To establish whether other components of a cholinergic signal‐transduction pathway are present in the embryonic heart, we localised the mRNAs encoding choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and the muscarinic receptor isoforms (mAChRs; m17ndash;m5). Methods Messenger RNA detection and localisation by in situ hybridisation and reverse transcriptase‐polymerase chain reaction were employed. Results Expression of ChAT and AChE mRNAs was observed from 15 embryonic days onward in the neural tissue covering the dorsocranial wall of the atria. Muscarinic receptors (m1, m2, m4) were observed at the same localisation as AChE and ChAT mRNAs, both during embryogenesis and after birth. In addition, m1 and m4 mAChRs showed a low level of expression in the atrial myocardium during the fetal period. No expression of the m3 or the m5 mAChRs was observed in or near the embryonic hearts. ChAT, AChE, and mAChRs (m1, m2, m4) mRNAs always colocalised in the cardiac ganglia. However, none of these mRNAs was found at a detectable level in the outflow tract and/or the ventricular trabeculations. Conclusons: The AChE activity in the arterial part of the embryonic heart is probably synthesised elsewhere and subserves a function different from the hydrolysis of locally produced acetylcholine. Anat. Rec. 248:110–120, 1997. © 1997 Wiley‐Liss, Inc.