Muscarinic receptor-dependent activation of phospholipase C in the developing human fetal central nervous system

• Published in: Brain research Vol. 653; no. 1; pp. 9 - 15
• Main Authors: Larocca, Jorge N., Rodriguez-Gabin, Alicia G., Rashbaum, William K., Weidenheim, Karen M., Lyman, William D.
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 08.08.1994; Amsterdam Elsevier; New York, NY
• Subjects: Atropine - pharmacology; Biological and medical sciences; Brain - embryology; Carbachol - pharmacology; Cytidine Diphosphate Diglycerides - metabolism; Embryology: invertebrates and vertebrates. Teratology; Embryonic and Fetal Development; Enzyme Activation; Female; Fetal CNS; Fetus - metabolism; Fundamental and applied biological sciences. Psychology; Human neurodevelopment; Humans; In Vitro Techniques; Inositol Phosphates - metabolism; Molecular embryology; Neural cell differentiation; Pirenzepine - pharmacology; Pregnancy; Pregnancy Trimester, Second; Receptors, Muscarinic - physiology; Second Messenger Systems; Signal transduction; Type C Phospholipases - metabolism; Human neurodevelopment; Neural cell differentiation; Signal transduction; Fetal CNS; Human; Embryonic development; Cholinergic receptor; Enzyme; Central nervous system; Hydrolases; Fetus; Esterases; Muscarinic receptor; Phosphoric diester hydrolases; Phospholipase C
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/0006-8993(94)90365-4

The coupling of muscarinic-cholinergic receptors (mAChR) to adenylate cyclase and phospholipase C (PLC) second messenger systems has been demonstrated in many animal species. However, little is known about this association in the developing human central nervous system. Because of the proposed role of acetylcholine in the regulation of development and differentiation of neural cells, an understanding of these relationships during human fetal development gains importance. We report, in this communication, the coupling of mAChR with PLC in the human fetal brain. This coupling was determined using two independent approaches that relied upon estimating the accumulation of inositol phosphates (IPs) and cytidine diphosphate diacylglycerol (CDP-DAG). Carbachol treatment of brain slices, in the presence of lithium, resulted in the accumulation of IPs. Analysis of the kinetics of this accumulation showed that IP 3 and IP 2 increased rapidly, reaching a peak or plateau before IP. The results also showed that agonist-stimulated PLC produced two second messengers, IP 3 and DAG. The production of DAG was strongly supported by the carbachol-dependent increase of CDP-DAG. The accumulation of IP and CDP-DAG was dependent on agonist concentration. The obtained EC 50 values were approximately: carbachol 47 μM; acetylcholine 6 μM; and oxotremorine 25 μM. Unexpectedly, all three agonists demonstrated a similar efficacy. The cholinergic stimulation of inositide hydrolysis appears to be the result of activation of the m1 muscarinic receptor.