Acetylcholine signaling genes are required for cocaine-stimulated egg laying in Caenorhabditis elegans

Abstract

The toxicity and addictive liability associated with cocaine abuse are well-known. However, its mode of action is not completely understood, and effective pharmacotherapeutic interventions remain elusive. The cholinergic effects of cocaine on acetylcholine receptors, synthetic enzymes, and degradative enzymes have been the focus of relatively little empirical investigation. Due to its genetic tractability and anatomical simplicity, the egg laying circuit of the hermaphroditic nematode, Caenorhabditis elegans, is a powerful model system to precisely examine the genetic and molecular targets of cocaine in vivo. Here, we report a novel cocaine-induced behavioral phenotype in C. elegans, cocaine-stimulated egg laying. In addition, we present the results of an in vivo candidate suppression screen of synthetic enzymes, receptors, degradative enzymes, and downstream components of the intracellular signaling cascades of the main neurotransmitter systems that control C. elegans egg laying. Our results show that cocaine-stimulated egg laying is dependent on acetylcholine synthesis and synaptic release, functional nicotinic acetylcholine receptors, and the C. elegans acetylcholinesterases.

Keywords: Caenorhabditis elegans; Gq alpha subunit; L-amino acid decarboxylase; acetylcholine; acetylcholinesterase; cocaine; dopamine; egg laying; muscarinic acetylcholine receptor; nicotinic acetylcholine receptor; octopamine; serotonin; tyramine; tyrosine beta-hydroxylase; tyrosine decarboxylase; vesicular acetylcholine transporter.