A common muscarinic pathway for diapause recovery in the distantly relatednematode species Caenorhabditis elegans and Ancylostoma caninum

Converging TGF-beta and insulin-like neuroendocrine signaling pathways regu late whether Caenorhabditis elegans develops reproductively or arrests at t he dauer larval stage. We examined whether neurotransmitters act in the dau er entry or recovery pathways. Muscarinic: agonists promote recovery from d auer arrest induced by pheromone as well as by mutations in the TGF-beta pa thway. Dauer recovery in these animals is inhibited by the muscarinic antag onist atropine. Muscarinic agonists do not induce dauer recovery of either daf-a or age-1 mutant animals, which have defects in the insulin-like signa ling pathway. These data suggest that a metabotropic acetylcholine signalin g pathway activates an insulin-like signal during C. elegans dauer recovery . Analogous and perhaps homologous cholinergic regulation of mammalian insu lin release by the autonomic nervous system has been noted. In the parasiti c nematode Ancylostoma caninum, the dauer larval stage is the infective sta ge, and recovery to the reproductive stage normally is induced by host fact ors. Muscarinic agonists also induce and atropine potently inhibits in vitr o recovery of A. caninum dauer arrest. We suggest that host or parasite ins ulin-like signals may regulate recovery of A. caninum and could be potentia l targets for antihelminthic drugs.