Abstract
Hard ticks depend upon an ability to precisely and dynamically regulate their saliva to successfully evade host haemostatic and immune defences during extended blood feeding. Although pilocarpine, an exogenous muscarinic acetylcholine receptor (mAChR) agonist, can stimulate salivation experimentally, the endogenous control of saliva secretion by acetylcholine remains poorly understood. Here, we identify and characterise two pharmacologically distinct mAChRs (type A and B) in the genome of the medically important tick Ixodes ricinus. Molecular dynamics simulations and targeted mutagenesis reveal that type B mAChRs exhibit an atypical muscarinic profile, suggesting unconventional receptor signalling. Combining immunolabelling, in vivo pharmacology, and proteomics, we show that specific central neurons interact with distinct salivary gland regions via mAChR type-specific axons, coordinating fluid and protein secretion through separate acini and likely acting upstream of a neuropeptide-dependent cascade. This previously unrecognised mechanism of neural control offers new insights into how ticks modulate their saliva advancing our understanding of vector-host interactions, with potential implications for disrupting pathogen transmission.
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All data generated or analysed in this study are included in the article and the supplementary information files. Mass spectrometry proteomics data have been deposited in the ProteomeXchange Consortium via the PRIDE87 repository under dataset identifier PXD055362 (https://proteomecentral.proteomexchange.org). Source data are provided with this paper.
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Acknowledgements
This study was supported by the French National Research Agency (ANR-21-CE14-0012, project AxoTick; L.Š). UMR BIPAR was supported by the French Government’s Investissement d’Avenir programme, Laboratoire d’Excellence Integrative Biology of Emerging Infectious Diseases (ANR-10-LABX-62-IBEID; institutional support). Additional support was provided by the Czech Science Foundation (22-18424M; J.P.), (22-30920S; R.Š.), (21-08826S; P.K.), and the Ministry of Health of the Czech Republic (NU20-05-00396 R.Š.). The study was also supported by a grant from the Centre-Val de Loire Region, under the Electro-CELL, Appel à projet d’intérêt regional (APR IR 21060LBL; S.H.T.). We acknowledge the BC CAS core facility LEM supported by MEYS CR (LM2023050 Czech-BioImaging and OP VVV CZ.02.1.01/0.0/0.0/18_046/0016045; M.V.). We are grateful to Jan Veenstra from the University of Bordeaux, France, for providing the anti-SIFamide and anti-leucokinin antibodies.
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L. Šimo designed the study and supervised all work. C.N., L.M.-H., S.R., L.A.-D., L. Šofranková, K.B., A.C., E.T., H.F., V.U., T.K., F.D., O.H., R.Š., J.T., T.B., M.T., M.V., J.P., S.H.T., and L. Šimo performed the experiments and analysed and interpreted the data. J.J.V. performed the molecular dynamics analyses and wrote this part of the manuscript. N.H., M.S., H.A., P.K., and J.P. provided resources. L. Šimo prepared the final figures and wrote the manuscript. All authors revised and approved the final version.
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Nìng, C., Valdés, J.J., Mateos-Hernández, L. et al. Two types of axonal muscarinic acetylcholine receptors mediate formation of saliva cocktail in the tick Ixodes ricinus. Nat Commun (2026). https://doi.org/10.1038/s41467-026-68654-3
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DOI: https://doi.org/10.1038/s41467-026-68654-3
