Regulatory factors controlling tick salivary glands (SGs) are direct upstream neural signaling pathways arising from the tick's central nervous system. Here we investigated the cholinergic signaling pathway in the SG of two hard tick species. We reconstructed the organization of the cholinergic gene locus, and then used in situ hybridization to localize mRNA encoding choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) in specific neural cells in the Ixodes synganglion. Immunohistochemical staining revealed that cholinergic axonal projections exclusively reached type I acini in the SG of both Ixodes species. In type I acini, the rich network of cholinergic axons terminate within the basolateral infoldings of the lamellate cells. We also characterized two types (A and B) of muscarinic acetylcholine receptors (mAChRs), which were expressed in Ixodes SG. We pharmacologically assessed mAChR-A to monitor intracellular calcium mobilization upon receptor activation. In vivo injection of vesamicol-a VAChT blocker-at the cholinergic synapse, suppressed forced water uptake by desiccated ticks, while injection of atropine, an mAChR-A antagonist, did not show any effect on water volume uptake. This study has uncovered a novel neurotransmitter signaling pathway in Ixodes SG, and suggests its role in water uptake by type I acini in desiccated ticks.

• MeSH
• acinární buňky metabolismus   fyziologie   MeSH
• axony metabolismus   MeSH
• centrální nervový systém metabolismus   MeSH
• cholin-O-acetyltransferasa genetika   metabolismus   MeSH
• cholinergní látky metabolismus   MeSH
• klíště metabolismus   MeSH
• messenger RNA metabolismus   MeSH
• neurony cholinergní metabolismus   fyziologie   MeSH
• neurony metabolismus   MeSH
• signální transdukce genetika   MeSH
• slinné žlázy metabolismus   fyziologie   MeSH
• vezikulární transportní proteiny acetylcholinu genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND: Chronic renal failure is frequently associated with a high risk of sudden cardiac death due to dysfunction of the autonomic nervous system. The pathogenic mechanisms underlying the parasympathetic cardiac dysautonomia are not fully elucidated yet. METHODS: Chronic renal failure was induced in rats by 5/6 nephrectomy. Blood pressure, resting heart rate and plasma levels of creatinine, urea and asymmetric dimethylarginine (ADMA) were measured. To characterize the parasympathetic innervation of the heart, chronotropic responses to atropine, metipranolol and to vagal stimulation in the absence or presence of ADMA were investigated in vivo. In vitro, chronotropic and inotropic effects of carbachol and ADMA and mRNA expression of muscarinic M2 receptors, high affinity choline transporter (CHT1), vesicular acetylcholine transporter (VAChT) and choline acetyltransferase (ChAT) were assessed in the isolated cardiac tissues. RESULTS: In 5/6 nephrectomy rats, the resting heart rate was significantly higher and the parasympathetic tone, measured as the effect of atropine after administration of metipranolol was significantly lower than in control animals. Plasma ADMA levels were significantly elevated in the uraemic rats and significantly inversely correlated with the effect of atropine on the heart rate. No differences were revealed in the plasma norepinephrine concentrations, negative chronotropic responses to stimulation of the vagus nerves, chronotropic and inotropic responses to carbachol and the relative expression of M2 receptors, CHT1, VAChT and ChAT. CONCLUSION: The data suggest that cardioacceleration in chronic renal failure is caused by a diminished cardiac parasympathetic tone in the presence of a functionally intact intrinsic cardiac cholinergic signalling system.

• MeSH
• atropin farmakologie   MeSH
• beta blokátory farmakologie   MeSH
• cholin-O-acetyltransferasa genetika   metabolismus   MeSH
• karbachol farmakologie   MeSH
• kardiotonika farmakologie   MeSH
• krysa rodu rattus MeSH
• ledviny chirurgie   metabolismus   účinky léků   MeSH
• messenger RNA genetika   metabolismus   MeSH
• metipranolol farmakologie   MeSH
• nefrektomie MeSH
• nervus vagus fyziologie   účinky léků   MeSH
• noradrenalin metabolismus   MeSH
• parasympatický nervový systém fyziologie   účinky léků   MeSH
• parasympatolytika farmakologie   MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• potkani Wistar MeSH
• proteiny nervové tkáně genetika   metabolismus   MeSH
• proteiny přenášející neurotransmitery přes plazmatickou membránu genetika   metabolismus   MeSH
• srdce inervace   MeSH
• srdeční frekvence fyziologie   MeSH
• vezikulární transportní proteiny acetylcholinu genetika   metabolismus   MeSH
• western blotting MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH