Dissection of Ethanol Actions on Cholinergic Nerve Endings

Summary

Principal Investigator: TIMOTHY SEARL
Abstract: [unreadable] DESCRIPTION (provided by applicant): The LONG TERM OBJECTIVE of this proposal is to elucidate the molecular mechanisms by which alcohol affects neurotransmitter secretion. For this application, we will study the effects of ethanol on the secretion of acetylcholine. Ethanol has biphasic concentration dependent effects on acetylcholine release in the CNS. Preliminary experiments show very similar biphasic concentration dependent effects of ethanol on acetylcholine release at the more experimentally accessible mammalian synapse, the skeletal neuromuscular junction. Mammalian motor nerve endings are very sensitive to alcohols, with increases in neurotransmitter release being observed at low millimolar concentrations of ethanol. There are 2 SPECIFIC AIMS underlying the overall objectives as follows: SPECIFIC AIM 1: To determine the global nerve terminal targets by which ethanol affects the release of the neurotransmitter acetylcholine (Ach). Our preliminary data show that some of the effects of ethanol are due to actions directly on the secretory machinery. For evoked Ach release, we will inquire which of the effects of ethanol on Ach release are due to an action on presynaptic ionic channels or on the neurotransmitter release machinery downstream of membrane ionic channels. To this end, we will make simultaneous electrophysiological measurements of presynaptic ionic currents and evoked neurotransmitter release. SPECIFIC AIM 2: To examine the effect of ethanol after alteration of presynaptic proteins associated with the secretory apparatus. For the deletion studies, the starting point will be the Rab3A knockout mouse. Preliminary experiments reveal an increased sensitivity to ethanol of spontaneous Ach release after deletion of the Rab3A gene; this effect occurs downstream of membrane ionic channels. For the cleavage studies, we will cleave the strategic core proteins of the secretory apparatus at specific residues using various fractions of botulinum toxins, and determine if Ach release elicited independently of the cleaved proteins is affected by ethanol. Our preliminary data with botulinums toxins demonstrate that the synaptic vesicle protein synaptobrevin is an important target for the effects of ethanol. [unreadable] [unreadable] [unreadable] [unreadable]
Funding Period: 2007-07-10 - 2010-06-30
more information: NIH RePORT

Top Publications

  1. pmc Mechanisms of neuromodulation as dissected using Sr2+ at motor nerve endings
    Timothy J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, IL 60611, USA
    J Neurophysiol 99:2779-88. 2008
  2. pmc Selective disruption of the mammalian secretory apparatus enhances or eliminates calcium current modulation in nerve endings
    Eugene M Silinsky
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611, USA
    Proc Natl Acad Sci U S A 105:6427-32. 2008
  3. pmc Post-junctional interactions between neuromuscular blocking agents and ethanol at the mouse neuromuscular junction
    T J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, IL, USA
    Br J Pharmacol 161:659-67. 2010
  4. pmc The mechanism for prejunctional enhancement of neuromuscular transmission by ethanol in the mouse
    T J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611, USA
    J Pharmacol Exp Ther 335:465-71. 2010
  5. pmc Evidence for constitutively-active adenosine receptors at mammalian motor nerve endings
    Timothy J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
    Eur J Pharmacol 685:38-41. 2012
  6. pmc Modulation of purinergic neuromuscular transmission by phorbol dibutyrate is independent of protein kinase C in murine urinary bladder
    T J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
    J Pharmacol Exp Ther 342:312-7. 2012
  7. ncbi Low-frequency neuromuscular depression is a consequence of a reduction in nerve terminal Ca2+ currents at mammalian motor nerve endings
    Eugene M Silinsky
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
    Anesthesiology 119:326-34. 2013

Detail Information

Publications7

  1. pmc Mechanisms of neuromodulation as dissected using Sr2+ at motor nerve endings
    Timothy J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, IL 60611, USA
    J Neurophysiol 99:2779-88. 2008
    ..The results demonstrate both the utility of the binomial distribution in Sr2+ solutions and the dual effects of cyclic AMP on both PKA-dependent and PKA-independent processes at the amphibian neuromuscular junction...
  2. pmc Selective disruption of the mammalian secretory apparatus enhances or eliminates calcium current modulation in nerve endings
    Eugene M Silinsky
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611, USA
    Proc Natl Acad Sci U S A 105:6427-32. 2008
    ..In contrast, cleavage of the synaptic vesicle SNARE (synaptobrevin) in conjunction with deletion of the vesicle-docking protein Rab3A greatly enhances the efficacy of calcium current modulation...
  3. pmc Post-junctional interactions between neuromuscular blocking agents and ethanol at the mouse neuromuscular junction
    T J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, IL, USA
    Br J Pharmacol 161:659-67. 2010
    ..Here, we report on the effects of ethanol on evoked neuromuscular transmission and the interaction of ethanol with non-depolarizing blocking drugs...
  4. pmc The mechanism for prejunctional enhancement of neuromuscular transmission by ethanol in the mouse
    T J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611, USA
    J Pharmacol Exp Ther 335:465-71. 2010
    ..Identifying the mechanism through which ethanol enhances neurotransmitter release at the neuromuscular junction may be useful in determining the processes underlying the enhancement of neurotransmitter release at other synapses...
  5. pmc Evidence for constitutively-active adenosine receptors at mammalian motor nerve endings
    Timothy J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
    Eur J Pharmacol 685:38-41. 2012
    ....
  6. pmc Modulation of purinergic neuromuscular transmission by phorbol dibutyrate is independent of protein kinase C in murine urinary bladder
    T J Searl
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, IL 60611, USA
    J Pharmacol Exp Ther 342:312-7. 2012
    ..These results suggest that PDBu increases the purinergic component of detrusor transmission through increasing neurogenic ATP release via a PKC-independent mechanism...
  7. ncbi Low-frequency neuromuscular depression is a consequence of a reduction in nerve terminal Ca2+ currents at mammalian motor nerve endings
    Eugene M Silinsky
    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
    Anesthesiology 119:326-34. 2013
    ..The decline in voluntary muscle contraction during low-frequency nerve stimulation is used clinically to assess the type and degree of neuromuscular block. The mechanism underlying this depression is unknown...