Effects of acamprosate on neuronal receptors and ion channels expressed in Xenopus oocytes.
BACKGROUND
Acamprosate (calcium acetylhomotaurinate) has proven to be a moderately effective pharmacological adjunct for the treatment of alcoholism. However, the central nervous system mechanism by which acamprosate reduces alcohol relapse remains unclear. Here we survey a number of metabotropic receptors, ligand-gated ion channels, and voltage-gated ion channels, to determine if acamprosate has actions at these sites in the central nervous system.


METHODS
Xenopus oocytes were injected with cDNAs or cRNAs encoding metabotropic glutamate receptors 1 and 5, M1 muscarinic receptors, glycine alpha1 homomeric and alpha1beta1 heteromeric receptors, gamma-aminobutyric acid A (GABA(A)alpha4beta3delta, alpha4beta3gamma2s, and alpha1beta2gamma2s) receptors, vanilloid receptor 1, and various combinations of alpha and beta subunits of voltage-gated Na+ channels. Electrophysiological responses were measured using two-electrode voltage clamp parameters after activation with agonists or voltage steps (for the voltage-gated channels). Acamprosate (0.1 to 100 microM) was pre-applied for 1 minute, followed by co-application with agonist. Acamprosate was also applied with ethanol to determine if it altered ethanol responses at some of these receptors and channels.


RESULTS
None of the receptors or ion channels responded to acamprosate alone. Acamprosate also failed to alter the activation of receptors or channels by agonists or after activation of voltage-gated channels. There was no effect of acamprosate on ethanol responses at GABA(A)alpha1beta2gamma2s receptors or Na+ channels.


CONCLUSIONS
Acamprosate does not significantly modulate the function of these receptors and ion channels at clinically relevant concentrations. Thus, the clinical effectiveness of acamprosate in the treatment of alcoholism is not likely due to direct effects on these receptors or ion channels.
Reilly
Matthew T
MT
Waggoner Center for Alcohol & Addiction Research, The University of Texas at Austin, Austin, Texas 78712-1095, USA. reillym@mail.utexas.edu
Lobo
Ingrid A
IA
McCracken
Lindsay M
LM
Borghese
Cecilia M
CM
Gong
Diane
D
Horishita
Takafumi
T
Harris
R Adron
RA
D000077443:Acamprosate; D000427:Alcohol Deterrents / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects*; D009865:Oocytes / Q000187:drug effects; D064529:Receptor, Metabotropic Glutamate 5; D043643:Receptor, Muscarinic M1 / Q000187:drug effects; D011963:Receptors, GABA-A / Q000187:drug effects; D018009:Receptors, Glycine / Q000187:drug effects; D018094:Receptors, Metabotropic Glutamate / Q000187:drug effects; D017981:Receptors, Neurotransmitter / Q000187:drug effects*; D015222:Sodium Channels / Q000187:drug effects; D050916:TRPV Cation Channels / Q000187:drug effects; D013654:Taurine / Q000031:analogs & derivatives* / Q000494:pharmacology; D014982:Xenopus laevis
D000427:Alcohol Deterrents; D007473:Ion Channels; D064529:Receptor, Metabotropic Glutamate 5; D043643:Receptor, Muscarinic M1; D011963:Receptors, GABA-A; D018009:Receptors, Glycine; D018094:Receptors, Metabotropic Glutamate; D017981:Receptors, Neurotransmitter; D015222:Sodium Channels; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; C104077:metabotropic glutamate receptor type 1; D013654:Taurine; D000431:Ethanol; D000077443:Acamprosate