title: Optogenetic analysis of synaptic function.
abstract: We introduce optogenetic investigation of neurotransmission (OptIoN) for time-resolved and quantitative assessment of synaptic function via behavioral and electrophysiological analyses. We photo-triggered release of acetylcholine or gamma-aminobutyric acid at Caenorhabditis elegans neuromuscular junctions using targeted expression of Chlamydomonas reinhardtii Channelrhodopsin-2. In intact Channelrhodopsin-2 transgenic worms, photostimulation instantly induced body elongation (for gamma-aminobutyric acid) or contraction (for acetylcholine), which we analyzed acutely, or during sustained activation with automated image analysis, to assess synaptic efficacy. In dissected worms, photostimulation evoked neurotransmitter-specific postsynaptic currents that could be triggered repeatedly and at various frequencies. Light-evoked behaviors and postsynaptic currents were significantly (P <or= 0.05) altered in mutants with pre- or postsynaptic defects, although the behavioral phenotypes did not unambiguously report on synaptic function in all cases tested. OptIoN facilitates the analysis of neurotransmission with high temporal precision, in a neurotransmitter-selective manner, possibly allowing future investigation of synaptic plasticity in C. elegans.
authors.affiliation: Institute of Biochemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University Frankfurt, Biocenter N220, Frankfurt, Germany.
authors.forename: Jana F
authors.initials: JF
authors.lastname: Liewald
authors.forename: Martin
authors.initials: M
authors.lastname: Brauner
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Stephens
authors.forename: Magali
authors.initials: M
authors.lastname: Bouhours
authors.forename: Christian
authors.initials: C
authors.lastname: Schultheis
authors.forename: Mei
authors.initials: M
authors.lastname: Zhen
authors.forename: Alexander
authors.initials: A
authors.lastname: Gottschalk
mesh_terms: D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D008027:Light; D009046:Motor Neurons / Q000502:physiology; D009119:Muscle Contraction; D009126:Muscle Relaxation; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission; D005680:gamma-Aminobutyric Acid / Q000502:physiology
chemical_list: D002352:Carrier Proteins; C523009:channelopsin-2, Chlamydomonas reinhardtii; D005680:gamma-Aminobutyric Acid; D000109:Acetylcholine