Optogenetic analysis of synaptic function.
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.
Liewald
Jana F
JF
Institute of Biochemistry, Department of Biochemistry, Chemistry and Pharmacy, Goethe University Frankfurt, Biocenter N220, Frankfurt, Germany.
Brauner
Martin
M
Stephens
Greg J
GJ
Bouhours
Magali
M
Schultheis
Christian
C
Zhen
Mei
M
Gottschalk
Alexander
A
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
D002352:Carrier Proteins; C523009:channelopsin-2, Chlamydomonas reinhardtii; D005680:gamma-Aminobutyric Acid; D000109:Acetylcholine