Circadian- and light-dependent regulation of resting membrane potential and spontaneous action potential firing of Drosophila circadian pacemaker neurons.
The ventral lateral neurons (LNvs) of adult Drosophila brain express oscillating clock proteins and regulate circadian behavior. Whole cell current-clamp recordings of large LNvs in freshly dissected Drosophila whole brain preparations reveal two spontaneous activity patterns that correlate with two underlying patterns of oscillating membrane potential: tonic and burst firing of sodium-dependent action potentials. Resting membrane potential and spontaneous action potential firing are rapidly and reversibly regulated by acute changes in light intensity. The LNv electrophysiological light response is attenuated, but not abolished, in cry(b) mutant flies hypomorphic for the cell-autonomous light-sensing protein CRYPTOCHROME. The electrical activity of the large LNv is circadian regulated, as shown by significantly higher resting membrane potential and frequency of spontaneous action potential firing rate and burst firing pattern during circadian subjective day relative to subjective night. The circadian regulation of membrane potential, spontaneous action potential firing frequency, and pattern of Drosophila large LNvs closely resemble mammalian circadian neuron electrical characteristics, suggesting a general evolutionary conservation of both physiological and molecular oscillator mechanisms in pacemaker neurons.
Sheeba
Vasu
V
Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA 92697, USA.
Gu
Huaiyu
H
Sharma
Vijay K
VK
O'Dowd
Diane K
DK
Holmes
Todd C
TC
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D030801:Animals, Genetically Modified; D002940:Circadian Rhythm / Q000502:physiology*; D056931:Cryptochromes; D004307:Dose-Response Relationship, Radiation; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004558:Electric Stimulation; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D005420:Flavoproteins / Q000494:pharmacology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D066298:In Vitro Techniques; D008027:Light; D008564:Membrane Potentials / Q000502:physiology*; D009154:Mutation / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000235:genetics / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013493:Suprachiasmatic Nucleus / Q000166:cytology; D013779:Tetrodotoxin / Q000494:pharmacology
D056931:Cryptochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D015221:Potassium Channels; D043562:Receptors, G-Protein-Coupled; D026941:Sodium Channel Blockers; C119828:cry protein, Drosophila; D049452:Green Fluorescent Proteins; D013779:Tetrodotoxin