title: Novel stimulus-induced calcium efflux in Drosophila mushroom bodies.
abstract: The mushroom body (MB) is an important part of the Drosophila brain, and is involved in many behaviors, including olfactory learning and memory and some visual cognition. However, the physiological properties of MB neurons remain elusive. Here we used a calcium-imaging technique to study calcium signals in Drosophila MB. We found that, rather than increasing calcium spread, electrical stimuli dramatically decreased calcium signals in the terminals of MB fibers. This novel calcium decrease occurred at all developmental stages from larvae to adults, but was specific for certain regions of the MB neurons. GABA receptor blockade promoted calcium propagation through the MB fibers, but did not disrupt the stimulus-induced decrease in calcium. Furthermore, this decrease in calcium was independent of extracellular calcium concentration and was not due to altered uptake by intracellular calcium stores and mitochondria. Rather, we found that inhibition of sodium-calcium exchangers significantly attenuated the stimulus-induced decrease in calcium, whereas the decrease persisted when membrane calcium pumps were blocked. Our findings indicate that MB neurons exhibit a novel stimulus-induced calcium efflux, which may be importantly regulated by sodium-calcium exchangers in the Drosophila MB.
authors.affiliation: Institute of Neuroscience, Key Laboratory of Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.
authors.forename: Yueqing
authors.initials: Y
authors.lastname: Peng
authors.forename: Aike
authors.initials: A
authors.lastname: Guo
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000502:physiology; D004558:Electric Stimulation; D018756:GABA Antagonists / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D024521:Mushroom Bodies / Q000166:cytology / Q000378:metabolism; D009538:Nicotine / Q000378:metabolism; D018722:Nicotinic Agonists / Q000378:metabolism; D010852:Picrotoxin / Q000378:metabolism; D018079:Receptors, GABA / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D002118:Calcium; D018756:GABA Antagonists; D009538:Nicotine; D018722:Nicotinic Agonists; D010852:Picrotoxin; D018079:Receptors, GABA; D019831:Sodium-Calcium Exchanger; D005680:gamma-Aminobutyric Acid