Drosophila Mushroom Body Kenyon Cells Generate Spontaneous Calcium Transients Mediated by PLTX-Sensitive Calcium Channels

• Published in: Journal of neurophysiology 2005-07, Vol.94 (1), p.491-500
• Main Authors: Jiang, Shaojuan Amy, Campusano, Jorge M, Su, Hailing, O'Dowd, Diane K
• Format: Article
• Language: English
• Subjects: 6-Cyano-7-nitroquinoxaline-2,3-dione - pharmacology; Age Factors; Analysis of Variance; Animals; Caffeine - pharmacology; Calcium - metabolism; Calcium Channels - physiology; Cells, Cultured; Chlorine - pharmacology; Cobalt - pharmacology; Curare - pharmacology; Diagnostic Imaging - methods; Dose-Response Relationship, Radiation; Drosophila; Drug Combinations; Drug Interactions; Electric Stimulation - methods; Enzyme Inhibitors - pharmacology; Excitatory Amino Acid Antagonists - pharmacology; Fura-2 - metabolism; GABA Antagonists - pharmacology; gamma-Aminobutyric Acid - pharmacology; Green Fluorescent Proteins - metabolism; Iodine - pharmacology; Mushroom Bodies - cytology; Neurons - drug effects; Neurons - physiology; Nicotine - pharmacology; Nicotinic Antagonists - pharmacology; Patch-Clamp Techniques - methods; Phenols - pharmacology; Picrotoxin - pharmacology; Pupa; Salicylates - pharmacology; Spider Venoms - pharmacology; Tetrodotoxin - pharmacology; Thapsigargin - pharmacology; Time Factors; Valine - analogs & derivatives; Valine - pharmacology
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00096.2005

Departments of Anatomy and Neurobiology, Developmental and Cell Biology, University of California, Irvine California Submitted 25 January 2005; accepted in final form 12 March 2005 Spontaneous calcium oscillations in mushroom bodies of late stage pupal and adult Drosophila brains have been implicated in memory consolidation during olfactory associative learning. This study explores the cellular mechanisms regulating calcium dynamics in Kenyon cells, principal neurons in mushroom bodies. Fura-2 imaging shows that Kenyon cells cultured from late stage Drosophila pupae generate spontaneous calcium transients in a cell autonomous fashion, at a frequency similar to calcium oscillations in vivo (10–20/h). The expression of calcium transients is up regulated during pupal development. Although the ability to generate transients is a property intrinsic to Kenyon cells, transients can be modulated by bath application of nicotine and GABA. Calcium transients are blocked, and baseline calcium levels reduced, by removal of external calcium, addition of cobalt, or addition of Plectreurys toxin (PLTX), an insect-specific calcium channel antagonist. Transients do not require calcium release from intracellular stores. Whole cell recordings reveal that the majority of voltage-gated calcium channels in Kenyon cells are PLTX-sensitive. Together these data show that influx of calcium through PLTX-sensitive voltage-gated calcium channels mediates spontaneous calcium transients and regulates basal calcium levels in cultured Kenyon cells. The data also suggest that these calcium transients represent cellular events underlying calcium oscillations in the intact mushroom bodies. However, spontaneous calcium transients are not unique to Kenyon cells as they are present in approximately 60% of all cultured central brain neurons. This suggests the calcium transients play a more general role in maturation or function of adult brain neurons. Address for reprint requests and other correspondence: D. K. O'Dowd, Dept. of Anatomy and Neurobiology, 112 Irvine Hall, UC Irvine, Irvine, CA 92697-1280 (E-mail: dkodowd{at}uci.edu )