title: Metabolic signaling between photoreceptors and glial cells in the retina of the drone (Apis mellifera).
abstract: Experimental evidence showing metabolic interaction and signaling between photoreceptors-neurons and glial cells of the honeybee drone retina is presented. In this tissue [3H]2-deoxyglucose ([3H]2DG) in the dark and during repetitive light stimulation is phosphorylated to [3H]2-deoxyglucose-6P ([3H]2DG-6P) almost exclusively in the glial cells. Hence, stimulus-induced changes in the rate of formation of [3H]2DG-6P occurs predominantly in the glial cells. Repetitive stimulation of the photoreceptors with light flashes induced about a 47% rise in the rate of formation of [3H]2DG-6P in the glial cells and this effect is probably due to the activation of hexokinase. The potent inhibitor of glycolysis iodoacetic acid (IAA), inhibited this phosphorylation by about 75%. Probably this was largely due to an about 70% decrease of adenosine triphosphate (ATP). Exposure of the retina to IAA suppressed the transient rise in oxygen consumption (delta QO2) in the photoreceptors and subsequently the light-induced receptor potential. This indicates that the supply of a glycolytic substrate by glial cells to the photoreceptors is greatly reduced by IAA. Anoxia, by rapidly suppressing QO2, abolished the receptor potential of the photoreceptors and caused a rapid drop of about 50% in the ATP content of the retina. At the same time the formation of [3H]2DG-6P was inhibited by about 30%. This indicates that respiring photoreceptors send a metabolic signal to glial cells which is suppressed by anoxia.
authors.affiliation: Department of Oto-neuro-ophthalmology, University of Geneva Medical School, Switzerland.
authors.forename: P D
authors.initials: PD
authors.lastname: Brazitikos
authors.forename: M
authors.initials: M
authors.lastname: Tsacopoulos
mesh_terms: D019325:3-O-Methylglucose; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D001516:Bees / Q000502:physiology*; D003847:Deoxyglucose / Q000378:metabolism*; D004594:Electrophysiology; D008297:Male; D008757:Methylglucosides / Q000378:metabolism*; D009457:Neuroglia / Q000166:cytology / Q000502:physiology*; D009928:Organ Specificity; D009943:Organophosphorus Compounds / Q000378:metabolism; D010766:Phosphorylation; D010775:Photic Stimulation; D010786:Photoreceptor Cells / Q000166:cytology / Q000502:physiology*; D012160:Retina / Q000166:cytology / Q000502:physiology*
chemical_list: D008757:Methylglucosides; D009943:Organophosphorus Compounds; C015441:phospho-L-arginine; D019325:3-O-Methylglucose; D000255:Adenosine Triphosphate; D001120:Arginine; D003847:Deoxyglucose