title: Sulforhodamine 101, a widely used astrocyte marker, can induce cortical seizure-like activity at concentrations commonly used.
abstract: Sulforhodamine 101 (SR101) is a preferential astrocyte marker widely used in 2-photon microscopy experiments. Here we show, that topical loading of two commonly used SR101 concentrations, 100 μM and 250 μM when incubated for 10 min, can induce seizure-like local field potential (LFP) activity in both anaesthetized and awake mouse sensori-motor cortex. This cortical seizure-like activity develops in less than ten minutes following topical loading, and when applied longer, these neuronal discharges reliably evoke contra-lateral hindlimb muscle contractions. Short duration (<1 min) incubation of 100 μM and 250 μM SR101 or application of lower concentrations 25 μM and 50 μM of SR101, incubated for 30 and 20 min, respectively, did not induce abnormal LFP activity in sensori-motor cortex, but did label astrocytes, and may thus be considered more appropriate concentrations for in vivo astrocyte labeling. In addition to label astrocytes SR101 may, at 100 μM and 250 μM, induce abnormal neuronal activity and interfere with cortical circuit activity. SR101 concentration of 50 μM or lower did not induce abnormal neuronal activity. We advocate that, to label astrocytes with SR101, concentrations no higher than 50 μM should be used for in vivo experiments.
authors.affiliation: Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York 14642, USA.|Center for Basic and Translational Neuroscience, University of Copenhagen Faculty of Medicine, 2200 Copenhagen N, Denmark.
authors.forename: Rune
authors.initials: R
authors.lastname: Rasmussen
authors.affiliation: Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York 14642, USA.|Center for Basic and Translational Neuroscience, University of Copenhagen Faculty of Medicine, 2200 Copenhagen N, Denmark.
authors.forename: Maiken
authors.initials: M
authors.lastname: Nedergaard
authors.affiliation: Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York 14642, USA.|Department of Nutrition, Exercise and Sports, University of Copenhagen, 2200 Copenhagen N, Denmark.|Department of Neuroscience and Pharmacology, University of Copenhagen, 2200 Copenhagen N, Denmark.
authors.forename: Nicolas Caesar
authors.initials: NC
authors.lastname: Petersen
mesh_terms: D000200:Action Potentials; D000758:Anesthesia; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D051379:Mice; D012235:Rhodamines / Q000009:adverse effects*; D012640:Seizures / Q000139:chemically induced* / Q000473:pathology* / Q000503:physiopathology; D066191:Sensorimotor Cortex / Q000473:pathology / Q000503:physiopathology; D013997:Time Factors; D014851:Wakefulness
chemical_list: D015415:Biomarkers; D012235:Rhodamines; C050829:sulforhodamine 101