Robust axonal sprouting and synaptogenesis in organotypic slice cultures of rat cerebellum exposed to increased potassium chloride.
Organotypic slices of the rat cerebellum, cultured in physiological levels [K+]o (5 mM) for 14 days, loose the majority of granule cells in the anterior lobe resulting in few axons and atypical Purkinje cell dendrites with vacant spines. When the culture medium was switched from 5 mM to 20, 30 or 40 mM [K+]o during the last 7 days of cultures, slices developed axons with numerous vesicle-filled boutons that made synaptic contact with Purkinje cell spines. Most boutons had one or two spine profile contacts, while some were unusually large. Enlarged boutons abutted Purkinje cell somata or their dendrites, causing intervening spines to invaginate terminals to form rosette synaptic complexes. Calbindin immuno-labeling excluded Purkinje cell axonal collaterals as the source of rosette boutons and suggested a granule cell origin. Quantification of vacant spines as compared to those on boutons revealed a threshold for potassium, between 10 and 20 mM, where the number of synaptic spines increased and vacant spines decreased drastically. These findings suggest that elevated [K+]o triggers an activity-dependent plasticity in rat cerebellar slice cultures by promoting axonal sprouting with formation of vesicle-filled boutons and synaptogenesis on open receptor sites of Purkinje cell spines.
Chen
Suzanne
S
Department of Otolaryngology and Physiology and Neuroscience, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA.
Hirata
Kasunari
K
Ren
Yuqin
Y
Sugimori
Mutsuyuki
M
Llinas
Rodolfo
R
Hillman
Dean E
DE
D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000187:drug effects* / Q000648:ultrastructure; D002531:Cerebellum / Q000166:cytology* / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000648:ultrastructure; D009924:Organ Culture Techniques; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000187:drug effects* / Q000648:ultrastructure; D013997:Time Factors
D011189:Potassium Chloride