Induction of LTD by increasing extracellular Ca2+ from a low level in the dentate gyrus in vitro.
Long-term depression (LTD) of field excitatory postsynaptic potentials was induced in the medial path of the dentate gyrus in juvenile rats in vitro by a protocol involving returning the Ca2+ concentration of the external media to the control level (2 mM) following a period (30 min) in low Ca2+ (1.2 mM), with stimulation at the test frequency throughout. Directly increasing Ca2+ from the control level did not induce LTD (or long-term potentiation). Such LTD showed mutual occlusion with low frequency stimulation (LFS, 1 Hz, 900 stimuli)-induced LTD. The Ca2+-induced LTD was shown to be induced by the procedure of elevating the Ca2+ from the low to the control concentration, and not by the procedure of lowering of Ca2+, as full amplitude LFS induced LTD could be induced in the low Ca2+ media. Ca2+-induced LTD was inhibited by Ni2+ (25 microM) and 2-amino-5-phosphonopentanoate (50 microM), demonstrating the necessity for activation of T/R-type voltage-gated Ca2+ channels and N-methyl-D-aspartate receptors, respectively.
Camodeca
N
N
Department of Physiology, Trinity College, Dublin, Ireland.
Rowan
M J
MJ
Anwyl
R
R
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003470:Culture Media / Q000378:metabolism; D018891:Dentate Gyrus / Q000378:metabolism*; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005110:Extracellular Space / Q000378:metabolism*; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D009532:Nickel / Q000494:pharmacology; D009994:Osmolar Concentration; D051381:Rats
D003470:Culture Media; D018691:Excitatory Amino Acid Antagonists; D015763:2-Amino-5-phosphonovalerate; D009532:Nickel; D002118:Calcium