Co-induction of long-term potentiation and long-term depression at a central synapse in the leech

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Abstract

Most studies of long-term potentiation (LTP) have focused on potentiation induced by the activation of postsynaptic NMDA receptors (NMDARs). However, it is now apparent that NMDAR-dependent signaling processes are not the only form of LTP operating in the brain [Malenka, R. C., & Bear, M. F. (2004). LTP and LTD: An embarrassment of riches. Neuron, 44, 5-21]. Previously, we have observed that LTP in leech central synapses made by the touch mechanosensory neurons onto the S interneuron was NMDAR-independent [Burrell, B. D., & Sahley, C. L. (2004). Multiple forms of long-term potentiation and long-term depression converge on a single interneuron in the leech CNS. Journal of Neuroscience, 24, 4011-4019]. Here we examine the cellular mechanisms mediating T-to-S (T → S) LTP and find that its induction requires activation of metabotropic glutamate receptors (mGluRs), voltage-dependent Ca2+ channels (VDCCs) and protein kinase C (PKC). Surprisingly, whenever LTP was pharmacologically inhibited, long-term depression (LTD) was observed at the tetanized synapse, indicating that LTP and LTD were activated at the same time in the same synaptic pathway. This co-induction of LTP and LTD likely plays an important role in activity-dependent regulation of synaptic transmission.

Original languageEnglish (US)
Pages (from-to)275-279
Number of pages5
JournalNeurobiology of Learning and Memory
Volume90
Issue number1
DOIs
Publication statusPublished - Jul 1 2008

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Keywords

  • Invertebrate
  • Long-term depression
  • Long-term potentiation
  • Metabotropic glutamate receptor
  • Neuroplasticity
  • Protein kinase C
  • Voltage-dependent Ca channel

ASJC Scopus subject areas

  • Experimental and Cognitive Psychology
  • Cognitive Neuroscience
  • Behavioral Neuroscience

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