Paper Information

Title: 

THE ROLE OF L-TYPE VOLTAGE DEPENDENT CALCIUM CHANNELS ON LONG-TERM AND SHORT-TERM SYNAPTIC PLASTICITY

Type: PAPER
Author(s): MOTAMEDI F.,LASHGARI R.
 
 
 
Name of Seminar: IRANIAN CONGRESS OF PHYSIOLOGY AND PHARMACOLOGY
Type of Seminar:  CONGRESS
Sponsor:  PHYSIOLOGY AND PHARMACOLOGY SOCIETY, MASHHAD UNIVERSITY OF MEDICAL SCIENCE
Date:  2007Volume 18
 
 
Abstract: 

Introduction: In vivo and in vitro electrophysiological recordings of hippocampal neurons have demonstrated involvement of L-type voltage dependent calcium channels (VDCCs) in long-term potentiation (LTP), which is one form of long term synaptic plasticity and also considers being one possible cellular mechanism underlying learning and memory. VDCCs are also important in the shortest forms of synaptic plasticity which is a defining feature of neuronal activity crucial for regulating the temporal code and information processing between neurons in a network. It has been demonstrated that in addition to N- and P/Q-type Ca2+ channels, the L-type Ca2+ channels exist at presynaptic terminals of central synapses, and are activated by membrane depolarization. There is currently debate over the contribution of L-type VDCCs on the long term and short-term plasticity but, the underlying mechanisms are poorly understood. Moreover, there are controversial reports about memory impairment of chronic and acute administration of VDCC blockers. Therefore, in the present work the role of L- type VDCCs on long term and short term synaptic plasticity in hippocampal dentate gyrus (DG) have been investigated.
Results: Our behavioral study has shown that chronic but not acute treatment of verapamil an L-type VDCC blocker has no effect on passive avoidance learning whereas, its chronic application decreased memory retrieval. In electrophysiological studies, verapamil inhibited LTP induction of field excitatory postsynaptic potential slope and population spike amplitude. For assessment of possible effects of the VDCC blocker on the short term synaptic plasticity, paired pulse facilitation was observed in the perforant path-DG synapses.
Conclusion: Long term application of verapamil impairs memory retention and affects short and long term synaptic plasticity in hippocampal DG synapses.

 
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