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Long term potentiation and long term depression

erika erika at ebi.ac.uk
Thu Mar 23 05:05:47 PST 2006


Dear all,
I am annotating ionotropic gluatamate receptor and I would like to  
insert terms about long term potentiation (LTP) and long term  
depression (LTD).
I know that there are these two terms that described two form of  
synaptic plasticity.

GO:0048169 regulation of long-term neuronal synaptic plasticity: A  
process that modulates long-term neuronal synaptic plasticity, the  
ability of neuronal synapses to change long-term as circumstances  
require. Long-term neuronal synaptic plasticity generally involves  
increase or decrease in actual synapse numbers.

GO:0048172 regulation of short-term neuronal synaptic plasticity: A  
process that modulates short-term neuronal synaptic plasticity, the  
ability of neuronal synapses to change in the short-term as  
circumstances require. Short-term neuronal synaptic plasticity  
generally involves increasing or decreasing synaptic sensitivity.

So I can not understand if we should add new terms about LTP and LTD  
or we could use GO:0048172 (regulation of short-term neuronal  
synaptic plasticity) and GO:0048169 (regulation of long-term neuronal  
synaptic plasticity) for LTP and for LTD
This is a new topic for me so any help will be appreciated.
I have read that LTD is a weakening of a synapse that lasts from  
hours to days. So I am not sure that short term plasticity could be  
the correct term for LTD because GO:0048172 (regulation of short-term  
neuronal synaptic plasticity) describes changes in the short time.  
LTD results from either strong synaptic stimulation (as occurs in the  
cerebellum Purkinje cells) to persistent weak synaptic stimulation  
(as in the hippocampus).
In addiction, LTD refers only to a weakening of a synapse and not to  
an increasing of it.
LTD is thought to result from changes in postsynaptic receptor  
density, although changes in presynaptic release may also play a  
role. Slow, weak stimulation of CA1 neurons also brings about long- 
term changes in the synapses, in this case, a reduction in the  
sensitivity. It involves Glu binding to a different type of NMDA  
receptor.
Instead, long-term potentiation (LTP) is the long-lasting  
strengthening of the connection between two nerve cells.  
Experimentally, a series of short, high-frequency electric  
stimulations to a nerve cell synapse can strengthen, or potentiate,  
that synapse for minutes to hours. In living cells, LTP occurs  
naturally and can last from hours to days, months, and years. The  
biological mechanisms of LTP, largely via the interplay of protein  
kinases, phosphatases, and gene expression, give rise to synaptic  
plasticity and provide the foundation for a highly adaptable nervous  
system.
Researches in Geneva, Switzerland have demonstrated that formation of  
LTP in rat brains coincides with the formation of additional synapses  
(at least one more) between the presynaptic axon terminal and the  
dendrite it synapses with. (Report by Toni, N., et al, Nature, 25 Nov  
99). Presumably this, too, increases the efficiency of synaptic  
transmission.
I am confused because both LTP and LTD refer to changes in the long  
term.
So are they part of process of regulation of ONLY long term synaptic  
plasticity regulation GO:0048169?

Thanks very much
Erika

Erika Feltrin, PhD student
Bioinformatics Lab-CRIBI
Padua University
erika at cribi.unipd.it

c/o EMBL-European Bioinformatics Institute
Wellcome Trust Genome Campus
Cambridge CB10 1SD
United Kingdom

  erika at ebi.ac.uk
+44 (0) 1223 492600 (work)



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