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Alexey Semyanov semyanov at venus.iteb.serpukhov.su
Sun Oct 18 10:19:40 EST 1998

Yes, there are two different types of facts about the role of an anoxia in

1 Anoxia can induce LTP:
Hammond C, et al. Anoxic LTP sheds light on the multiple facets of NMDA
receptors. Trends Neurosci. 1994 17(11):497-503.
Crepel V, et al. A selective LTP of NMDA receptor-mediated currents induced
by anoxia in CA1 hippocampal neurons. J Neurophysiol. 1993 70(5):2045-55.
Crepel V, et al. Anoxia-induced LTP of isolated NMDA receptor-mediated
synaptic responses. J Neurophysiol. 1993 69(5):1774-8.
Hsu KS, et al. Characterization of the anoxia-induced long-term synaptic
potentiation in area CA1 of the rat hippocampus. Br J Pharmacol. 1997
Huang CC, et al. Nitric oxide signalling is required for the generation of
anoxia-induced long-term potentiation in the hippocampus. Eur J Neurosci.
1997 9(10):2202-6.
Gozlan H, et al. Anoxic LTP is mediated by the redox modulatory site of the
NMDA receptor. J Neurophysiol. 1994 72(6):3017-22.

2 Anoxia inhibit tetanic LTP:
Arai A, et al. Anoxia reveals a vulnerable period in the development of
long-term potentiation. Brain Res. 1990 19;511(2):353-7.
Izumi Y, et al. Oxygen deprivation produces delayed inhibition of long-term
potentiation by activation of NMDA receptors and nitric oxide synthase. J
Cereb Blood Flow Metab. 1998 Jan;18(1):97-108.

However, I think that these are not conflicting data. There are many types
of LTP. Tetanic LTP seems to have mainly presynaptic origin, but anoxic may
be NMDA receptor associated.

A. Semyanov, Ph.D.
 ITEB RAS, Pushchino,
Moscow region, 142292, Russia

"F. Frank LeFever" wrote:

> Sorry that I don't have info you need.  However, I need YOUR info: can
> you tell me more about anoxia inducing LTP?  Do you have references to
> published reports?  Just a guess: anoxia and many other brain insults
> can initiate intense excitotoxic (excitatory amino acid) reactions; at
> a given moment, NMDA activation and NO amplification might be just at
> the level to induce LTP. (outside this window of opportunity, I think
> it would block LTP--see Izumi & Zorumski)
> (If publication is in Russian,, OK; I can read NYEMNOGA...and I have
> Russian friends.)
> F. Frank LeFever, Ph.D.
> New York Neuropsychology Group
> In <36274082.8C9B9C74 at venus.iteb.serpukhov.su> Alexey Semyanov
> <semyanov at venus.iteb.serpukhov.su> writes:
> >
> >Short-term potassium increase is known to lead long-lasting increase
> in
> >synaptic efficiency. According to our own data it can lead EPSP-spike
> >potentiation in CA1 hippocampal slices. On other hand there are some
> >experimental evidences that brief anoxic episode can induce LTP also.
> >It seems to be due to potassium increase during anoxia.
> >Unfortunately, when I attempt to test it changing solution with gas
> >mixture O2+CO2 to solution with N2+CO2 I was not successful. I haven’t
> >seen any depression of responses during 30 min !!!
> >The volume of my recording chamber is about 2 ml; it is open for air.
> >The speed of superfusion is 2.5 ml/min. I think this problem is
> because
> >of wrong chamber construction. Could anybody suggest me something
> about
> >this situation? I will be very grateful for suitable references or
> >design of such chamber with a description.
> >
> >

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