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anoxia

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
LTP.

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
122(4):671-81.
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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