Age dependence of homosynaptic non-NMDA mediated long-term depression in field CA1 of rat hippocampal slices.
It has been hypothesized that high levels of presynaptic activity that fail to activate postsynaptic N-methyl-D-aspartate (NMDA) receptors may lead to long-term depression (LTD). Therefore, we tested the ability of high-frequency (50 Hz) synaptic stimulation in the presence of a blocker of NMDA receptors to elicit homosynaptic LTD at Schaffer collateral-CA1 synapses in hippocampal slices from 15-, 30- and 60-day-old rats. In control slices, there were no developmental differences in the incidence of long-term potentiation (LTP) of either EPSP slope or population spike amplitude. However, while NMDA receptor blockade with the specific antagonist D-2-amino-5-phosphonopentanoic acid (AP5; 25 microM) completely eliminated LTP in 30 and 60-day-olds, a significant number of slices from 15-day-old rats displayed some non-NMDA LTP of synaptic transmission. Moreover, under NMDA receptor blockade, the same high-frequency stimulation now induced homosynaptic LTD of population spike amplitude in a significant number of slices from 15- and 60-day-old rats (47% and 42%, respectively) but not in 30-day-olds (7%). LTD of population spike amplitude was most pronounced in 15-day-old slices (27 +/- 6% of baseline), whereas, in 60-day-old slices, LTD was 81 +/- 3% of baseline. LTD of EPSP slopes occurred in 44% of 15-day-olds, 13% of 30-day-olds, and 33% of slices from 60-day-old rats; the magnitude of EPSP was similar in 15 and 60-day-old slices (70 +/- 9% versus 81 +/- 1% of baseline).(ABSTRACT TRUNCATED AT 250 WORDS)
Velísek
L
L
Department of Neurology, Albert Einstein College of Medicine, Bronx, NY 10461.
Moshé
S L
SL
Stanton
P K
PK
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000375:Aging / Q000502:physiology*; D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000254:growth & development / Q000502:physiology*; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects; D008297:Male; D009415:Nerve Net / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D017981:Receptors, Neurotransmitter / Q000502:physiology*; D012640:Seizures / Q000503:physiopathology; D013569:Synapses / Q000502:physiology*
D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D015763:2-Amino-5-phosphonovalerate