1413 Substrates for fyn at the synapse in rat brain

S163 RE:PETL'I'IVI< S'l'IMULATION POTENTIATED TI1E STIMUI.US-FVOKED FIRING 1N TIIE TRIGEMlNAL C/1UDALtS - IN VITRO STUDY. Ml CHLKO IlAMHA. Dept.. of Physiol., Sch. Of DeJJt. , Showa Univ. Tokyo 142, Japan.

1412

In brainstem-trigcminal nerve trunk preparations isolated from O-6 day-old rats. the effect of repetitive stimulation (0.2 ms. 40 PA. 0.5 Hz) of primary nfferents was studied on activities of the trigeminal caudal neurons extracellularly recorded. Ninety-two neurons had a mean spike firing of 1.6/s and were excited synaptically by stimulation applied to nerve trunks with first spike latencies of 38.8 2 14 ms (mean + SD) in a Kreb's solution. Repetitive stimulation produced either a stepwise increase of spike numbers in evoked responses and in subsequent spontaneous discharges (Type I, n = 36), a steptyise decrease (Type II, n = 29), or little change (Type III, n = 27). The progressively increasing spike firing was only produced by rep2Eitive stimulation in Type I neurons isolated from 4-6 day old rats in a low Mg solution, but was not induced in neurons from O-3 day old rats. The increase of spike number was sustained for minutes after stimulation and was antagonized with a bath application of 20 )r'M of MK-801. These results suggest that 1) prolongation of a stimulus-evoked response similar to wind-up in vivo studies (Hamba, 1992) possibly involves NMDA receptors, and 2) this phenomenon is related to the development of synapse formation in the central nervous system.

SUBSTRATES FOR FYN AT THE SYNAPSE IN RAT BRAIN. TATSUO SUZUEI,

1413

Ctr.

390,

Janan

(PSD) fraction

unique

subunit Fyn.

rat

subunit

&l (NR2A) was also

in the modulation

Sch.

were

highly

There

substrates

PSD-gplfJ0,

NMDA receptor

Univ.

forebrain.

One of the major

blotting

which

in the

in the postsynaptic

a number

of Fyn substrates

PSD fraction

supported for

through

the

Fyn.

These

Matsumoto

Asahi,

was found

is the N-methyl-D-aspartate

a substrate

efficacy

3-l-l

concentrated

were

and immunoprecipitation

of synaptic

of Med.,

of Neuronlasticitv.

to be a

(NMDA) receptor

phosphorylation

of E2 by

results

that

the phosphorylation

suggest

of synapse-specific

such as the NMDA receptor/channel.

LONG-TERM HIROFUMI

Intracellular

recording

The tetantc

strmulatron(ZOOHz,20s)

was

neurons,

hyperpolanzing

threshold

substrates

from the

glycoprotein,

.Mre Unrv.

induced

kinase, and its

Western

1414

III pyramrdal

Shinshu

~2 (NRZB).

involved

tetanrc

and Adaptation,

prepared

A-binding

substrates

the

Asinq

to the PSD fraction.

concanavalin

is

for

protein tyrosine

Fyn, density

Res.

DeDt.

whrch

the cell stimulation

by the

tetanrc

Ca channel

due

KITAGAWA, Sch.

carned

out

rn layer

was blocked

Tsu,

Inductron

NISHIMURA,

5 14,

III and

promrnent

V pyramrdal

In the

presence

of APV-rnsensmve

neurons

depolanng

by NMDA

of IPSPs In layer

TETSURO

CORTEX

YAMAMOTO

IN UITRO

Dept.

of Physrol.,

Japan

matter

completely

to the summation

strmulatron

IN THE CRT SENSORIMOTOR

YOSHIHIRO

of Med.,

of the whrte

was more

to the

POTENTIRTIIJN

also

V than of APV.

the receptor

Induced In layer

from

the

antagonist,

APV(SO-1

LTP of EPSPs

The contnbutton

preparatron

Long-Term

III pyramidal

LTP was examrned.

strce

cell Induced

in layer cells.

OOfi

free

cat

M).The

Ill pyramrdal

In some

of rntracellular

of the

sensonmotor

Potentration(LTP)

layer

of tetanic

Ca++

and

rn layer

strmulatton

cells.Potentration V pyramidal

cortex.

EPSPs

cells,

activatron

of

EPSPs

LTP could of the

low-

be

by

Fyn