Domain-specific actions of amyloid precursor protein on developing synapses

s22

so9-3

Phenotypic Expression of Transmitter Receptors Regulated By Neurotrophic Factors

HIROYUKI NAWA’, MAKO SAITO’, KOICHI WAKABAYASHIZ, HITOSHI TAKAHASHIP ‘Dept. Mol. Neurobiol., 2 Dept. Neuropathol., Brain Res. Inst., Niigata Univ., Niigata 951-8585 A large variety of and development neurotransmitters synaptic plasticity

DOMAIN-SPECIFIC

so9-4 TAKAKO

neurotrophic factors such as neurotrophins and cytokines are known to influence differentiation of brain neurons. Recently, we found that neurotrophic factors can alter the expression of and their receptors both in vivo and in vitro. Potential contribution of neurotrophic factors to and neurological diseases will be discussed.

DEVELOPING

MORIMOTO,

Dept. of Neurochem.,

ACTIONS

OF AMYLOID

PRECURSOR

PROTEIN ON

SYNAPSES

IKURO OHSAWA,

CHIZUKO TAKAMURA,

Natl. Inst. of Neurosci.,

Kodaira, Tokyo,

AND SHINICHI KOHSAKA

187-8502

Effect of secretory form of amyloid precursor protein (sAPP) on synaptic activity was examined using cultured neuromuscular

synapses prepared from Xenopus

embryos.

Spontaneous

and evoked post-synaptic

currents (SSCs

and ESCs) were recorded from the innervated muscle cells. The mean frequency of SSCs was reduced by extracellularly

applied sAPP, without affecting the SSCs properties.

ESCs was increased by sAPP. C-terminal ESCs. By contrast, N-terminal

On the other hand, the mean amplitude of

fragment of sAPP only reduced SSC frequency,

reduction of SSC frequency by sAPP appears to be mediated by a cGMP-dependent ESC amplitude is considered

but did not affect

fragment of sAPP did not affect SSCs, but did increase ESC amplitude. pathway.

The

While the increase of

to be mediated by a different pathway involving activation of protein kinase(s).

sAPP may serve as a modulator of the synaptic activity by two specific domains.

Thus,