Preferential potentiation of fast-releasing synaptic vesicles by cAMP at the calyx of Held.
Proc Natl Acad Sci U S A
; 98(1): 331-6, 2001 Jan 02.
Article
in En
| MEDLINE
| ID: mdl-11134533
ABSTRACT
We have studied the effects of cAMP on synaptic transmission at the calyx of Held and found that forskolin (an activator of adenylate cyclase) and 8-Br-cAMP (a membrane-permeable analog of cAMP) potentiated excitatory postsynaptic currents (EPSCs). Direct sampling of miniature EPSCs (mEPSCs) and nonstationary fluctuation analysis showed that mEPSCs were not modulated by cAMP, suggesting that the locus of modulation is presynaptic. Deconvolution was used to examine effects of cAMP on quantal-release rates. By using this method, it was shown recently that release probabilities of readily releasable vesicles are heterogeneous. Here, we show that cAMP selectively increases the number of vesicles with higher release probabilities, whereas a slow component of the EPSC, representing vesicles that fuse more slowly, is unchanged. cAMP increases the apparent Ca2+ sensitivity for secretion, but this increase does not reflect an increase in release probability necessarily but rather an increase in the number of highly sensitive vesicles.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Synaptic Vesicles
/
Brain Stem
/
Cyclic AMP
/
Synaptic Transmission
Limits:
Animals
Language:
En
Journal:
Proc Natl Acad Sci U S A
Year:
2001
Document type:
Article
Affiliation country:
Germany