- Abstract:
-
It is well established that synaptic transmission declines at temperatures below physiological, but many in vitro studies are conducted at lower temperatures. Recent evidence suggests that temperature-dependent changes in presynaptic mechanisms remain in overall equilibrium and have little effect on transmitter release at low transmission frequencies (Kushmerick et al., 2006). Our objective is to examine the postsynaptic effects of temperature. Whole-cell patch clamp recordings from principle neurons in the medial nucleus of the trapezoid body (MNTB) showed that a rise from 25 C to 35 C increased miniature EPSC (mEPSC) amplitude from -33 2.3 to -46 5.7pA (n=6) and accelerated mEPSC kinetics. Evoked EPSC amplitude increased from -3.14 0.59 to -4.15 0.73 nA with fast decay time constant accelerating from 0.75 0.09 ms at 25 oC to 0.56 0.08 ms at 35oC. Postsynaptic responses to direct glutamate puffing increased in amplitude from -0.76 0.10nA at 25 C to -1.11 0.19nA 35 C, with decay time constant decreasing from 38.7 4.3ms at 25 C to 25.4 2.4ms at 35 C. Kinetic modelling of fast AMPA receptors showed that a temperature-dependent scaling of all reaction rate constants by a single multiplicative factor (Q10=2.4) drives the channels into higher-conducting states at higher temperature. Furthermore, Monte Carlo simulation of transmission at the calyx showed that this acceleration of the AMPA receptor kinetics explained mEPSC and evoked EPSC temperature-dependence. We propose that acceleration in postsynaptic AMPA receptor kinetics, rather than altered presynaptic release, is the mechanism by which temperature changes alter synaptic transmission.
- Links To Paper
- 1st Link
- Bibtex format
- @Article{EDI-INF-RR-0880,
- author = {
Michael Postlethwaite
and Matthias Hennig
and Joern Steinert
and Bruce Graham
and Ian Forsythe
},
- title = {Acceleration of AMPA receptor kinetics underlies temperature-dependent changes in synaptic strength at the rat calyx of Held},
- journal = {Journal of Physiology},
- publisher = {The Physiological Society},
- year = 2007,
- month = {Feb},
- volume = {579},
- pages = {69-84},
- doi = {10.1113/jphysiol.2006.123612},
- url = {http://jp.physoc.org/cgi/content/short/579/1/69},
- }
|
