INVESTIGADORES
URBANO SUAREZ Francisco Jose
congresos y reuniones científicas
Título:
A novel neuromodulating effect of Pregabalin on neurotransmitter release at the mouse calyx of Held
Autor/es:
M N DI GUILMI, FJ URBANO, C GONZALEZ INCHAUSPE, OD UCHITEL
Lugar:
Mc Cormick Place, Chicago, IL, U.S.A.
Reunión:
Congreso; 2009 Society for Neuroscience Meeting; 2009
Institución organizadora:
Society for Neuroscience
Resumen:
Pregabalin [S-[+]-3-isobutylGABA, Lyrica] is an anticonvulsant and analgesic
medication which was originally synthesized with the intention of modulating
brain GABA receptors, resulting ineffective. The mechanism of action of
pregabalin (PGB) has been only partially characterized; it is generally accepted
that PBG subtly reduce calcium-dependent overflow of neurotransmitters in
several tissues. However, the cellular and molecular basis of its inhibitory
action on neurotransmitter release is unknown. The á2-ä type 1 auxiliary
subunit of voltage-gated calcium channels is the primary high-affinity binding
site for PGB (Gee et al., 1996). The exact action of PGB on presynaptic
calcium channels function is still a matter of controversy.
Here, we studied the effect of PGB on the Calyx of Held-Medial Nucleus of
the Trapezoid Body (MNTB) synapse in brainstem slices using whole cell patch
clamp recordings. Excitatory postsynaptic currents (EPSCs) and presynaptic
calcium currents were recorded at Calyx of Held-MNTB complex at both low
and high frequency stimulation.
The amplitude of EPSCs at the Calyx - MNTB was reduced by a 30%. No
differences were observed in the depression rate from high frequency trains but
a faster rate of recovery from synaptic depression at 100 Hz was observed in
the presence of PGB (500 ìM)(p=0.043). We found no differences in the mean
amplitude of miniature EPSCs (39± 2pA in -PGB (n =11) and 38± 2pA in
+PGB (n =10), while observing greater minis frequencies -PGB versus +PGB
conditions (1.71±0.35 Hz and 0.49±0.06 Hz, respectively (p=0.0044)). The
release probability (Pr) was 0.45 ± 0.024 (n =6) for -PGB and 0.35 ± 0.015 (n
=6) for +PGB (p = 0.00014) indicating a decrement of the Pr after PGB
application. On the other hand, P/Q-type calcium channels mediated currents
decreased in presence of PGB (500 microM) after high frequency trains
(100-300Hz). The calcium current was partially recovered by isoleucine (1.5
mM), suggesting specific PGB-mediated effects. Calcium currents activation
curves, obtained from plotting tail currents versus command voltage showed no
differences. However, two pulses inactivation protocol shows a larger rescue of
the inactivation.
These results suggest that PGB effects on Calyx of Held-MNTB synapse is two
fold: 1) blocking presynaptic P/Q-type mediated calcium currents that would
reduce synaptic transmission, and 2) accelerating the recovery of P/Q channels
from inactivated states that would allow for lower recovery times after high
frequency synaptic stimulation.
(100-300Hz). The calcium current was partially recovered by isoleucine (1.5
mM), suggesting specific PGB-mediated effects. Calcium currents activation
curves, obtained from plotting tail currents versus command voltage showed no
differences. However, two pulses inactivation protocol shows a larger rescue of
the inactivation.
These results suggest that PGB effects on Calyx of Held-MNTB synapse is two
fold: 1) blocking presynaptic P/Q-type mediated calcium currents that would
reduce synaptic transmission, and 2) accelerating the recovery of P/Q channels
from inactivated states that would allow for lower recovery times after high
frequency synaptic stimulation.
amplitude of miniature EPSCs (39± 2pA in -PGB (n =11) and 38± 2pA in
+PGB (n =10), while observing greater minis frequencies -PGB versus +PGB
conditions (1.71±0.35 Hz and 0.49±0.06 Hz, respectively (p=0.0044)). The
release probability (Pr) was 0.45 ± 0.024 (n =6) for -PGB and 0.35 ± 0.015 (n
=6) for +PGB (p = 0.00014) indicating a decrement of the Pr after PGB
application. On the other hand, P/Q-type calcium channels mediated currents
decreased in presence of PGB (500 microM) after high frequency trains
(100-300Hz). The calcium current was partially recovered by isoleucine (1.5
mM), suggesting specific PGB-mediated effects. Calcium currents activation
curves, obtained from plotting tail currents versus command voltage showed no
differences. However, two pulses inactivation protocol shows a larger rescue of
the inactivation.
These results suggest that PGB effects on Calyx of Held-MNTB synapse is two
fold: 1) blocking presynaptic P/Q-type mediated calcium currents that would
reduce synaptic transmission, and 2) accelerating the recovery of P/Q channels
from inactivated states that would allow for lower recovery times after high
frequency synaptic stimulation.
(100-300Hz). The calcium current was partially recovered by isoleucine (1.5
mM), suggesting specific PGB-mediated effects. Calcium currents activation
curves, obtained from plotting tail currents versus command voltage showed no
differences. However, two pulses inactivation protocol shows a larger rescue of
the inactivation.
These results suggest that PGB effects on Calyx of Held-MNTB synapse is two
fold: 1) blocking presynaptic P/Q-type mediated calcium currents that would
reduce synaptic transmission, and 2) accelerating the recovery of P/Q channels
from inactivated states that would allow for lower recovery times after high
frequency synaptic stimulation.
subunit of voltage-gated calcium channels is the primary high-affinity binding
site for PGB (Gee et al., 1996). The exact action of PGB on presynaptic
calcium channels function is still a matter of controversy.
Here, we studied the effect of PGB on the Calyx of Held-Medial Nucleus of
the Trapezoid Body (MNTB) synapse in brainstem slices using whole cell patch
clamp recordings. Excitatory postsynaptic currents (EPSCs) and presynaptic
calcium currents were recorded at Calyx of Held-MNTB complex at both low
and high frequency stimulation.
The amplitude of EPSCs at the Calyx - MNTB was reduced by a 30%. No
differences were observed in the depression rate from high frequency trains but
a faster rate of recovery from synaptic depression at 100 Hz was observed in
the presence of PGB (500 ìM)(p=0.043). We found no differences in the mean
amplitude of miniature EPSCs (39± 2pA in -PGB (n =11) and 38± 2pA in
+PGB (n =10), while observing greater minis frequencies -PGB versus +PGB
conditions (1.71±0.35 Hz and 0.49±0.06 Hz, respectively (p=0.0044)). The
release probability (Pr) was 0.45 ± 0.024 (n =6) for -PGB and 0.35 ± 0.015 (n
=6) for +PGB (p = 0.00014) indicating a decrement of the Pr after PGB
application. On the other hand, P/Q-type calcium channels mediated currents
decreased in presence of PGB (500 microM) after high frequency trains
(100-300Hz). The calcium current was partially recovered by isoleucine (1.5
mM), suggesting specific PGB-mediated effects. Calcium currents activation
curves, obtained from plotting tail currents versus command voltage showed no
differences. However, two pulses inactivation protocol shows a larger rescue of
the inactivation.
These results suggest that PGB effects on Calyx of Held-MNTB synapse is two
fold: 1) blocking presynaptic P/Q-type mediated calcium currents that would
reduce synaptic transmission, and 2) accelerating the recovery of P/Q channels
from inactivated states that would allow for lower recovery times after high
frequency synaptic stimulation.
(100-300Hz). The calcium current was partially recovered by isoleucine (1.5
mM), suggesting specific PGB-mediated effects. Calcium currents activation
curves, obtained from plotting tail currents versus command voltage showed no
differences. However, two pulses inactivation protocol shows a larger rescue of
the inactivation.
These results suggest that PGB effects on Calyx of Held-MNTB synapse is two
fold: 1) blocking presynaptic P/Q-type mediated calcium currents that would
reduce synaptic transmission, and 2) accelerating the recovery of P/Q channels
from inactivated states that would allow for lower recovery times after high
frequency synaptic stimulation.
amplitude of miniature EPSCs (39± 2pA in -PGB (n =11) and 38± 2pA in
+PGB (n =10), while observing greater minis frequencies -PGB versus +PGB
conditions (1.71±0.35 Hz and 0.49±0.06 Hz, respectively (p=0.0044)). The
release probability (Pr) was 0.45 ± 0.024 (n =6) for -PGB and 0.35 ± 0.015 (n
=6) for +PGB (p = 0.00014) indicating a decrement of the Pr after PGB
application. On the other hand, P/Q-type calcium channels mediated currents
decreased in presence of PGB (500 microM) after high frequency trains
(100-300Hz). The calcium current was partially recovered by isoleucine (1.5
mM), suggesting specific PGB-mediated effects. Calcium currents activation
curves, obtained from plotting tail currents versus command voltage showed no
differences. However, two pulses inactivation protocol shows a larger rescue of
the inactivation.
These results suggest that PGB effects on Calyx of Held-MNTB synapse is two
fold: 1) blocking presynaptic P/Q-type mediated calcium currents that would
reduce synaptic transmission, and 2) accelerating the recovery of P/Q channels
from inactivated states that would allow for lower recovery times after high
frequency synaptic stimulation.
(100-300Hz). The calcium current was partially recovered by isoleucine (1.5
mM), suggesting specific PGB-mediated effects. Calcium currents activation
curves, obtained from plotting tail currents versus command voltage showed no
differences. However, two pulses inactivation protocol shows a larger rescue of
the inactivation.
These results suggest that PGB effects on Calyx of Held-MNTB synapse is two
fold: 1) blocking presynaptic P/Q-type mediated calcium currents that would
reduce synaptic transmission, and 2) accelerating the recovery of P/Q channels
from inactivated states that would allow for lower recovery times after high
frequency synaptic stimulation.