TY - JOUR
T1 - Inhibitory Control at A Synaptic Relay
AU - Awatramani, Gautam B.
AU - Turecek, Rostislav
AU - Trussell, Laurence O.
PY - 2004/3/17
Y1 - 2004/3/17
N2 - The mammalian medial nucleus of the trapezoid body (MNTB) harbors one of the most powerful terminals in the CNS, the calyx of Held. The mechanisms known to regulate this synaptic relay are relatively ineffective. Here, we report the presence of a remarkably robust and fast-acting glycinergic inhibitory system capable of suppressing calyceal transmission. Evoked glycinergic IPSCs were relatively small in 2-week-old rats, an age by which calyceal maturation has reportedly neared completion. However, by postnatal day 25 (P25), glycinergic transmission had undergone a vigorous transformation, resulting in peak synaptic conductances as high as 280 nS. These are comparable with glutamatergic conductances activated by calyceal inputs. Decay kinetics for IPSCs were severalfold faster than for glycinergic synaptic events reported previously. At physiological temperatures in P25 rats, IPSCs decayed in ∼1 msec and could be elicited at frequencies up to 500 Hz. Moreover, EPSPs triggered by glutamatergic signals derived from the calyx or simulated by conductance clamp were suppressed when preceded by simulated glycinergic IPSPs. The matching of excitatory transmission in the calyx of Held by a powerful, precision inhibitory system suggests that the relay function of the MNTB may be rapidly modified during sound localization.
AB - The mammalian medial nucleus of the trapezoid body (MNTB) harbors one of the most powerful terminals in the CNS, the calyx of Held. The mechanisms known to regulate this synaptic relay are relatively ineffective. Here, we report the presence of a remarkably robust and fast-acting glycinergic inhibitory system capable of suppressing calyceal transmission. Evoked glycinergic IPSCs were relatively small in 2-week-old rats, an age by which calyceal maturation has reportedly neared completion. However, by postnatal day 25 (P25), glycinergic transmission had undergone a vigorous transformation, resulting in peak synaptic conductances as high as 280 nS. These are comparable with glutamatergic conductances activated by calyceal inputs. Decay kinetics for IPSCs were severalfold faster than for glycinergic synaptic events reported previously. At physiological temperatures in P25 rats, IPSCs decayed in ∼1 msec and could be elicited at frequencies up to 500 Hz. Moreover, EPSPs triggered by glutamatergic signals derived from the calyx or simulated by conductance clamp were suppressed when preceded by simulated glycinergic IPSPs. The matching of excitatory transmission in the calyx of Held by a powerful, precision inhibitory system suggests that the relay function of the MNTB may be rapidly modified during sound localization.
KW - Auditory
KW - Development
KW - GABA
KW - Glycine
KW - Inhibition
KW - MNTB
UR - http://www.scopus.com/inward/record.url?scp=1642372178&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=1642372178&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.5144-03.2004
DO - 10.1523/JNEUROSCI.5144-03.2004
M3 - Article
C2 - 15028756
AN - SCOPUS:1642372178
SN - 0270-6474
VL - 24
SP - 2643
EP - 2647
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 11
ER -