Structural determinants of transmission at large hippocampal mossy fiber synapses.
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Structural determinants of transmission at large hippocampal mossy fiber synapses. / Rollenhagen, Astrid; Sätzler, Kurt; Rodríguez, E Patricia; Jonas, Peter; Frotscher, Michael; Lübke, Joachim H R.
In: J NEUROSCI, Vol. 27, No. 39, 39, 2007, p. 10434-10444.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - Structural determinants of transmission at large hippocampal mossy fiber synapses.
AU - Rollenhagen, Astrid
AU - Sätzler, Kurt
AU - Rodríguez, E Patricia
AU - Jonas, Peter
AU - Frotscher, Michael
AU - Lübke, Joachim H R
PY - 2007
Y1 - 2007
N2 - Synapses are the key elements for signal processing and plasticity in the brain. To determine the structural factors underlying the unique functional properties of the hippocampal mossy fiber synapse, the complete quantitative geometry was investigated, using electron microscopy of serial ultrathin sections followed by computer-assisted three-dimensional reconstruction. In particular, parameters relevant for transmitter release and synaptic plasticity were examined. Two membrane specializations were found: active zones (AZs), transmitter release sites, and puncta adherentia, putative adhesion complexes. Individual boutons had, on average, 25 AZs (range, 7-45) that varied in shape and size (mean, 0.1 microm2; range, 0.07-0.17 microm2). The mean distance between individual AZs was 0.45 microm. Mossy fiber boutons and their target structures were mostly ensheathed by astrocytes, but fine glial processes never reached the active zones. Two structural factors are likely to promote synaptic cross talk: the short distance between AZs and the absence of fine glial processes at AZs. Thus, synaptic cross talk may contribute to the efficacy of hippocampal mossy fiber synapses. On average, a bouton contained 20,400 synaptic vesicles; approximately 900 vesicles were located within 60 nm from the active zone, approximately 4400 between 60 and 200 nm, and the remaining beyond 200 nm, suggesting large readily releasable, recycling, and reserve pools. The organization of the different pools may be a key structural correlate of presynaptic plasticity at this synapse. Thus, the mossy fiber bouton differs fundamentally in structure and function from the calyx of Held and other central synapses.
AB - Synapses are the key elements for signal processing and plasticity in the brain. To determine the structural factors underlying the unique functional properties of the hippocampal mossy fiber synapse, the complete quantitative geometry was investigated, using electron microscopy of serial ultrathin sections followed by computer-assisted three-dimensional reconstruction. In particular, parameters relevant for transmitter release and synaptic plasticity were examined. Two membrane specializations were found: active zones (AZs), transmitter release sites, and puncta adherentia, putative adhesion complexes. Individual boutons had, on average, 25 AZs (range, 7-45) that varied in shape and size (mean, 0.1 microm2; range, 0.07-0.17 microm2). The mean distance between individual AZs was 0.45 microm. Mossy fiber boutons and their target structures were mostly ensheathed by astrocytes, but fine glial processes never reached the active zones. Two structural factors are likely to promote synaptic cross talk: the short distance between AZs and the absence of fine glial processes at AZs. Thus, synaptic cross talk may contribute to the efficacy of hippocampal mossy fiber synapses. On average, a bouton contained 20,400 synaptic vesicles; approximately 900 vesicles were located within 60 nm from the active zone, approximately 4400 between 60 and 200 nm, and the remaining beyond 200 nm, suggesting large readily releasable, recycling, and reserve pools. The organization of the different pools may be a key structural correlate of presynaptic plasticity at this synapse. Thus, the mossy fiber bouton differs fundamentally in structure and function from the calyx of Held and other central synapses.
KW - Animals
KW - Rats
KW - Models, Animal
KW - Synaptic Transmission physiology
KW - Imaging, Three-Dimensional
KW - Synapses physiology
KW - Rats, Wistar
KW - Neuronal Plasticity physiology
KW - Microscopy, Electron
KW - Mossy Fibers, Hippocampal physiology
KW - Neurotransmitter Agents physiology
KW - Synaptic Vesicles physiology
KW - Animals
KW - Rats
KW - Models, Animal
KW - Synaptic Transmission physiology
KW - Imaging, Three-Dimensional
KW - Synapses physiology
KW - Rats, Wistar
KW - Neuronal Plasticity physiology
KW - Microscopy, Electron
KW - Mossy Fibers, Hippocampal physiology
KW - Neurotransmitter Agents physiology
KW - Synaptic Vesicles physiology
M3 - SCORING: Zeitschriftenaufsatz
VL - 27
SP - 10434
EP - 10444
JO - J NEUROSCI
JF - J NEUROSCI
SN - 0270-6474
IS - 39
M1 - 39
ER -