PT  - JOURNAL ARTICLE
AU  - Yoshiyuki Kubota
AU  - Yasuo Kawaguchi
TI  - Dependence of GABAergic Synaptic Areas on the Interneuron Type and Target Size
AID  - 10.1523/JNEUROSCI.20-01-00375.2000
DP  - 2000 Jan 01
TA  - The Journal of Neuroscience
PG  - 375--386
VI  - 20
IP  - 1
4099  - http://www.jneurosci.org/content/20/1/375.short
4100  - http://www.jneurosci.org/content/20/1/375.full
SO  - J. Neurosci.2000 Jan 01; 20
AB  - In the neostriatum, several types of interneuron with distinct firing patterns and expression of neuroactive substances are known to exist. We found two types of neostriatal interneurons, parvalbumin-containing fast-spiking (FS) cells and somatostatin-containing low-threshold spike (LTS) cells to both be immunoreactive for GABA at their axon terminals in immersion-fixed brain slices from rat. To reveal the differences in synaptic connections between these two types of GABAergic interneurons, the postsynaptic target and their synaptic structure were compared by three-dimensional reconstructions from electron microscopic images of intracellularly stained axon terminals. FS cells made a greater proportion of synaptic contacts onto somata than LTS cells. Although terminal boutons of FS and LTS cells were similar in volume, their synaptic junctional areas differed in size distribution and relation to the dimensions of postsynaptic dendritic shafts or spines. Whereas the synaptic junctional areas of FS cells (0.024–0.435 μm2; n = 28) sharply and linearly increased with the circumference of the postsynaptic dendrites or spines (0.939–5.146 μm), the slope for the junctional area of LTS cells (0.02–0.103 μm2; n = 29) against circumference (0.844–4.252 μm) was less steep, and a much weaker correlation was seen. In addition to the differences in firing patterns, expressed molecules, axonal arborizations, and postsynaptic targets, this variation in dependency of the synaptic area on the target size suggests functional differentiation of GABAergic interneurons.