The Journal of Neuroscience, February 28, 2007, 27(9):2241-2252; doi:10.1523/JNEUROSCI.3345-06.2007
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Development/Plasticity/Repair
Brain-Derived Neurotrophic Factor Regulates the Maturation of Layer 4 Fast-Spiking Cells after the Second Postnatal Week in the Developing Barrel Cortex
Chiaki Itami,1
Fumitaka Kimura,2 and
Shun Nakamura1
1Division of Biochemistry and Cellular Biology, National Institute of Neuroscience, Tokyo 187-8502, Japan, and 2Division of Neurophysiology, Osaka University Graduate School of Medicine, Osaka 565-0871, Japan
Correspondence should be addressed to Dr. Chiaki Itami, Department of Physiology, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama, Saitama 350-0495, Japan. Email: chiaki{at}saitama-med.ac.jp
Brain-derived neurotrophic factor (BDNF) has been reported to play a critical role in modulating plasticity in developing sensory cortices. In the visual cortex, maturation of neuronal circuits involving GABAergic neurons has been shown to trigger a critical period. To date, several classes of GABAergic neurons are known, each of which are thought to play distinct functions. Of these, parvalbumin (PV)-containing, fast-spiking (FS) cells are suggested to be involved in the initiation of the critical period. Here, we report that BDNF plays an essential role in the normal development of PVFS cells during a plastic period in the barrel cortex. We found that characteristic electrophysiological properties of PVFS cells, such as low spike adaptation ratio, reduced voltage sags in response to hyperpolarization, started to develop around the second postnatal week and attained adult level in several days. We also found that immunoreactivity against PV was also acquired after the similar developmental time course. Then, using BDNF(/) mice, we found that these electrophysiological as well as chemical properties were underdeveloped or did not appear at all. We conclude BDNF regulates the development of electrophysiological and immunohistochemical characteristics in PVFS cells. Because BDNF is suggested to regulate the initiation of plasticity, our results strongly indicate that BDNF is involved in the regulation of the critical period by promoting the functional development of PVFS GABAergic neurons.
Key words: BDNF; GABAergic neurons; parvalbumin; barrel cortex; fast spiking; critical period; local circuit
Received Aug. 3, 2006;
revised Jan. 22, 2007;
accepted Jan. 23, 2007.
Correspondence should be addressed to Dr. Chiaki Itami, Department of Physiology, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama, Saitama 350-0495, Japan. Email: chiaki{at}saitama-med.ac.jp
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Y. Liu, L. I. Zhang, and H. W. Tao
Heterosynaptic Scaling of Developing GABAergic Synapses: Dependence on Glutamatergic Input and Developmental Stage
J. Neurosci.,
May 16, 2007;
27(20):
5301 - 5312.
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