The Journal of Neuroscience, February 28, 2007, ():
Brain-Derived Neurotrophic Factor Regulates the Maturation of Layer 4 Fast-Spiking Cells after the Second Postnatal Week in the Developing Barrel Cortex
J. Neurosci. Itami et al.
27: 2241
Supplemental Data
Files in this Data Supplement:
- supplemental material
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Quantitative analysis of age-dependent changes in the PV-positive cells in the barrel cortex from BDNF (+/+) (P7-9; n=5, P10-12; n=10, P13-15; n=11, P16-18; n=10, P19-23; n=18, P30 -; n =6), and BDNF(-/-) mice (P7-9; n=10, P10-12; n=10, P13-15; n=10, P16-18; n=9, P19-23; n=7). Left graph was constructed from the number of positive cell in a squared of a fixed size (165 x 165 μm). Based on the left graph, density was calculated by simply dividing the cell count by the area. In BDNF (-/-), the layer IV becomes thinner due to impaired development of soma size without losing the number of cells, as previously reported. As a result, the cell density became larger than in BDNF (+/+) mice. But the number of cells was not actually increased as demonstrated in the left graph.
- supplemental material
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Involvement of sensory input in the maturation of PV immunoreactivity. As cortical inhibitory neurons do not express mRNA for BDNF (Altar et al., 1997; Kohara et al., 2001), it follows that they are unable to produce BDNF by themselves and thus their content is completely dependent upon receiving from surrounding cells (Alcantara et al., 1996; Kohara et al., 2003). Since the transfer of BDNF has been reported to be activity-dependent (Kohara et al. 2003), reducing neural activity by sensory deprivation may result in lowered content of BDNF in the inhibitory cells. We, thus, asked whether sensory deprivation might have any comparable effects on inhibitory neurons in a manner similar to BDNF (-/-) mice. To test this possibility, we deprived all the whiskers on one side of the animal by plucking them every other day from P9 to P19. PV immunoreactivity in the contralateral barrel cortex was then examined on P23. (A-F) PV immunohistochemical (B, C and E, F) as well as cytochrome oxydase staining (A and D) are presented. As can be seen in the higher magnification (C and F), PV staining was substantially weaker in the deprived animal (F). In the control, not only the cell body but also some of the neuropil were immunostained (C), while in the deprived case, staining was so weak that most of the cell bodies were only weakly recognized and none of the neuropil was clearly stained (F). On the other hand, there was no difference in PV staining between the control and deprived animals in thalamic reticular nucleus with the same slices (G and H). Quantitative analysis indicated that the number of stained cells were statistically smaller in the deprived cortex (I). These results are consistent with the idea that BDNF controls the maturation of PV-containing inhibitory neurons in an activity-dependent way.
