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Differential effects of NT‐4, NGF and BDNF on development of neurochemical architecture and cell size regulation in rat visual cortex during the critical period
Author(s) -
Engelhardt Maren,
Di Cristo Graziella,
Berardi Nicoletta,
Maffei Lamberto,
Wahle Petra
Publication year - 2007
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2006.05301.x
Subject(s) - period (music) , interneuron , neuroscience , soma , biology , neurochemical , neurotrophin , neurotrophin 3 , neuroplasticity , ocular dominance , visual cortex , medicine , endocrinology , neurotrophic factors , brain derived neurotrophic factor , receptor , inhibitory postsynaptic potential , genetics , physics , acoustics
Development of inhibition is a crucial determinant of the time course of visual cortical plasticity. BDNF strongly affects interneuron development and the onset and closure of the critical period for ocular dominance plasticity. Less is known on the effects of NT‐4 despite a clear involvement in ocular dominance plasticity. We have investigated the effects of NT‐4 on interneuron development by supplying NT‐4 with osmotic minipumps during two time windows overlapping the onset (P12–20) and the peak (P20–28) of the critical period. We assessed the expression of interneuronal markers and soma size maturation either after the end of the infusion periods or at the end of the critical period (P45). We found that NT‐4 was very effective in regulating interneuron development. NPY, SOM and PARV neuron somata grew faster during both infusion periods whereas CR neurons only responded during the early infusion period. The effects of soma size elicited during the earlier infusion period were still present at P45. In PARV neurons, NT‐4 caused a long‐lasting stabilization of CB and NPY expression. Furthermore, NT‐4 accelerated the expression of GAD‐65 mRNA in a subset of non‐PARV neurons of layer V, which normally up‐regulate GAD‐65 towards the end of the critical period. Most of these effects were shared by NT‐4 and BDNF. Some were unexpectedly also shared by NGF, which promoted growth of layer V PARV neurons, stabilized the CB expression and accelerated the GAD‐65 expression. The results suggest that neurotrophins act on critical period plasticity by strengthening inhibition.