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Expression of nerve growth factor, brain‐derived neurotrophic factor, and neurotrophin‐3 in the somatosensory cortex of the mature rat: Coexpression with high‐affinity neurotrophin receptors
Author(s) -
Pitts Andrew F.,
Miller Michael W.
Publication year - 2000
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(20000313)418:3<241::aid-cne1>3.0.co;2-m
Subject(s) - neurotrophin , tropomyosin receptor kinase b , nerve growth factor , neurotrophin 3 , biology , tropomyosin receptor kinase a , neuroscience , brain derived neurotrophic factor , neurotrophic factors , tropomyosin receptor kinase c , autocrine signalling , paracrine signalling , low affinity nerve growth factor receptor , microbiology and biotechnology , receptor , growth factor , biochemistry , platelet derived growth factor receptor
Neurotrophins, including nerve growth factor (NGF), brain‐derived neurotrophic factor (BDNF), and neurotrophin‐3 (NT‐3), are critical for the maintenance and plasticity of central nervous system (CNS) neurons. We tested the hypothesis that cortical neurons participate in redundant autocrine/paracrine systems. Three sets of studies determined the distribution of NGF‐, BDNF‐, and NT‐3‐expressing neurons, the frequency of neurons coexpressing NGF and BDNF, and the frequency of neurons expressing a neurotrophin and its associated high‐affinity receptor. The distribution of NGF‐, BDNF, and NT‐3‐immunoreactive neurons was identical. Neurotrophin‐positive cells were parceled throughout the cortex, although the labeling frequency was not the same in all layers. More than 30% of the neurons in layers II/III, V, and VI were labeled, whereas only 5–10% of the neurons in layer IV was immunopositive for a neurotrophin. Some glia were also neurotrophin positive, particularly BDNF‐positive glia. About 70% of the neurons in layers II/III and V coexpressed NGF and BDNF or coexpressed NGF and NT‐3. Ligand‐receptor colabeling was also common among cortical neurons. For example, nearly 70% of the NGF‐, BDNF‐, and NT‐3‐positive neurons in layer V colabeled with their respective high‐affinity receptors, i.e., trk A, trk B, and trk C, respectively. Thus, (a) neurons express multiple neurotrophins and (b) cortical neurons (e.g., layer V neurons) contain the components required for autocrine/paracrine and/or anterograde communication (e.g., neurons in layer II/III support layer V neurons). These systems mean that the cortex is capable of regulating itself autonomously. J. Comp. Neurol. 418:241–254, 2000. Published 2000 Wiley‐Liss, Inc.