Neurotrophin secretion from cultured microglia.
Because microglia have been suggested to produce neurotrophins, we tested this ability in vitro. Rat primary microglia were found to constitutively secrete a limited amount of brain-derived neurotrophic factor (BDNF), but nerve growth factor (NGF) and neurotrophin-3 (NT-3) were undetectable in the conditioned medium. Stimulation of the cells with lipopolysaccharide (LPS) increased BDNF secretion, and induced NGF secretion. As a first step to examine this regulation system, the association of protein kinase C (PKC) was pharmacologically analyzed. A PKC activator, phorbol-12-myristate-13-acetate, enhanced the secretion of BDNF. Pre-treatment of microglia with a PKC inhibitor, bisindolylmaleimide, suppressed LPS-stimulated BDNF secretion as well as the constitutive one. These results suggest that the PKC signaling cascade is closely associated with BDNF secretion. Among PKC isoforms, PKCalpha probably plays a role in BDNF secretion, based on the results of experiments using a specific PKC activator, 1-oleoyl-2-acetyl-sn-glycerol, and a specific PKC inhibitor, Gö 6976, and by immunoblotting. Taken together, these findings suggest that the secretion of BDNF from microglia is regulated through PKCalpha-associated signal transduction mechanism.
Nakajima
K
K
Institute of Life Science, Soka University, 1-236, Tangi-machi, Hachioji, Tokyo 192-8577. nakajima@t.soka.ac.jp
Honda
S
S
Tohyama
Y
Y
Imai
Y
Y
Kohsaka
S
S
Kurihara
T
T
D000818:Animals; D000906:Antibodies; D019208:Brain-Derived Neurotrophic Factor / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D002227:Carbazoles / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004075:Diglycerides / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D017628:Microglia / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D009414:Nerve Growth Factors / Q000032:analysis / Q000276:immunology / Q000378:metabolism*; D020933:Neurotrophin 3 / Q000032:analysis / Q000276:immunology / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051571:Protein Kinase C-alpha; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000906:Antibodies; D019208:Brain-Derived Neurotrophic Factor; D002227:Carbazoles; D002273:Carcinogens; D017077:Culture Media, Conditioned; D004075:Diglycerides; D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D008070:Lipopolysaccharides; D008301:Maleimides; D009414:Nerve Growth Factors; D020933:Neurotrophin 3; C081021:Go 6976; C038237:1-oleoyl-2-acetylglycerol; D020932:Nerve Growth Factor; D011493:Protein Kinase C; D051571:Protein Kinase C-alpha; C088060:bisindolylmaleimide; D013755:Tetradecanoylphorbol Acetate