BDNF is upregulated by postnatal development and visual experience: quantitative and immunohistochemical analyses of BDNF in the rat retina.
OBJECTIVE
This study sought to elucidate changes in the levels and distribution of brain-derived neurotrophic factor (BDNF) in the retina throughout aging and depending on visual experience.


METHODS
Protein and mRNA levels of BDNF were quantified by enzyme-linked immunosorbent assay (ELISA) and semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), respectively. Levels were assayed in the retinas of rats on postnatal day (P)2, P7, and P14 (approximate time of eye opening) and at 1 month (M), 3M, 8M, and 18M of age. Changes in BDNF expression and localization in the retina were assessed by immunohistochemistry. The effect of monocular deprivation during infancy on retinal BDNF expression was also examined, by ELISA and immunohistochemistry.


RESULTS
Both protein and mRNA levels of BDNF in the rat retina increased after P14. Immunohistochemical analyses revealed that the increase in BDNF protein levels occurred in retinal ganglion cells (RGCs) between P14 and 1M. BDNF immunoreactivity in Müller cell processes was observed in the inner nuclear layer at 1M, but not at P14. The levels of BDNF protein in the retinas of visually deprived eyes were lower than those of control eyes, as quantified by ELISA. Immunohistochemistry showed that BDNF immunoreactivity in RGCs was diminished by visual deprivation, whereas Müller cells were unaffected.


CONCLUSIONS
These observations indicate that BDNF expression in RGCs is upregulated in an activity-dependent manner, whereas that in Müller cells is regulated only by development.
Seki
Masaaki
M
Department of Molecular Neurobiology, Brain Research Institute, and Division of Ophthalmology and Visual Science, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
Nawa
Hiroyuki
H
Fukuchi
Takeo
T
Abe
Haruki
H
Takei
Nobuyuki
N
D000375:Aging / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000254:growth & development* / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012683:Sensory Deprivation; D015854:Up-Regulation; D014785:Vision, Ocular / Q000502:physiology*
D019208:Brain-Derived Neurotrophic Factor; D012333:RNA, Messenger