Does neuroglobin protect neurons from ischemic insult? A quantitative investigation of neuroglobin expression following transient MCAo in spontaneously hypertensive rats.
Neuroglobin (NGB) is a recently characterized heme globin expressed primarily in retinal nerve cells and at very low levels in endocrine-active regions of vertebrate brains. When artificially over-expressed, NGB reduces the infarct size observed after transient Middle Cerebral Artery occlusion (tMCAo) in rats. This study addresses the post-ischemic NGB expression in vivo. Ten Spontaneously Hypertensive Rats (SHRs) were randomized to tMCAo (n = 6) or sham (n = 4), and euthanized 24 h later. NGB mRNA expression was determined by means of quantitative Reverse Transcription Polymerase Reaction (qRT-PCR). Thirteen animals subjected to either 90 min tMCAo (n = 7) or sham (n = 6) surgery, were euthanized 1 week after surgery. Post-ischemic expression of NGB and the neuronal marker NeuN was studied using free-floating immunohistochemistry. Design-based stereological quantification of NGB- and NeuN-positive cells in the striatum was performed using the optical fractionator. Significantly less NGB mRNA was expressed in the ischemic hemispheres of tMCAo animals after 24 h (P < or = 0.002). At the protein level, we found a significantly lower number of NGB- and NeuN-positive striatal neurons in tMCAo rats (P < or = 0.004). NGB expression was mainly confined to the hypothalamus and amygdala. Less than one out of every two thousand neurons expressed NGB in the striatum. In the ischemic territory we did not observe selective sparing of NGB expressing neurons. No significant change in the NGB/NeuN ratio was observed. Our data indicate that endogenous expressed NGB does not provide protection against ischemic injury induced by tMCAo in SHRs.
Hundahl
Christian
C
Department of Zoophysiology, Institute of Biology, University of Aarhus, DK-8000 Aarhus, Denmark.
Kelsen
Jesper
J
Kjaer
Katrine
K
Rønn
Lars Christian Biilmann
LC
Weber
Roy Edwin
RE
Geuens
Eva
E
Hay-Schmidt
Anders
A
Nyengaard
Jens Randel
JR
D000679:Amygdala / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D000704:Analysis of Variance; D000818:Animals; D002452:Cell Count / Q000379:methods; D007839:Functional Laterality; D015870:Gene Expression / Q000502:physiology*; D005914:Globins / Q000235:genetics / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D007150:Immunohistochemistry / Q000379:methods; D020244:Infarction, Middle Cerebral Artery / Q000473:pathology / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D000078787:Neuroglobin; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D011918:Rats, Inbred SHR; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D012333:RNA, Messenger; D005914:Globins; D010751:Phosphopyruvate Hydratase