Different expression of low density lipoprotein receptor and ApoE between young adult and old rat brains after ischemia.
OBJECTIVE
Reduction of brain plasticity underlies the poor outcome of aged stroke patients. The molecular mechanism of plasticity reduction by aging is uncertain, but disturbed lipid metabolism may be implicated.


METHODS
We investigated the expression of low density lipoprotein receptors (LDL-R) and apolipoprotein E (ApoE), both of which play active roles in lipid metabolism in young adult and old rat brains after ischemia.


RESULTS
LDL-R, trivially expressed in the sham-operated brain neurons, was increased from day 1 and became prominent at days 7 and 21 at the peri-ischemic cortex. The magnitude was smaller in the old than in the young adult rats. ApoE was increased in the astrocytes and neurons of the peri-ischemic cortex at day 1, which became further pronounced in the neurons but not in the astrocytes at days 7 and 21. ApoE expression was again less prominent in the old animals at days 7 and 21.


CONCLUSIONS
As ApoE-containing lipoprotein is recruited via LDL-R, the present results suggest that old brains had less capability to induce LDL-R, which resulted in impaired recruitment of lipoprotein after the ischemic injury. Impaired lipid recruitment causes disturbance of synaptogenesis and thus brain plasticity reduction. This molecular mechanism may result in poor functional recovery of aged stroke patients.
Hayashi
Takeshi
T
Department of Neurology, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan. thayashi@cc.okayama-u.ac.jp
Kamada
Hiroshi
H
Jin
Guang
G
Deguchi
Kentaro
K
Nagotani
Shoko
S
Sehara
Yoshihide
Y
Zhang
Hanzhe
H
Nagano
Isao
I
Shoji
Mikio
M
Abe
Koji
K
D000367:Age Factors; D000818:Animals; D001057:Apolipoproteins E / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism* / Q000473:pathology; D002452:Cell Count / Q000379:methods; D002540:Cerebral Cortex / Q000473:pathology; D005786:Gene Expression Regulation / Q000502:physiology*; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D009474:Neurons / Q000378:metabolism; D051381:Rats; D011973:Receptors, LDL / Q000378:metabolism*; D013997:Time Factors
D001057:Apolipoproteins E; D011973:Receptors, LDL