Insulin-like growth factor-II uptake into choroid plexus and brain of young and old sheep.
Insulin-like growth factor II (IGF-II) is a major growth factor in brain and is involved in neuroprotection in later life. However, synthesis and delivery of IGF-II to brain by the choroid plexus (CP) in later life is not well understood. This study investigated these issues in old sheep (7-10 years) in comparison to young adult sheep (1-2 years). IGF-II messenger RNA expression at the CP did not change with age although cerebrospinal fluid (CSF) levels fell. 125I-IGF-II uptake in the CP was saturated from either side of the CP, whereas age-related decrease of the uptake was seen at the CSF side but not at the blood side of the CP. The insulin-like growth factor binding protein-2 (IGFBP-2) at 0.01 or 0.1 microg/mL tended to enhance IGF-II uptake at the young CP but not the old CP or other brain tissues, whereas bovine serum albumin generally inhibited the uptake. These age-related changes suggest that the normal autocrine/paracine role of IGF-II at the CP is attenuated with age.
Chen
Ruo L
RL
Pharmaceutical Science Research Division, King's College London, Guy's Campus, London Bridge, London SE1 1UL. ronnie.chen@kcl.ac.uk
Kassem
Nouhad A
NA
Sadeghi
Mahvand
M
Preston
Jane E
JE
D000375:Aging / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002831:Choroid Plexus / Q000378:metabolism*; D015870:Gene Expression; D007335:Insulin-Like Growth Factor II / Q000235:genetics / Q000378:metabolism*; D007457:Iodine Radioisotopes; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D034561:Sheep, Domestic
D007457:Iodine Radioisotopes; D012333:RNA, Messenger; D007335:Insulin-Like Growth Factor II