TY  - JOUR
A1  - ,  
T1  - Receptor-mediated internalization of insulin-like growth factor-l in neurons and glia of the central nervous system of the adult rat
JO  - Eur. J. Anat.
SN  - 1136-4890
Y1  - 1998
VL  - 2
SP  - 147
EP  - 158
UR  - http://www.eurjanat.com/web/paper.php?id=98030003
KW  - Insulin-like growth factor I - Insulin - Growth factors - Cerebrospinal fluid.
N2  - Insulin-like   growth    factor-I   is  produced     in  the developing   brain   where   it acts  as  a  trophic   sig­ nal for different   neuronal    and  glial  populations. While  its synthesis   declines    in  most  brain  areas with  adulthood,    expression    of  its  receptor    per­ sists,  together   with  a  broad   distribution    of  cells imrnunoreactive     for   the   peptide.     In   the   adult brain,  insulin-like   growth   factor-I  acts  as  a neu­ rornodulator    and   a  neuroendocrine       messenger and  is also  involved    in  neurodegenerative       pro­ cesses,  reducing   neuronal    loss  after  brain  injury, To determine   whether    adult   brain  cells  are  able to  uptake   insulin-like    growth    factor-I   from   the cerebrospinal      fluid,    the    peptide     was    labeled with  digoxigenin     and   injected    into   the   lateral cerebral     ventricle.      A   large     population       of ependymal   cells,  glial  cells  and  neurons    located throughout     the   entire    central    nervous    system accumulated    labeled    peptide.    Their  distribution,-  corresponded    to that  of cells  expressing    insulin­like  growth    factor-I   receptors    and   also   to  the distribution   of cells  immunoreactive     for the  pep­ tide  in the  adult   rat  brain.   Accumulation    of  the growth   factor   was   receptor-media    red,   since   it was  blocked    by  simultaneous     intracerebroven­ tricular   injection    of  unlabeled     peptide    and   by JBl,  a specific   antagonist    of  insulin-like   growth factor-I   receptors.     Insulin,    at   a   concentration known   to  interact   with  insulin-like    growth   fac­ tor-I receptors   also  blocked   accumulation    of the growth  factor. These   results  indicate   that  insulin­ like  growth   factor-I   is  internalized     by  its  target cells in the  adult  central  nervous   system  and  that intracerebroventricular        injections    are   a   useful mean  to dispense    the  growth   factor  to  its target cells.
ER  -