A cell adhesion molecule mimetic, FGL peptide, induces alterations in synapse and dendritic spine structure in the dentate gyrus of aged rats: a three-dimensional ultrastructural study

TY - JOUR

T1 - A cell adhesion molecule mimetic, FGL peptide, induces alterations in synapse and dendritic spine structure in the dentate gyrus of aged rats: a three-dimensional ultrastructural study

AU - Popov, Victor I

AU - Medvedev, Nikolay I

AU - Kraev, Igor V

AU - Gabbott, Paul L

AU - Davies, Heather A

AU - Lynch, Marina

AU - Cowley, Thelma R

AU - Berezin, Vladimir

AU - Bock, Elisabeth

AU - Stewart, Michael G

PY - 2008/1/1

Y1 - 2008/1/1

N2 - The FGL peptide is a neural cell adhesion molecule (NCAM) mimetic comprising a 15-amino-acid-long sequence of the FG loop region of the second fibronectin type III module of NCAM. It corresponds to the binding site of NCAM for the fibroblast growth factor receptor 1. FGL improves cognitive function through enhancement of synaptic function. We examined the effect of FGL on synaptic and dendritic structure in the brains of aged (22-month-old) rats that were injected subcutaneously (8 mg/kg) at 2-day intervals until 19 days after the start of the experiment. Animals were perfused with fixative, brains removed and coronal sections cut at 50 microm. The hippocampal volume was measured, tissue embedded and ultrathin sections viewed in a JEOL 1010 electron microscope. Analyses were made of synaptic and dendritic parameters following three-dimensional reconstruction via images from a series of approximately 100 serial ultrathin sections. FGL affected neither hippocampal volume nor spine or synaptic density in the middle molecular layer of the dentate gyrus. However, it increased the ratio of mushroom to thin spines, number of multivesicular bodies and also increased the frequency of appearance of coated pits. Three-dimensional analysis showed a significant decrease in both post-synaptic density and apposition zone curvature of mushroom spines following FGL treatment, whereas for thin spines the convexity of the apposition zone increased. These data indicate that FGL induces large changes in the fine structure of synapses and dendritic spines in hippocampus of aged rats, complementing data showing its effect on cognitive processes.

AB - The FGL peptide is a neural cell adhesion molecule (NCAM) mimetic comprising a 15-amino-acid-long sequence of the FG loop region of the second fibronectin type III module of NCAM. It corresponds to the binding site of NCAM for the fibroblast growth factor receptor 1. FGL improves cognitive function through enhancement of synaptic function. We examined the effect of FGL on synaptic and dendritic structure in the brains of aged (22-month-old) rats that were injected subcutaneously (8 mg/kg) at 2-day intervals until 19 days after the start of the experiment. Animals were perfused with fixative, brains removed and coronal sections cut at 50 microm. The hippocampal volume was measured, tissue embedded and ultrathin sections viewed in a JEOL 1010 electron microscope. Analyses were made of synaptic and dendritic parameters following three-dimensional reconstruction via images from a series of approximately 100 serial ultrathin sections. FGL affected neither hippocampal volume nor spine or synaptic density in the middle molecular layer of the dentate gyrus. However, it increased the ratio of mushroom to thin spines, number of multivesicular bodies and also increased the frequency of appearance of coated pits. Three-dimensional analysis showed a significant decrease in both post-synaptic density and apposition zone curvature of mushroom spines following FGL treatment, whereas for thin spines the convexity of the apposition zone increased. These data indicate that FGL induces large changes in the fine structure of synapses and dendritic spines in hippocampus of aged rats, complementing data showing its effect on cognitive processes.

KW - Aging

KW - Animals

KW - Biomimetic Materials

KW - Cell Adhesion Molecules

KW - Dendritic Spines

KW - Dentate Gyrus

KW - Imaging, Three-Dimensional

KW - Male

KW - Neural Cell Adhesion Molecules

KW - Rats

KW - Rats, Wistar

KW - Synapses

U2 - 10.1111/j.1460-9568.2007.06004.x

DO - 10.1111/j.1460-9568.2007.06004.x

M3 - Journal article

C2 - 18215229

SN - 0953-816X

VL - 27

SP - 301

EP - 314

JO - European Journal of Neuroscience

JF - European Journal of Neuroscience

IS - 2

ER -