LOXL null mice demonstrate selective dentate structural changes but maintain dentate granule cell and CA1 pyramidal cell potentiation in the hippocampus.
Lysyl oxidase-like protein (LOXL), part of the lysyl oxidase copper-dependent amine oxidase family, is expressed in the extracellular matrix and in the nucleus. It likely plays a role in cross-linking collagen and elastin, possibly modulating cellular functions. Immunohistochemical studies show the presence of LOXL in the pyramidal cell layer of the hippocampus; and in this study, we report that cells in the granule cell layer have significantly smaller somas in LOXL -/- compared to LOXL +/+ mice. In addition we tested the hypothesis that these structural alterations in the dentate granule layer were associated with synaptic efficacy and thus muted long-term potentiation in mice lacking the protein. Electrical recordings were obtained in 300-mum hippocampal slices in dentate and CA1 pyramidal cell layers in age-matched wild type and LOXL null mice. Potentiation in the CA1 cell layer of 10 LOXL -/- and 8 LOXL +/+ mice was 191.0+/-9.3% and 181.6+/-9.1%, respectively (mean+/-S.E.M.). Dentate potentiation was 120.8+/-7.0% and 121.0+/-3.4% in 11 LOXL -/- and 11 LOXL +/+ mice, respectively. No phenotypic difference in potentiation of population spike amplitude (or in EPSP slope) in either layer was observed. Thus, contrary to expectation, structural changes in the hippocampus of LOXL -/- mice did not affect synaptic remodeling in a manner that impaired the establishment of LTP.
Bronson
Nathan W
NW
Section of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, CA 95616, USA.
Hamilton
Jock S
JS
Han
Mei
M
Li
Ping-An
PA
Hornstra
Ian
I
Horowitz
John M
JM
Horwitz
Barbara A
BA
D000594:Amino Acid Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D048430:Cell Shape; D018891:Dentate Gyrus / Q000166:cytology*; D004594:Electrophysiology; D005260:Female; D006624:Hippocampus / Q000166:cytology* / Q000378:metabolism; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009474:Neurons / Q000166:cytology* / Q000502:physiology*; D017966:Pyramidal Cells / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology
D000594:Amino Acid Oxidoreductases; C482019:Loxl1 protein, mouse