title: Long-term UVA eye irradiation causes decreased learning ability in mice.
abstract: BACKGROUND
  Long-term eye radiation with ultraviolet A (UVA) denatures the cells of the cerebral hippocampus. However, the influence on memory and learning ability in mice is not known.
  
  
  METHODS
  HR-1 mice were used. We irradiated the eyes or dorsal skin of the mice with UVA at a dose of 110 kJ/m(2) using an FL20SBLB-A lamp for 6, 12, and 24 months.
  
  
  RESULTS
  The mean escape latency in the water maze was significantly increased in the UVA-irradiated mice in comparison with that seen in the controls. In the mice in which UVA eye irradiation was performed for 24 months, the depression of memory and learning ability was remarkable. The acetylcholinesterase activity, choline acetyltransferase activity, and acetylcholine content in the brain in the UVA eye-irradiated mice were significantly less than those observed in the control mice. Furthermore, during UVA eye irradiation, the levels of β-amyloid (Aβ), γ-secretase, which produces Aβ peptide, and advanced glycation end products increased. Moreover, the effects of UVA eye irradiation increased with the duration of irradiation (or aging), and the introduction of glucose into the brain also decreased with UVA eye irradiation.
  
  
  CONCLUSIONS
  These results indicate that UVA eye irradiation induces a decreased memory and learning ability in mice.
authors.affiliation: Department of Pharmaceutical Science, Suzuka University of Medical Science, Suzuka, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Hiramoto
authors.affiliation: Department of Physiology, Osaka City University Graduate School of Medicine, Osaka, Japan.
authors.forename: Emiko
authors.initials: E
authors.lastname: Kasahara
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000110:Acetylcholinesterase / Q000378:metabolism; D000375:Aging / Q000502:physiology*; D053829:Amyloid Precursor Protein Secretases / Q000378:metabolism; D016229:Amyloid beta-Peptides / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000528:radiation effects*; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D004924:Escape Reaction / Q000528:radiation effects; D005123:Eye / Q000528:radiation effects; D005947:Glucose / Q000378:metabolism; D017127:Glycation End Products, Advanced / Q000378:metabolism; D007858:Learning / Q000528:radiation effects*; D008297:Male; D008568:Memory / Q000528:radiation effects*; D051379:Mice; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D016229:Amyloid beta-Peptides; D017127:Glycation End Products, Advanced; D002795:Choline O-Acetyltransferase; D000110:Acetylcholinesterase; D053829:Amyloid Precursor Protein Secretases; D005947:Glucose; D000109:Acetylcholine
keywords: acetylcholine; advanced glycation end products; learning ability; ultraviolet A; β-amyloid