title: Age-dependent decline of blood-brain barrier P-glycoprotein expression in the canine brain.
abstract: The efflux transporter P-glycoprotein serves as a major molecular gatekeeper at the blood-brain barrier. It has been suggested that a reduction of P-glycoprotein activity with aging might enhance exposure of brain tissue to exogenous and endogenous compounds thereby contributing to the development of neurodegenerative diseases. Brain tissue from owner-kept dogs renders an excellent tool to study the impact of aging on the background of variable environmental and genetic influencing factors. Therefore, we determined expression rates of P-glycoprotein in canine post-mortem tissue from 23 non-laboratory dogs. P-glycoprotein expression in the parahippocampal cortex exhibited a negative correlation with age. Analysis of the area labeled for P-glycoprotein in dogs aged >100 months revealed a 72% drop in P-glycoprotein expression as compared to young adults aged 23-36 months. Respective data from the dentate hilus and dentate gyrus indicated an earlier drop with a reduction by 77 and 80% in dogs aged 37-99 months in comparison with younger individuals. In contrast to the decline observed with aging in dogs without plaques, P-glycoprotein expression rates rather tended to increase with further aging in dogs with plaque formation. In conclusion, the thorough analysis of P-glycoprotein expression rates in non-laboratory dogs revealed a significant decline with aging. The data strongly support the concept that age-dependent changes might predispose to neurodegenerative diseases. In the early pathogenesis of Alzheimer's disease which is modelled by diffuse plaques in the canine brain, an up-regulation of P-glycoprotein might act as a compensatory mechanism to enhance Abeta efflux from the brain. Future studies are necessary to further evaluate the correlation between Abeta deposits and P-glycoprotein expression in different phases of the disease.
authors.affiliation: Inst. of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University Munich, Koeniginstr. 16, 80539 Munich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Pekcec
authors.forename: E L
authors.initials: EL
authors.lastname: Schneider
authors.forename: W
authors.initials: W
authors.lastname: Baumgärtner
authors.forename: V M
authors.initials: VM
authors.lastname: Stein
authors.forename: A
authors.initials: A
authors.lastname: Tipold
authors.forename: H
authors.initials: H
authors.lastname: Potschka
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000096:biosynthesis* / Q000502:physiology; D000375:Aging / Q000473:pathology / Q000502:physiology*; D000686:Amyloidosis / Q000378:metabolism / Q000473:pathology; D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism*; D001921:Brain / Q000098:blood supply* / Q000378:metabolism*; D004285:Dogs; D005260:Female; D008297:Male; D019636:Neurodegenerative Diseases / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D058225:Plaque, Amyloid / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D015854:Up-Regulation / Q000502:physiology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1