title: Adult-onset calorie restriction delays the accumulation of mitochondrial enzyme abnormalities in aging rat kidney tubular epithelial cells.
abstract: Adult-onset calorie restriction (A-CR) is an experimental model of life extension and healthy aging less explored, compared with calorie restriction begun at early ages, but one more realistic for human application. We examined the effect of A-CR on the aging rat kidney with respect to common structural age-dependent changes and the accumulation of mitochondrial enzyme abnormalities in tubular epithelial cells. A 40% calorie restriction was initiated in middle-aged rats, before the onset of significant age-related changes in the Fischer x Brown Norway rat kidney. This dietary intervention effectively reduced glomerulosclerosis and tubular atrophy within 6 mo and changed the rate of interstitial fibrosis formation within 1 yr and vascular wall thickening and the expression cytochrome c oxidase (COX)-deficient tubular epithelial cells in 18 mo compared with age-matched ad libitum-fed rats. Our histological approach (histochemical staining for mitochondrial enzyme activity and laser capture microdissection) coupled with mitochondrial DNA (mtDNA) PCR analyses demonstrated that COX-deficient renal tubular epithelial cells accumulated mtDNA deletion mutations and that these cells contained unique, clonally expanded mtDNA deletion mutations. Renal tubular epithelial cells with mitochondrial abnormalities presented cellular characteristics indicative of physiological dysfunction.
authors.affiliation: Department of Animal Health and Biomedical Sciences, University of Wisconsin, Madison, WI 53706, USA. mckiernan@svm.vetmed.wisc.edu
authors.forename: Susan H
authors.initials: SH
authors.lastname: McKiernan
authors.forename: Victoria C
authors.initials: VC
authors.lastname: Tuen
authors.forename: Katherine
authors.initials: K
authors.lastname: Baldwin
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wanagat
authors.forename: Arjang
authors.initials: A
authors.lastname: Djamali
authors.forename: Judd M
authors.initials: JM
authors.lastname: Aiken
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001835:Body Weight / Q000502:physiology; D031204:Caloric Restriction; D004272:DNA, Mitochondrial / Q000235:genetics; D004032:Diet; D003576:Electron Transport Complex IV / Q000378:metabolism; D004847:Epithelial Cells / Q000201:enzymology; D017353:Gene Deletion; D007684:Kidney Tubules / Q000166:cytology / Q000201:enzymology*; D007834:Lasers; D008297:Male; D008928:Mitochondria / Q000201:enzymology*; D009929:Organ Size / Q000502:physiology; D051381:Rats; D011916:Rats, Inbred F344; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013385:Succinate Dehydrogenase / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; D013385:Succinate Dehydrogenase; D003576:Electron Transport Complex IV