Impaired succinic dehydrogenase activity of rat Purkinje cell mitochondria during aging.
The perikaryal Purkinje cell mitochondria positive to the copper ferrocyanide histochemical reaction for succinic dehydrogenase (SDH) have been investigated by means of semiautomatic morphometric methods in rats of 3, 12 and 24 months of age. The number of organelles/microm3 of Purkinje cell cytoplasm (Numeric density: Nv), the average mitochondrial volume (V) and the mitochondrial volume fraction (Volume density: Vv) were the ultrastructural parameters taken into account. Nv was significantly higher at 12 than at 3 and 24 months of age. V was significantly decreased at 12 and 24 months of age, but no difference was envisaged between adult and old rats. Vv was significantly decreased in old animals vs. the other age groups. In young and old rats, the percentage of organelles larger than 0.32 microm3 was 13.5 and 11%, respectively, while these enlarged mitochondria accounted for less than 1% in the adult group. Since SDH activity is of critical importance when energy demand is high, the marked decrease of Vv supports an impaired capacity of the old Purkinje cells to match actual energy supply at sustained transmission of the nervous impulse. However, the high percentage of enlarged organelles found in old rats may witness a morphofunctional compensatory response.
Fattoretti
P
P
Neurobiology of Aging Laboratory, N. Masera INRCA Research Department, Ancona, Italy. p.fattoretti@inrca.it
Bertoni-Freddari
C
C
Caselli
U
U
Paoloni
R
R
Meier-Ruge
W
W
D000375:Aging / Q000378:metabolism*; D000818:Animals; D002531:Cerebellum / Q000201:enzymology / Q000473:pathology; D005260:Female; D008928:Mitochondria / Q000201:enzymology*; D011689:Purkinje Cells / Q000201:enzymology*; D051381:Rats; D017208:Rats, Wistar; D013385:Succinate Dehydrogenase / Q000378:metabolism*
D013385:Succinate Dehydrogenase