Mitochondrial function and mitochondria-induced apoptosis in an overstimulated rat ovarian cycle.
Female rats were treated with FSH (40 IU/kg) on the first and second diestrus days (D1 and D2) and with LH (40 IU/kg) on the proestrus (P) day to synchronize and maximize ovarian changes. Follicle area increased by 50% from D1 to P, and the estrus (E) phase showed multiple corpora lutea and massive apoptosis. Increased oxygen uptakes (42-102%) were determined in ovary slices and in isolated mitochondria in active state 3 along the proliferation phase (D1-D2-P) that returned to initial values in the E phase. Mitochondrial content and the electron transfer activities of complexes I and IV were also maximal in the P phase (20-79% higher than in D1). Production of NO by mitochondrial nitric oxide synthase (mtNOS), biochemically determined, and the mtNOS functional activity in regulating state 3 oxygen uptake were also maximal at P and 79-88% higher than at D1. The moderately increased rate of NO in the proliferative phase is associated with mitochondrial biogenesis, whereas the high rate of NO generation by mtNOS at phase P appears to trigger mitochondria-dependent apoptosis. The calculated fraction of ovary mitochondria in state 3 was at a minimal value at the P phase. Mitochondrial oxidative damage, with increased thiobarbituric acid-reactive substances and protein carbonyls, indicates progressive mitochondrial dysfunction between phases P and E. The roles of mitochondria as ATP provider, as a source of NO to signal for mitochondrial proliferation and mitochondria-dependent apoptosis, and as a source of O(2)(-) and H(2)O(2) appear well adapted to serve the proliferation-apoptosis sequence of the ovarian cycle.
Navarro
Ana
A
Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, University Hospital of Puerto Real, Plaza Fragela 9, 11003 Cádiz, Spain. ana.navarro@uca.es
Torrejón
Rafael
R
Bández
Manuel J
MJ
López-Cepero
José M
JM
Boveris
Alberto
A
D000818:Animals; D017209:Apoptosis; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000494:pharmacology; D008597:Menstrual Cycle / Q000187:drug effects* / Q000502:physiology*; D008928:Mitochondria / Q000502:physiology* / Q000648:ultrastructure; D019001:Nitric Oxide Synthase / Q000378:metabolism; D006080:Ovarian Follicle / Q000033:anatomy & histology; D010053:Ovary / Q000502:physiology / Q000648:ultrastructure*; D018384:Oxidative Stress; D010101:Oxygen Consumption; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000378:metabolism
D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D019001:Nitric Oxide Synthase; D013482:Superoxide Dismutase