Inhibition by tocopherol of prostaglandin-induced apoptosis in ovine corpora lutea.

Accumulation of toxic oxidants within corpora lutea is a prelude of apoptotic cell death. Vitamin E (alpha-tocopherol) is a biological antioxidant that protects cells from the inductive effects of reactive oxygen on DNA damage and nuclear/cytoplasmic condensation that dictate apoptosis. Ewes were challenged with a luteolytic dose of PGF2 alpha on d 10 of the estrous cycle. The acute decline in circulatory progesterone indicative of the onset of functional luteolysis was not affected by systemic administration of alpha-tocopherol; however, corpora lutea consequently (beyond 24 h) rebounded from the steroidogenic insult. Luteal tissues obtained at 24 h after PGF2 alpha revealed that internucleosomal DNA fragmentation and cellular collapse were inhibited by alpha-tocopherol. These observations indicate that regressive corpora lutea can be spared from terminal involution by diminishing the apoptotic influence of luteolytic hormone with an antioxidant.