title: Tumor necrosis factor alpha enhances oocyte/follicle apoptosis in the neonatal rat ovary.
abstract: Tumor necrosis factor alpha (TNFalpha) is a multifunctional cytokine present in oocytes and macrophages in the neonatal rat ovary. The presence of both TNFalpha and its receptors in the neonatal rat ovary suggests a potential role for it in follicle assembly or oocyte atresia. Previous studies have provided support for effects of TNFalpha on isolated granulosa and theca cells and intact follicles; however, to our knowledge, this is the first study to investigate the effects of TNFalpha on the earliest stages of follicular development. Effects of TNFalpha on oocyte/follicle number and apoptosis were investigated using an ovarian organ-culture system that supported assembly of primordial follicles in vitro. Ovaries were collected on the day of birth and treated with TNFalpha (0, 0.1, 1.0, 10, or 50 ng/ml), a function-blocking TNFalpha antibody (5 microg/ml), or control immunoglobulin (Ig) G. At 1 ng/ml, TNFalpha decreased follicle and oocyte numbers during 3 days of culture, whereas higher (10 and 50 ng/ml) or lower (0.1 ng/ml) doses had no effect. Treatment with TNFalpha antibodies increased the number of oocytes and follicles compared to nonspecific IgG control. To determine whether the decreased oocyte/follicle numbers were due to an apoptotic effect of TNFalpha, apoptosis was examined by DNA laddering. At 1 ng/ml, TNFalpha increased apoptotic DNA laddering twofold, with no significant effect from lower or higher doses. The cells undergoing apoptosis, as determined by in situ end-labeling, were oocytes, interstitial cells, and granulosa cells. These findings suggest that TNFalpha may be involved in oocyte atresia that normally occurs during the perinatal period.
authors.affiliation: Department of Biological Sciences, Kent State University, Kent, Ohio 44242-0001, USA.
authors.forename: Leisa J
authors.initials: LJ
authors.lastname: Morrison
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Marcinkiewicz
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D019138:Antibodies, Blocking / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002850:Chromatography, Gel; D004247:DNA / Q000302:isolation & purification; D005260:Female; D020287:In Situ Nick-End Labeling; D007202:Indicators and Reagents; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects*; D009924:Organ Culture Techniques; D006080:Ovarian Follicle / Q000166:cytology* / Q000187:drug effects*; D010053:Ovary / Q000166:cytology* / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013268:Stimulation, Chemical; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology*
chemical_list: D019138:Antibodies, Blocking; D007202:Indicators and Reagents; D014409:Tumor Necrosis Factor-alpha; D004247:DNA