Apoptosis induced in rats by 4-vinylcyclohexene diepoxide is associated with activation of the caspase cascades

X. Hu, P. J. Christian, K. E. Thompson, I. G. Sipes, P. B. Hoyer

Research output: Contribution to journalArticle

73 Scopus citations

Abstract

Previous studies have shown that ovotoxicity induced in rats by dosing with 4-vinylcyclohexene diepoxide (VCD) is likely via acceleration of the normal rate of atresia (apoptosis). The present study was designed to investigate the apoptosis-related caspase cascades as a component of this phenomenon in isolated ovarian small follicles. Female F344 rats were given a single dose of VCD (80 mg/kg, i.p., on Day 1; a time when ovotoxicity has not been initiated), or dosed daily for 15 days (80 mg/kg, i.p., on Day 15; a time when significant ovotoxicity is underway). Ovaries were collected after the final dose. Small preantral follicles (25-100 μm in diameter) were isolated, cellular fractions were prepared, and cleavage activity or protein expression levels of caspases-3, -8, and -9 were measured. Cytosolic caspase-3 activity was increased in small follicles (P < 0.01) by VCD treatment (Day 1, 2.86 ± 0.23; Day 15, 3.25 ± 0.64, VCD/control, n = 3). This activation was not seen in large or antral follicles (not targeted by VCD). Procaspase-3 protein was increased (P < 0.05) by VCD treatment 212% over controls in small ovarian follicles in Day 15, but not Day 1-dosed rats. Immunofluorescence staining intensity was evaluated by confocal microscopy. Caspase-3 protein, located in the cytosolic compartment of oocytes and granulosa cells of preantral follicles in various stages of development, was selectively increased (P < 0.05) in primordial and small primary follicles from Day 15 VCD-dosed rats. Caspase-8 activity was increased in small follicles in Day 15, but not in Day 1-treated rats; whereas caspase-9 activity was increased by VCD on Day I in the mitochondrial fraction. Thus, these data provide evidence that accelerated atresia induced in small ovarian follicles in rats by VCD is associated with activation of a caspase-mediated cascade.

Original languageEnglish (US)
Pages (from-to)87-93
Number of pages7
JournalBiology of reproduction
Volume65
Issue number1
DOIs
StatePublished - Jan 1 2001

Keywords

  • Apoptosis
  • Follicle
  • Ovary
  • Signal transduction

ASJC Scopus subject areas

  • Reproductive Medicine
  • Cell Biology

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