| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Regular Article |
a Department of Physiology and
b Pharmacology and Toxicology,
c Southwest Environmental Health Sciences Center, The University of Arizona, Tucson, Arizona 85724
ABSTRACT
Previous studies have shown that 4-vinylcyclohexene diepoxide (VCD)-induced ovotoxicity in rats is likely caused by acceleration of the normal rate of atresia (apoptosis). VCD-induced ovotoxicity is specific for small preantral follicles and is associated with increased activity of caspase cascades. The present study was designed to investigate the alteration of expression and distribution of several Bcl-2 family member proteins induced by dosing of VCD in rat small ovarian follicles. Female F344 rats were given a single dose of VCD (80 mg/kg, i.p., 1 day; a time when ovotoxicity is not initiated), or dosed daily for 15 days (80 mg/kg, i.p., 15 days; a time when significant ovotoxicity is underway). Four hours following the final dose, livers and ovaries were collected. Ovarian small (25–100 µm) and large (100–250 µm) preantral follicles were isolated, and subcellular fractions (cytosolic and mitochondrial) were prepared. Compared with controls, levels of the proapoptotic protein, Bad, were greater in both cytosolic and mitochondrial fractions of small preantral follicles collected from 15-day VCD-treated rats (cytosol, 1.97 ± 0.16; mitochondria, 2.20 ± 0.24, VCD/control, P < 0.05). After 15 days of daily VCD dosing, total cellular antiapoptotic Bcl-xL protein levels were unaffected in small preantral follicles, but its distribution in mitochondrial and cytosolic components was altered (mitochondria, 0.635 ± 0.08; cytosol, 1.39 ± 0.14, VCD/control, P < 0.05). Likewise, VCD did not affect protein levels of proapoptotic Bax in small follicles on Day 15. However, consistent with a Bax-mediated mechanism of apoptosis, the relative ratio of Bax/Bcl-xL in the mitochondrial fraction of small preantral follicles was significantly increased by VCD dosing (1.62 ± 0.21, VCD/control, P < 0.05). Immunofluorescence staining intensity evaluated by confocal microscopy visualized cytochrome c protein in the cytosolic compartment in granulosa cells of preantral follicles in various stages of development. Relative to controls, within the population of small preantral follicles, staining intensity was less (P < 0.05) and presumably more diffuse, specifically in stage 1 primary follicles from VCD-treated animals (15 days). VCD caused none of these effects in large preantral follicles or liver (not targeted by VCD). These data provide evidence that the apoptosis induced by VCD in ovarian small preantral follicles of rats is associated with increased expression of Bad protein, redistribution of Bcl-xL protein and cytochrome c from the mitochondria to the cytosolic compartment, and an increase in the Bax/Bcl-xL ratio in the mitochondria. These observations are consistent with the involvement of Bcl-2 gene family members in VCD-induced acceleration of atresia.
1 Supported by National Institutes of Health grant RO1-ESO9246 and Center Grant ESO6694 (X.H., P.C., and P.B.H.).
2 Correspondence: Patricia B. Hoyer, Department of Physiology, The University of Arizona, P.O. Box 245051, Tucson, AZ 85724. FAX: 520 626 2382; hoyer{at}u.arizona.edu
This article has been cited by other articles:
|
|
 |
|
  Z. Rivera, P. J. Christian, S. L. Marion, H. L. Brooks, and P. B. Hoyer Steroidogenic Capacity of Residual Ovarian Tissue in 4-Vinylcyclohexene Diepoxide-Treated Mice Biol Reprod, February 1, 2009; 80(2): 328 - 336. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. F. Keating, K. S. Rajapaksa, I. G. Sipes, and P. B. Hoyer Effect of CYP2E1 Gene Deletion in Mice on Expression of Microsomal Epoxide Hydrolase in Response to VCD Exposure Toxicol. Sci., October 1, 2008; 105(2): 351 - 359. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. M. Fernandez, A. F. Keating, P. J. Christian, N. Sen, J. B. Hoying, H. L. Brooks, and P. B. Hoyer Involvement of the KIT/KITL Signaling Pathway in 4-Vinylcyclohexene Diepoxide-Induced Ovarian Follicle Loss in Rats Biol Reprod, August 1, 2008; 79(2): 318 - 327. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. S. Rajapaksa, I. G. Sipes, and P. B. Hoyer Involvement of Microsomal Epoxide Hydrolase Enzyme in Ovotoxicity Caused by 7,12-Dimethylbenz[a]anthracene Toxicol. Sci., April 1, 2007; 96(2): 327 - 334. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. R Greenfeld, J. K Babus, P. A Furth, S. Marion, P. B Hoyer, and J. A Flaws BAX is involved in regulating follicular growth, but is dispensable for follicle atresia in adult mouse ovaries Reproduction, January 1, 2007; 133(1): 107 - 116. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Desmeules and P. J. Devine Characterizing the Ovotoxicity of Cyclophosphamide Metabolites on Cultured Mouse Ovaries Toxicol. Sci., April 1, 2006; 90(2): 500 - 509. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. E Valdez, S P. Cuneo, and A. M Turzillo Regulation of apoptosis in the atresia of dominant bovine follicles of the first follicular wave following ovulation Reproduction, July 1, 2005; 130(1): 71 - 81. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. P. Mayer, P. J. Devine, C. A. Dyer, and P. B. Hoyer The Follicle-Deplete Mouse Ovary Produces Androgen Biol Reprod, July 1, 2004; 71(1): 130 - 138. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. J. Guigon, S. Mazaud, M. G. Forest, S. Brailly-Tabard, N. Coudouel, and S. Magre Unaltered Development of the Initial Follicular Waves and Normal Pubertal Onset in Female Rats after Neonatal Deletion of the Follicular Reserve Endocrinology, August 1, 2003; 144(8): 3651 - 3662. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Takai, J. Canning, G. I. Perez, J. K. Pru, J. J. Schlezinger, D. H. Sherr, R. N. Kolesnick, J. Yuan, R. A. Flavell, S. J. Korsmeyer, et al. Bax, Caspase-2, and Caspase-3 Are Required for Ovarian Follicle Loss Caused by 4-Vinylcyclohexene Diepoxide Exposure of Female Mice in Vivo Endocrinology, January 1, 2003; 144(1): 69 - 74. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
X. Hu, J. A. Flaws, I. G. Sipes, and P. B. Hoyer Activation of Mitogen-Activated Protein Kinases and AP-1 Transcription Factor in Ovotoxicity Induced by 4-Vinylcyclohexene Diepoxide in Rats Biol Reprod, September 1, 2002; 67(3): 718 - 724. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
