| 1. |
- Ny, A, et al.
(författare)
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Ovulation in plasminogen-deficient mice.
- 1999
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Ingår i: Endocrinology. - 0013-7227 .- 1945-7170. ; 140:11, s. 5030-5
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Tidskriftsartikel (refereegranskat)abstract
- Many different studies suggest that plasmin generated from plasminogen plays a crucial role in the degradation of the follicular wall at the time of ovulation. We have assessed the physiological relevance of plasmin on ovulation by studying plasminogen-deficient mice. Ovulation efficiency (mean number of ova released per mouse) was determined both in a standardized ovulation model in which 25-day-old immature mice were injected with finite amounts of gonadotropins to induce ovulation and during physiological ovulation using adult normally cycling mice. Our results revealed that the temporal onset of follicular wall rupture (first ova observed in bursa or oviduct) was not delayed in plasminogen-deficient mice during gonadotropin-induced ovulation. However, there was a trend toward slightly reduced ovulation efficiency in the plasminogen-deficient mice. This reduction was only 13% and not statistically significant (P = 0.084) and may be connected to a delayed maturation of these mice manifested in reduced body and ovary weights. During physiological ovulation adult plasminogen-deficient mice had normal ovulation efficiency compared with plasminogen wild-type mice. Taken together our results indicate that under the conditions used in this study plasmin is not required for efficient follicular rupture or for activation of other proteases involved in this process. Alternatively, the role of plasmin may be effectively compensated for by other mechanisms in the absence of plasmin.
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| 2. |
- Leonardsson, G, et al.
(författare)
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Ovulation efficiency is reduced in mice that lack plasminogen activator gene function : functional redundancy among physiological plasminogen activators.
- 1995
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 92:26, s. 12446-50
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Tidskriftsartikel (refereegranskat)abstract
- Several lines of indirect evidence suggest that plasminogen activation plays a crucial role in degradation of the follicular wall during ovulation. However, single-deficient mice lacking tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA), or PA inhibitor type 1(PAI-1) gene function were recently found to have normal reproduction, although mice with a combined deficiency of tPA and uPA were significantly less fertile. To investigate whether the reduced fertility of mice lacking PA gene function is due to a reduced ovulation mechanism, we have determined the ovulation efficiency in 25-day-old mice during gonadotropin-induced ovulation. Our results reveal that ovulation efficiency is normal in mice with a single deficiency of tPA or uPA but reduced by 26% in mice lacking both physiological PAs. This result suggests that plasminogen activation plays a role in ovulatory response, although neither tPA nor uPA individually or in combination is obligatory for ovulation. The loss of an individual PA seems to be functionally complemented by the remaining PA but this compensation does not appear to involve any compensatory up-regulation. Our data imply that a functionally redundant mechanism for plasmin formation operates during gonadotropin-induced ovulation and that PAs together with other proteases generate the proteolytic activity required for follicular wall degradation.
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| 3. |
- Ny, A, et al.
(författare)
-
Studies of mice lacking plasminogen activator gene function suggest that plasmin production prior to ovulation exceeds the amount needed for optimal ovulation efficiency.
- 1997
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Ingår i: European Journal of Biochemistry. - 0014-2956 .- 1432-1033. ; 244:2, s. 487-93
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Tidskriftsartikel (refereegranskat)abstract
- Many studies suggest that the plasminogen activator (PA) system plays a role in the proteolytic degradation of the follicle wall at the time of ovulation. Consistently, the ovulation efficiency is reduced by 26% in mice where both physiological PA genes have been inactivated. To reveal the mechanism behind reduced ovulation efficiency in PA-deficient mice and its effect on ovarian proteolysis. we have studied the regulation of plasmin activity in the ovaries of 25-day-old wild-type mice and mice with deficient PA gene function during gonadotropin-induced ovulation. In wild-type mice the plasmin activity was low in ovarian extracts from mice treated with pregnant mare's serum gonadotropin. However, this activity was increased between 2-8 h after an ovulatory dose of human choriogonadotropins. In mice lacking either tissue-type PA (tPA) or PA inhibitor type 1 (PAI-1) the plasmin activity levels prior to ovulation were similar to wild-type mice, while extracts prepared from urokinase-type PA (uPA) deficient mice had 10% or less of the plasmin activity. This indicates that most of the plasmin activity in the mouse ovary is generated by uPA. In addition, as the ovulation efficiency is impaired in tPA/uPA-deficient mice but appears normal in uPA-deficient mice, our data indicates that the amount of plasmin generated by PAs prior to ovulation in wild-type mice greatly exceeds the amount required for efficient ovulation.
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