Equine oocyte maturation with epidermal growth factor.
Abstract: Epidermal growth factor (EGF) has been shown to have a positive effect during oocyte in vitro maturation in several species. This study was performed to establish the capacity of equine oocytes to undergo nuclear maturation in the presence of EGF and to localise its receptor in the equine ovary by immunohistochemical methods. Oocytes were obtained by aspiration and subsequent scraping from equine follicles (15-25 mm diameter) and cultured in 3 different treatment groups for 36 h: control Group (modified TCM 199 with 0.003% BSA), EGF Group (TCM-199 supplemented with 50 ng/ml EGF) and EMS Group (TCM 199 supplemented with 10% v/v oestrous mare serum). Each group was divided further into 3 treatments with tyrphostin A-47, a specific tyrosine kinase inhibitor, at 0, 10(-4) and 10(-6) mmol/l. Maturation was determined as the percentage of oocytes reaching metaphase II stage at the end of the culture period. Immunohistochemical detection of EGF-receptor (EGFR) was performed using a streptoavidin-biotin method. The recovery rate and oocyte retrieval were 84.6% (recovered oocytes/follicles aspirated) and 6.55 (oocytes/mare), respectively. Treatment with EGF significantly (P<0.05) increased the incidence of metaphase II stage compared with the control group (69.4 vs. 26.9% in controls, respectively). The specific-tyrosine kinase inhibitor A-47 was effective in suppressing EGF-effect on EGF-cultured oocytes; no significant differences were observed in EMS-supplemented oocytes when cultured with A-47. EGF-receptor was localised in follicles, with localisation being more prominent in the cumulus than in mural granulosa cells. This finding, together with the increase of oocyte nuclear maturation rate when using EGF in culture media and the inhibition of maturation by tyrphostin A-47, suggests a physiological role for EGF in the regulation of equine oocyte maturation. The results should help successful development of assisted reproductive technology in the horse.
Publication Date: 2002-07-16 PubMed ID: 12117110DOI: 10.2746/042516402776249065Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research studies the effect of Epidermal Growth Factor (EGF) on the maturation of horse oocytes, or egg cells, in laboratory conditions. The results showed that EGF significantly increased the maturation rate of these ovules, suggesting a regulatory role for EGF in horse reproduction.
Methodology
- The researchers collected oocytes from horse follicles of 15-25mm diameter via aspiration and scraping.
- They divided the collected oocytes into three different groups for culture, each receiving a different treatment for 36 hours: a Control group (with just modified TCM 199 and 0.003% BSA), an EGF group (TCM-199 supplemented with 50 ng/ml EGF), and an EMS group (TCM 199 supplemented with 10% v/v oestrous mare serum).
- Each of these groups were further divided into three treatments with Tyrphostin A-47—a specific tyrosine kinase inhibitor—at varied concentrations.
- The maturation of the oocytes was determined by the percentage that reached the Metaphase II stage at the end of the culture period.
- The researchers also performed immunohistochemical detection of the EGF-receptor (EGFR), using a streptoavidin-biotin method.
Results
- The recovery rate of the oocytes was about 84.6%, with an average of 6.55 oocytes recovered per mare.
- Compared with the control group, the group treated with EGF had significantly more oocytes reach the Metaphase II stage (69.4% vs 26.9% in the control group).
- The use of Tyrphostin A-47 successfully suppressed the EGF-cultured oocytes’ response to EGF, indicating its effectiveness as a tyrosine kinase inhibitor. Meanwhile, no significant differences were observed in the oocytes supplemented with EMS when they were cultured with A-47.
- The EGF-receptor was found in the follicles and was more prominently identified in the cumulus cells rather than the mural granulosa cells.
Conclusion
- Considering the significant increase in oocyte maturation when EGF is used in culture media, along with the successful inhibition of maturation by Tyrphostin A-47, the research suggests a physiological role for EGF in regulating equine oocyte maturation.
- The findings could aid in the development of assisted reproductive technology in horses.
Cite This Article
APA
Lorenzo PL, Liu IK, Carneiro GF, Conley AJ, Enders AC.
(2002).
Equine oocyte maturation with epidermal growth factor.
Equine Vet J, 34(4), 378-382.
https://doi.org/10.2746/042516402776249065 Publication
Researcher Affiliations
- Departamento de Fisiología Animal, Facultad de Veterinaria, Universidad Complutense, Madrid, Spain.
MeSH Terms
- Animals
- Enzyme Inhibitors / pharmacology
- Epidermal Growth Factor / pharmacology
- ErbB Receptors / isolation & purification
- ErbB Receptors / metabolism
- Female
- Horses
- Immunohistochemistry / veterinary
- In Vitro Techniques
- Oocytes / drug effects
- Oocytes / growth & development
- Protein-Tyrosine Kinases / antagonists & inhibitors
- Tyrphostins / pharmacology
Citations
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