Influence of epidermal growth factor on mammalian oocyte maturation via tyrosine-kinase pathway.
Epidermal growth factor (EGF) has been reported to promote different functions in mammalian ovaries, including oocyte maturation. The aim of the present study was to establish: that EGF influences oocyte maturation in ovine and equine, that a tyrosine kinase-dependent intracellular mechanism mediates EGF effect and, that EGF-R receptor is detectable in ovarian follicles by immunohistochemistry methods. Selected ovine and equine oocytes were aspirated from 2-5 mm (ovine) or 25 mm (equine) follicles and cultured in TCM 199 for 22 (ovine) or 36 hours (equine). They are then subjected to culture with EGF and two specific tyrosine-kinase inhibitors (TKIs, tyrphostins A-23 y A-47). Maturation was determined as the percentage of oocytes at metaphase II stage after culture. Treatments with EGF significantly increased incidences of metaphase II stage compared to controls (86.2% vs. 55% and 70.4% vs. 22.5% in ovine and equine oocytes, respectively). Tyrphostins A-23 and A-47 were effective in suppressing EGF-effect on oocytes. EGF-receptor was localized in follicles, being more prominent in cumulus and granulosa cells. These results confirm that EGF has a physiological role in the regulation of oocyte maturation via tyrosine-kinase pathway.
Lorenzo
P L
PL
Departamento de Fisiología Animal, Facultad de Veterinaria, Univ. Complutense, Madrid, Spain. lorenzopl@vet.ucm.es
Liu
I K
IK
Illera
J C
JC
Picazo
R A
RA
Carneiro
G F
GF
Illera
M J
MJ
Conley
A J
AJ
Enders
A C
AC
Illera
M
M
D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000502:physiology*; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D006736:Horses; D007150:Immunohistochemistry; D009865:Oocytes / Q000254:growth & development*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013552:Swine
D004791:Enzyme Inhibitors; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases