Leptin accelerates pronuclear formation following intracytoplasmic sperm injection of porcine oocytes: Possible role for MAP kinase inactivation.
Leptin, a multifunctional hormone, is present in mammalian oocytes and follicular fluids and cumulus cells. While leptin modulates oocyte maturation in vitro which seems to result in enhancement of embryo development, it is unclear whether leptin treatment of oocytes affects cytoplasmic maturation and fertilization processes. In order to gain a better understanding of the role of leptin during oocyte maturation, we examined microtubule and microfilament assembly following oocyte maturation and blastocyst formation, mitogen-activated protein kinase (MAPK) activity, and pronuclear formation following parthenogenetic stimuli or intracytoplasmic sperm injection (ICSI) in leptin-treated oocytes. Addition of 10 or 100 ng/ml leptin during oocyte maturation did not increase the proportion of metaphase II oocytes, but enhanced development to blastocyst stage by day 7 (P<0.01) after parthenogenetic activation (PA), accompanied by increased cell number. However there was no effect on the number of apoptotic cells in blastocysts. Following maturation in the presence of leptin, there were more oocytes with normal spindle formation. MAPK activity decreased more rapidly, and pronuclear formation was accelerated after parthenogenetic activation or ICSI of leptin-treated oocytes. These results suggested that exogeneous leptin enhanced spindle assembly and accelerated pronuclear formation following fertilization, possibly via the MAPK pathway.
Jin
Yong-Xun
YX
Department of Animal Sciences, Chungbuk National University, Gaesin-dong, Cheongju, Chungbuk 361-763, South Korea.
Cui
Xiang-Shun
XS
Han
Young-Joon
YJ
Kim
Nam-Hyung
NH
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000502:physiology; D000818:Animals; D054885:Cumulus Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D047108:Embryonic Development / Q000187:drug effects / Q000502:physiology; D005260:Female; D020287:In Situ Nick-End Labeling; D020738:Leptin / Q000494:pharmacology*; D008297:Male; D008870:Microtubules / Q000187:drug effects / Q000502:physiology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors*; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy; D020554:Sperm Injections, Intracytoplasmic / Q000379:methods* / Q000662:veterinary*; D013094:Spermatozoa / Q000502:physiology; D013552:Swine
D020738:Leptin; D020929:Mitogen-Activated Protein Kinase Kinases