Effects of leptin on in vitro maturation, fertilization and embryonic cleavage after ICSI and early developmental expression of leptin (Ob) and leptin receptor (ObR) proteins in the horse.
BACKGROUND
The identification of the adipocyte-derived obesity gene product, leptin (Ob), and subsequently its association with reproduction in rodents and humans led to speculations that leptin may be involved in the regulation of oocyte and preimplantation embryo development. In mice and pigs, in vitro leptin addition significantly increased meiotic resumption and promoted preimplantation embryo development in a dose-dependent manner. This study was conducted to determine whether leptin supplementation during in vitro maturation (IVM) to horse oocytes could have effects on their developmental capacity after fertilization by IntraCytoplasmic Sperm Injection (ICSI).


METHODS
Compact and expanded-cumulus horse oocytes were matured in medium containing different concentrations (1, 10, 100, 1000 ng/ml) of recombinant human leptin and the effects on maturation, fertilization and embryo cleavage were evaluated. Furthermore, early developmental expression of Ob and leptin receptor (Ob-R) was investigated by immunocytochemical staining.


RESULTS
In expanded-cumulus oocytes, the addition of leptin in IVM medium improved maturation (74% vs 44%, for 100 ng/ml leptin-treated and control groups, respectively; P < 0.05) and fertilization after ICSI (56% vs 23% for 10 ng/ml leptin-treated and control groups, respectively; P < 0.05). However, the developmental rate and quality of 8-cell stage embryos derived from leptin-treated oocytes (100 ng/ml) was significantly reduced, in contrast to previous data in other species where leptin increased embryo cleavage. Ob and Ob-R proteins were detected up to the 8-cell stage with cortical and cytoplasmic granule-like distribution pattern in each blastomere.


CONCLUSIONS
Leptin plays a cumulus cell-mediated role in the regulation of oocyte maturation in the mare. Species-specific differences may exist in oocyte sensitivity to leptin.
Lange Consiglio
Anna
A
Università degli Studi di Milano, Reproduction Unit, Large Animal Hospital, Faculty of Veterinary Medicine, Via dell'Università 6,-26900 Lodi, Italy. anna.langeconsiglio@unimi.it
Dell'Aquila
Maria Elena
ME
Fiandanese
Nadia
N
Ambruosi
Barbara
B
Cho
Yoon S
YS
Bosi
Giampaolo
G
Arrighi
Silvana
S
Lacalandra
Giovanni M
GM
Cremonesi
Fausto
F
D000818:Animals; D002478:Cells, Cultured; D002970:Cleavage Stage, Ovum / Q000166:cytology / Q000187:drug effects*; D004622:Embryo, Mammalian; D047108:Embryonic Development / Q000187:drug effects*; D005260:Female; D005306:Fertilization / Q000187:drug effects*; D006736:Horses / Q000378:metabolism / Q000502:physiology; D020738:Leptin / Q000378:metabolism* / Q000494:pharmacology*; D008297:Male; D009866:Oogenesis / Q000187:drug effects*; D011786:Quality Control; D054411:Receptors, Leptin / Q000378:metabolism*; D020554:Sperm Injections, Intracytoplasmic
D020738:Leptin; D054411:Receptors, Leptin