Browsing by Author "Aktar, A."

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Effect of GnRH and hCG treatment following a short-term estrus synchronization protocol on ovulation and the fertility in merino ewes, during the breeding season
(Hellenic Veterinary Medical Soc, 2023-10-01) Doğan, I.; Toker, M. B.; Aktar, A.; Yılmaz, M. M.; DOĞAN, İBRAHİM; TOKER, MEHMED BERK; Menekşe Yılmaz, Mine; Aktar, A.; Bursa Uludağ Üniversitesi/Veteriner Fakültesi/Döllenme ve Suni Tohumlama Anabilim Dalı.; 0000-0003-1976-1814; 0000-0002-9242-8447; A-2794-2014; R-8366-2018; AAG-6393-2020; ELR-5822-2022
This study aimed to compare the effect of hCG or GnRH administered 36 h following a short-term estrus synchronization treatment on the ovulation time and pregnancy rates of Merino ewes during the breeding season. The estrus cycles of ewes were synchronized with an intravaginal sponge containing 60 mg of medroxyprogesterone acetate for 6 days, and an injection of 400 IU of eCG and 125 mu g of d-cloprostenol 24 h before sponge removal. Thirty-six h after the sponge removal, ewes were injected intramuscularly either 1 ml of physiological saline solution (control-group; n=14), 100 IU of hCG (hCG-group; n=14) or 0.004 mg of buserelin acetate (GnRH-group; n=14). The estrus behavior was observed using teaser rams and the ovulation time was monitored using transrectal ultrasonography twice daily for 96 h after the sponge removal. Ewes in estrus were allowed a single mating using fertile rams. Estrus response was higher (P<0.05) in the control group (92.86%) than in the GnRH group (50.00%). The interval from sponge removal to ovulation and from hCG to ovulation were shorterin the control group than in the hCG group(70.55, 80.83 h; 34.55, 44.83 h, respectively, P<0.05). In conclusion, administration of hCG or GnRH at 36 h following a short-term estrus synchronization protocol did not affect estrus behavior, ovarian findings and pregnancy rate in ewes during the breeding season.
Vincristine-associated total antioxidant and oxidant status of ovaries and in vitro nuclear oocyte maturation in dogs with canine transmissible venereal tumor
(Elsevier, 2023-05-15) Avcı, G.; Denk, B.; Aktar, A.; Özalp, G. R.; Üstüner, B.; Bari, O.; Yılmaz, Mehmet Melih; Bursa Uludağ Üniversitesi/Veteriner Fakültesi.; 0000-0001-6050-791X; AAE-3607-2019
The aim of this study is to evaluate the effects of scheduled vincristine sulfate therapy on canine oocyte quality and nuclear oocyte maturation, associated with total antioxidant and oxidant status of ovaries and Anti-Mullerian Hormone (AMH) concentrations in dogs with Canine Transmissible Venereal Tumor (CTVT). Six bitches suffering from CTVT and six healthy bitches were included in the study. Hemogram was carried out weekly. AMH measurements and ovariohysterectomy operations were performed after the termination of vincristine sulfate therapies. Tissue samples from ovaries were utilized for Malondialdehyde (MDA), reduced Glutathione (GSH), Superoxide Dismutase (SOD), Total Anti-oxidative Status (TAS), Total Oxidative Status (TOS) measurements, and Oxidative Stress Index (OSI) was calculated. Collected oocytes were evaluated for meiotic competence, after In Vitro Maturation (IVM) and parthenogenetic activation. No difference between the two groups was observed in hematologic parameters (P > 0.05). Meiotic stages of Germinal Vesicle Break Down (GVBD), Metaphase I (MI), and Metaphase II (MII) were significantly different between groups (P < 0.05). The number of oocytes reaching MII and meiotic resumption was lower in the CTVT group. Furthermore, AMH concentrations, oxidant parameters (OSI, TOS, and MDA), and antioxidant parameters (GSH, SOD, and TAS) were also statistically different between groups (P < 0.05).The results of this study show that vincristine sulfate application in the treatment of CTVT could alter oxidant/antioxidant status in ovaries. Apart from these, oocyte quality and IVM rates seem to decline related to gonadotoxicity. Moreover, AMH could be an important marker in the evaluation of oocyte qualities in bitches, as it is in women.