Browsing by Author "Toker, Mehmed Berk"

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Brain thromboxane A2 via arachidonic acid cascade induces the hypothalamic-pituitary-gonadal axis activation in rats
(Elsevier, 2015-05) Erkan, Leman G.; Altınbaş, Burçin; Güvenç, Gökçen; Alçay, Selim; Toker, Mehmed Berk; Üstüner, Burcu; Küçükşen, Duygu Udum; Yalçın, Murat; Uludağ Üniversitesi/Veteriner Fakültesi/Fizyoloji Anabilim Dalı.; Uludağ Üniversitesi/Veteriner Fakültesi/Dölerme ve Suni Tohumlama Anabilim Dalı.; Uludağ Üniversitesi/Veteriner Fakültesi/Biyokimya Anabilim Dalı.; 0000-0002-9534-736X; 0000-0002-1413-3651; 0000-0002-2472-8157; 0000-0003-4033-9749; 0000-0001-7052-1694; 0000-0002-5600-8162; CNS-3398-2022; IYS-2646-2023; AAR-6815-2021; CBC-7350-2022; A-2794-2014; AAG-7238-2021; FGX-3813-2022; AAG-6956-2021; 56529371200; 55356919300; 56529426800; 56099810300; 56480349200; 18937724600; 31967936400; 57192959734
The current study was designed to determine the effect of centrally administrated arachidonic acid (AA) on plasma gonadotropin hormone-releasing hormone (GnRH), follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone level, and sperm parameters, and to show the mediation of the central cyclooxygenase (COX) to thromboxane A(2) (TXA(2)) signaling pathway in AA-induced hormonal and sperm parameter effects. Studies were performed in male Sprague-Dawley rats. A total of 150 or 300 mu l/5 mu l doses of AA were injected intracerebroventricularly (icv). AA significantly caused dose- and time-dependent increases in plasma FSH, LH and testosterone levels of animals, but not plasma GnRH level. AA also significantly increased sperm motility of the rats without change sperm number. Pretreated with ibuprofen, a nonselective COX inhibitor (250 mu g/5 mu l; icv), and furegrelate, a TXA(2) synthesis inhibitor (250 mu g/5 mu l; icv), prevented AA-evoked increase in plasma FSH, LH and testosterone levels, and sperm motility. In conclusion, our findings show that centrally administered AA increases plasma FSH, LH and testosterone levels and sperm motility of conscious male rats. Moreover, according to our findings, central COX-TXA(2) signaling pathway mediates these AA-induced effects.
Comparison and assessment of ovarian follicular dynamics during the breeding and non-breeding season in saanen goats
(B W K Publishing Solutions & Verlag, 2020-01-01) Dogan, İbrahim; DOĞAN, İBRAHİM; Toker, Mehmed Berk; TOKER, MEHMED BERK; Alcay, Selim; ALÇAY, SELİM; Küçüksen, D. Udum; Bursa Uludağ Üniversitesi/Veteriner Fakültesi/Biyokimya Bölümü.; 0000-0003-1976-1814; A-2794-2014; R-8366-2018
We describe and compare the ovarian follicular dynamics and plasma progesterone concentrations in nulliparous Saanen does during the breeding and non-breeding seasons. Does were monitored daily using transrectal ovarian ultrasonography for a full oestrous cycle in the breeding (n = 19) and a 21-day period in the non-breeding season (n = 20). At two-day intervals, blood samples were taken to determine plasma progesterone by ELISA. The pattern of follicular growth was characterised by four and five follicular waves in both seasons. Although the number of follicular waves was similar in the two seasons, the number of codominant follicles (p=0.027), the diameter of the largest follicle of waves 1 (p=0.036) and 4 (p=0.031), the duration of waves 3 (p=0.029) and 4 (p=0.034), the diameter of the largest follicle (p=0.042), the sums of the durations of all waves (p=0.037), the interwave interval (p=0.026) and the follicle growth rate (p=0.044) were higher in the breeding than in the non-breeding season. In addition, the numbers of small, medium and large follicles and the total number of all follicles of all waves differed between the seasons (p=0.037). In the breeding season, we found significant differences between the waves in the diameter of the largest follicles (p=0.042) and the duration of the waves (p=0.037); in the non-breeding season, no significant differences were found. Ovulatory follicles were most common in the fifth follicle wave. In the breeding season, the mean inter-oestrus and inter-ovulatory intervals and the numbers of ovulations after a synchronized oestrus with PGF2a were 21.47 +/- 0.19 days, 20.47 +/- 0.19 days and 1.84 +/- 0.86. The results indicate that follicular growth in Saanen goats during the breeding and non-breeding season is characterised by a wave-like pattern that differs between seasons.
Comprehensive effects of fetal calf serum in soybean-lecithin based goat semen cryopreservation extenders and impacts on incubation resilience
(Kafkas Univ, Veteriner Fakultesi Dergisi, 2022-06-24) Toker, Mehmed Berk; TOKER, MEHMED BERK; Alcay, Selim; ALÇAY, SELİM; Bursa Uludağ Üniversitesi/Veteriner Fakültesi.; A-2794-2014
The aim of this study was to investigate the effects of various fetal calf serum (FCS) doses on %1 soybean lecithin-based semen extenders for goat semen cryopreservation and the impacts on spermatological parameters over post-thaw and post-incubation (6 h) time periods. Sperm samples collected via electro-ejaculation method were pooled to overcome the individual differences and were used in the study. The samples then were split into four equal aliquots to create study groups as; 0.25%, 0.50%, 0.75% FCS supplemented and a sample of FCS-free control group. Each sample group was diluted to approximately 150 x 106 spermatozoon/mL final concentration and two step dilution method was used for cryopreservation. Study groups were examined for sperm motility, plasma membrane functional integrity with hypoosmotic swelling test (HOST), acrosome integrity by FITC-Pisum sativum agglutinin (PSA-FITC) and DNA damage by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay (TUNEL). All samples were incubated for further 6 h in a humidified air chamber with 5% CO2 at 39 degrees C. The results indicated that FCS supplementation in soybean lecithin-based extenders for goat sperm cryopreservation had significant effects on post-thawing time point motility (P < 0.05), plasma membrane integrity (P < 0.05) and acrosomal integrity (P < 0.05) parameters. Subsequently to 6 h of incubation period, DNA integrity results yielded better scores comparing to control group in addition with other spermatological parameters (P < 0.05).
Drone semen cryopreservation with protein supplemented tl-hepes based extender
(Kafkas Univ, Veteriner Fakultesi Dergisi, 2019-07-01) Alcay, Selim; ALÇAY, SELİM; Çakmak, Selvinar; Çakmak, İbrahim; ÇAKMAK, İBRAHİM; Mülkpınar, Emine; Toker, Mehmed Berk; TOKER, MEHMED BERK; Üstüner, Burcu; ÜSTÜNER, BURCU; Şen, Hasan; Nur, Zekariya; NUR, ZEKARİYA; Bursa Uludağ Üniversitesi/Veteriner Fakültesi; 0000-0002-1438-221X; AAH-2635-2021; AAH-2558-2021; AAG-7238-2021; A-2794-2014
The aim of the current study was to determine the optimum concentration of bovine serum albumin for post-thawing quality of drone sperm and this is the first study to evaluate the effect of BSA supplemented TL-Hepes based extenders for drone semen cryopreservation. Sexually mature drones were used for semen collection. Pooled semen was diluted with TL-Hepes based extender supplemented with different concentrations of BSA (1 mg/mL, 3 mg/mL, and 5 mg/mL) or without BSA (control), at a final concentration of 100x10(6) spermatozoon/mL. Motility, plasma membrane functional integrity (HOST), and defected acrosome (PSA-FITC) were evaluated in the study. At post thaw, the highest sperm motility rates were obtained in the BSA5 group (P< 0.05). Functional integrity of sperm membrane was better preserved in the BSA3 and BSA5 groups compared to the other groups. The acrosomal integrity rates were higher in BSA5 group than in control group (P< 0.05). The study shows that bovine serum albumin supplemented TL-Hepes based extenders have beneficial effect on drone semen parameters at post-thaw. The results of the study demonstrated a notable advantage of using 5 mg/mL of BSA in TL-Hepes based extender.
Effect of gnrh treatment following a short-term estrous induction protocol on estrus and ovulation in saanen goats, during the transitional period
(Hellenic Veterinary Medical Soc, 2020-10-01) Doğan, İbrahim; DOĞAN, İBRAHİM; Toker, Mehmed Berk; TOKER, MEHMED BERK; Alcay, Selim; ALÇAY, SELİM; Küçüksen, Duygu Udum; Bursa Uludağ Üniversitesi/Veteriner Fakültesi/Biyokimya Anabilim Dalı.; 0000-0003-1976-1814; R-8366-2018; A-2794-2014
The objective of this study was to compare the effect on the ovulation time and estrus parameters of a GnRH agonist (buserelin acetate) administered 24 or 36 h following a short-term estrus induction and synchronization treatment in non-lactating Saanen goats during the transitional period. Goats received 20 mg FGA sponges for 6 days plus 300 IU eCG and 125 mu g d-cloprostenol 24 h prior to sponge removal. After removal of the sponges, goats were given either 1 ml physiological saline (0.9% NaCI) solution (Group 1; n = 9) after 12 h, 0.004 mg GnRH (Group 2; n = 10) after 24 h or 0.004 mg GnRH (Group 3; n = 10) after 36 h. The follicle development and ovulation in the ovaries were monitored by transrectal ultrasonography starting from the sponge application until the fifth day of the estrus cycle. Blood samples were collected on the same days to determine the plasma concentrations of progesterone (P-4) and estradiol (E-2). No statistical differences among groups were detected in any synchronization parameters, ultrasonic evaluations and plasma P-4 and E-2 concentrations. The evaluation of pooled data showed that the response of Saanen goats to treatments was comparable to the results of other published trials. Results of this study indicate that administration of GnRH at 24 h or 36 h after sponge removal, at the end of a short estrus induction and synchronization protocol, does not affect plasma P-4 and E-2 concentrations, estrus parameters and ovulation time in goats, during the transition period.
The effects of dietary restriction and administration of β-glucan from Euglena gracilis on the sperm characteristics and reproductive organs of rats
(Wiley, 2018) Sonat, Füsün Ak; Alçay, Selim; Toker, Mehmed Berk; Peker, Sabire; Üstüner, Burcu; Uludağ Üniversitesi/Veteriner Fakültesi/Fizyoloji Anabilim Dalı.; Uludağ Üniversitesi/Veteriner Fakültesi/Üreme ve Suni Tohumlama Anabilim Dalı.; Uludağ Üniversitesi/Veteriner Fakültesi/Histoloji ve Embriyoloji Anabilim Dalı.; 0000-0003-4033-9749; AAG-7238-2021; A-2794-2014; 35219544300; 56099810300; 56480349200; 55109615900; 18937724600
The aim of this study was to demonstrate the possible individual and/or synergistic effects of -glucan and dietary restrictions on the reproductive parameters of rats. For this purpose, forty male Sprague-Dawley rats were randomly divided into four equal groups (n=10 per group). The first group was the control, the second group was kept under dietary restriction (DR), the third group was kept under a dietary restriction and given -glucan (DR+G) and the fourth group was supplemented only with -glucan (G; 20mg/kg) intragastrically for 14days. Motility, vitality and morphology of spermatozoa, reproductive organ weights (testis, vesicula seminalis and epididymis) and seminiferous tubule diameters were evaluated in experimental rats. -glucan had excellent effects on motility, live spermatozoa rate and the acrosome integrity when compared to the control group (p<0.05). We also observed that -glucan administration to rats having dietary restriction could improve sperm motility and acrosome integrity (p<0.05). While the -glucan improved seminiferous tubule diameter (p<0.05), weights of the reproductive organs did not change positively as a result. This study demonstrated that -glucan treatment significantly improved some spermatological characteristics in rats. Therefore, treatment with -glucan could be used for its positive effects on motility, spermatozoa vitality rate and acrosome integrity for infertile men.
Intracerebroventricular injection of histamine induces the hypothalamic-pituitary-gonadal axis activation in male rats
(Elsevier, 2018-11-15) Niaz, Nasir; Güvenç, Gökçen; Altınbaş, Burçin; Toker, Mehmed Berk; Aydın, Begüm; Udum, Duygu Küçükşen; Alçay, Selim; Gökçe, Elif; Üstüner, Burcu; Yalçın, Murat; Uludağ Üniversitesi/Veteriner Fakültesi/Fizyoloji Anabilim Dalı.; Uludağ Üniversitesi/Veteriner Fakültesi/Üreme ve Suni Tohumlama Anabilim Dalı.; Uludağ Üniversitesi/Veteriner Fakültesi/Biyokimya Anabilim Dalı.; 0000-0002-9534-736X; 0000-0002-7678-3289; 0000-0003-4033-9749; 0000-0002-5600-8162; AAR-6815-2021; IYS-2646-2023; ABA-6294-2020; A-2794-2014; AAC-4975-2022; AAG-6956-2021; AAG-7238-2021; 57060367600; 56529426800; 55356919300; 56780223500; 57194022849; 31967936400; 56099810300; 56779799700; 18937724600; 57192959734
Brain histamine holds a key position in the regulation of behavioral states, biological rhythms, body weight, energy metabolism, thermoregulation, fluid balance, stress and reproduction in female animals. However, it is not clear whether central histamine exerts any effect on hypothalamic-pituitary-testicular in male rats and if so, the involvement of type of central histamine receptors. The current study was designed to determine the effect of centrally administrated histamine on plasma gonadotropin hormone-releasing hormone (GnRH), luteinizing hormone (LH), follicle stimulating hormone (FSH) and testosterone level, and sperm parameters, and to show the mediation of the central histaminergic H1, H2 and H3/H4 receptors on histamine-evoked hormonal and sperm parameters' effects. Studies were performed in male Sprague-Dawley rats. A total of 50 or 100 nmol doses of histamine were injected intracerebroventricularly (icy). 100 nmol dose of histamine significantly caused increases in plasma GnRH, LH, FSH and testosterone levels of animals, but not 50 nmol dose of histamine. Moreover, central pretreatment with chlorpheniramine, histaminergic H1 receptor antagonist (100 nmol), ranitidine and histaminergic H2 receptor antagonist (100 nmol) completely prevented histamine evoked increase in plasma GnRH, LH, FSH and testosterone levels, while thioperamide, histaminergic H3/H4 receptor antagonist (100 nmol) pretreatment failed to reverse sex hormones responses to histamine. Both central histamine treatment alone and central histamine treatment after central histaminergic receptors antagonists' pretreatments did not alter any sperm parameters in rats. In conclusion, our findings show that centrally administered histamine increases plasma GnRH, LH, FSH and testosterone levels of conscious male rats without change any sperm parameters. Moreover, according to our findings, central histaminergic H1, and H2 receptors mediate these histamine-induced effects.
Long term incubation resilience of post-thaw ram semen diluted with lecithin-based extender supplemented with bovine serum albumin
(Kafkas Üniversitesi, 2019-05) Gökçe, Elif; Alçay, Selim; Toker, Mehmed Berk; Önder, N. Tekin; Üstüner, Burcu; Nur, Zekariya; Uludağ Üniversitesi/Veteriner Fakültesi/Dölerme ve Suni Tohumlama Anabilim Dalı; 0000-0001-5141-0008; 0000-0002-1438-221X; 0000-0003-4033-9749; JJQ-9411-2023; A-2794-2014; JAC-3152-2023; AAG-7238-2021; AH-2635-2021; 56099810300; 56480349200; 55670728900; 18937724600; 6508060684
The objective of the study was to determine the optimum concentration of BSA in lecithin-based extender for post-thawing quality and incubation resilience (0 h, 6 h and 10 h) of ram sperm. Ejaculates were collected from five rams via electro ejaculation. Ejaculates were mixed to obtain pooled semen.Then, pooled semen was diluted with soybean lecithin-based extender without BSA (control) or supplemented with different concentrations of BSA (2.5 mg/mL, 5 mg/mL, 7.5 mg/mL and 10 mg/mL), at a final concentration of 150x106 spermatozoon/mL. Sperm motility, plasma membrane functional integrity (HOST), mitochondrial activity (rhodamine123), capacitation status (CTC), and DNA integrity (TUNEL) were evaluated. At the 10 h incubation, motility, plasma membrane functional integrity and mitochondria! function were better preserved in the BSA5 group compared to the control group. It was determined that high doses of BSA (5 mg/mL, 7.5 mg/mL and 10 mg/mL) affected acrosome reaction.The highest acrosome reaction rates were obtained in BSA10 groups in 6 h and 10 h incubation (P<0.05). TUNEL assay demonstrated that there were no differences among groups for DNA fragmentation at post-thaw and during incubation periods. The study shows that BSA supplemented extenders may have beneficial effect on ram semen parameters at 0 h, 6 h and 10 h of incubation. The results of the present study demonstrated a remarkable advantage of using 5 mg/mL of BSA in 1% lecithin-based extender.
Methionine, cysteine ve BHT ilave edilmiş TRIS-yumurta sarısı ile dondurulan koç spermasının IN-vitro olarak değerlendirilmesi
(Bursa Uludağ Üniversitesi, 2018-12-21) Toker, Mehmed Berk; Doğan, İbrahim; Bursa Uludağ Üniversitesi/Sağlık Bilimleri Enstitüsü/Dölerme ve Suni Tohumlama Anabilim Dalı.
Bu çalışmada TRIS-sitrik asit yumurta sarısı (%20) temel sulandırıcısına 2,5mM, 5mM metiyonin, 1mM, 2mM sistein, 1mM, 2mM bütil hidroksitolüen (BHT) eklenerek sulandırılan ve dondurulan koç spermasında çözüm sonrası bazı spermatolojik parametreler üzerine antioksidanların etkileri ve karşılaştırılması amaçlandı. Sperma, beş baş Kıvırcık ırkı koçtan üreme sezonunda, elektro-ejakülatör ile haftada iki kez alındı ve birleştirildi. Pooling sonrası ortalama hacim (ml), motilite (%), yoğunluk (x109/ml), plazma membran bütünlüğü (HOST, %), akrozomal (%), diğer morfolojik (%) ve toplam morfolojik (%) bozukluk oranları sırasıyla 3,92, 84,0, 1,96, 93,8, 5,60, 0,4 ve 6,0 bulundu. Sulandırılan sperma örnekleri bir saat içinde 5ºC'a indirildi ve %6 gliserol eklendikten sonra iki saat boyunca ekilibrasyona tabi tutuldu. Sperma, payette (0,25ml) 200x106 spermatozoon olacak şekilde çekildi ve dondurma cihazıyla dondurularak (-120 oC) analize kadar sıvı azotun içinde saklandı. Çözdürme sonrası motilite, HOST, akrozomal bozukluk, diğer ve toplam morfolojik bozukluk muayeneleri yapıldı. Motilite ve HOST oranları, kontrol ile tüm antioksidan grupları arasında fark (P<0,05) ve pozitif korelasyon tespit edildi (r=0,880). Akrozomal bozukluk oranlarında kontrol ile 2,5mM, 5mM metiyonin ve 1mM, 2mM sistein grupları arasında fark saptandı (P<0,05). Ayrıca metiyonin ve sistein grupları kendi dozları arasında da farklıydı (P<0,05). Diğer morfolojik bozukluk oranlarında ise fark yalnızca 1mM sistein ile 2mM BHT grupları arasında tespit edildi (P<0,05). Toplam morfolojik bozukluk oranlarında ise 1mM, 2mM BHT ve 1mM sistein grupları hariç, kontrol ve diğer deneme grupları arasında fark görüldü (P<0,05). Sonuç olarak, koç sperma sulandırıcısına çeşitli dozlarda eklenen antioksidanların çözüm sonrası incelenen spermatolojik parametreler üzerine koruyucu etkilerde bulunduğu kanaatine varıldı.
Methionine, cysteine, and butylated hydroxytoluene enhance cryosurvival of ram semen on post-thaw and post-incubation time points
(Springer, 2023-06-01) Toker, Mehmed Berk; Doğan, İbrahim; TOKER, MEHMED BERK; DOĞAN, İBRAHİM; Bursa Uludağ Üniversitesi/Veteriner Fakültesi/Üreme ve Suni Tohumlama Anabilim Dalı; 0000-0003-1976-1814; 0000-0003-4033-9749; A-2794-2014; R-8366-2018
Despite there have been many experiments conducted about antioxidants, the best sole or combination use of antioxidants to include as a standard ingredient to freezing extenders is yet to be found. This study was designed to investigate the different doses of methionine (2.5 and 5 mM), cysteine (1 and 2 mM), and butylated hydroxytoluene (BHT) (1 and 2 mM) for ram semen cryopreservation on post-thaw and post-incubation (6 h) time points over spermatological parameters. Semen samples were collected from Kivircik rams via electro-ejaculator in breeding season. After essential spermatological evaluations, appropriate samples were pooled then split into 7 equal aliquots to create study groups (antioxidant free control, 2.5 mM methionine, 5 mM methionine, 1 mM cysteine, 2 mM cysteine, 1 mM BHT, and 2 mM BHT). Semen samples were put into French straws (0.25 mL), and freezing procedure (two-step) was conducted via a programmable gamete freezer. At both time points, motility, HOST, PSA-FITC, and TUNEL assays were made to discover the impacts of cryopreservation and incubation process over sperm cells. Antioxidant supplemented groups yielded better results compared to the control groups in terms of various spermatological parameters not only at post-thaw time point but after incubation for 6 h of time. The study demonstrated that supplementing sperm freezing extenders with previous antioxidants may create new approaches to cryopreservation procedures, and through increasing success rate of freezing, fertility results may increase to better results in near future.
Ovarian follicle dynamics and hormonal changes during early pregnancy in saanen goats
(Czech Academy Agricultural Sciences, 2020-01-01) Doğan, İbrahim; Toker, Mehmed Berk; Alcay, Selim; Küçükşen, Duygu Udum; DOĞAN, İBRAHİM; TOKER, MEHMED BERK; ALÇAY, SELİM; UDUM, DUYGU; 0000-0003-1976-1814; 0000-0003-4033-9749; A-2794-2014; R-8366-2018; CBC-7350-2022; FGX-3813-2022
This study is aimed at describing the ovarian follicular dynamics, corpora lutea and their hormonal control during early pregnancy in Saanen goats. The ovaries of pregnant goats (n = 10) were monitored daily for follicles (>= 2 mm) and corpora lutea by transrectal ultrasound over the 35 days after mating. Blood samples were collected by jugular venipuncture at the time of ultrasonography and were analysed for the concentrations of oestradiol (E-2) and progesterone (P-4), inhibin, FSH (follicle-stimulating hormone) and LH (luteinizing hormone). The pattern of follicular growth was characterised by five (n = 2; 20 %), six (n = 5; 50 %) and seven (n = 3; 30 %) follicular waves during early pregnancy. The first corpora lutea (size 6.8 +/- 0.4 mm, mean + SEM) were detected at 5.0 +/- 0.3 days after the mating with a maximum diameter (12.2 +/- 0.3 mm) observed on day 24.0 +/- 1.1 of pregnancy. The dominant follicle diameter of waves 1 and 4, and the duration of waves 1-4 and 7 were maximal during the early pregnancy period (P < 0.05). In addition, the inter-wave interval of the 5 waves was significantly (P < 0.05) longer compared to the six and seven inter-wave intervals (7.0 +/- 0.1, 5.8 +/- 0.1 and 5.0 +/- 0.2 days, respectively). Although the number of small and medium-sized follicles did not differ with the days post-breeding, the number of large-sized follicles in the same period significantly decreased between 16 and 26 days and was negatively correlated with the period of pregnancy (P < 0.05). The plasma LH and E-2 concentrations were negatively correlated with the P-4 concentration. The inhibin concentrations were negatively correlated with FSH, but positively correlated with the number of large-sized follicles. These results indicate that ovarian follicular growth during the first 35 days of pregnancy in goats was characterised by a wave-like pattern and there was a close relationship between the number of FSH peaks and the number of follicular waves.