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Öğe Effects of Peripheral Administration of Kisspeptin on Pubertal Maturation and Serum Leptin Levels in Female Rats(Ortadogu Ad Pres & Publ Co, 2011) Alcin, Ergul; Ozcan, Mete; Ayar, Ahmet; Yilmaz, Bayram; Turkoz, Yusuf; Kelestimur, HalukObjective: The aim of this study was to investigate the effects of exogenous kisspeptin on pubertal maturation in immature female rats. Material and Methods: Wistar female rats were weaned when they were 21 days old. The rats were divided into two groups. Controls (n=10) received saline only (1 ml/kg). Experimental rats (n=9) were intraperitoneally injected with daily 100 nmol kisspeptin-10 between 09.00h-10.00h a.m. starting from the day 26. Body weight and food intake were daily determined, and vaginal opening (VO) was daily monitored starting from day 26. The animals were decapitated when the first diestrus was determined by vaginal smears. Upon decapitation, serum was separated and stored at -20 degrees C until measurement of leptin, luteinizing hormone (LH) and estradiol. Uterus and ovaries were dissected out and weighed. Results: Intraperitoneal injection of 100 nmol kisspeptin-10 did not change median VO ages. There were no differences in food intake, and percentages of body weight change, between control and kisspeptin groups during the experimental period. Kisspeptin administration elicited significant (P<0.01) increases in uterus weight over control values. Serum leptin levels were significantly lower (P<0.05) in kisspeptin-treated group compared to vehicle group. Kisspeptin administration increased (P<0.05) serum LH and estradiol levels. Conclusion: Chronic peripheral administration of kisspeptin-10 does not advance puberty onset as estimated from the date of vaginal opening, but potentiates other conventional indices of maturation of reproductive axis such as elevated uterine weight and increased serum levels of LH and estradiol.Öğe Kisspeptin-10 elicits triphasic cytosolic calcium responses in immortalized GT1-7 GnRH neurones(Elsevier Ireland Ltd, 2011) Ozcan, Mete; Alcin, Ergul; Ayar, Ahmet; Yilmaz, Bayram; Sandal, Suleyman; Kelestimur, HalukKisspeptins, which are alternatively called as metastin since they were originally identified as products of metastasis suppressor gene KiSS-1, are the natural ligands for the G protein-coupled receptor 54 (GPR54). Kisspeptins are the most potent activators of hypothalamic-pituitary-gonadal (HPG) axis reported to date. The pulsatile pattern of GnRH release, which results in the intermittent release of gonadotropic hormones from the pituitary, has a critical importance for reproductive function but the factors responsible from this release pattern are not known. Therefore, the pattern of kisspeptin-induced intracellular signaling and the role of PKC in the intracellular signaling cascade were investigated by fluorescence calcium imaging using the immortalized GnRH-secreting GT1-7 hypothalamic neurons. Kisspeptin-10 caused a triphasic change characterized by an initial small increase followed by a significant decrease and increase in intracellular free calcium concentrations ([Ca2+](i)). The changes in [Ca2+](i) were significantly attenuated by pre-treatment with protein kinase C inhibitor. The compatibility of appeared mirrored-patterns of kisspeptin-10-induced changes in [Ca2+](i) concentrations in these neurons and GnRH secretion confirm the importance of intracellular calcium flux downstream from GPR54 through PKC signaling pathway. (C) 2011 Elsevier Ireland Ltd. All rights reserved.Öğe Melatonin elicits protein kinase C-mediated calcium response in immortalized GT1-7 GnRH neurons(Elsevier Science Bv, 2012) Kelestimur, Haluk; Ozcan, Mete; Kacar, Emine; Alcin, Ergul; Yilmaz, Bayram; Ayar, AhmetMelatonin is suggested to have effects on hypothalamic-pituitary-gonadal (HPG) axis. The pulsatile pattern of GnRH release, which results in the intermittent release of gonadotropic hormones from the pituitary, has a critical importance for reproductive function but the factors responsible from this release pattern are not known. Calcium is a second messenger involved in hormone release. Therefore, investigation of the effects of melatonin on intracellular free calcium levels ([Ca2+](i)) would provide critical information on hormone release in immortalized GnRH neurons. The pattern of melatonin-induced intracellular calcium signaling was investigated by fluorescence calcium imaging using the immortalized GnRH-secreting GT1-7 hypothalamic neurons. Melatonin caused a significant increase in [Ca2+](i), which was greatly blocked by luzindole, a melatonin antagonist, or attenuated by pre-treatment with protein kinase C inhibitor. This study suggests that melatonin seems to have a direct effect on GnRH neurons. (C) 2011 Elsevier B.V. All rights reserved.Öğe Oxytocin activates calcium signaling in rat sensory neurons through a protein kinase C-dependent mechanism(Springer, 2014) Ayar, Ahmet; Ozcan, Mete; Alcin, Ergul; Serhatlioglu, Ihsan; Ozcan, Sibel; Kutlu, Selim; Kelestimur, HalukIn addition to its well-known effects on parturition and lactation, oxytocin (OT) plays an important role in modulation of pain and nociceptive transmission. But, the mechanism of this effect is unclear. To address the possible role of OT on pain modulation at the peripheral level, the effects of OT on intracellular calcium levels ([Ca2+](i)) in rat dorsal root ganglion (DRG) neurons were investigated by using an in vitro calcium imaging system. DRG neurons were grown in primary culture following enzymatic and mechanical dissociation of ganglia from 1- or 2-day-old neonatal Wistar rats. Using the fura-2-based calcium imaging technique, the effects of OT on [Ca2+](i) and role of the protein kinase C (PKC)-mediated pathway in OT effect were assessed. OT caused a significant increase in basal levels of [Ca2+](i) after application at the doses of 30 nM (n=34, p<0.01), 100 nM (n=41, p<0.001) and 300 nM (n=46, p<0.001). The stimulatory effect of OT (300 nM) on [Ca2+](i) was persistent in Ca2+-free conditions (n=56, p<0.01). Chelerythrine chloride, a PKC inhibitor, significantly reduced the OT-induced increase in [Ca2+](i) (n=28, p<0.001). We demonstrated that OT activates intracellular calcium signaling in cultured rat primary sensory neurons in a dose-and PKC-dependent mechanism. The finding of the role of OT in peripheral pain modification may serve as a novel target for the development of new pharmacological strategies for the management of pain.Öğe Yeni Bir Antidepresan Olan Agomelatinin Periferal Nosisepsiyon Üzerindeki Etkinliğinin İn Vivo ve İn Vitro Yöntemlerle Araştırılması(2018) Özcan, Mete; Sandal, Süleyman; Önal, Selami Ateş; Canpolat, Sinan; Ayar, AhmetYasam kalitesini önemli ölçüde kısıtlayan nöropatik agrı, bunun yanısıra depresyon, anksiyete ve uyku bozuklukları gibi hastaların ruh hali üzerinde de ciddi yan etkilere sahiptir. Nöropatik agrı tedavisi trisiklik antidepresanlar, serotonin ve noradrenalin geri alım inhibitörleri, pregabalin ve gabapentin ilk seçenek olarak karsımıza çıkmaktadır. Opioidler ve nonstreoidal anti inflamatuvar ilaçlar tedavi için ikinci basamakta yer almaktadır. Yeni bir antidepresan olan ve yüksek afiniteli melatonin reseptör agonisti ve düsük duyarlılıklı serotonin reseptör antagonisti olma özelligine sahip agomelatinin akut ve artmıs agrı duyarlılıgında rol oynayan mekanizmalar üzerine etkinligi bu proje ile farklı yöntemlerle irdelendi. Agomelatinin, intak ve diyabetle indüklenmis nöropatik agrı üzerine etkinligi tek basına ve morfin ile kombine kullanımında incelendi. Aynı zamanda agomelatinin periferal nosiseptif iletim üzerine muhtemel rolü, agrının hücresel modeli olan dorsal kök gangliyonu (DKG) nöronlarında kalsiyum sinyallesmesi ve hücre canlılıgı incelenerek belirlendi. Agomelatin tek basına uygulamasının agrı davranısını azaltıcı etkiye sahip oldugu ve 15 gün boyunca günde iki defa morfin uygulaması ile olusan toleransı ortadan kaldırdıgı belirlendi. Agrı belirteci ve alakalı moleküllerden N-methil-D-Aspartat Reseptor NR1 Alt Ünitesi (GRIN1R), Transient Reseptor Potansiyel Vaniloid (TRPV1), Interlukin 1? (IL-1?) ve nörokinin 1 reseptörü (NK1/ TACR1) mRNA seviyelerini, agomelatinin kısa süreli (akut) ve uzun süreli (kronik) uygulamasının rafe nukleus, periaduktal gri bölge, amigdala ve nukleus akkumbens?de saglıklı ve diyabetik farelerde etkiledigi belirlendi. Aynı zamanda agomelatinin DKG nöronlarında kalsiyum sinyallesmesini etkiledigi ve hücre canlılıgı arttırdıgı tespit edildi. Tüm bu bulgular agomelatinin agrı dindirici özellige sahip oldugu ve morfin toleransını engelledigini göstermektedir.
