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Öğe Daily rhythm in serum melatonin and leptin levels in the Syrian hamster (Mesocricetus auratus)(Elsevier Science Inc, 2002) Gündüz, BülentMelatonin is produced and secreted by the pineal gland in a rhythmic manner; circulating levels are high at night and low in the day. Leptin is a hormone secreted by adipocytes as a product of the obese gene and plays an important role in regulating body energy homeostasis and reproductive function in rodents and humans. The present study was conducted to examine daily fluctuations in serum levels of melatonin and leptin in Syrian hamster. We measured serum leptin and melatonin levels by ELISA in (a) intact and pinealectomized (pinx) male hamsters kept under long daylight conditions [14 h of light (14L)]; (b) intact and pinx hamsters under short daylight (10L); and (c) intact hamsters in constant light (24L). Blood samples were obtained every 2 h throughout a 24-h period. Statistically significant circadian variations were found in both melatonin and leptin profiles. Their relationship was inverse, i.e. when melatonin was high in the serum, leptin was comparably low. These results suggest that there is a rhythm in leptin levels in the adult male Syrian hamster and this rhythm is pineal gland (melatonin) and/or photoperiod dependent.Öğe Effect of different photoperiods on gonadal maintenance and development in mongolian gerbils (Meriones unguiculatus)(Zoological Soc Japan, 2002) Karakaş, Alper; Gündüz, BülentThe role of photoperiod in adult testicular maintenance and body weight and juvenile development was assessed in male Mongolian gerbils (Meriones unguiculatus). Gerbils were raised on a 14L (14 hr of light) photoperiod. In the first study, adult gerbils with functional testes were transferred to thirteen different photoperiods (0L, 2L, 4L, 6L, 8L, 10L, 12L, 14L, 16L, 18L, 20L, 22L, or 24L) and body weights and testicular size were measured every week for 10 weeks. Body weights were similar in all groups. Testicular regression had occurred in animals housed on 0L, 2L, 4L, 6L, 8L, and 24L by week 10. In the second study, 14L-born prepubertal gerbils were transferred to thirteen different photoperiods as in the first study. Body weights and testicular development were examined for 10 weeks. At the end of 10 weeks the body weights of animals in all groups except 24L were similar to those of adults. Animals in 24L had a lower body weight gain. Exposure to 0L, 2L, and 24L inhibited testicular development and testes weights were significantly different from those of the other groups. These results demonstrate that maintenance of body weight in adult gerbils appears to be independent of photoperiodic signal. Exposure to very long (24L) and short photoperiods (<10 hr) causes testicular regression in adult gerbils. Moreover, different photoperiods experienced in early life can influence prepubertal testis growth and body weight gain.Öğe The effect of pinealectomy and leptin hormone on the proliferation and apoptosis activation in Syrian hamster testis in different photoperiods(Wiley-Blackwell Publishing, Inc, 2009) Gündüz, Bülent; Karakaş, Alper; Terzi, Hakan; Öner, Jale; Serin, Erdinç; Kükner, AyselP>The effects of pinealectomy and leptin hormone on proliferative and apoptotic processes in the epithelia of testicular seminiferous tubules of Syrian hamsters have been investigated. Proliferative and apoptotic processes were assessed semi-quantitatively by proliferating cell nuclear antigen (PCNA) and caspase-3 immune stainings. Animals used in the study were divided into four groups; control, pinealectomy (PinX), leptin-treated (10 mu g/mL/day/kg body weight, intraperitoneally) and pinealectomy + leptin groups. Half of the hamsters in each group were exposed to short and the other half to long photoperiods for 8 weeks. In short photoperiod, PCNA activity especially in spermatogonia was significantly higher in the pinealectomy and leptin-treated groups compared with the control group. Histological score (HSCORE) value of PCNA in the PinX + leptin group was lower than those of PinX and leptin-treated groups. HSCORE value of caspase-3 in PinX and PinX + leptin groups was increased. In the long photoperiod, PCNA activation in the PinX group was significantly lower than the control group while the differences between the controls and other groups were not significant. The difference between the increases in caspase-3 activity in the PinX and control groups was significant. Thus, it was observed that photoperiods had no effect on the proliferation activity in the control groups. The inhibiting effect of short photoperiod on testis was not observed throughout 8 weeks. PinX eliminated the inhibiting effect of short photoperiod but did not alter the stimulating effect of long photoperiod. Leptin did not show any effect in long photoperiod but decreased proliferation by stimulating melatonin in short photoperiod.Öğe The effect of pinealectomy, melatonin and leptin hormones on ovarian follicular development in female Syrian hamsters (Mesocricetus auratus)(Akademiai Kiado Zrt, 2010) Karakaş, Alper; Kaya, Aliye; Gündüz, BülentWe studied the effects of melatonin and leptin hormones on ovarian follicular development in intact and pinealectomized female Syrian hamsters. We first monitored the oestrous cycle of the hamsters by the vaginal smear samples throughout a ten day period to start the injections simultaneously in all groups and performed saline, melatonin and leptin hormone injection groups for both control and pinealectomized hamsters. Then the injections were applied for four days starting the oestrus phase of the cycle and the ovaries were removed for preparation of histological analysis. We measured the diameters and the numbers of the follicles and we classified the follicles according to the number of the granulosa cell layer. Leptin hormone injection increased melatonin hormone injection decreased the number and the diameter of the follicles. The stimulating effect of the leptin hormone was more pronounced in the pinealectomized group. The results of the present study indicate that the removal of the pineal gland and leptin hormone administration are playing a stimulatory while melatonin hormone administration is playing an inhibitory role on the follicular development in female Syrian hamsters.Öğe Effects of European mistletoe (Viscum album L. subsp album) extracts on activity rhythms of the Syrian hamsters (Mesocricetus auratus)(Taylor & Francis Ltd., 2008) Karakaş, Alper; Türker, Arzu Uçar; Gündüz, BülentAntitumor drugs may have some significant nervous system side-effects such as disrupted sleep, eating and drinking patterns. European Mistletoe has been investigated for many decades for its potential use against cancer. To test the hypothesis that the non-antineoplastic effects of mistletoe might be mediated by the actions on the circadian timing system, we have applied mistletoe extracts and vehicle and have measured locomotor activity, feeding and drinking rhythms under constant darkness. Four groups (vehicle, 20 mg kg(-1) ip injection, 40 mg kg(-1) ip injection and 6 g kg(-1) oral administration) were performed for both heat-treated and freeze-dried extracts. None of the administrations changed the locomotor activity, feeding and drinking rhythms in the groups except for 40 mg kg(-1) freeze-dried injected group. The locomotor activity levels decreased in 40 mg kg(-1) freeze-dried extract injected group. These results suggest that, side-effects of mistletoe on circadian timing system of the Syrian hamster depend on the dose and the preparation method of the extract.Öğe The effects of leptin hormone on locomotor activity in Syrian Hamsters (Mesocricetus Auratus)(2011) Gündüz, Bülent; Karakaş, AlperThe suprachiasmatic nucleus (SCN) generates and controls the circadian rhythms in mammals including the rhythm of locomotor activity. Leptin is a hormone secreted by adipose tissue that informs the brain about the fat stores. SCN neurons express leptin receptors. Here we investigated the effects of 3 different leptin administrations on the locomotor activity of the Syrian hamsters maintained in constant darkness. Animals were intraperitoneally (ip) injected (4 μg/kg), subcutaneously (sc) infused (4 μg/kg), or intra-SCN infused (0.4 μg/kg) with leptin for 3 days at circadian time 10 whereas the controls received saline (0.9% NaCl) at the same time in order to eliminate stress factors. Our results demonstrate that the locomotor activity of the hamsters can be phase advanced by the external leptin administrations. Leptin affected the level of phase-shifts in an administration method-dependent manner. The biggest phase advance was observed in intra-SCN infusion (P = 0.001), and the smallest was in the ip injection (P = 0.041) group. The wheel-turn amounts did not change significantly in the groups before and after the leptin administrations (P = 0.233); however, the period lengths increased (P = 0.011) significantly after leptin administrations. These results suggest for the first time that in vivo leptin administrations may change the rhythm of locomotor activity in adult male Syrian hamsters.Öğe The effects of mistletoe (Viscum Album L. Subsp. Album) extracts on isolated intestinal contractions(2008) Karakaş, Alper; Serin, Erdinç; Gündüz, Bülent; Türker, Arzu UçarThroughout history folk medicine has served as an alternative or complimentary method of treating disorders like intestinal colic. Mistletoe is a common name for many species of semi-parasitic plants that grow on trees throughout the world, and has been used widely to treat intestinal colic. We conducted a study to evaluate the effect of freeze-dried (group 1) and heat-treated (group 2) extracts of Viscum album subsp. album leaves on contractions induced by acetylcholine in isolated hamster intestinal segments (duodenum, jejunum, and ileum). Freeze-dried extracts decreased intestinal contractions in all the intestinal segments (P < 0.05). The strongest relaxant effect was observed in the jejunum and the weakest was seen in the duodenum. Higher doses of heat-treated extracts were required to affect segmental contractions than that of freeze-dried extracts (P < 0.05); heat-treated extracts had the greatest effect on reducing contractions in the jejunum and the least effect in the duodenum. Mistletoe extracts affected the level of contractions in a dose- and extraction preparation-dependent manner. The results of this study show that mistletoe extracts could be effective against intestinal motility problems and that they have potential use as a therapeutic remedy for intestinal colic.Öğe The effects of mistletoe (Viscum album L. subsp. album) extracts on ısolated ıntestinal contractions(2008) Karakaş, Alper; Serin, Erdinç; Gündüz, Bülent; Türker, Arzu UçarHalk ilaçları eski çağlardan bu yana bağırsak ağrıları gibi problemlerin tedavi edilmesinde alternatif ya da tamamlayıcı bir yol olmuşlardır. Ökseotu, tüm dünyada, ağaçlarda büyüyen gelişen yarı parazit bir bitkidir ve bağırsak kasılmalarına karşı yaygın olarak kullanılmaktadır. Çalışmamızda Viscum album subsp. album yapraklarının, bitkisinden dondurulup-kurutulma (Grup 1) ve sıcak su (Grup 2) ile ekstraksiyon suretiyle hazırlanan ekstraktların, izole edilmiş ince bağırsağın farklı segmentlerinde (duodenum, jejunum, ileum) asetilkolin ile oluşturulmuş kasılmalar üzerine olan etkilerini inceledik. 1. Gruptaki ekstraktlar tüm bağırsak segmentlerinde kasılmaları düşürdü (P < 0.05). En güçlü gevşetici etki jejunumda, en düşük etki ise duodenumda gözlendi. 2. Gruptaki ekstraktlar 1. Gruptaki ekstraktlardan daha yüksek dozlarda segmental kasılmaları etkiledi (P < 0.05); kasılmalardaki düşüş jejunumda daha fazla, daha düşük ileum ve en düşük etki duodenumda gözlendi. Ökseotu ekstraktlarının kasılmaları doza ve hazırlama yöntemlerine bağlı olarak etkilediği görülmektedir. Sonuç olarak ökseotu ekstraktları bağırsak hareket problemlerine karşı etkili olabilmekte ve bağırsak kasılmalarında tedavi edici ilaç olarak bir potansiyeli bulunmaktadır.Öğe The effects of mistletoe (Viscum album L.) extracts on isolated ileum contractions(Amer Assoc Clinical Chemistry, 2006) Serin, Erdinç; Karakaş, Alper; Türker, Arzu; Gündüz, BülentEuropean mistletoe (Viscum album L, Loranthaceae) is an evergreen, semiparasitic plant normally found growing on a variety of trees. Both in viva and in vitro studies have shown the cytotoxic, cardiotoxic, immunostimulant, hypoglycemic, antitumor and vasodilator effects of the extracts produced from this plant.Öğe Effects of photoperiod and food availability on growth, leptin, sexual maturation and maintenance in the Mongolian gerbils (Meriones unguiculatus)(Zoological Soc Japan, 2005) Karakaş, Alper; Çamsarı, Çağrı; Serin, Erdinç; Gündüz, BülentReproductive activity of Mongolian gerbils is regulated by photoperiod nevertheless body weight regulation is controlled without ambient photoperiod. Food intake is a major factor affecting rodent reproductive efficiency. Leptin is a hormone secreted by adipose tissue and modulates food intake, energy expenditure and body fat stores. In this study we studied the interaction of photoperiod and food availability on growth, sexual maturation and leptin concentration in the male and female gerbils. Gerbils were gestated and reared in either 14L:10D or 2L:22D. At weaning, gerbils were housed individually and divided into three groups: fed ad libitum, fed 80% of ad libitum or fed 60% of ad libitum. Body weights were recorded at weaning and every week thereafter. After twelve weeks of treatment, animals were sacrificed and testes and uterine weights were determined and blood was collected for leptin measurement. Food restriction reduced body weight and inhibited reproductive development. Absolute paired testis weights were similar in ad lib and 80% of ad lib groups but significantly different compared with the 60% of ad lib group in both photoperiods. Body weights were also directly dependent upon the level of food restriction. Uterine mass was only affected in the 60% of ad lib group in 14L but both food restriction levels significantly affected the uterine weights in 2L. Significant variations were found in leptin profiles. Leptin concentration was highest in ad lib and 80% of ad lib groups and lowest in 60% of ad lib groups. These results suggest that the reproductive activity of Mongolian gerbils is sensitive to food intake and multiple potential environmental cues (e.g., food availability, temperature) can be utilized.Öğe Effects of photoperiod and melatonin infusions on body weight in pinealectomized juvenile siberian hamsters (Phodopus Sungorus)(2001) Gündüz, Bülent; Karakaş, AlperWe examined the effects of daily melatonin (Mel) infusions in pinealectomized prepubertal male Siberian hamsters in three different conditions. In one study we investigated the body weight maturation response to one hour daily infusions of 10 ng, 25 ng, or 50 ng of Mel in pinealectomized hamsters. Animals received, at day 15 of life, programmed subcutaneous infusions of Mel or vehicle at one of five time points (1900-2000, 2000-2100, 2100-2200, 2400-0100, and 0300-0400 hours) for 30 days. In long-day-born (16L) animals, Mel infusion right after lights off (2000-2100 hours) significantly inhibited body growth; this dose was ineffective at other times. Doses of 10 ng and 25 ng Mel were ineffective at all time points. In a second study, hamsters received either 4-or 8-h infusions of Mel (either 50 ng/h or 50 ng/day) at various times throughout the day and night of a 16L or 10L photoperiod. Daily 4-h, 50 ng/h, Mel infusions at 1700-2100 hours inhibited body weight growth in 16L and daily 4-h Mel infusions (either 50 ng/h or 50 ng/day) inhibited body weight growth at 1700-2100 hours in 10L. In all cases, daily 8-h infusions suppressed body weight development. In a third study, long-day-born pinealectomized hamsters were infused with two signals of four hours separated by an interval of two hours. Mel infused groups had significantly inhibited body growth compared to vehicle infused animals. Body weight development was maximally inhibited only in those groups in which the period of Mel sensitivity was identified in the first study (2000-2100 hours) overlapped or immediately followed a period of Mel infusion These results show that the photoperiodic body weight response in juvenile Siberian hamsters is regulated by the coincidence in time of exogenously administered Mel with an intrinsic rhythm of sensitivity to Mel, and the duration of the Mel signal alone cannot explain the results.Öğe Effects of photoperiod and temperature on growth and reproductive organ mass in adult male Mongolian Gerbils, Meriones Unguiculatus(2002) Gündüz, BülentRates of growth and sexual maturation of Mongolian gerbils vary in response to photoperiod. Previous work has shown that the responses of the testes and body weight of juvenile and adult gerbils are influenced not only by the photoperiods but also by other factors. The present work sought to determine if Mongolian gerbils alter body mass, body composition and/or reproductive organ mass in response to different photoperiods and temperatures. Male Mongolian gerbils were raised under long (14L) or short (10L) photoperiods from 26 days of age. Photoperiods did not affect body mass and body length. Temperature affected body mass only under 10L with animals housed at 10°C being significantly ligter than gerbils housed at 20°C. Temperature did not affect the length of the body. Changes in body mass in response to photoperiod and/or temperature exposure were primarily due to the deposition or loss of fat-free dry mass and water. The mass of the reproductive organs (testes and seminal vesicles) was significantly dec reased in gerbils housed under 10L. The mass of reproductive organs at 86 or 160 days of age was not affected by the temperature. Taken together, these results suggest that male Mongolian gerbils use photoperiodic information and temperature to change their body mass and reproductive organs.Öğe The effects of pinealectomy and melatonin implants on circadian locomotor activity responses of the Mongolian Gerbils exposed to rapid photoperiodic transitions(2010) Gündüz, Bülent; Karakaş, AlperJet-lag sendromu ve vardiyalı çalışma rahatsızlığı fotoperiyoddaki hızlı değişimlerden kaynaklanır ve sıklıkla insanların hayatını olumsuz etkilemektedirler. Bu çalışmada jet-lag ve vardiyalı çalışma simüle edilmek istendi. Moğolistan gerbillerinin fotoperiyod değişimlerine karşı gösterdiği yeni ritim düzenlemesinde fotoperiyod, pineal bez ve melatonin hormonunun etkilerini araştırmak üzere, kontrol, pinealektomi ve melatonin implantları içeren gerbil grupları sırası ile uzun (14L:10D), kısa (8L:16D), sürekli karanlık (0L:24D) ve sürekli aydınlık (24L:0D) fotoperiyodlarına yerleştirildi. Gerbiller uzun ve kısa fotoperiyodlarda ışık/karanlık siklusu ile düzenlenen bir aktivite ritmi gösterirken, sürekli karanlıkta serbest koşu ve sürekli aydınlıkta ise aritmik bir aktivite vardı. Grupların periyod uzunlukları arasında anlamlı bir farklılık yoktu (p>0,05). Gerbillerin aktivitesi fotoperiyod değişiklikleri ile yeniden düzenlenirken, pinealektomi ve melatonin implantları ise bu düzenleme üzerine anlamlı bir etki yapmadı (p>0,05). Lokomotor aktivite miktarları fotoperiyod ve gruba bağlı olarak değişimler gösterdi. Bu çalışmanın sonuçları Moğolistan gerbillerinde lokomotor aktivite ritminin düzenlenmesinde fotoperiyodun etkili ancak pineal bez ve sürekli salınım yapan melatonin implantlarının ise etkili olmadığını gösterdi.Öğe Effects of pinealectomy and melatonin supplementation on endometrial explants in a rat model(Elsevier, 2010) Koç, Önder; Gündüz, Bülent; Topçuoğlu, Ata; Buğdaycı, Güler; Yılmaz, Fahri; Duran, BülentObjective To determine the effects of pinealectomy on endometrial explants in rats and evaluate the activity of superoxide dismutase (SOD) and catalase (CAT) and the levels of malondialdehyde (MDA) in the rat endometriosis model Study design Rats with experimentally induced endometriosis were randomly divided into three groups after second-look laparotomies Group 1 (pinealectomy n = 8) and Group 2 (pinealectomy + melatonin n = 8) underwent pinealectomies after the second-look laparotomies Group 3 was presented as control group (vehicle solution + without pinealectomy (n = 6)) Melatonin was administered intraperitoneally for 4 weeks in Group 2 whereas an equal volume of vehicle solution was given to Groups 1 and 3 Evaluation of the volume of the endometrial explants histopathological examination and preservation of explant epitheliums according to the scoring system were undertaken Results There was a statistically significant increase in spherical explant volumes of Group 1 compared to Groups 2 and 3 In Group 1 the level of MDA was significantly higher and SOD and CAT activity was significantly lower compared to Groups 2 and 3 A statistically significant increase in the epithelial lining scores of explants was noted in Group 1 compared to Groups 2 and 3 Conclusion The effects of pinealectomy on the progression of endometriosis explants were reversed by melatonin (C) 2010 Elsevier Ireland Ltd All rights reservedÖğe The effects of the intraamygdalar melatonin injections on the anxiety like behavior and the spatial memory performance in male Wistar rats(Elsevier, 2011) Karakaş, Alper; Coşkun, Hamit; Kaya, Aliye; Küçük, Ayşegül; Gündüz, BülentIn the present study, the effects of intraamygdalar administrations of melatonin (1 and 100 mu g/kg), saline and diazepam on the anxiety-like behavior and spatial memory performance in pinealectomized and sham-pinealectomized Wistar rats were investigated. The animals were tested by open field and elevated plus maze tests for anxiety-like behavior, and Morris water maze test for spatial memory. In open field, (a) diazepam was more effective in reducing the anxiety, (b) control subjects were more mobile than pinealectomized subjects and (c) 100 mu g/kg melatonin administrations reduced the velocity of the animals. In elevated plus maze, (a) 100 mu g/kg melatonin administrations increased the distance totally travelled and (b) enhanced the time spent in open arms, however, after the pinealectomy, 1 mu g/kg melatonin administrations decreased it and (c) control animals were less mobile than pinealectomized ones. In Morris water maze, (a) diazepam group travelled more distance than the others in control condition whereas, in pinealectomy condition high dose of melatonin and saline groups travelled more distance than the others, (b) in pinealectomy condition subjects who received 100 mu g/kg melatonin also travelled more distance than those who received 1 mu g/kg melatonin and diazepam, (c) the subjects who received 1 mu g/kg spent less time than those who received other treatments, and (d) in control condition subjects who received 100 mu g/kg melatonin were slower than those who received the other treatments. In conclusion, melatonin administration to amygdala decreased the anxiety; however, spatial memory performance of the rats was impaired by the pinealectomy and melatonin administrations. (C) 2011 Elsevier B.V. All rights reserved.Öğe Food restriction affects locomotor activity in Mongolian Gerbils (Meriones Unguiculatus)(2006) Karakaş, Alper; Serin, Erdinç; Gündüz, BülentThe circadian rhythm of the locomotor activity is regulated by at least 2 external pacemakers, environmental photoperiod and food availability. In the present study, the effects of short-term (2 weeks) food restriction on locomotor activity rhythm in adult male and female Mongolian gerbils were investigated. Animals were fed ad libitum with no restriction during the first week of the experiment and their daily ad libitum food consumptions were determined. Then the food was restricted 40% of ad libitum for the next 2 weeks. At constant temperature, locomotor activity was monitored by running wheel in animals exposed to a long photoperiod (14L) for 3 weeks. A significant phase advance was recorded in the locomotor activity rhythm in both male and female animals. The shift was bigger in males (12 ± 1.1 h) than in females (6 ± 0.5 h) (P < 0.05). Activity levels and body weights decreased in males (P < 0.01) and females (P < 0.012) compared with the first week values. The gerbils' locomotor activity was significantly affected by the food restriction. These results indicate that the rhythm and the level of the locomotor activity in the Mongolian gerbil can be entrained by food restriction.Öğe Maternal transfer of photoperiodic information in Siberian hamsters. vi. effects of time-dependent 1-hr melatonin infusions in the mother on photoperiod-induced testicular development of her offspring(Blackwell Munksgaard, 2003) Gündüz, Bülent; Stetson, Milton H.We tested in Siberian hamsters the nature of the maternal signal that relays photoperiodic information to the developing fetuses. As previous investigations have identified maternal hormonal and circadian components in this process, the specific goal of this presentation is to determine quality of the signal that connotes daylength when it is imparted to the fetus. Does the function of the signal received by the fetus best support the coincidence or duration hypotheses of photoperiodic induction? Pregnant hamsters received 1 or 8 hr melatonin or vehicle infusions everyday. Juveniles of intact mothers gestated on 16 hr of light per day (16L) experienced maximal suppression of testicular development when reared on 14L. However, when intact mothers gestated on 10L received a 1-hr melatonin infusion daily at 20:00-21:00 hr, their young responded to 14L with greatly accelerated testicular development. In the absence of the maternal pineal gland (and, therefore, the maternal melatonin signal), the effects of maternal melatonin infusions were reversed. Here, only the juveniles of 16L-gestated females infused at 20:00-21:00 hr daily responded to 14L with enhanced testicular development. All other groups showed the same extent of gonadal development, independent of the time or type of infusion their mothers received. Testicular development on 14L of all juveniles from pinealectomized mothers gestated on 10L was of the same magnitude, regardless of the type and time of infusion their mothers received during pregnancy. The results suggest that the maternal signal transferred to the fetuses during gestation consists not only of the daily melatonin signal, but also some circadian-based component that greatly affects the effect of the former. The timing, and not the duration, of the maternal melatonin signal with respect to the animals' (mother and fetus) circadian day is of crucial importance in the transfer of photoperiodic information from mother to fetus.Öğe Maternal transfer of photoperiodic information regulates the postnatal reproductive system development of the mongolian gerbil (Merinos unguiculatus)(2007) Karakaş, Alper; Gündüz, BülentÖzet: Moğolistan gerbillerinde hamilelik süresince fotoperiyodik bilginin anneden yavruya iletilip iletilmediği ve eğer bir ileti varsa bundan pineal bez ve hormonu melatonin'in sorumlu olup olmadığı araştırıldı. Yetişkin dişi gerbiller iki değişik fotoperiyot altında (12L12D, 8L:16D) çiftleştirildi. Hamile gerbillerin bulunduğu herbir fotoperiyotta üç farklı grup [kontrol (yalancı pinealektomi), pinealektomi ve pinealektomi + melatonin enjeksiyonu] oluşturuldu. Pinealektomiler, gerbiller çiftleştirilmeden önce yapıldı ve melatonin injeksiyonları pinealektomili gruba hamileliğin 8. gününden doğuma kadar uygulandı. Her iki fotoperiyotta doğan yavrular aynı gün anneleri ile birlikte ara fotoperiyot olan 10L14D transfer edildiler. Yavruların sütten kesilme sonrası vücut ağırlık artışı ve erkek gerbillerin gonadal gelişimi sekiz hafta süresince her hafta yapılan ölçümlerle kaydedildi. Hamileliklerini 12L12D fotoperiyodunda geçiren kontrol ve pinealetomi + melatonin enjeksiyonlu annelerden doğan gerbiller 10L:14D'ye kısa fotoperiyot cevabı verdiler ve pinealektomili annelerden doğan gerbillere göre daha küçük testislere sahip oldular (P < 0,05). Hamileliklerini 8L fotoperiyodunda geçiren kontrol ve pinealektomi + melatonin enjeksiyonlu annelerden doğan gerbiller 10L:l4D'ye uzun fotoperiyot cevabı verdiler ve pinealektomili annelerden doğan gerbillere göre daha büyük testislere sahip oldular (P < 0,05). Gruplar arasında vücut ağırlığı gelişimi bakımından anlamlı bir farklılık kaydedilmedi (P > 0,05). Bu sonuçlar göstermektedir ki, Moğolistan gerbillerinde fotoperiyodik bilginin iletiminde annelerin hamilelik süresince içinde bulundukları fotoperiyod etkili olmakta, pineal bezi ve hormonu melatonin önemli bir rol oynamaktadırlar.Öğe Maternal transfer of photoperiodic information regulates the postnatal reproductive system development of the Mongolian Gerbil (Meriones Unguiculatus)(2007) Karakaş, Alper; Gündüz, BülentWe investigated whether photoperiodic information is transferred from mother to young and whether the pineal gland and its hormone, melatonin, are involved in this transfer in Mongolian gerbils. Adult female gerbils were paired with males and housed in photoperiods of 12L:12D or 8L:16D. Three groups of pregnant gerbils in each photoperiod were prepared: one group was the sham-operated control, one group consisted of pinealectomized gerbils, and one group consisted of pinealectomized gerbils that were treated with melatonin. Pinealectomy was performed before pairing the animals and melatonin injections were applied to the pinealectomized group from day 8 of gestation until parturition. On the day of parturition, the mother and young were transferred to an intermediate photoperiod (10L:14D). After weaning, body weight gain and gonadal development of the male young were measured every week over 8 weeks. Animals gestated and born to control and pinealectomized + melatonin injected mothers exposed to 12L:12D responded to 10L:14D as a short day; they had significantly (P < 0.05) smaller testes than animals born to pinealectomized mothers. Animals gestated and born to control mothers exposed to 8L:16D responded to 10L:14D as a long day; they had significantly (P < 0.05) larger testes than animals born to pinealectomized and pinealectomized + melatonin injected mothers. Body weights of the gerbils did not vary significantly among the groups (P > 0.05). These results are the first evidence that the photoperiod to which the mother is exposed during gestation affects the postnatal gonadal development of the young and the pineal gland and melatonin play an important role in the transmission of photoperiodic information in the Mongolian gerbil.Öğe Melatonin implants have no effect of the testis volume and body weight in mongolian gerbils(2003) Karakaş, Alper; Gündüz, BülentMongolian gerbillerin üreme aktivitelerinin düzenlenmesinde fotoperiyot önemli bir faktördür. Fotoperiyodik bilgi en son pineal bez tarafından hormonal sinyale çevrilir. Bu çalışmada uzun fotoperiyotta (14L: 10D) tutulan Mongolian gerbillerin testis boyutlarına ve vücut ağırlıklarına, sürekli salınım gösteren melatonin hormonunun etkisini inceledik. Üç grup oluşturuldu; kontrol (n = 10), intakt + melatonin implantasyonu (n = 10) ve pinealektomi + melatonin implantasyonu (n = 10). Sekiz hafta süresince gerbillerin testis ve vücut ağırlık değişimleri haftada bir kaydedildi. Deney sonunda intakt + melatonin implantasyonu ve pinealektomi + melatonin implantasyonu gruplarının vücut ağırlığı (76 ± 2,0 g intakt + melatonin implantasyonu; 79 ± 3,0 g pinealektomi + melatonin implantasyonu) ve testis ağırlıkları (1,54 ± 0,21 g intakt + melatonin implantasyonu; 1,47 ± 0,19 g pinealektomi + melatonin implantasyonu) ile kontrol grubu (80 ± 3,1 g vücut ağırlığı; 1,55 ± 0,20 g testis ağırlığı; P > 0,05) arasında anlamlı bir farklılık tespit edilmedi. Uygulamalara bakmaksızın, hayvanlar uzun fotoperiyodun özelliklerini gösterdiler. Bu sonuçlar göstermektedir ki sürekli salınan melatonin implantasyonları ile maskelenen endojen melatonin ritmi, hayvanlar uzun fotoperiyotta tutuldukları zaman testis hacmi ve vücut ağırlığı üzerinde bir etki göstermemektedir.
