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    Circadian Rhythm and Leptin Hormone Responses to Nutritional Restriction in Gerbils (Meriones unguiculatus) with Suprachiasmatic Nucleus Lesions
    (ABADER (Adıyaman Bilimsel Arastırmalar Dernegi), 2023) Gündüz, Bülent; Önder, Betül; Ekin, Ahmet; Hasanoğlu, Nursel
    Rhythmically-regulated feeding behavior is in harmony with physiologic and metabolic activities in mammals. This rhythmic regulation is orchestrated by Suprachiasmatic Nucleus (SCN). However, it is not entirely clear how the SCN, which generates endogenous (internal) rhythms, influences body weight and serum leptin profile with activity rhythms in relation to feeding timing. In this study, animals in long photoperiod (14L:10D) were divided into two groups as control (sham-SCNx) and SCN lesions (SCNx). Then, these groups were split into four separate subgroups: a) ad libitum feeding; b) feeding only during the dark phase; c) feeding only during the light phase; and d) feeding during a specific period of the day (11:00-14:00 h). Locomotor activity and leptin hormone changes were observed in animals fed in cages attached to activity wheels for one month. Under the conditions of food restriction, the locomotor activities of the groups with SCNx and sham-SCNx demonstrated a phase shift toward the time of feeding. Serum leptin level did not change with feeding conditions but decreased in lesioned groups (SCNx). In conclusion, nutritional restriction caused phase shifts in activity rhythms and it was found that the SCN in gerbils was in charge of these rhythmic changes in the presence and absence of nutrients. © 2023, ABADER (Adıyaman Bilimsel Arastırmalar Dernegi). All rights reserved.
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    Effects of Supplementation with Iron, Selenium and Magnesium on Galleria mellonella Cell-Mediated Immune Responses
    (2021) Kaya, Serhat; Gündüz, Bülent
    Immune responses play a key role in the survival of all living things. Intake of inorganic materials is ofcritical importance in living organisms because of their participation in metabolism and some component ofcells. Iron (Fe), magnesium (Mg) and selenium (Se) were selected for this study because of their participation incritical constituents of cells, such as nucleic acids and enzymes in living organisms, and their indirect and directeffects on immunity. Although the separate effects of these inorganic materials are known, there is no study ontheir combined effects. Galleria mellonella, which is used as a model organism, is frequently used in evaluatingof effects of human pathogens due to its various properties. Total hemocyte counts and encapsulationmelanization responses are the most commonly observed parameters when examining the immune responsesof this model organism. In our study, the effects of the selected inorganic materials added in the ratio of 0.1%,0.25%, 0.5% and 1% in the nutrient content of G. mellonella on the immune responses of this organism wereinvestigated. As a result of the study, it was found that only 0.25% of the doses increased the hemocyte countand that the other doses significantly decreased compared to the control group. However, it was determinedthat 0.5% and 1% feeding caused a significant decrease in both hemocyte count and encapsulationmelanization responses. According to our findings, the nutrients which have over a certain dose by inorganicsubstances have negative effects on immunity.
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    Influence of Helichrysum arenarium on hemocyte-mediated immune responses and phenoloxidase enzyme activity of model organism Galleria mellonella (L.)
    (Springer Science and Business Media Deutschland GmbH, 2021) Kaya, Serhat; Akkuş, Gülsüm; Türkdoğan, Seranay; Gündüz, Bülent
    Helichrysum arenarium (L.) (Asterales:Asteraceae) Moench is a therapeutic plant which contains etheric oil, flavones and flavon glycosides, sterins, bitter substances and tannins having various coumarins. This plant is thought to have important characteristics such as diuretic effect, dropping stones and sand from the kidney, regulating digestive disorders, strengthening the immune system, and having antibiotic and antioxidant effects. Additionally, this plant is traditionally used in liver and biliary tract diseases and also shows anti-inflammatory and detoxifying properties. Model organism Galleria mellonella L. (Lepidoptera:Pyralidae) is an invertebrate species that is frequently used to study the effects of human pathogens and various pesticides, hormones, etc. on immune system. In our study, we examined the effect of various doses of H. arenarium on the hemocyte count and behavior of G. mellonella larvae. According to the findings obtained at the end of our study, H. arenarium caused an increase in hemocyte count with the injection of 0.25% and 0.5% doses compared to the untreated and DMSO groups. At the same time, the 0.25% and 0.5% doses showed a strong encapsulation-melanization response and an increase in phenoloxidase enzyme activity over 24 h compared to the other injected groups. Based on these results, H. arenarium extract has an anti-mitotic activity at high doses (above 0.5%). This effect may be due to the fact that the plant extract supports mitosis at a certain dose, while being toxic when exceeding it.
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    Methyl donor supplementation alters serum leptin levels and increases appetite but not body weight in cross-fostered male Syrian hamster offspring (Mesocricetus auratus)
    (Wiley-VCH GmbH, 2022) Gündüz, Bülent; Okimoto, Darren K.
    A pregnant hamster's exposure to changes in environmental factors, such as light, temperature and nutrition, may influence behavioural and physiological changes in offspring. In this study, dietary methyl donor supplementation was employed to examine the role of maternal diet on appetite, body weight, serum leptin levels and locomotor activity in male Syrian hamster offspring. Dams were fed a standard control (SC) or methyl donor-supplemented (MDSD) diet through pregnancy and lactation. At birth, offspring were cross-fostered to dams fed an SC or MDSD diet (SC-MDSD and MDSD-SC) or remained with their birth mothers (SC-SC and MDSD-MDSD). At weaning, offspring were fed a SC or MDSD diet until 60 days of age. Food intake, serum leptin levels and locomotor activity were measured from 30-60 days of age. Offspring fed a MDSD diet post-weaning (MDSD-MDSD and SC-MDSD) consumed more than double the amount of food daily compared with offspring fed a SC diet post-weaning (SC-SC, MDSD-SC). Interestingly, there were no observed differences in body weight among all four groups. Serum leptin levels at 60 days of age were depressed in offspring fed a MDSD diet post-weaning (MDSD-MDSD and SC-MDSD). There were no observed differences in wheel running activity between the SC-SC and MDSC-SC groups. Wheel running activity was at least twice the amount in offspring fed a MDSD diet post-weaning (SC-MDSD and MDSD-MDSD). Taken together, these results indicate that the timing of methyl donor supplementation appears to be an important factor during the development of offspring.
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    The effects of pinealectomy and melatonin implants on circadian locomotor activity responses of the mongolian gerbils exposed to rapid photoperiodic transitions
    (Ege University Press, 2010) Gündüz, Bülent; Karakaş, Alper
    The jet-lag syndrome and the shift-work malaise take place by rapid changes in photoperiod and disturb people's life frequently. In the present study; we wanted to simulate these conditions. Control, pinealectomized and melatonin including silastic tube implanted Mongolian gerbils were respectively exposed into long (14L:10D), short (8L:16D), constant darkness (0L:24D) and constant light (24L:0D) photoperiods in order to investigate the effects of photoperiod, pineal gland and melatonin hormone in the photoperiodic reentrainment of this species. Gerbils showed an light/dark cycle entrained locomotor activity rhythm in long and short photoperiods, free-running in constant darkness and arrhythmic locomotor activity in constant light. The period lengths were similar to each other in the groups (p>0,05). Gerbils were reentrained by the changes in photoperiod nevertheless pinealectomy and melatonin implants did not make any significant influence on this reentrainment (p>0,05). Locomotor activity amounts varied in a group-photoperiod-dependent manner. These data suggest that photoperiod but not the pineal gland and constant release melatonin hormone is effective on the activity rhythm of the Mongolian gerbil.