Hamile ve pinealektomili suriye hamsterlarına (Mesocricetus auratus) leptin infüzyonu ve yavrularda lokomotor aktivite

A circadian rhythm generator suprachiasmatic nucleus (SCN) which synchronizes the daily variations in light intensity and integrates environmental light signals located in the hypothalamus. In rodents, circadian rhythms are synchronized to the outside environment through the maternal system which is in synchrony with those of their mothers during late embryonic and early neonatal development. Melatonin exerts a ?chronobiotic? effect by acting directly on the SCN, which contain melatonin receptors and the endogeneous melatonin peak is phase-advanced with the direct application of exogenous melatonin into the SCN. Adipose tissue derived hormone leptin has receptors on the SCN and the activity rhythm is phase advanced by leptin treatment both in vivo and in vitro. In this thesis, the regulatory effects of leptin through maternal system on fetal SCN were investigated. iv Long day housed (LD 14:10) pregnant hamsters were cannulated from back and subcutaneous leptin infusion has started at the 10th day of pregnancy until the parturition. After parturition, 15 days of age juvenile Syrian hamsters were weaned from their mothers and placed in cages for their locomotor activity records. Body weights were recorded. Locomotor activities were recorded for 3 weeks by using Vital View Software. The results showed that the wheel running turns of juveniles (leptin infusion to mother between 00.00-01.00 h) was significantly higher in control group (p<0.05) and wheel running turns of this group (00.00-01.00 h) were not statistically different between control and pinealectomized animals. The wheel running turns of juveniles from mothers of leptin infusion between 12.00-13.00 h and between 13.30-19.30 h groups were not statistically different in both control and pinealectomized groups (p>0.05). Body weights of juveniles were statistically different between control and pinealectomized groups (p<0.05) in both 00.00-01.00 h and 13.30-19.30 h leptin infused groups, but not in 12.00-13.00 h leptin infused group (p>0.05). In conclusion, the locomotor activities of juveniles were influenced by maternal leptin and SCN would possibly play an important role. Body weight of juvenile Syrian hamsters might also be controlled by maternal leptin in the postnatal period. Keywords: SCN, Pineal gland, Leptin, Infusion, Maternal system, Syrian hamster