Yang-Ho Choi

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UNLABELLED Normal mice and leptin-deficient ob/ob mice were treated with leptin to study effects on osteogenesis and adipogenesis in bone marrow. Leptin treatment significantly decreased bone marrow adipocyte size and number in ob/ob mice while increasing bone formation, BMC, and BMD. The results suggest that, in leptin-sensitive animals, the reduction in(More)
The melanocortin (MC) system is a known downstream mediator of leptin signaling in the brain; thus, activation of MC receptors by melanotan II (MTII), a MC3/4 receptor agonist, was hypothesized to increase adipose apoptosis, a phenomenon seen after leptin treatments. To test this hypothesis, male Sprague-Dawley rats received pretreatments of(More)
The melanocortin (MC) system in the brain is believed to be an important downstream effector of leptin signaling; interference with MC functioning results in severe obesity. Melanotan II (MTII), an MC3/4-receptor agonist, produces similar behavioral and metabolic outcomes to those observed after leptin treatments, which enhance apoptosis in specific fat(More)
OBJECTIVE Leptin-deficient ob/ob mice are more sensitive to exogenous leptin than lean mice and leptin treatment normalizes many of the phenotypic characteristics of ob/ob mice. The primary objective of this experiment was to investigate whether this altered leptin sensitivity in ob/ob mice was reflected in the hypothalamic mRNA profile. RESEARCH METHODS(More)
The accumulation of fat cells (adipocytes) in bone marrow is now thought to be a factor contributing to age-related bone loss. Women with osteoporosis have higher numbers of marrow adipocytes than women with healthy bone, and bone formation rate is inversely correlated with adipocyte number in bone tissue biopsies from both men and women. Adipogenic(More)
The present study compared the plasma corticosterone concentrations between meat- and layer-type neonatal chicks (Gallus gallus) (1) exposed to isolation-induced stress or (2) injected intracerebroventricularly (ICV) with corticotropin-releasing factor (CRF). Both types of neonatal chicks housed in groups were individually introduced to an open field arena(More)
The objective of this study was to determine whether centrally administered leptin decreased liver and adipose SCD1 expression or adipose resistin expression, and whether these effects were mediated by central melanocortin receptors. Male Sprague-Dawley rats were injected into the lateral cerebral ventricle (i.c.v.) once daily for 4 days with artificial(More)
Melatonin is involved in a variety of biological functions including sleep and stress. Our previous study indicated that neonatal layer chicks were more susceptible to stress than broilers. However, it is not clear whether differences exist in melatonin concentrations between both types of chickens, nor is it known whether melatonin is directly involved in(More)
Although leptin causes negative energy balance by reducing food intake and increasing energy expenditure, the effect of leptin on spontaneous physical activity (SPA) is not clearly established. To test the hypothesis that leptin enhances SPA in rats, male Sprague-Dawley rats were injected intracerebroventricularly (ICV) with either 10mug of leptin or(More)
Thyrotropin-releasing hormone (TRH) is a key regulator of the hypothalamus-pituitary-thyroid axis, which plays an important role in energy homeostasis and is involved in the regulation of feeding behavior. In the present study, we investigated the effects of acute and chronic TRH treatment on water intake, body temperature and feeding behavior in rats. TRH(More)