Se-Il Kim is a professor of European Cultures at Chung-Ang University. His latest research interest is multi-dimensional approach to understand characteristics of human beings.
The appetite-stimulating hormone, ghrelin involves not only energy homeostasis but also reward-based eating behaviors. This study aims to investigate if level of fasting ghrelin influences hedonic craving which is driven by external highly palatable food-cues when not physically hungry. A total of 55 female participants with normal range of BMI were divided into two groups according to ghrelin level: high ghrelin (HG) and low ghrelin (LG) groups. Participants performed a fasting blood draw to compare ghrelin levels and consumed standard breakfast. And then, they performed free-viewing task to record eye-movements toward food cues with high (e.g. pizza, hamburger) and low palatability (e.g. vegetables). The results showed that there were differences between two groups in visual attentional pattern to food cues depending on palatability of food. The HG group showed biased attention toward highly than lowly palatable food cues. Whereas at the LG group, there were no differences in visual attentional pattern to food cues whether the food had high or low palatability. The results suggest that high level of fasting ghrelin might promote selective attention to highly palatable foods even when not hungry. Thus, a role of ghrelin in reward-based eating behavior potentially related to differential attentional processing depending on hedonic aspects of foods.
Dr. Elena Makarova (PhD – biology) now is a senior researcher in the Laboratory of Physiological Genetics in the Institute of Cytology and Genetics (Novosibirsk, Russia). Her researches focus on the studies of sex-specific influence of maternal leptin on metabolic characteristics in progeny of rodents. She with her colleagues found maternal leptin retarded obesity development in male progeny and improves glucose metabolism in progeny of both sexes in mice.
Maternal obesity increases the risk of obesity in offspring. Leptin is increased in obese animals, and elevation of maternal leptin may affect the metabolic phenotype of the offspring. We explore the effects of leptin elevation during midpregnancy on the offspring metabolic phenotypes, foetal growth, and placental gene expression. C57BL mice received a single injection of leptin or saline on pregnancy day 12. Body weight (BW) was measured weekly in offspring, which consumed standard show or palatable food, and the mRNA expression of glucose and amino acid transporters, insulin-like growth factor 2 and its receptor was measured 3 h, and the placental and foetal weights were measured 24 h after the injection. The offspring born to leptin-treated mothers exhibited growth retardation before and catch-up growth after weaning, and mature male offspring had an increased BW on a standard diet. Prenatal exposure to leptin did not influence the obesity development but prevented the development of obesity-associated hyperglycemia. The leptin injection decreased the foetal weight by 5% and the placental mRNA level of amino acid transporter SNAT2. The results suggest that elevation of maternal leptin in midpregnancy has positive effect on glucose metabolism in mature offspring and this effect is associated with leptin influence on fetal growth and amino acid transporter expression in placentas. (Supported by the RFBR, Grant 17-04-01357).