Thermoregulatory role of ghrelin in the induction of torpor under a restricted feeding condition

Ghrelin, a circulating orexigenic hormone secreted from the stomach, stimulates appetite and food intake by activating the hypothalamic arcuate nucleus. Administration of exogenous ghrelin exerts anabolic effects, causing weight gain, increased adiposity, and decreased metabolism. Body temperature (BT), which is determined by the balance of heat production and heat loss, must be strictly regulated to maintain proper cellular function and metabolism. However, the role of ghrelin in thermoregulation remains unclear. In this study, we found that ghrelin was essential for decreasing BT when mice are placed under calorie restriction. Elevated ghrelin concentrations induced by fasting correlated with significant decreases in BT, a hibernation-like state called torpor. Ghrelin-deficient (Ghrl−/−) animals could not enter torpor. The BT of Ghrl−/− mice also remained high under restricted feeding, but the animals gradually entered precipitous hypothermia, indicating thermoregulatory impairment. These effects of ghrelin on thermoregulation were the result of suppression of sympathetic nervous system activity input to brown adipose tissue; in the absence of ghrelin, it was not possible to suppress uncoupling protein 1 (ucp1) expression and decrease BT in low-energy states. Together, these findings demonstrate that ghrelin is an essential circulating hormone involved in lowering BT.

Effects of bearing lubrication conditions on rotor dynamic behavior

Usually, rotor dynamic analyses do not consider the effects of the lubricant supply condition, although this is an important aspect of journal bearing performance. Therefore, this work has implemented a mass-conserving model to realistically describe the oil feeding condition and evaluate its influence on rotor dynamics. This analysis was carried out by varying feeding pressure and groove position and the results indicate that the oil supply conditions significantly influence the bearing performance and affect the dynamic behavior of the entire rotor. In general, lower flow rates lead to a bearing with a greater stability region, as observed mainly in the bearing with a groove at 270° and, on the other hand, the increase in feeding pressure reduces the instability threshold.

Growth Performance of Arsi, Borana, Harar and HF-Crossbred Bulls Finished under Similar Feeding Condition

The study was conducted to evaluate the fattening performance of Arsi, Borana, Harar and HF-Crossbred bulls finished under similar feeding condition at the beef farm in Haramaya University. A total of 24 bulls with age categories of 2-3 and 4-5 years were used in the complete block design for the experiment. Total mixed ration was provided at 3% of their BW during experimental periods. The average daily weight gain of the four breeds range from 0.49 to 0.71 kg. Feed conversion efficiency also ranges from 0.11 – 0.15. Simple linear regression models were used to explore the relationship between live body weight change and change in BCS as well as seven linear body measurements for all age groups. An average change for a unite of body condition score was equivalent to 20.3, 20.61, 22.42 and 27.78kg for Borana, Arsi, Harar and HF-crossbred bulls respectively. BCS was significantly (P<0.01) influenced by breeds. There was a significant (P<0.05) breed by age interaction effect on the initial body condition score of the four breeds. There was a significant and positive strong association between change in BW and BCS. There was a significant and strong correlation between change in BW and change in Total topline, neck length, heart girth, flank circumference and rump length having correlation coefficient ranges (r = 0.57 to 0.97). Higher (P<0.01) net profit of 7,380.47 ETB per head was recorded by Borana bulls followed by Harar bulls, Arsi and HF Crossbred with net profit of 5,406.86, 5193.29 and 3,384.98 ETB per head respectively.

The Effect of Choline on DNA Methylation in the Hippocampus of the Offspring of Gestational Diabetes Mellitus (GDM) Mice

Objectives The objective of this project is to determine the effects of choline supplementation on DNA methylation in the hippocampus of the offspring from mouse dams with GDM. Methods In this study, female mice were divided into four groups: high fat (HF) feeding (to induce GDM), HF with choline supplementation, normal fat (NF) control and NF with choline supplementation. The experimental groups followed their diets and supplements for 4 weeks before timed mating and throughout gestation. Thereafter, they were fed the NF diet during lactation. After weaning, the offspring were fed the HF diet for 6 weeks before dissection. Brain hippocampus was then dissected for DNA extraction and global DNA methylation analysis. Results Global DNA methylation was increased in the NF choline supplemented group versus the NF control group (P = 0.056); however, there were no differences between the HF choline versus the HF or NF control groups (P = 0.992). Conclusions In summary, there was an interaction between maternal HF feeding and choline supplementation in influencing global DNA methylation. Maternal HF feeding eliminated the increase in offspring hippocampal DNA methylation by choline supplementation observed under the NF feeding condition. Funding Sources NIGMS.

Absence of GIP secretion alleviates age-related obesity and insulin resistance

Glucose-dependent insulinotropic polypeptide (GIP) is an incretin secreted from enteroendocine K cells after nutrient ingestion. Fat strongly induces GIP secretion, and GIP hypersecretion is involved in high-fat diet-induced obesity and insulin resistance. Aging also induces GIP hypersecretion, but its effect on body weight gain and insulin sensitivity remains unclear. In the present study, we investigated the effect of GIP on age-related body weight gain and insulin resistance using GIP-knockout homozygous (GIP−/−) and heterozygous (GIP+/−) mice, which have entirely absent and 50% reduced GIP secretion compared to wild-type (WT) mice, respectively. Under 12% fat-containing normal diet feeding condition, body weight was significantly lower in GIP−/− mice compared to that in WT and GIP+/− mice from 38 weeks of age, while there was no significant difference between WT and GIP+/− mice. Visceral and s.c. fat mass were also significantly lower in GIP−/− mice compared to those in WT and GIP+/− mice. During oral glucose tolerance test, blood glucose levels did not differ among the three groups. Insulin levels were significantly lower in GIP−/− mice than those in WT and GIP+/− mice. During insulin tolerance test, GIP−/− mice showed higher insulin sensitivity than that of WT and GIP+/− mice. Adiponectin mRNA levels were increased and leptin mRNA levels tended to be decreased in adipose tissue of GIP−/− mice. These results demonstrate that GIP is involved in age-related obesity and insulin resistance and that inhibition of GIP secretion alleviates age-related fat mass gain and insulin resistance under carbohydrate-based diet feeding condition.