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Marc Schneeberger, Ramon Gomis, and Marc Claret

energy balance through behavioral, autonomic, and endocrine outputs. These sophisticated biological programs are influenced by multiple factors, including environmental, genetic, and epigenetic mechanisms. The immense complexity of these systems

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Ruben Nogueiras, Sulay Tovar, Sharon E Mitchell, Perry Barrett, D Vernon Rayner, Carlos Dieguez, and Lynda M Williams

hypothalamus ( Graham et al. 2003 ). These nuclei are important in controlling circadian rhythms, appetite and energy balance ( Takahashi & Zatz 1982 , Williams et al. 2001 ). In contrast, NMU expression in the rat is limited to the SCN, relatively few

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Shin-ya Ueda, Takahiro Yoshikawa, Yoshihiro Katsura, Tatsuya Usui, Hayato Nakao, and Shigeo Fujimoto

variations in appetite and post-exercise energy intake (EI), leading to negative energy balance (EB; Blundell & King 1998 , Hubert et al . 1998 ). Recently, there has been growing concern that appetite and energy homeostasis are controlled by a variety of

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Pryscila D S Teixeira, Angela M Ramos-Lobo, Mariana Rosolen Tavares, Frederick Wasinski, Renata Frazao, and Jose Donato Jr

Introduction The adipocyte-derived hormone leptin has fundamental importance on the regulation of body weight and feeding. In this respect, the brain uses circulating leptin levels as a major signal to indicate the balance between energy

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Sharon E Mitchell, Ruben Nogueiras, Kellie Rance, D Vernon Rayner, Sharon Wood, Carlos Dieguez, and Lynda M Williams

Introduction Studies of rodents with either single gene mutations or gene knockouts have led to the discovery of a number of key components of the hypothalamic appetite and energy balance control system ( Williams et al. 2001

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Christian Doyon, Pierre Samson, Josée Lalonde, and Denis Richard

of the CRF 1 receptor in the regulation of energy balance, these antagonists may also prove useful in the pharmacological treatment of obesity, especially in cases where obesity is associated with hyperactivity of the stress axis. Animal

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K Scrimgeour, M J Gresham, L R Giles, P C Thomson, P C Wynn, and R E Newman

remaining one-third from the small intestine ( Peeters 2005 ). Ghrelin has been shown to have numerous physiological functions that affect energy balance ( Horvath et al . 2001 , Govoni et al . 2005 ), gastrointestinal motility and secretion ( Masuda et

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AR Assali, A Ganor, Y Beigel, Z Shafer, T Hershcovici, and M Fainaru

Weight reduction is recommended for the treatment of subjects with insulin resistance (IR) syndrome; however, the relative importance of the decrease in body fat or the negative energy balance achieved during a hypo-energetic diet in the improvement of this metabolic syndrome is still debated. Therefore, we undertook to study their relative impact on amelioration of the metabolic abnormalities associated with IR in obese subjects. Twelve obese subjects (six males and six females, mean+/-s.d. body mass index 36.1+/-4.7 kg/m(2)) aged 38-57 years were investigated. During the first phase they were fed a hypo-energetic diet for 6 weeks (week 0-6). During the second phase, lasting 4 weeks (week 6-10) they consumed an iso-energetic diet. During the third phase (week 10-16) the subjects were put again on a hypo-energetic diet. Insulin sensitivity (SI) was assessed by an insulin-enhanced, frequently sampled i.v. glucose tolerance test with minimal model analysis. All subjects reduced weight during both hypo-energetic periods: 5.49+/-0.75 and 2.32+/-0.37%, means+/-s.e.m., P<0.005, week 0-6 and 10-16 respectively. One-third of this loss was achieved within the first week of each period. SI increased by 353+/-121 and 147+/-38% (P<0.005), means+/-s.e.m., at the end of both hypo-energetic periods (week 6 vs 0 and 16 vs 10 respectively). Two-thirds of this improvement were observed within the first week of each period (week 1 vs 0 and 11 vs 10 respectively). During the iso-energetic weight-maintaining period (week 10 vs 6), SI decreased by 43.5+/-7.9% (P<0.002). Serum levels of leptin and triglyceride followed a similar pattern, but to a lesser extent. It may be concluded that negative energy balance is more effective when compared with maintaining a stable lower weight in achieving an improvement in the metabolic parameters of the IR syndrome.

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SS Block, WR Butler, RA Ehrhardt, AW Bell, ME Van Amburgh, and YR Boisclair

Dairy cows suffer from an intense energy deficit at parturition due to the onset of copious milk synthesis and depressed appetite. Despite this deficit, maternal metabolism is almost completely devoted to the support of mammary metabolism. Evidence from rodents suggests that, during periods of nutritional insufficiency, a reduction in plasma leptin serves to co-ordinate energy metabolism. As an initial step to determine if leptin plays this role in periparturient dairy cows, changes in the plasma concentration of leptin were measured during the period from 35 days before to 56 days after parturition. The plasma concentration of leptin was reduced by approximately 50% after parturition and remained depressed during lactation despite a gradual improvement in energy balance; corresponding changes occurred in the abundance of leptin mRNA in white adipose tissue. To determine whether negative energy balance caused this reduction in circulating leptin, cows were either milked or not milked after parturition. Absence of milk removal eliminated the energy deficit of early lactation, and doubled the plasma concentration of leptin. The plasma concentration of leptin was positively correlated with plasma concentrations of insulin and glucose, and negatively correlated with plasma concentrations of growth hormone and non-esterified fatty acids. In conclusion, the energy deficit of periparturient cows causes a sustained reduction in plasma leptin. This reduction could benefit early lactating dairy cows by promoting a faster increase in feed intake and by diverting energy from non-vital functions such as reproduction.

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Victoria Diedrich, Elena Haugg, Carola Dreier, and Annika Herwig

: maintaining energy balance during winter. Studying seasonal adaptations of mammals is fascinating because they are very extreme, tightly regulated but also fully reversible. Understanding the underlying regulatory mechanisms will largely contribute to our