Influence of short- and long-term treadmill exercises on levels of ghrelin, obestatin and NPY in plasma and brain extraction of obese rats

This study aims to clarify the effects of exercise on levels of appetite regulatory hormones in plasma and hypothalamus of obese rats. Diet-induced obese rats undergo short- (40 min) and long-term (40 min, 5 days/week for 8 weeks) exercises. The rats ran at a speed of 20 m/min on a 5° slope treadmill. Rats undergoing short-term exercise were divided into C, E0, E1, E3, E12, and E24. Rats undergoing long-term exercise (LE) were compared to long-term control (LC). Concentrations of ghrelin, obestatin, and neuropeptide Y (NPY) were measured using radio immuno-assay. Expression of ghrelin receptor (GHSR-1a), putative obestatin receptor (GPR-39), and NPY in the hypothalamus was measured by quantitative RT-PCR. After short-term exercise, the plasma concentrations of ghrelin and obestatin were not changed, but NPY decreased. Ghrelin and obestatin in the hypothalamus decreased, and recovered 12 until 24 h. NPY increased and recovered after 24 h. Expression of GHSR-1a and NPY was not changed and GPR-39 was not observed. In LE, these changes are different in plasma and hypothalamus. It would be concluded appetite and body weight of obese rats are decreased by exercise through reduced level of ghrelin in the hypothalamus. Obestatin seems to have no effect in exercise-induced change in appetite.     

胰高血糖素样肽-1与下丘脑食欲调节

下丘脑是神经内分泌中枢,也是食欲调节中枢.胰高血糖素样肽-1(GLP-1)是一种胃肠道激素,能够在下丘脑表达并对食欲中枢有调节作用.GLP-1作为一种厌食信号肽,通过促肾上腺皮质激素释放激素(CRH)通路、组胺神经元通路、神经肽和刺鼠相关蛋白(NPY/AgRP)以及前阿片黑皮质素原和可卡因-苯丙胺调节转录肽(POMC/CART)通路及AMP活化蛋白激酶(AMPK)介导的摄食负反馈信号通路参与调节摄食活动.针对GLP-1调节摄食作用机制的研究对肥胖、胰岛素抵抗和2型糖尿病的防治有重要的理论意义.     

Nicotine withdrawal increases body weight, neuropeptide Y and Agouti-related protein expression in the hypothalamus and decreases uncoupling protein-3 expression in the brown adipose tissue in high-fat fed mice

Nicotine is known to decrease body weight in normal rodents and human smokers, whereas nicotine withdrawal or smoking cessation can increase body weight. We have found that mice fed a high fat diet do not show the anorectic effect of chronic nicotine treatment, but do increase their body weight following nicotine withdrawal. Nicotine withdrawal is accompanied by increased expression of the orexigenic peptides neuropeptide Y and Agouti-related protein in the hypothalamus, and decreased expression of the metabolic protein uncoupling protein-3 in brown adipose tissue. These data suggest that diet can influence the ability of nicotine to modulate body weight regulation and demonstrate that chronic nicotine exposure results in adaptive changes in central and peripheral molecules which regulate feeding behavior and energy metabolism.     

Caffeine Transiently Affects Food Intake at Breakfast

Background

Caffeine is frequently added to dietary supplements with claims it facilitates weight loss.

Appetite loss may be induced by lower serum ghrelin and higher serum leptin concentrations in subarachnoid hemorrhage patients

Background

Patients with aneurysmal subarachnoid hemorrhage (SAH) typically develop appetite loss. However, the mechanisms regulating appetite are not understood. Ghrelin and leptin, both of which signal nutritional status and energy storage levels to the hypothalamus, are essential elements of the appetite system. Thus, the goal of this study was to investigate the relationship between appetite and ghrelin and leptin concentrations in patients with SAH.

Methods

Blood plasma or serum profiles and appetite status were measured in 19 patients with SAH who underwent aneurysmal clipping within 48 hours of SAH onset. Appetite status was measured using dietary oral calorie intake. All outcome variables were measured at an early (day 3) and late (day 8) time point after SAH onset (day 0).

Results

Of the 19 patients studied, 6 (31.6%) showed lower dietary oral calorie intake at the late time point than at the early time point. In these patients with appetite loss, plasma hemoglobin (P < 0.02), albumin (P < 0.01), glucose (P < 0.01), plasma insulin (P < 0.04), and serum ghrelin (P < 0.03) concentrations were lower at the late time point than at the early time point. Serum leptin was higher at the late time point than at the early time point (P < 0.02).

Conclusion

In SAH patients, appetite loss may be induced by lower serum ghrelin and higher serum leptin concentrations resulting from high plasma glucose and insulin levels due to a catecholamine surge following SAH.     

Short-term dietary supplementation with fructose accelerates gastric emptying of a fructose but not a glucose solution

ObjectiveShort-term dietary glucose supplementation has been shown to accelerate the gastric emptying rate of both glucose and fructose solutions. The aim of this study was to examine gastric emptying rate responses to monosaccharide ingestion following short-term dietary fructose supplementation.MethodsThe gastric emptying rate of a fructose solution containing 36 g of fructose and an equicaloric glucose solution containing 39.6 g glucose monohydrate were measured in 10 healthy non-smoking men with and without prior fructose supplementation (water control) using a randomized crossover design. Gastric emptying rate was assessed for a period of 1 h using the [¹³C]breath test with sample collections at baseline and 10-min intervals following drink ingestion. Additionally, appetite ratings of hunger, fullness, and prospective food consumption were recorded at baseline and every 10 min using visual analog scales.ResultsIncreased dietary fructose ingestion resulted in significantly accelerated half-emptying time of a fructose solution (mean = 48, SD = 6 versus 58, SD = 14 min control; P = 0.037), whereas the emptying of a glucose solution remained unchanged (mean = 85, SD = 31 versus 78, SD = 27 min control; P = 0.273). Time of maximal emptying rate of fructose was also significantly accelerated following increased dietary fructose intake (mean = 33, SD = 6 versus 38, SD = 9 min control; P = 0.042), while it remained unchanged for glucose (mean = 45, SD = 14 versus 44, SD = 14 min control; P = 0.757). No effects of supplementation were observed for appetite measures.ConclusionThree d of supplementation with 120 g/d of fructose resulted in an acceleration of gastric emptying rate of a fructose solution but not a glucose solution.     

A Mediterranean-like breakfast affects energy intake and appetite-related feelings

Energy intake and appetite feelings after the consumption of two different types of breakfast, a high-fiber, traditional, Mediterranean-type breakfast and a low-fiber, Western-type breakfast were compared. Sixteen non-obese young men received the two treatments on separate days: the Mediterranean- and the Western-type breakfasts were isocaloric, similar in volume and macronutrient content, but different in fiber content. Following a 4-hour fast, subjects offered an ad libitum lunch. Food consumed and subjective feelings of hunger, fullness, and desire to eat were evaluated. Energy intake in the ad libitum lunch was significantly lower after the Mediterranean-type, compared to the Western-type breakfast, adjusting for previous day’s energy intake (1488?±?468 versus 1674?±?416?kcal, respectively), whereas no energy compensation was made throughout the day. Furthermore, those who had the Mediterranean-type breakfast reported lower values in the desire to eat during study's course. These findings propose a fulfilling effect of a traditional, Mediterranean, high in fiber breakfast.     

Apelin-36通过中枢途径对大鼠摄食、胃肠运动调节作用的研究

目的探讨Apelin-36对大鼠摄食行为、胃肠运动的影响以及可能的途径。 方法健康成年雄性SD大鼠共88只。采用随机数字表法从中随机选取32只大鼠,侧脑室埋管并注射生理盐水或Apelin-36(10 nmol/L) 3 μl、6 μl、9 μl,每组8只,测定48 h摄食量。采用随机数字表法选取16只大鼠侧脑室埋管并注射生理盐水或Apelin-36(10 nmol/L) 9 μl,每组8只,计算胃排空率。采用随机数字表法选取16只大鼠,麻醉后在十二指肠降部放置水囊,连接压力感受器,在体检测侧脑室注射生理盐水或Apelin-36后十二指肠运动变化情况,每组8只。随机数字表法选取16只大鼠,在体检测结肠的运动变化情况,每组8只。另外,随机数字表法选取8只大鼠,剖离胃体、十二指肠、结肠平滑肌条,离体条件下检测生理盐水或Apelin-36对平滑肌运动的影响。 结果48 h累计单位体重摄食结果显示,Apelin-36 3 μl、6 μl、9 μl组摄食量分别为(147.75±33.06)g/Kg、(127.69±23.94)g/Kg、(99.91±18.48)g/Kg,少于生理盐水组[(160.84±28.51)g/kg],并依次递减,差异有统计学意义(F＝7.99,P<0.01),Apelin-36 9 μl组摄食量较生理盐水组、Apelin-36 3 μl组降低,均差异有统计学意义(t＝6.49, 5.10;均P<0.01);Apelin-36 9 μl组黑夜(24 h)累计单位摄食量[(45.08±11.86)g/Kg],明显少于生理盐水组[(70.77±23.23)g/Kg](t＝4.44,P<0.05)。侧脑室注射Apelin-36后大鼠胃排空率为(68.10±6.03)%,较生理盐水组[(79.21±7.94)%]降低,差异有统计学意义(t＝3.15,P<0.01)。侧脑室注射Apelin-36后十二指肠降部平滑肌运动幅度降低至(0.29±0.08)g,明显低于生理盐水组[(0.81±0.16)g](t＝8.36,P<0.01);而远端结肠的运动幅度[(0.20±0.09)g],较生理盐水组[(0.22±0.08)g]差异无统计学意义(t＝0.31,P>0.05)。离体条件下Apelin-36对胃体[(0.19±0.06)g]、十二指肠[(0.09±0.02)g]、结肠平滑肌运动[(0.07±0.01)g]均无显著影响,与生理盐水组[(0.19±0.06)g、(0.08±0.01)g、(0.06±0.02)g]比较,均差异无统计学意义(t＝0.13, 0.22, 0.41;均P>0.05)。 结论侧脑室注射Apelin-36可减少摄食,抑制胃排空、十二指肠运动,但离体条件下Apelin-36对胃肠道平滑肌运动无直接影响。     

胃促生长素的胃肠动力学作用研究进展

胃促生长素(ghrelin)对胃肠动力作用机制是目前研究热点。ghrelin在外周作为饥饿信号分子可提高食欲、增加摄食,诱发移行性复合运动III相提前出现,加速胃排空。最近研究表明,ghrelin基因还可编码合成另一胃肠动力作用相反的肽—obestatin;下丘脑、迷走神经、肠神经系统参与了ghrelin对胃肠动力的生理调节作用。