Different responses of circulating ghrelin, obestatin levels to fasting, re-feeding and different food compositions, and their local expressions in rats

Obestatin, a sibling of ghrelin derived from preproghrelin, opposes several physiological actions of ghrelin. Our previous study has demonstrated that both plasma ghrelin and obestatin levels were decreased significantly 2h after food intake in human. To further expand current knowledge, we investigated the temporal profiles of their levels in ad libitum fed rats, 48h fasted rats and 48h fasted rats refed 2h with a standard chow, crude fiber, 50% glucose or water, and their expressions in stomach, liver and pancreatic islets immunohistochemically. Plasma ghrelin and obestatin levels were measured by EIA. Plasma leptin, insulin and glucose levels were also evaluated. Both plasma ghrelin and obestatin levels increased significantly in fasted rats compared with ad libitum fed rats. The ingestion of standard chow produced a profound and sustained suppression of ghrelin levels, whereas plasma obestatin levels decreased significantly but recovered quickly. Intake of crude fiber or 50% glucose, however, produced a more profound and sustained suppression of obestatin levels, though they had relatively less impact on ghrelin levels. Plasma glucose was the only independent predictor of ghrelin levels, obestatin levels, and ghrelin to obestatin ratios. Obestatin immunoreactivity was detected in the fundus of stomach, liver and pancreatic islets, with roughly similar patterns of distribution to ghrelin. These data show quantitative and qualitative differences in circulating ghrelin and obestatin responses to the short-term feeding status and nutrient composition, and may support a role for obestatin in regulating metabolism and energy homeostasis.     

The Analysis of Copper,Selenium, and Molybdenum Contents in Frequently Consumed Foods and an Estimation of Their Daily Intake in Korean Adults

This study aimed to analyze the amounts of copper, selenium, and molybdenum among trace minerals in foods and to evaluate their daily intakes in Korean adults. Contents of copper, selenium, and molybdenum in 366 varieties of foods commonly consumed by Koreans were analyzed using inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry, techniques with low detection limits as well as high reproducibility and precision. Next, we evaluated the status of trace mineral intake using the 24-h recall method after conducting anthropometric measurements on 249 male and 344 female adults aged 20 or older. The average daily energy intake for males was 7,452.8 kJ, significantly higher than the 6,118.3 kJ for females (p < 0.001). The average daily copper, selenium, and molybdenum intakes by males were 1,156.7, 135.5, and 12.2 μg, respectively, compared to 1,028.5, 122.9, and 10.1 μg, respectively, by females. In males, the intake levels of copper and molybdenum were both significantly higher than in females. By continuously evaluating intake levels in this manner, it is anticipated that reference intakes of trace minerals will be established.     

Tendency Toward Eveningness Is Associated With Unhealthy Dietary Habits

Subjects with higher preference for evening hours in daily activities (eveningness) have been repeatedly shown to practice adverse health behaviors as compared to those preferring morning hours (morningness). However, associations between chronotype and dietary intake have not been explored intensively. The authors explored whether the human chronotype is associated with food and nutrient intakes in a random sample of the population aged 25 to 74 yrs. The cross-sectional study included 4493 subjects from the National FINRISK 2007 Study. Chronotype was assessed using a shortened version of Horne and Östberg's Morningness-Eveningness Questionnaire. Diet was assessed using a validated food frequency questionnaire. Associations between morningness-eveningness (ME) score and dietary intakes were analyzed by linear regression and difference between lowest (eveningness) and highest (morningness) ME score quintiles by Tukey's test. In the multivariable model, intakes of whole grain, rye, potatoes, and vegetables and roots decreased, whereas those of wine and chocolate increased with lower ME scores. Participants in the lowest ME score quintile consumed less fish (p?<?.001) and fruits (p?=?.025) and more chocolate (p?=?.001) and soft drinks (p?=?.015) compared to the highest quintile. No linear association was found between ME score and total energy intake. In regression analyses, intake of alcohol (as a percentage of total energy intake; E%) and sucrose (E%) increased, whereas intake of carbohydrates (E%), protein (E%), fiber, folic acid, and sodium decreased with lower ME scores. Furthermore, participants in the lowest ME score quintile ingested more fat (E%) (p?<?.001) and less vitamin D (p?<?.001) compared to the highest quintile, even though no linear trend between ME score and these nutrients emerged. In conclusion, these results support existing evidence that individuals with circadian preference toward eveningness have less healthy lifestyles, such as unfavorable dietary habits, than those with tendency toward morningness, which could put them at higher risk of several chronic diseases. (Author correspondence: noora.kanerva@thl.fi)     

Feeding low-fat milk during infancy

Despite the widespread agreement that low-fat milk should not be used during infancy, there is a sizable portion of infants in the United States who were fed a diet that included low-fat milk (less than or equal to 2% fat). In 1985, 14% of infants 8 months old, 20% of infants 10 months old, and 32% of infants 12 months old were fed low-fat milk. The reasons given most often by mothers for low-fat milk use was their consideration that low-fat milk has less fat than whole cow's milk and that low-fat milk use was recommended/suggested by their physician. Nutrient intakes of infants fed low-fat milk are compared to those of infants fed whole cow's milk and infant formula. Except for fat, nutrient intakes of infants fed low-fat milk or whole cow's milk were similar. A majority of infants fed either low-fat milk or whole cow's milk received amounts of sodium, potassium, and chloride that exceeded the recommended safe and adequate ranges and amounts of iron below the RDA. These data are considered in relation to dietary requirements during infancy.     

Are Girls Good and Boys Bad for Parental Longevity?

Using historical data from the Utah Population Database, this analysis finds significant, consistent, but small adverse mortality effects for mothers after age 50 who had mostly sons. Examination of age-dependent effects indicates that this association increases with mother’s age. Additionally, mothers who had mostly daughters faced mortality risks that increased with age. Offspring sex composition did not have a significant effect on paternal mortality. Interaction analyses were conducted to examine the effect of offspring sex composition with regard to historical period, residential location, socioeconomic status, and childhood survival. No other interactions were found to be statistically significant. Having mostly boys remained detrimental to maternal mortality regardless of childhood survival.

Experimentally induced sickness decreases food intake, but not hoarding, in Siberian hamsters (Phodopus sungorus)

A wide range of physiological and behavioral alterations occur in response to sickness. Sickness behaviors, rather than incidental by-products or side-effects of acute illness, serve as adaptive functional responses that allow animals to cope with a pathogenic challenge. Among the more salient sickness behaviors is a reduction in food intake; virtually all sick animals display marked decreases in this behavior. Food intake, however, is only one component of the food-related behavioral repertoire. For many mammalian species, food hoarding represents a substantial portion of the total energetic budget. Here we tested the effects of experimental sickness on food hoarding and food intake in a naturally food hoarding species, Siberian hamsters (Phodopus sungorus). Adult male and female hamsters received injections of lipopolysaccharide (LPS) to induce sickness or control injections. LPS-induced sickness resulted in a marked decrease in food intake in both males and females, but did not decrease hoarding in either sex. These results support previous findings suggesting that food hoarding and food intake appear to be differentially regulated at the physiological level.     

Cholecystokinin octapeptide decreases intake of solid food in man

Cholecystokinin octapeptide (CCK-OP) was reported to decrease the intake of liquid food in lean and in obese man. This study investigated the effect of CCK-OP on the consumption of real life food, i.e., of standardized sandwiches. Sixteen young non-obese females and males participated, after an overnight fast, each in two experiments. After a basal 30 min, saline or CCK-OP, 1.5 or 3.0 Ivy Dog Units/kg body weight/15 min, was infused in random double blind fashion, while sandwiches were placed in front of the subjects. For the next three 15-min periods, the subjects were instructed to eat as much as they liked. In the first 15 min after 3.0 as well as 1.5 U CCK-OP/kg/15 min significantly fewer sandwiches (50 and 17 percent) were eaten than after saline (p less than 0.01 and p less than 0.05) and less hunger was reported (p less than 0.02 and p less than 0.05). Self-reported activation decreased only with 3.0 U CCK-OP (p less than 0.005). Reports of well-bring , electroencephalogram, heart rate, and respiration were not altered. The results support the notion that CCK is involved in the regulation of food intake.     

Food-Entrained Feeding and Locomotor Circadian Rhythms in Rats Under Different Lighting Conditions

It has been suggested that two endogenous timekeeping systems, a light-entrainable pacemaker (LEP) and a food-entrainable pacemaker (FEP), control circadian rhythms. To understand the function and interaction between these two mechanisms better, we studied two behavioral circadian rhythmicities, feeding and locomotor activity, in rats exposed to two conflicting zeitgebers, food restriction and light-dark cycles. For this, the food approaches and wheel-running activity of rats kept under light-dark (LD) 12:12, constant darkness (DD), or constant light (LL) conditions and subjected to different scheduled feeding patterns were continuously recorded. To facilitate comparison of the results obtained under the different lighting conditions, the period of the feeding cycles was set in all three cases about Ih less than the light-entrained or free-running circadian rhythms. The results showed that, depending on the lighting conditions, some components of the feeding and wheel-running circadian rhythms could be entrained by food pulses, while others retained their free-running or light-entrained state. Under LD, food pulses had little influence on the light-entrained feeding and loco-motor rhythms. Under DD, relative coordination between free-running and food-associated rhythms may appear. In both cases, the feeding activity associated with the food pulses could be divided into a prominent phase-dependent peak of activity within the period of food availability and another afterward. Wheel-running activity mainly followed the food pulses. Under LL conditions, the food-entrained activity consisted mainly of feeding and wheel-running anticipatory activity. The results provide new evidence that lighting conditions influence the establishment and persistence of food-entrained circadian rhythms in rats. The existence of two coupled pacemakers, LEP and FEP, or a multioscillatory LEP may both explain our experimental results.     

Food-Entrained Feeding and Locomotor Circadian Rhythms in Rats Under Different Lighting Conditions

It has been suggested that two endogenous timekeeping systems, a light-entrainable pacemaker (LEP) and a food-entrainable pacemaker (FEP), control circadian rhythms. To understand the function and interaction between these two mechanisms better, we studied two behavioral circadian rhythmicities, feeding and locomotor activity, in rats exposed to two conflicting zeitgebers, food restriction and light-dark cycles. For this, the food approaches and wheel-running activity of rats kept under light-dark (LD) 12:12, constant darkness (DD), or constant light (LL) conditions and subjected to different scheduled feeding patterns were continuously recorded. To facilitate comparison of the results obtained under the different lighting conditions, the period of the feeding cycles was set in all three cases about Ih less than the light-entrained or free-running circadian rhythms. The results showed that, depending on the lighting conditions, some components of the feeding and wheel-running circadian rhythms could be entrained by food pulses, while others retained their free-running or light-entrained state. Under LD, food pulses had little influence on the light-entrained feeding and loco-motor rhythms. Under DD, relative coordination between free-running and food-associated rhythms may appear. In both cases, the feeding activity associated with the food pulses could be divided into a prominent phase-dependent peak of activity within the period of food availability and another afterward. Wheel-running activity mainly followed the food pulses. Under LL conditions, the food-entrained activity consisted mainly of feeding and wheel-running anticipatory activity. The results provide new evidence that lighting conditions influence the establishment and persistence of food-entrained circadian rhythms in rats. The existence of two coupled pacemakers, LEP and FEP, or a multioscillatory LEP may both explain our experimental results.     

鱼腥藻(Anabaena sp．)营养成分分析

研究分析了混合鱼腥藻粉的营养成分,结果表明混合鱼腥藻粉蛋白质含量为４０．５％;氨基酸组成符合联合国粮农卫生组织规定的标准;并含有较丰富的糖类、脂肪酸、无机元素和色素。证实了鱼腥藻可以作为蛋白饲料资源开发和利用。     

Do Obese Eat Faster Than Lean Subjects? Food Intake Studies in Pima Indian Men

Food intake rate has previously been derived from observation of eating behavior in laboratory settings or in public eating establishments. Although it has been suggested that obese individuals eat faster than lean individuals, observations of such an “obese eating style” have yielded mixed results. In the present study, the relationship between ad-libitum food intake rate and obesity was evaluated over 4 days on a metabolic ward in 28 healthy Pima Indian men (Mean ± SD; 29 ± 7 y, 100.4 ± 27.1 kg, 33 ± 10% body fat) using an automated food selection system containing a large variety of foods . Total energy intake averaged 18829 ± 3299 kJ/d consisting of 47 ± 4,40 ± 3, and 13 ± 1 percent of carbohydrate, fat and protein, respectively. The average meal duration was 25 ± 7 min. Food intake rate was 68 ± 21 g/min while carbohydrate, fat and protein intake rates were 23 ± 6, 9 ± 3 and 6 ± 2 g/min, respectively. Food intake rate correlated negatively with %body fat (1=0.61, P<0.01). Similar relationships were found between the intake rates of carbohydrate, fat and protein and body fatness. Only prospective studies will indicate whether a slow food intake rate may contribute to the etiology of obesity by possibly reducing satiety .     

侧脑室注射orexin-A对大鼠昼夜摄食的影响

目的:探讨侧脑室注射orexin-A对大鼠昼夜摄食的影响。方法:将Wistar大鼠随机分组,采用单剂量侧脑室注射和连续侧脑室注射以及外周注射法,分别于日间和夜间给药,测量大鼠24小时内各阶段的摄食量以及相应生化指标。结果:在光照期间,侧脑室微量注射orexin-A,大鼠4小时内摄食量显著增加(P0.05),且呈剂量依赖关系(P0.05)。在夜间初期(18:00)侧脑室注射orexin-A,大鼠食物摄入量无显著差异(P0.05)。但在中午12:00给予侧脑室注射orexin-A,注射后4小时内大鼠摄食量显著高于NS对照组(P0.05)。连续8日给予orexin-A侧脑室注射,可使注射后日间摄食量显著增加(P0.05),而夜间摄食量显著减少(P0.05),但24小时内总的摄食量不变(P0.05)。orexin-A并未改变棕色脂肪组织温度、末梢血糖、血浆瘦素等指标的水平。结论:orexin-A对大鼠摄食的调节具有昼夜节律性。     

结节乳头体在小鼠运动和摄食中的作用及机制研究

目的:探讨结节乳头体在小鼠运动和摄食中的作用及机制。方法:选择雄性ddy小鼠,180-200 g,通过单侧植入电极损毁TMN-E2区。采用荧光金逆行追踪方法检测小鼠Me5与TMN之间的神经纤维联系;采用免疫组化方法检测小鼠TMN中组氨酸脱羧酶(HDC)免疫反应阳性细胞数;采用旷场试验箱记录小鼠全天、夜间以及白天的自主活动和摄食摄水;采用PCR检测小鼠穹窿周和下丘脑外侧区的orexin m RNA的表达。结果:荧光金逆行追踪实验显示小鼠Me5可向TMN-E2发出神经纤维投射。单侧TMN损毁,两侧TMN中HDC反应阳性细胞显著减少(P0.05),且损毁侧比未损毁侧HDC免疫反应阳性细胞数减少(P0.05)。TMN损毁对小鼠24 h自主活动和摄食摄水无明显影响。单侧TMN损毁,小鼠从暗期到光期的自主活动和摄食摄水显著减少(P0.05)。单侧TMN损毁,小鼠正常昼夜活动摄食节律无显著改变。单侧TMN损毁,小鼠穹隆周和下丘脑外侧区白天的orexin m RNA表达显著减少(P0.05)。结论:Me5与TMN之间存在神经通路,该通路可能通过调节穹隆周区或下丘脑外侧区的orexin神经元的激活从而调控摄食及相关行为的昼夜节律。     

Effects of nutrient recycling by zooplankton and fish on phytoplankton communities

In laboratory experiments we tested the hypothesis that nutrients supplied by fish and zooplankton affect the structure and dynamics of phytoplankton communities. As expected from their body size differences, fish released nutrients at lower mass-specific rates than Daphnia. On average, these consumers released nutrients at similar N:P ratios, although the ratios released by Daphnia were more variable than those released by fish. Nutrient supply by both fish and Daphnia reduced species richness and diversity of phytoplankton communities and increased algal biomass and dominance. However, nutrient recycling by fish supported a more diverse phytoplankton community than nutrient recycling by Daphnia. We conclude that nutrient recycling by zooplankton and fish have different effects on phytoplankton community structure due to differences in the quality of nutrients released. Received: 21 December 1998 / Accepted: 31 May 1999     

饲料膨化加工方法对其营养成分的影响

目的观察饲料生产过程中的膨化处理对各种营养素的影响情况。方法随机选取不同批次的膨化饲料按GB/T14924.9-2001标准,进行水分、粗蛋白、粗脂肪、粗纤维、氨基酸、维生素及矿物质的测定,得出膨化前后理化检测数据并进行分析。结果饲料中粗蛋白质、粗脂肪、粗纤维、氨基酸、维生素经过膨化处理后,均出现了不同程度的损失,其中维生素损失较大,致使维生素B1、维生素B2、维生素B6、叶酸大部分损失。结论膨化加工方法对于饲料中的常规营养成分、氨基酸、维生素水平有较大程度的影响,为满足动物生长、发育、繁殖等需要,应采取添补措施,以保证其营养成分。     

鱼腥藻（Anabaena sp．）营养成分分析

研究分析了混合鱼腥藻粉的营养成分,结果表明混合鱼腥藻粉蛋白质含量为４０．５％;氨基酸组成符合联合国粮农卫生组织（ＦＡＯ／ＷＨＯ）规定的标准;并含有较丰富的糖类、脂肪酸、无机元素和色素。证实了鱼腥藻可以作为蛋白饲料资源开发和利用。