Plasma ghrelin levels in rainbow trout in response to fasting, feeding and food composition, and effects of ghrelin on voluntary food intake

Ghrelin, a peptide hormone which stimulates growth hormone (GH) release, appetite and adiposity in mammals, was recently identified in fish. In this study, the roles of ghrelin in regulating food intake and the growth hormone (GH)-insulin-like growth factor I (IGF-I) system of rainbow trout (Oncorhynchus mykiss) were investigated in three experiments: 1) Pre- and postprandial plasma levels of ghrelin were measured in relation to dietary composition and food intake through dietary inclusion of radio-dense lead-glass beads, 2) the effect of a single intraperitoneal (i.p.) injection with rainbow trout ghrelin on short-term voluntary food intake was examined and 3) the effect of one to three weeks fasting on circulating ghrelin levels and the correlation with plasma GH and IGF-I levels, growth and lipid content in the liver and muscle was studied. There was no postprandial change in plasma ghrelin levels. Fish fed a normal-protein/high-lipid (31.4%) diet tended to have higher plasma ghrelin levels than those fed a high-protein/low-lipid (14.1%) diet. Plasma ghrelin levels decreased during fasting and correlated positively with specific growth rates, condition factor, liver and muscle lipid content, and negatively with plasma GH and IGF-I levels. An i.p. ghrelin injection did not affect food intake during 12-hours post-injection. It is concluded that ghrelin release in rainbow trout may be influenced by long-term energy status, and possibly by diet composition. Further, in rainbow trout, ghrelin seems to be linked to growth and metabolism, but does not seem to stimulate short-term appetite through a peripheral action.     

Plasma ghrelin levels during exercise - effects of intensity and duration

Ghrelin, a recently discovered hormone of gastric origin has been shown to stimulate appetite and food intake. In man it is considered to play a role in energy homeostasis and regulation of somatropic function. As exercise affects hunger/satiety sensations and food intake, at least under some experimental conditions, we investigated the effect of exercise intensity and duration on ghrelin release and subsequent ad libitum food intake in normal weight subjects. Bicycle exercise on an ergometer for 30 min at 50 W which was below the aerob-anaerobic threshold led to an increase of ghrelin which remained unchanged during the higher intensity at 100 W. Respective hunger/satiety ratings and subsequent food intake and postprandial ghrelin suppression were identical and not different from controls. In a second group 7 subjects cycled at 50 W for 30, 60 and 120 min, respectively. Ghrelin concentrations rose significantly by 50-70 pg/ml above baseline for the respective period of exercise. While postexercise premeal ghrelin levels were not significantly different subsequent food intake after 120 min of cycling was significantly greater compared to control, 30 min and 60 min exercise, respectively. The present data suggest that low rather than high-intensity exercise stimulates ghrelin levels independent of exercise duration. Stimulation of food intake during prolonged exercise is most likely not due to changes of ghrelin.     

Plasma levels of total and active ghrelin in acromegaly and growth hormone deficiency

Ghrelin is an endogenous growth hormone (GH) secretagogue recently isolated from the stomach. Although it possesses a strong GH releasing activity in vitro and in vivo, its physiological significance in endogenous GH secretion remains unclear. The aim of this study was to characterize plasma ghrelin levels in acromegaly and growth hormone deficiency (GHD). We investigated plasma total and active ghrelin in 21 patients with acromegaly, 9 patients with GHD and 24 age-, sex- and BMI-matched controls. In all subjects, we further assessed the concentrations of leptin, soluble leptin receptor, insulin, IGF-I, free IGF-I and IGFBP-1, 2, 3 and 6. Patients with acromegaly and GHD as well as control subjects showed similar levels of total ghrelin (controls 2.004+/-0.18 ng/ml, acromegalics 1.755+/-0.16 ng/ml, p=0.31, GHD patients 1.704+/-0.17 ng/ml, p=0.35) and active ghrelin (controls 0.057+/-0.01 ng/ml, acromegalics 0.047+/-0.01 ng/ml, p=0.29, GHD patients 0.062+/-0.01 ng/ml, p=0.73). In acromegalic patients plasma total ghrelin values correlated negatively with IGF-I (p<0.05), in GHD patients active ghrelin correlated with IGF-I positively (p<0.05). In the control group, total ghrelin correlated positively with IGFBP-2 (p<0.05) and negatively with active ghrelin (p=0.05), BMI (p<0.05), WHR (p<0.05), insulin (p=0.01) and IGF-I (p=0.05). Plasma active ghrelin correlated positively with IGFBP-3 (p=0.005) but negatively with total ghrelin and free IGF-I (p=0.01). In conclusion, all groups of the tested subjects showed similar plasma levels of total and active ghrelin. In acromegaly and growth hormone deficiency plasma ghrelin does not seem to be significantly affected by changes in GH secretion.     

The effect of high-fat diet on plasma ghrelin and leptin levels in rats

Ghrelin and leptin regulate appetite and energy homeostasis in humans and rodents. The effects of different nutritional factors on ghrelin and leptin secretion are not well documented in rats. Therefore, the aim of our study was to investigate the effect of a high-fat diet on plasma ghrelin and leptin levels and on adiposity. Twenty male Wistar rats, body weight220–260 g, were used in the study. Rats were randomized either on a standard chow diet (n=10) or on a high-fat diet (a mixture of nuts) forad libitum 11-week period. Body weight was measured once per week. At the end of the nutritional period, rats were sacrificed. Blood was collected for determination of lipids and glucose, as well as plasma ghrelin and leptin levels by ELISA method. The weight of different organs was determined. Rats fed on a high-fat diet showed significant increase in total body weight compared to control group. The long-term intake of high-fat diet caused hyperleptinemia and hypoghrelinemia. There was a significant positive correlation between plasma leptin levels and epididymal fat mass, liver and heart. In contrast, ghrelin levels showed inverse correlation with epididymal fat mass and liver weight. In conclusion, long-term intake of high-fat diet induced changes in plasma ghrelin and leptin in male rats, as well as in epididymal fat mass, liver and heart weights.     

A comparison of leptin and ghrelin levels in plasma and saliva of young healthy subjects

In the last 10 years, saliva has been increasingly used as a diagnostic fluid and in predictions of disease progression. Leptin and ghrelin are synthesized in several tissues including the salivary glands. The action of ghrelin is antagonistic to that of leptin. This study was undertaken to measure and compare the saliva ghrelin-leptin and plasma ghrelin-leptin levels in healthy young subjects. In 30 healthy subjects, after an overnight fast, saliva and plasma leptin levels were measured using the ELISA method while saliva and plasma immunoreactive ghrelin levels were measured using a commercial radioimmunoassay (RIA). The latter uses 125I-labeled bioactive ghrelin as a tracer and a rabbit polyclonal antibody raised against full-length octanoylated human ghrelin (Phoenix, Europe, Karlsruhe, Germany). The results of this investigation revealed that saliva leptin levels (6.19+/-2.10 microg/l) were lower than plasma levels (7.39+/-3.23 microg/l) while saliva ghrelin levels (188.5+/-84.7 pg/ml) were higher than plasma levels (126.4+/-38.5 pg/ml), when male and female subjects were considered together. Saliva leptin levels (5.93+/-1.94 microg/l) were lower than plasma levels (6.22+/-2.92 pg/ml) while saliva ghrelin levels (190.3+/-80.2 pg/ml) were higher than plasma levels (120.4+/-35.7 pg/ml) in young males. Saliva leptin levels (6.47+/-2.29 microg/l) were lower than plasma levels (8.73+/-3.14 microg/l) while saliva ghrelin levels (183.2+/-90.2 pg/ml) were higher than plasma levels (129.3+/-42.8 pg/ml) in young females, and both saliva and plasma leptin levels were slightly lower in male subjects in comparison with female subjects. Also, Immunohistochemistry study indicated that ghrelin positivity was found in ductus epithelium of salivary gland. We have demonstrated for the first time that saliva ghrelin levels were higher than in plasma while saliva leptin levels were almost the same as in plasma. Measurements of ghrelin and leptin in saliva is non-invasive, simple, and generally much preferred by patients and thus may be an acceptable alternative to plasma sampling.     

Vitamin A levels are decreased but not influenced by glucose- or lipid-lowering medications in subjects with type 2 diabetes

Background and aimType 2 diabetes (T2D) is a complex polygenic disease with unclear mechanisms. Clinical studies on the association of vitamin A with T2D in humans are still controversial. Herein, we aimed to investigate the plasma levels of vitamin A, predictor factors, and its correlations with clinical phenotypes in Emirati population. The effect of glucose-and lipid-lowering medications on vitamin A levels was also studied.MethodsA cross-sectional cohort comprised 158 T2D-subjects and 90 healthy controls were recruited from the United Arab Emirates National Diabetes Study (UAEDIAB). All anthropometric, clinical, and biomedical measurements were collected. Plasma levels of vitamin A were determined using ELISA assay.ResultsLevels of vitamin A were significantly lower in T2D-subjects compared to healthy control (p < 0.01). Vitamin A levels were unaffected by gender base and inversely correlated with age, fasting blood glucose (FBG), glycated hemoglobin (HbA1c), waist circumference, triglycerides, and body mass index (BMI). Regression analysis revealed that HbA1c and age are predictors for vitamin A. Intake of glucose- or lipid-lowering medications showed no effect on vitamin A levels.ConclusionHbA1c and age are predictors for low levels of vitamin A among Emirati-T2D subjects. No influence of glucose and lipid-lowering medications on the plasma levels of vitamin A.     

Verification of hypocholesterolemic effect of fermented milk on human subjects with different cholesterol levels

The possible hypocholesterolemic effect of acidophilus milk was evaluated on 27 human subjects having different levels of serum cholesterol, i.e. < 2.0 (group C1), 2.0-2.2 (C2), 2.2-2.5 (C3) and > 2.5 g/L (C4). The acidophilus milk was prepared by fermentation of low-fat milk with Lactobacillus acidophilus and was fed to each volunteer at the rate of 200 mL/d for 20 d. Blood samples from the volunteers were collected and analyzed for lipid profile twice prior to, during and after feeding, keeping a gap of 10 d between two collections. A significant decrease (p < 0.05) in average total cholesterol was found in the C2 and C3 groups, amounting to 21 and 12%, respectively. The average LDL cholesterol decreased in C2, C3 and C4 groups by 0.54, 0.26 and 0.46 g/L, respectively. In the C2 group, the LDL/HDL and total/HDL ratio was also reduced by 1.4 and 1.3, respectively. However, in the C1 group, the average total and LDL cholesterol level did not show any significant change but serum triacylglycerols and VLDL cholesterol showed a significant (p < 0.05) increase of 0.53 and 0.11 g/L, respectively. Regression analysis of the data revealed a square trend in most of the parameters over time period. Overall, the feeding had the best effect in the subjects with lipidemic status of borderline cholesterol level (2.0-2.2 g/L) group.     

Plasma ghrelin levels and hunger scores in humans initiating meals voluntarily without time- and food-related cues

Ghrelin is an orexigenic hormone that is implicated in meal initiation, in part because circulating levels rise before meals. Because previous human studies have examined subjects fed on known schedules, the observed preprandial ghrelin increases could have been a secondary consequence of meal anticipation. A causal role for ghrelin in meal initiation would be better supported if preprandial increases occurred before spontaneously initiated meals not prompted by external cues. We measured plasma ghrelin levels among human subjects initiating meals voluntarily without cues related to time or food. Samples were drawn every 5 min between a scheduled lunch and a freely requested dinner, and hunger scores were obtained using visual analog scales. Insulin, glucose, fatty acids, leptin, and triglycerides were also measured. Ghrelin levels decreased shortly after the first meal in all subjects. A subsequent preprandial increase occurred over a wide range of intermeal intervals (IMI; 320-425 min) in all but one subject. Hunger scores and ghrelin levels showed similar temporal profiles and similar relative differences in magnitude between lunch and dinner. One subject displayed no preprandial ghrelin increase and was also the only individual whose insulin levels did not return to baseline between meals. This finding, along with a correlation between area-under-the-curve values of ghrelin and insulin, suggests a role for insulin in ghrelin regulation. The preprandial increase of ghrelin levels that we observed among humans initiating meals voluntarily, without time- or food-related cues, and the overlap between these levels and hunger scores are consistent with a role for ghrelin in meal initiation.     

Food restriction,ghrelin, its antagonist and obestatin control expression of ghrelin and its receptor in chicken hypothalamus and ovary

The purpose of the present study was to identify the role of age, nutritional state and some metabolic hormones in control of avian hypothalamic and ovarian ghrelin/ghrelin receptor system. We examined the effect of food restriction, administration of ghrelin 1–18, ghrelin antagonistic analogue (D-Lys-3)-GHRP-6, obestatin and combinations of them on the expression of ghrelin and ghrelin receptor (GHS-R1a) in hypothalamus and ovary of old (23 months of age) and young (7 months of age) chickens. Expression of mRNAs for ghrelin and GHS-R1a in both hypothalamus and largest ovarian follicle was measured by RT-PCR. It was observed that food restriction could promote the expression of ghrelin and GHS-R1a in hypothalamus and ovary of the old chickens, but in the young chickens it reduced expression of ghrelin and did not affect expression of GHS-R1a in the ovary. Administration of ghrelin 1–18 did not affect hypothalamic or ovarian ghrelin mRNA, but significantly increased the expression of GHS-R1a in hypothalamus, but not in ovary. (D-Lys-3)-GHRP-6, significantly stimulated accumulation of ghrelin, but not GHS-R1a mRNA in hypothalamus or ghrelin or GHS-R1a in the ovary. Ghrelin 1–18 and (D-Lys-3)-GHRP-6, when given together, were able either to prevent or to induce effect of these hormones. Obestatin administration increased expression of ghrelin gene in the hypothalamus, but not expression of hypothalamic GHS-R1a, ovarian ghrelin and GHS-R1a. Furthermore, obestatin was able to modify effect of both ghrelin and fasting on hypothalamic and ovarian mRNA for ghrelin GHS-R1a. Our results (1) confirm the existence of ghrelin and its functional receptors GHS-R1a in the chicken hypothalamus and ovary (2) confirm the age-dependent control of ovarian ghrelin by feeding, (3) demonstrate, that nutritional status can influence the expression of both ghrelin and GHS-R1a in hypothalamus and in the ovary (3) demonstrates for the first time, that ghrelin can promote generation of its functional receptor in the hypothalamus, but not in the ovary, (4) show that ghrelin1–18 and (D-Lys-3)-GHRP-6 could not only be antagonists in the action on chicken hypothalamus and ovaries, but also independent regulators and even agonists, and (5) provide first evidence for action of obestatin on hypothalamic ghrelin and on the response of hypothalamic and ovarian ghrelin/GHS-R1a system to food restriction. These data indicate the involvement of both hypothalamic and ovarian ghrelin/GHS-R1 systems in mediating the effects of nutritional status, ghrelin and obestatin on reproductive processes.     

Plasma tumor necrosis factor-alpha levels and insulin resistance in nondiabetic hypertensive subjects

OBJECTIVES: Tumor necrosis factor-alpha (TNF-alpha) is associated with insulin resistance in certain conditions. However, whether TNF-alpha is related to insulin resistance in hypertensive subjects is still controversial. The aim of this study was to determine the status of TNF-alpha and insulin resistance in hypertension. METHODS: Newly diagnosed nondiabetic 17 essentially hypertensive (6 men, 11 women) patients, and 11 control healthy subjects (5 men, 6 women) are involved in the study. Body mass index (BMI), insulin, fasting blood glucose, cholesterol, triglyceride, and TNF-alpha levels were measured. Insulin resistance is assessed according to homeostasis model of assessment (HOMA-IR). RESULTS: Serum insulin (8.4 +/- 2.7 vs. 6.1 +/- 1.4 mIU/ml; p < 0.01), triglyceride (245.0 +/- 39.9 vs. 193.0 +/- 22.8 mg/dl; p < 0.01), and TNF-alpha (4.2 +/- 0.7 vs. 3.0 +/- 0.6 pg/ml; p < 0.001) levels, and HOMA-IR (2.0 +/- 0.8 vs. 1.3 +/- 0.3; p < 0.001) were significantly higher in the hypertensive patients compared to the normotensive control group. There were positive correlations between TNF-alpha levels and body mass index (r = 0.64, p < 0.01), and triglyceride (r = 0.55 p = 0.02) levels in the whole study group. However, there was no correlation of either TNF-alpha or HOMA-IR. CONCLUSIONS: Our data revealed that hypertensive patients have insulin resistance and higher TNF-alpha levels, but there is no relation between TNF-alpha levels and insulin resistance.     

Obese subjects respond to the stimulatory effect of the ghrelin agonist growth hormone-releasing peptide-2 on food intake

Objective: The administration of the growth hormone (GH) secretagogue GH‐releasing peptide (GHRP)‐2, like ghrelin, increases food intake (FI) in lean healthy men. The aim of this study was to investigate whether this effect occurs in obese subjects and whether it is dose‐dependent. Research Methods and Procedures: Nineteen subjects (10 lean and nine obese), all healthy and weight stable, received a double‐blind randomized subcutaneous infusion of GHRP‐2 at high dose (HD; 1 μg/kg per hour), low dose (0.1 μg/kg per hour), or placebo for 270 minutes over three study visits. Blood for hormone assays was collected through an intravenous forearm catheter. Hunger and fullness were rated on visual analog scales before and after a fixed breakfast (320 kcal at 120 minutes) and a buffet lunch at 240 minutes. Before lunch, subjects received taped instructions to eat as much as they wanted. Results: GHRP‐2 infusion significantly increased ad libitum FI in a dose‐dependent manner by 10.2 ± 3.9% at low dose (p = 0.011) and by 33.5 ± 5.8% at HD (p = 0.000) compared with placebo. Obesity status did not influence the effect of GHRP‐2 on FI. All subjects had greater ratings of appetite before but similar levels of fullness after the meal with the HD GHRP‐2. Serum GH levels increased dose dependently in all subjects. Discussion: The dual stimulatory effect of GHRP‐2 on FI and human GH is dose dependent. Obese individuals retain their ability to respond to GHRP‐2 both in terms of FI and human GH.     

Infectious morbidity in the USSR: its structure, levels, dynamics and economic significance

Taking well-grounded strategic decisions on the control of infectious diseases requires the knowledge of modern epidemiological situation with respect to the total infectious pathology. The structure, levels and dynamics of morbidity in infectious diseases, registered according to Form No. 85 (Infection), on the territory of the USSR are considered. Besides, the evaluation of the economic damage inflicted to the national economy of the USSR by infectious morbidity is presented.     

Plasma apolipoprotein L concentrations correlate with plasma triglycerides and cholesterol levels in normolipidemic, hyperlipidemic, and diabetic subjects

Apolipoprotein L is a newly recognized component of human plasma lipoproteins. Mainly associated with apoA-I-containing lipoproteins, it is a marker of distinct HDL subpopulations. In an effort to gain inference as to its as yet unknown function, we studied biological determinants of apoL levels in human plasma. The distribution of apoL in normal subjects is asymmetric, with marked skewing toward higher values. No difference was found in apoL concentrations between males and females, but we observed an elevation of apoL in primary hypercholesterolemia (10.1 vs. 8.5 microgram/mL in control), in endogenous hypertriglyceridemia (13.8 microgram/mL, P < 0.001), combined hyperlipidemia phenotype (18.7 g/mL, P < 0.0001), and in patients with type II diabetes (16.2 microgram/mL, P < 0.02) who were hyperlipidemic. Significant positive correlations were observed between apoL and the log of plasma triglycerides in normolipidemia (0.446, P < 0.0001), endogenous hypertriglyceridemia (0.435, P < 0.01), primary hypercholesterolemia (0.66, P < 0.02), combined hyperlipidemia (0.396, P < 0.04), hypo-alphalipoproteinemia (0.701, P < 0.005), and type II diabetes with hyperlipidemia (0.602, P < 0. 01). Apolipoprotein L levels were also correlated with total cholesterol in normolipidemia (0.257, P < 0.004), endogenous hypertriglyceridemia (0.446, P = 0.001), and non-insulin-dependent diabetes mellitus (NIDDM) (0.548, P < 0.02). No significant correlation was found between apoL and body mass index, age, sex, HDL-cholesterol or fasting glucose and glycohemoglobin levels. ApoL levels in plasma of patients with primary cholesteryl ester transfer protein deficiency significantly increased (7.1 +/- 0.5 vs. 5.47 +/- 0.27, P < 0.006).     

Plasma 24S-hydroxycholesterol levels in elderly subjects with late onset Alzheimer's disease or vascular dementia: a case-control study

Background  

In central nervous system cholesterol cannot be degraded but is secreted into circulation predominantly in the form of its polar metabolite 24(S)-hydroxycholesterol (24S-OH-Chol). Some studies suggested an association between 24S-OH-Chol metabolism and different neurological diseases including dementia. A possible decrease in 24S-OH-Chol plasma levels has been reported late onset Alzheimer's disease (LOAD) and vascular dementia (VD), but results of previous studies are partially contradictory.     

Anti-cachectic effect of ghrelin in nude mice bearing human melanoma cells

Ghrelin is a novel brain-gut peptide that stimulates food intake and body weight gain. We studied the anabolic effect of ghrelin in a cancer cachexia mouse model. SEKI, a human melanoma cell line, was inoculated into nude mice to examine the effects of ghrelin on food intake and body weight. The intraperitoneal administration of ghrelin twice a day (6 nmol/mice/day) for 6 days suppressed weight loss in SEKI-inoculated mice and increased the rate of weight gain in vehicle-treated nude mice. Ghrelin administration also increased food intake in both SEKI- and vehicle-treated mice. Both the weight of white adipose tissue and the plasma leptin concentration were reduced in tumor-inoculated mice compared with vehicle-treated mice; these factors increased following ghrelin administration. The levels of both ghrelin peptide and mRNA in the stomach were upregulated in tumor-inoculated mice. The anabolic effect of ghrelin efficiently reverses the cachexia in mice bearing SEKI human melanoma. Ghrelin therefore may have a therapeutic ability to ameliorate cancer cachexia.     

Lipid-lowering effect of berberine in human subjects and rats

Due to serious adverse effects and the limited effectiveness of currently available pharmacological therapies for obesity, many research efforts have focused on the development of drugs from natural products. Our previous studies demonstrated that berberine, an alkaloid originally isolated from traditional Chinese herbs, prevented fat accumulation in vitro and in vivo. In this pilot study, obese human subjects (Caucasian) were given 500 mg berberine orally three times a day for twelve weeks. The efficacy and safety of berberine treatment was determined by measurements of body weight, comprehensive metabolic panel, blood lipid and hormone levels, expression levels of inflammatory factors, complete blood count, and electrocardiograph. A Sprague-Dawley rat experiment was also performed to identify the anti-obesity effects of berberine treatment. The results demonstrate that berberine treatment produced a mild weight loss (average 5 lb/subject) in obese human subjects. But more interestingly, the treatment significantly reduced blood lipid levels (23% decrease of triglyceride and 12.2% decrease of cholesterol levels) in human subjects. The lipid-lowering effect of berberine treatment has also been replicated in the rat experiment (34.7% decrease of triglyceride and 9% decrease of cholesterol level). Cortisol, calcitriol, ACTH, TSH, FT4, and SHBG levels were not significantly changed following 12 weeks of berberine treatment. However, there was interestingly, an increase in calcitriol levels seen in all human subjects following berberine treatment (mean 59.5% increase, p=0.11). Blood inflammatory factors (CRP, IL-6, TNFα, COX-2) and erythrocyte sedimentation rate (ESR) were not significantly affected by treatment with berberine. Tests of hematological, cardiovascular, liver, and kidney function following berberine treatment showed no detrimental side effects to this natural compound. Collectively, this study demonstrates that berberine is a potent lipid-lowering compound with a moderate weight loss effect, and may have a possible potential role in osteoporosis treatment/prevention.