Normal Neurodevelopment and Fertility in Juvenile Male Rats Exposed to Polyethylene Glycol Following Dosing With PEGylated rFIX (Nonacog Beta Pegol, N9-GP): Evidence from a 10-Week Repeat-Dose Toxicity Study.

N9-GP/Rebinyn®/Refixia® is an approved PEGylated (polyethylene glycol-conjugated) recombinant human factor IX intended for prophylactic and/or on-demand treatment in adults and children with haemophilia B. A juvenile neurotoxicity study was conducted in male rats to evaluate effects on neurodevelopment, sexual maturation, and fertility following repeat-dosing of N9-GP. Male rats were dosed twice weekly from Day 21 of age with N9-GP or vehicle for 10 weeks, followed by a dosing-free recovery period for 13 weeks and terminated throughout the dosing and recovery periods. Overall, dosing N9-GP to juvenile rats did not result in any functional or pathological effects, as measured by neurobehavioural/neurocognitive tests, including motor activity, sensory function, learning and memory as well as growth, sexual maturation, and fertility. This was further supported by the extensive histopathologic evaluation of brain tissue. Exposure and distribution of polyethylene glycol was investigated in plasma, choroid plexus, cerebrospinal fluid, and brain sections. PEG did not cross the blood brain barrier and PEG exposure did not result in any effects on neurodevelopment. In conclusion, dosing of N9-GP to juvenile rats did not identify any effects on growth, sexual maturation and fertility, clinical and histological pathology, or neurodevelopment related to PEG exposure and supports the prophylactic use of N9-GP in children.

Effects of a selective long-acting amylin receptor agonist on alcohol consumption, food intake and body weight in male and female rats.

Alcohol use disorder is a complex neuropsychiatric disorder affecting both males and females worldwide; however, the efficacy of current pharmacotherapies varies. Recent advances show that gut-brain peptides, like amylin, regulate alcohol behavioural responses by acting on brain areas involved in alcohol reward processes. Thus, the activation of amylin receptors (AMYRs) by salmon calcitonin (sCT) decreases alcohol behaviours in male rodents. Given that sCT also activates the sole calcitonin receptor (CTR), studies of more selective AMYR agonists in both male and female rodents are needed to explore amylinergic modulation of alcohol behaviours. Therefore, we investigated the effects of repeated administration of a selective long-acting AMYR agonist, NNC0174-1213 (AM1213), on alcohol, water and food intake, as well as body weight in male and female rats chronically exposed to alcohol. We confirm our previous studies with sCT in male rats, as repeated AM1213 administration for 2 weeks initially decreased alcohol intake in both male and female rats. However, this reduction ceases in both sexes on later sessions, accompanied by an increase in males. AM1213 reduced food intake and body weight in both male and female rats, with sustained body weight loss in males after discontinuation of the treatment. Moreover, AM1213 administration for 3 or 7 days, differentially altered dopamine, serotonin and their metabolites in the reward-related areas in males and females, providing tentative, but different, downstream mechanism through which selective activation of AMYR may alter alcohol intake. Our data provide clarified insight into the importance of AMYRs for alcohol intake regulation in both sexes.

Kisspeptin-52 partially rescues the activity of the hypothalamus-pituitary-gonadal axis in underweight male rats dosed with an anti-obesity compound.

Energy metabolism and reproduction are closely linked and reciprocally regulated. The detrimental effect of underweight on reproduction complicates the safety evaluation of anti-obesity drugs, making it challenging to distinguish pathological changes mediated through the intended drug-induced weight loss from direct drug effects on reproductive organs. Four-weeks dosing of normal weight Sprague Dawley rats with a glucagon-like peptide 1 (GLP-1)/glucagon receptor co-agonist induced a robust weight loss, accompanied by histological findings in prostate, seminal vesicles, mammary glands, uterus/cervix and vagina. Characterization of the hypothalamus-pituitary-gonadal (HPG) axis in male rats revealed reduced hypothalamic Kiss1 mRNA levels and decreased serum luteinizing hormone (LH) and testosterone concentrations following co-agonist dosing. These alterations resemble hypogonadotropic hypogonadism typically seen in adverse energy deprived conditions, like chronic food restriction. Concomitant daily administration of kisspeptin-52 from day 21 to the end of the four-week co-agonist dosing period evoked LH and testosterone responses without normalizing histological findings. This incomplete rescue by kisspeptin-52 may be due to the rather short kisspeptin-52 treatment period combined with a desensitization observed on testosterone responses. Concomitant leptin treatment from day 21 did not reverse co-agonist induced changes in HPG axis activity. Furthermore, a single co-agonist injection in male rats slightly elevated LH levels but left testosterone unperturbed, thereby excluding a direct acute inhibitory effect on the HPG axis. Our data suggest that the reproductive phenotype after repeated co-agonist administration was driven by the intended weight loss, however, we cannot exclude a direct organ related effect in chronically treated rats.

Uterine glycolytic enzyme expression is affected by knockout of different estrogen receptor subtypes.

The estrogen signaling pathway via nuclear estrogen receptors (ER) α and ß is considered to be the master regulator of the cellular glucose metabolism in the uterus. While in vivo animal studies have demonstrated that 17ß-estradiol (E2) treatment increases the expression levels and activities of several glycolytic enzymes in the uterus, the specific ER subtype-dependent regulation of key glycolytic enzymes in the uterus has not been experimentally verified. In this study, the localization of ERα and ERß in human and mouse endometria were evaluated using immunohistology. Given that ERα and ERß are not functionally equivalent, ERα, ERß and ERαß knockout (ERα-/-, ERß-/- and ERαß-/-) mice were utilized to determine the expression pattern of glycolytic enzymes in the uterus. It was found that the level of ERα was higher than that of ERß in the human and mouse endometrial epithelial and stromal cells, and both receptors were downregulated by E2 treatment in the mouse uterus. The expression of the hexokinase 1 and GAPDH was increased in ERα-/- and ERß-/- mice compared with wild-type controls. Increased phosphofructokinase expression was observed in ERα-/- and ERαß-/- mice, whereas increased pyruvate kinase isozyme M2 and pyruvate dehydrogenase expression was observed in ERß-/- and ERαß-/- mice. The findings indicated for the first time that while estrogen regulates ERα and ERß expression in the uterus, ERα and ERß selectively regulate uterine glycolytic enzyme expression during glycolysis. Additionally, the link between endometrial ER subtypes and glycolysis in women with polycystic ovary syndrome (PCOS) is discussed. The findings suggested that the E2-dependent ER-mediated regulation of glycolysis may be involved in the disturbance of the glucose metabolism in patients with PCOS with endometrial dysfunction.

The additive effect of allopregnanolone on ghrelin's orexigenic effect in rats.

The progesterone metabolite, allopregnanolone (AlloP), is a GABAA receptor modulating steroid and is known to have orexigenic and pro-obesity effects. The neurobiological mechanisms underpinning these effects are most likely due to enhanced GABAergic signaling in the lateral arcuate nucleus (ARC) and medial paraventricular nucleus (PVN) of the hypothalamus. Inspired by the finding that GABAergic signaling is also important for the orexigenic effects of the circulating hormone, ghrelin, we sought to determine the extent to which AlloP (one of the most potent endogenous GABAA-receptor modulators) operates alongside ghrelin to enhance food intake. Male rats with ad libitum access to standard chow were injected intravenously with AlloP and/or ghrelin, alone or in combination. The intake of the standard chow was greater after AlloP 1 mg/kg together with ghrelin 30 µg/kg than with 30 µg/kg ghrelin alone. Food intake was also increased for the combined treatment of AlloP 0.5 mg/kg + ghrelin 10 µg/kg, AlloP 1 mg/kg + ghrelin 10 µg/kg, and AlloP 0.5 mg/kg + ghrelin 30 µg/kg. There was no significant difference in food intake between the two ghrelin doses or between the two doses of AlloP and the vehicle. In electrophysiological studies, physiologically relevant concentrations of AlloP prolonged the current decay time of spontaneous inhibitory post-synaptic current of dissociated cells of the ARC and PVN. We conclude that AlloP enhances the hyperphagic effect of ghrelin, findings of potential relevance for the hyperphagia associated with the luteal phase of the reproductive cycle.

Interleukin-6 is important for regulation of core body temperature during long-term cold exposure in mice.

Interleukin-6 (IL6) is a cytokine important for inducing the fever response during infection and has been reported to uphold core body temperature during acute cold exposure. Recently it has also been indicated that IL6 in serum increases in cold-exposed mice. The aim of the present study was to investigate if IL6 is important for core body temperature regulation following a long-term cold exposure in mice. Experiments were performed with global IL6 deficient (-/-) mice, mice with conditional IL6 receptor α (IL6Rα) knockdown in the central nervous system (CNS; IL6RαNesCre) and appropriate wild-type (Wt) controls. All mice were placed in a cold environment (4°C) for 6 days. Core body temperature and oxygen consumption were measured by telemetry probes and indirect calorimetry at room temperature (20°C), and during the first and last day of cold exposure. Brain stem, hypothalamus and white and brown adipose tissues from the cold-exposed mice were subjected to gene expression analysis. After 6 days in 4°C, the IL6-/- mice exhibited significantly lower body temperature and oxygen consumption compared with Wt mice (P<0.05). The IL6RαNesCre mice also exhibited lower body temperature compared with WtNesCre controls during the last day of cold exposure (P<0.05). Furthermore, an increase in the mRNA level of brain-derived neurotrophic factor (Bdnf) was detected in the brain stem of both IL6-/- and IL6RαNesCre mice compared with the Wt groups (P<0.05). The finding that body temperature was decreased in IL6-/- and IL6RαNesCre mice indicates a decrease in thermogenesis in these animals. Bdnf has previously been indicated to increase body temperature and could in the present study be a mechanistic factor involved in counteracting the low body temperature in IL6-/- and IL6RαNesCre mice. These results suggest that IL6 is not only involved in body temperature regulation during infection, but also during long-term cold exposure, probably through mechanisms in the CNS.

The glucagon-like peptide 1 receptor agonist Exendin-4 decreases relapse-like drinking in socially housed mice.

Glucagon-like peptide-1 (GLP-1) is a gut peptide that regulates food intake and glucose metabolism. GLP-1 is also produced and released in the brain, and GLP-1 receptors are expressed in brain regions important for alcohol and drug reward, and for the development of addiction. GLP-1 receptor agonists can decrease alcohol intake acutely in rodents. However, alcohol use disorder is a chronic condition that requires treatments to be effective in promoting abstinence from excessive alcohol consumption over time. Here, we assessed the effect of daily treatment with the GLP-1 receptor agonist Exendin-4 in an assay of relapse-like drinking in socially housed mice. Male C57BL/6NTac mice were allowed continuous access to alcohol without tastant in the home cage for 37days. Then, alcohol bottles were removed and Exendin-4 (1.5µg/kg/day) or saline was administered subcutaneously for 8days during alcohol deprivation. Treatment continued for 8 additional days after reintroducing access to alcohol. A high-precision automated fluid consumption system was used to monitor intake of alcohol and water, drinking kinetics, and locomotor activity. Exendin-4 prevented the deprivation-induced increase in alcohol intake observed in control mice, without significantly affecting total fluid intake, body weight, or locomotor activity. The reduced alcohol intake was caused by a protracted latency to the first drink of alcohol and a reduced number of drinking bouts, while bout size and duration were not affected. The effect was maintained undiminished throughout the treatment period. These findings support the possible use of GLP-1 receptor agonists in the treatment of alcohol use disorder.

Thylakoids reduce body fat and fat cell size by binding to dietary fat making it less available for absorption in high-fat fed mice.

BACKGROUND: Dietary thylakoids derived from spinach have beneficial effects on body fat accumulation and blood lipids as demonstrated in humans and rodents. Important mechanisms established include delayed fat digestion in the intestine, without causing steatorrhea, and increased fatty acid oxidation in intestinal cells. The objective of our study was to elucidate if increased fecal fat excretion is an important mechanism to normalize adipose tissue metabolism during high-fat feeding in mice supplemented with thylakoids. METHODS: Mice were randomized to receive HFD or thylHFD for 14 days (n = 14 for the control group and 16 for the thylakoid group). The effect of thylakoids on body fat distribution, faecal and liver fat content, and adipose tissue metabolism was investigated following high-fat feeding. RESULTS: Thylakoid supplementation for 14 days caused an increased faecal fat content without compensatory eating compared to control. As a result, thylakoid treated animals had reduced fat mass depots and reduced liver fat accumulation compared to control. The size distribution of adipocytes isolated from visceral adipose tissue was narrowed and the cell size decreased. Adipocytes isolated from thylakoid-treated mice displayed a significantly increased lipogenesis, and protein expression of peroxisome proliferator-activated receptor gamma (PPARγ), down-stream target FAS, as well as transcription factor coactivators PGC1-α and LPIN-1 were upregulated in adipose tissue from thylakoid-fed mice. CONCLUSIONS: Together, these data suggest that thylakoid supplementation reduces body fat and fat cell size by binding to dietary fat and increasing its fecal excretion, thus reducing dietary fat available for absorption.

Central administration of the anorexigenic peptide neuromedin U decreases alcohol intake and attenuates alcohol-induced reward in rodents.

By investigating the neurochemical mechanisms through which alcohol activates the brain reward systems, novel treatment strategies for alcohol use disorder (AUD), a chronic relapsing disease, can be developed. In contrast to the common view of the function of gut-brain peptides, such as neuromedin U (NMU), to regulate food intake and appetite, a novel role in reinforcement mediation has been implied. The anorexigenic effects of NMU are mediated via NMU2 receptors, preferably in the arcuate nucleus and paraventricular nucleus. The expression of NMU2 receptors is also expressed in several reward-related areas in the brain, suggesting a role in reward regulation. The present experiments were therefore set up to investigate the effect of intracerebroventricular administration of NMU on alcohol-mediated behaviors in rodents. We found that central administration of NMU attenuated alcohol-induced locomotor stimulation, accumbal dopamine release and the expression of conditioned place preference in mice. In addition, NMU dose dependently decreased alcohol intake in high, but not in low, alcohol-consuming rats. Central NMU administration did not alter the blood alcohol concentrations nor change the corticosterone levels in rodents. Given that AUD is a major health-care challenge causing an enormous cost to society and novel treatment strategies are warranted, our data suggest that NMU analogues deserve to be evaluated as novel treatment of AUD in humans.

Dietary thylakoids reduce visceral fat mass and increase expression of genes involved in intestinal fatty acid oxidation in high-fat fed rats.

Thylakoids reduce body weight gain and body fat accumulation in rodents. This study investigated whether an enhanced oxidation of dietary fat-derived fatty acids in the intestine contributes to the thylakoid effects. Male Sprague-Dawley rats were fed a high-fat diet with (n = 8) or without thylakoids (n = 8) for 2 wk. Body weight, food intake, and body fat were measured, and intestinal mucosa was collected and analyzed. Quantitative real-time PCR was used to measure gene expression levels of key enzymes involved in fatty acid transport, fatty acid oxidation, and ketogenesis. Another set of thylakoid-treated (n = 10) and control rats (n = 10) went through indirect calorimetry. In the first experiment, thylakoid-treated rats (n = 8) accumulated 25% less visceral fat than controls. Furthermore, fatty acid translocase (Fat/Cd36), carnitine palmitoyltransferase 1a (Cpt1a), and mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (Hmgcs2) genes were upregulated in the jejunum of the thylakoid-treated group. In the second experiment, thylakoid-treated rats (n = 10) gained 17.5% less weight compared with controls and their respiratory quotient was lower, 0.86 compared with 0.91. Thylakoid-intake resulted in decreased food intake and did not cause steatorrhea. These results suggest that thylakoids stimulated intestinal fatty acid oxidation and ketogenesis, resulting in an increased ability of the intestine to handle dietary fat. The increased fatty acid oxidation and the resulting reduction in food intake may contribute to the reduced fat accumulation in thylakoid-treated animals.

The role of ghrelin signalling for sexual behaviour in male mice.

Ghrelin, a gut-brain signal, is well known to regulate energy homeostasis, food intake and appetite foremost via hypothalamic ghrelin receptors (GHS-R1A). In addition, ghrelin activates the reward systems in the brain, namely the mesolimbic dopamine system, and regulates thereby the rewarding properties of addictive drugs as well as of palatable foods. Given that the mesolimbic dopamine system mandates the reinforcing properties of addictive drugs and natural rewards, such as sexual behaviour, we hypothesize that ghrelin plays an important role for male sexual behaviour, a subject for the present studies. Herein we show that ghrelin treatment increases, whereas pharmacological suppression (using the GHSR-1A antagonist JMV2959) or genetic deletion of the GHS-R1A in male mice decreases the sexual motivation for as well as sexual behaviour with female mice in oestrus. Pre-treatment with L-dopa (a dopamine precursor) prior to treatment with JMV2959 significantly increased the preference for female mouse compared with vehicle treatment. On the contrary, treatment with 5-hydroxythyptohan (a precursor for serotonin) prior to treatment with JMV2959 decreased the sexual motivation compared to vehicle. In separate experiments, we show that ghrelin and GHS-R1A antagonism do not affect the time spent over female bedding as measured in the androgen-dependent bedding test. Collectively, these data show that the hunger hormone ghrelin and its receptor are required for normal sexual behaviour in male mice and that the effects of the ghrelin signalling system on sexual behaviour involve dopamine neurotransmission.

The glucagon-like peptide 1 receptor agonist liraglutide attenuates the reinforcing properties of alcohol in rodents.

The incretin hormone, glucagon-like peptide 1 (GLP-1), regulates gastric emptying, glucose-dependent stimulation of insulin secretion and glucagon release, and GLP-1 analogs are therefore approved for treatment of type II diabetes. GLP-1 receptors are expressed in reward-related areas such as the ventral tegmental area and nucleus accumbens, and GLP-1 was recently shown to regulate several alcohol-mediated behaviors as well as amphetamine-induced, cocaine-induced and nicotine-induced reward. The present series of experiments were undertaken to investigate the effect of the GLP-1 receptor agonist, liraglutide, on several alcohol-related behaviors in rats that model different aspects of alcohol use disorder in humans. Acute liraglutide treatment suppressed the well-documented effects of alcohol on the mesolimbic dopamine system, namely alcohol-induced accumbal dopamine release and conditioned place preference in mice. In addition, acute administration of liraglutide prevented the alcohol deprivation effect and reduced alcohol intake in outbred rats, while repeated treatment of liraglutide decreased alcohol intake in outbred rats as well as reduced operant self-administration of alcohol in selectively bred Sardinian alcohol-preferring rats. Collectively, these data suggest that GLP-1 receptor agonists could be tested for treatment of alcohol dependence in humans.

Buserelin treatment to rats causes enteric neurodegeneration with moderate effects on CRF-immunoreactive neurons and Enterobacteriaceae in colon, and in acetylcholine-mediated permeability in ileum.

BACKGROUND: The gonadotropin-releasing hormone (GnRH) analog buserelin causes enteric neuronal loss. Acute stress or injection of corticotropin-releasing factor (CRF) affects motility, secretion, and barrier function of the gastrointestinal tract. The aim of the study was to characterize the CRF immunoreactivity in enteric neurons after buserelin treatment, and to evaluate possible effects of enteric neuropathy on gut microbiota, intestinal permeability, and stress response behavior. RESULTS: Sixty rats were given buserelin (20 µg) or saline subcutaneously for 5 days, repeated four times with 3 weeks in-between. At the study end, enteric neuronal density, enteric expression of CRF, gut microbial composition, and plasma levels of adrenocorticotropic hormone (ACTH) and CRF were analyzed. Intestinal permeability was examined in Ussing chambers and the reaction to stressful events was measured by behavior tests. Buserelin treatment reduced the number of neurons along the entire gastrointestinal tract, with increased relative numbers of CRF-immunoreactive submucosal and myenteric neurons in colon (p < 0.05 and p < 0.01, respectively). The overall microbial diversity and relative abundance did not differ between groups, but Enterobacteriaceae was decreased in colon in buserelin-treated rats (p = 0.020). Basal intestinal permeability did not differ between groups, whereas carbachol stimulation increased ileum permeability in controls (p < 0.05), but not in buserelin-treated rats. Buserelin did not affect stress behavior. CONCLUSIONS: Although buserelin treatment leads to enteric neuronal loss along the gastrointestinal tract with an increased percentage of CRF-immunoreactive neurons in colon, the physiology is well preserved, with modest effects on colon microbiota and absence of carbachol-induced permeability in ileum as the only observed changes.

Ghrelin and GHS-R1A signaling within the ventral and laterodorsal tegmental area regulate sexual behavior in sexually naïve male mice.

In addition to food intake and energy balance regulation, ghrelin mediate the rewarding and motivational properties of palatable food as well as addictive drugs. The ability of ghrelin to regulate reinforcement involves the cholinergic-dopaminergic reward link, which encompasses a cholinergic projection from the laterodorsal tegmental area (LDTg) to the ventral tegmental area (VTA) together with mesolimbic dopaminergic projections from the VTA to the nucleus accumbens (NAc). Recently, systemic ghrelin was shown to regulate sexual behavior and motivation in male mice via dopamine neurotransmission. The present study therefore elucidates the role of ghrelin and ghrelin receptor (GHS-R1A) antagonist treatment within NAc, VTA or LDTg for sexual behavior in sexually naïve male mice. Local administration of the GHSR-1A antagonist, JMV2959, into the VTA or LDTg was found to reduce the preference for female mice, the number of mounts and the duration of mounting as well as to prolong the latency to mount. This was further substantiated by the findings that ghrelin administration into the VTA or LDTg increased the number of mounts and the duration of mounting and decreased the latency to mount. Moreover, ghrelin administered into the LDTg increased the preference for female mice. Accumbal administration of ghrelin increased whereas GHS-R1A antagonist decreased the intake of palatable food, but did not alter sexual behavior. In males exposed to sexual interaction, systemic administration of ghrelin increases whereas JMV2959 decreases the turnover of dopamine in the VTA. These data suggest that ghrelin signaling within the tegmental areas is required for sexual behavior in sexually naïve male mice.

Blockade of growth hormone secretagogue receptor 1A signaling by JMV 2959 attenuates the NMDAR antagonist, phencyclidine-induced impairments in prepulse inhibition.

RATIONALE: Schizophrenic-spectrum patients commonly display deficits in preattentive information processing as evidenced, for example, by disrupted prepulse inhibition (PPI), a measure of sensorimotor gating. Similar disruptions in PPI can be induced in rodents and primates by the psychotomimetic drug phencyclidine (PCP), a noncompetitive inhibitor of the NMDA receptor. Mounting evidence suggests that the hunger hormone ghrelin and its constitutively active receptor influences neuronal circuits involved in the regulation of mood and cognition. OBJECTIVES: In the present series of experiments, we investigated the effects of ghrelin and the growth hormone secretagogue receptor (GHS-R1A) neutral antagonist, JMV 2959, on acoustic startle responses (ASR), PPI, and PCP-induced alterations in PPI. RESULTS: Intraperitoneal (i.p.) administration of ghrelin (0.033, 0.1, and 0.33 mg/kg) did not alter the ASR or PPI in rats. Conversely, i.p. injection of JMV 2959 (1, 3, and 6 mg/kg), dose dependently decreased the ASR and increased PPI. Pretreatment with JMV 2959 at a dose with no effect on ASR or PPI per se, completely blocked PCP-induced (2 mg/kg) deficits in PPI while pretreatment with the highest dose of ghrelin did not potentiate or alter PPI responses of a sub-threshold dose of PCP (0.75 mg/kg). CONCLUSION: These findings indicate that the GHS-R1A is involved in specific behavioral effects of PCP and may have relevance for patients with schizophrenia.

Consumption of thylakoid-rich spinach extract reduces hunger, increases satiety and reduces cravings for palatable food in overweight women.

Green-plant membranes, thylakoids, have previously been found to increase postprandial release of the satiety hormone GLP-1, implicated in reward signaling. The purpose of this study was to investigate how treatment with a single dose of thylakoids before breakfast affects homeostatic as well as hedonic hunger, measured as wanting and liking for palatable food (VAS). We also examined whether treatment effects were correlated to scores for eating behavior. Compared to placebo, intake of thylakoids significantly reduced hunger (21% reduction, p < 0.05), increased satiety (14% increase, p < 0.01), reduced cravings for all snacks and sweets during the day (36% reduction, p < 0.05), as well as cravings for salty (30%, p < 0.01); sweet (38%, p < 0.001); and sweet-and-fat (36%, p < 0.05) snacks, respectively, and decreased subjective liking for sweet (28% reduction, p < 0.01). The treatment effects on wanting all snacks, sweet-and-fat snacks in particular, were positively correlated to higher emotional eating scores (p < 0.01). The treatment effect of thylakoids on scores for wanting and liking were correlated to a reduced intake by treatment (p < 0.01 respectively), even though food intake was not affected significantly. In conclusion, thylakoids may be used as a food supplement to reduce homeostatic and hedonic hunger, associated with overeating and obesity. Individuals scoring higher for emotional eating behavior may have enhanced treatment effect on cravings for palatable food.

Body weight loss, reduced urge for palatable food and increased release of GLP-1 through daily supplementation with green-plant membranes for three months in overweight women.

The frequency of obesity has risen dramatically in recent years but only few effective and safe drugs are available. We investigated if green-plant membranes, previously shown to reduce subjective hunger and promote satiety signals, could affect body weight when given long-term. 38 women (40-65 years of age, body mass index 25-33 kg/m(2)) were randomized to dietary supplementation with either green-plant membranes (5 g) or placebo, consumed once daily before breakfast for 12 weeks. All individuals were instructed to follow a three-meal paradigm without any snacking between the meals and to increase their physical activity. Body weight change was analysed every third week as was blood glucose and various lipid parameters. On days 1 and 90, following intake of a standardized breakfast, glucose, insulin and glucagon-like peptide 1 (GLP-1) in plasma were measured, as well as subjective ratings of hunger, satiety and urge for different palatable foods, using visual analogue scales. Subjects receiving green-plant membranes lost significantly more body weight than did those on placebo (p < 0.01). Mean weight loss with green-plant extract was 5.0 ± 2.3 kg compared to 3.5 ± 2.3 kg in the control group. Consumption of green-plant membranes also reduced total and LDL-cholesterol (p < 0.01 and p < 0.05 respectively) compared to control. Single-meal tests performed on day 1 and day 90 demonstrated an increased postprandial release of GLP-1 and decreased urge for sweet and chocolate on both occasions in individuals supplemented with green-plant membranes compared to control. Waist circumference, body fat and leptin decreased in both groups over the course of the study, however there were no differences between the groups. In conclusion, addition of green-plant membranes as a dietary supplement once daily induces weight loss, improves obesity-related risk-factors, and reduces the urge for palatable food. The mechanism may reside in the observed increased release of GLP-1.

Influence of ghrelin on the central serotonergic signaling system in mice.

The central ghrelin signaling system engages key pathways of importance for feeding control, recently shown to include those engaged in anxiety-like behavior in rodents. Here we sought to determine whether ghrelin impacts on the central serotonin system, which has an important role in anxiety. We focused on two brain areas, the amygdala (of importance for the mediation of fear and anxiety) and the dorsal raphe (i.e. the site of origin of major afferent serotonin pathways, including those that project to the amygdala). In these brain areas, we measured serotonergic turnover (using HPLC) and the mRNA expression of a number of serotonin-related genes (using real-time PCR). We found that acute central administration of ghrelin to mice increased the serotonergic turnover in the amygdala. It also increased the mRNA expression of a number of serotonin receptors, both in the amygdala and in the dorsal raphe. Studies in ghrelin receptor (GHS-R1A) knock-out mice showed a decreased mRNA expression of serotonergic receptors in both the amygdala and the dorsal raphe, relative to their wild-type littermates. We conclude that the central serotonin system is a target for ghrelin, providing a candidate neurochemical substrate of importance for ghrelin's effects on mood.