Nesfatin-1 inhibits gastric acid secretion via a central vagal mechanism in rats

Nesfatin-1, a novel hypothalamic peptide, inhibits nocturnal feeding behavior and gastrointestinal motility in rodents. The effects of nesfatin-1 on gastrointestinal secretory function, including gastric acid production, have not been evaluated. Nesfatin-1 was injected into the fourth intracerebral ventricle (4V) of chronically cannulated rats to identify a nesfatin dose sufficient to inhibit food intake. Nesfatin-1 (2 μg) inhibited dark-phase food intake, in a dose-dependent fashion, for >3 h. Gastric acid production was evaluated in urethane-anesthetized rats. Nesfatin-1 (2 μg) was introduced via the 4V following endocrine stimulation of gastric acid secretion by pentagastrin (2 μg·kg(-1)·h(-1) iv), vagal stimulation with 2-deoxy-d-glucose (200 mg/kg sc), or no stimulus. Gastric secretions were collected via gastric cannula and neutralized by titration to determine acid content. Nesfatin-1 did not affect basal and pentagastrin-stimulated gastric acid secretion, whereas 2-deoxy-d-glucose-stimulated gastric acid production was inhibited by nesfatin-1 in a dose-dependent manner. c-Fos immunofluorescence in brain sections was used to evaluate in vivo neuronal activation by nesfatin-1 administered via the 4V. Nesfatin-1 caused activation of efferent vagal neurons, as evidenced by a 16-fold increase in the mean number of c-Fos-positive neurons in the dorsal motor nucleus of the vagus (DMNV) in nesfatin-1-treated animals vs. controls (P < 0.01). Finally, nesfatin-induced Ca(2+) signaling was evaluated in primary cultured DMNV neurons from neonatal rats. Nesfatin-1 caused dose-dependent Ca(2+) increments in 95% of cultured DMNV neurons. These studies demonstrate that central administration of nesfatin-1, at doses sufficient to inhibit food intake, results in inhibition of vagally stimulated secretion of gastric acid. Nesfatin-1 activates DMNV efferent vagal neurons in vivo and triggers Ca(2+) signaling in cultured DMNV neurons.     

Central nesfatin-1 reduces the nocturnal food intake in mice by reducing meal size and increasing inter-meal intervals

Nesfatin-1 is well established to reduce food intake upon brain injection in rats, while in mice its anorexigenic action and brain expression are largely unexplored. We characterized the influence of intracerebroventricular (icv) and peripheral (intraperitoneal, ip, subcutaneous, sc) injection of nesfatin-1 on dark phase ingestive behavior using an automated feeding monitoring system and co-localized NUCB2/nesfatin-1 immunoreactivity in the associated brain areas. Nesfatin-1 (0.3, 1 or 3 μg/mouse, icv) caused a dose-related reduction of 4-h dark phase food intake by 13%, 27%, and 46% respectively. Nesfatin-1 (3 μg/mouse, icv) action had a 2-h delayed onset, 82% peak inhibition occurring at 3-4 h post-injection and was long lasting (30% reduction for 12 h period post-injection). Nesfatin-1 (3 μg/mouse, icv)-treated mice had a 46% lower meal frequency associated with 2-times longer inter-meal intervals and a 35% reduction in meal size compared to vehicle during the 1-4 h post-injection (p < 0.05). NUCB2/nesfatin-1-immunopositive neurons were found in hypothalamic (supraoptic, paraventricular, arcuate, dorsomedial, lateral) and brainstem (dorsal vagal complex) feeding regulatory nuclei. When injected peripherally, neither food intake nor feeding microstructure parameters were altered. These results demonstrate that NUCB2/nesfatin-1 is prominently expressed in mouse hypothalamus and medulla and acts in the brain to curtail the dark phase feeding by inducing satiation and satiety indicated by reduced meal size and prolonged inter-meal intervals respectively. The lack of nesfatin-1 effect when injected peripherally at a 23-times higher dose indicates a primarily central site of the anorexigenic action for nesfatin-1 in mice.     

Nesfatin-1(30-59) but not the N- and C-terminal fragments, nesfatin-1(1-29) and nesfatin-1(60-82) injected intracerebroventricularly decreases dark phase food intake by increasing inter-meal intervals in mice

Nesfatin-1 is an 82 amino acid N-terminal fragment of nucleobindin2 that was consistently shown to reduce dark phase food intake upon brain injection in rodents. We recently reported that nesfatin-1(1-82) injected intracerebroventricularly (icv) reduces dark phase feeding in mice. Moreover, intraperitoneal injection of mid-fragment nesfatin-1 (nesfatin-1(30-59)) mimics the food intake-reducing effects of nesfatin-1(1-82), whereas N-terminal (nesfatin-1(1-29)) and C-terminal fragments (nesfatin-1(60-82)) did not. We therefore characterized the structure-activity relationship of nesfatin-1 injected icv to influence the dark phase meal pattern in mice. Mouse nesfatin-1(1-29), nesfatin-1(30-59), nesfatin-1(60-82) or vehicle was injected icv in freely fed C57Bl/6 mice immediately before the dark phase and food intake was monitored using an automated episodic feeding monitoring system. Nesfatin-1(30-59) (0.1, 0.3, 0.9 nmol/mouse) induced a dose-related reduction of 4-h food intake by 28%, 49% and 49% respectively resulting in a 23% decreased cumulative 24-h food intake compared to vehicle at the 0.3 nmol/mouse dose (p<0.05). The peak reduction occurred during the 3rd (-96%) and 4th hour (-91%) post injection and was associated with a reduced meal frequency (0-4h: -47%) and prolonged inter-meal intervals (3.1-times) compared to vehicle (p<0.05), whereas meal size was not altered. In contrast, neither nesfatin-1(1-29) nor nesfatin-1(60-82) reduced dark phase food intake at equimolar doses although nesfatin-1(60-82) prolonged inter-meal intervals (1.7-times, p<0.05). Nesfatin-1(30-59) is the active core of nesfatin-1(1-82) to induce satiety indicated by a reduced meal number during the first 4h post injection. The delayed onset may be indicative of time required to modulate other hypothalamic and medullary networks regulating nocturnal feeding as established for nesfatin-1.     

中枢注射Nesfatin-1与Exendin(9-39)对大鼠摄食和胃肠动力调节的影响

目的:探讨下丘脑室旁核注射GLP-1R拮抗剂Exendin(9-39)对Nesfatin-1所致大鼠摄食和胃肠动力改变的影响及作用机制。方法:选择40只雄性Wistar大鼠,随机分成正常对照组(NC组)、Nesfatin-1组(NS组)、Exendin(9-39)组(ES组)、Nesfatin-1联合Exendin(9-39)组(NE组)。采用下丘脑室旁核(PVN)埋置套管并分别给予以上药物干预,干预前和干预后的12小时、24小时记录和比较各组大鼠的摄食、饮水及体重变化。2天后,采用甲基纤维素-酚红溶液灌胃法测各组大鼠胃排空率,实时荧光定量法(RT-PCR)检测下丘脑及胃组织GLP-1Rm RNA的表达。结果:与基础摄食量比较,NS组大鼠给药后12 h、24 h的摄食量减少(P0.05),NE组大鼠给药后12 h、24 h的摄食量减少(P0.05),但较NS组增加(P0.05);与基础饮水量比较,NS组、NE组给药后12 h饮水量减少(P0.05);与基础体重比较,NS组大鼠给药后12 h、24 h的体重降低(P0.05),NE组大鼠给药后12 h的体重降低(P0.05),但较NS组增加(P0.05);NS组大鼠给药后胃排空率较NC、NE组大鼠显著下降(P0.05),NS组大鼠下丘脑GLP-1Rm RNA的表达量较NC组增加(P0.05)。结论:中枢给予GLP-1R拮抗剂能减弱Nesfatin-1引起的摄食抑制、胃排空延迟及体重下降效应,Nesfatin-1可能通过与GLP-1的协同作用参与摄食及胃肠动力的调节。     

下丘脑Nesfatin-1抑食效应及机制研究

目的:探讨下丘脑nesfatin-1与组胺信号通路间的相互作用及对摄食的影响。方法:采用第三脑室置管、药物注射、免疫组化、ELISA等方法,观察氟甲基组氨酸(FMH)、α螺旋促肾上腺皮质激素释放激素(CRH)和促甲状腺激素释放激素(TRH)对Nesfatin-1诱导的抑制摄食的影响,以及Nesfatin-1与组胺信号通路相互影响调控摄食机制。结果:第三脑室注射nesfatin-1可显著减少大鼠摄食量,而第三脑室内预先注射FMH,nesfatin-1抑制摄食效应明显减弱,但FMH本身并不影响大鼠夜间摄食量。第三脑室注射nesfatin-1,可显著增加优降宁诱发的PVN、腹内侧核(VMH)、结节乳头核(TMN)内t-MH的积累;但腹腔注射nesfatin-1没有引起大鼠摄食改变,t-MH蓄积也无显著变化。第三脑室注射α螺旋CRH或抗TRH血清均可显著减弱nesfatin-1的抑食效应,而α螺旋CRH、抗TRH血清本身并不显著影响大鼠摄食量。第三脑室注射nesfatin-1可显著增加下丘脑PVN内CRH和TRH水平,且nesfatin-1可显著增加优降宁诱导的PVN、VMH和TMN内t-MH的表达,而α螺旋CRH或抗TRH血清可显著抑制nesfatin-1诱导的PVN、VMH和TMH内t-MH的蓄积。第三脑室注射组胺可显著增加大鼠下丘脑PVN内nesfatin-1含量,但LH、VMH、TMN以及血浆内nesfatin-1水平无显著改变。免疫组化研究显示,PVN内有nesfatin-1和H1-R免疫反应阳性神经元,且部分神经元共存。结论:Nesfatin-1的抑食效应可能与下丘脑组胺信号通路介导。     

Effects of morphine on electrical activity of the emotion-producing zones in the hypothalamus of adult and aged rats

In the experiments performed on adult and aged rats, the effect of morphine on the electrical activity, recorded from the emotion-producing zones of the hypothalamus, the ventromedial nucleus (VMN), and the lateral hypothalamic area (LHA), was studied. In thein vitro experiments, an age-dependent reduction of background impulse activity (BIA) was found in the VMN single neurons, but not in the LHA neurons. Morphine reduced BIA in most of the VMN neurons, but enhanced it in the LHA neurons of adult rats, and enhanced BIA in the neurons of both structures of the aged rats. The inhibitory effect of morphine on the VMN and LHA neurons and its excitatory effect on the LHA neurons decreased with age. In thein vivo experiments, an age-dependent reduction of the background field electrical activity (background electrogram, BEG) was found in the neurons of both emotion-producing zones. Morphine reduced the BEG magnitude in the VMN and LHA more effectively in the aged rats than in the adult rats. The results allow us to suggest that both the opiate regulation of hypothalamic functions and formation of an opiate dependence in the adult rats essentially differ from those in the aged rats.Neirofiziologiya/Neurophysiology, Vol. 27, No. 2, pp. 126–133, March–April, 1995.     

Endogenous GLP-1 acts on paraventricular nucleus to suppress feeding: Projection from nucleus tractus solitarius and activation of corticotropin-releasing hormone,nesfatin-1 and oxytocin neurons

Glucagon-like peptide-1 (GLP-1) receptor agonists have been used to treat type 2 diabetic patients and shown to reduce food intake and body weight. The anorexigenic effects of GLP-1 and GLP-1 receptor agonists are thought to be mediated primarily via the hypothalamic paraventricular nucleus (PVN). GLP-1, an intestinal hormone, is also localized in the nucleus tractus solitarius (NTS) of the brain stem. However, the role of endogenous GLP-1, particularly that in the NTS neurons, in feeding regulation remains to be established. The present study examined whether the NTS GLP-1 neurons project to PVN and whether the endogenous GLP-1 acts on PVN to restrict feeding. Intra-PVN injection of GLP-1 receptor antagonist exendin (9–39) increased food intake. Injection of retrograde tracer into PVN combined with immunohistochemistry for GLP-1 in NTS revealed direct projection of NTS GLP-1 neurons to PVN. Moreover, GLP-1 evoked Ca²⁺ signaling in single neurons isolated from PVN. The majority of GLP-1-responsive neurons were immunoreactive predominantly to corticotropin-releasing hormone (CRH) and nesfatin-1, and less frequently to oxytocin. These results indicate that endogenous GLP-1 targets PVN to restrict feeding behavior, in which the projection from NTS GLP-1 neurons and activation of CRH and nesfatin-1 neurons might be implicated. This study reveals a neuronal basis for the anorexigenic effect of endogenous GLP-1 in the brain.     

Differential effects of central administration of relaxin‐3 on food intake and hypothalamic neuropeptides in male and female rats

Relaxin‐3 (RLN3) is an orexigenic neuropeptide that produces sex‐specific effects on food intake by stronger stimulation of feeding in female compared with male rats. This study determined which hypothalamic nuclei and associated neuropeptides may be involved in the sex‐specific orexigenic effects of RLN3. Relaxin‐3 (800 pmol) or vehicle was injected into the lateral ventricle of female and male rats. Food and water intake were measured after the first injection, and rats were euthanized after the second injection to determine the mRNA expression of the hypothalamic neuropeptides. Food but not water intake showed sex‐specific effects of RLN3. Stimulation of food intake by RLN3 was significantly higher in female than in male rats. No effect of RLN3 injection was found on c‐fos mRNA expression in the arcuate, dorsomedial and ventromedial hypothalamic nuclei. Increased c‐fos mRNA expression was observed in the paraventricular hypothalamic nucleus (PVN) in both sexes and in the lateral hypothalamic area (LHA) in female rats. Relaxin‐3 injections led to a sex‐nonspecific increase in the expression of oxytocin mRNA in the magnocellular PVN. Conversely, RLN3‐induced expression of anorexigenic neuropeptide arginine vasopressin (AVP) was significantly higher in the parvocellular PVN in male compared with female rats. Finally, RLN3 administration significantly increased the expression of orexin (ORX) mRNA in the LHA in female but not in male rats. Stronger expression of anorexigenic AVP in the PVN in male rats and increased expression of ORX in the LHA in female rats may contribute to stronger orexigenic effects of RLN3 in female rats compared with male rats.     

CCK-8S activates c-Fos in a dose-dependent manner in nesfatin-1 immunoreactive neurons in the paraventricular nucleus of the hypothalamus and in the nucleus of the solitary tract of the brainstem

Recently, a new neuropeptide, named nesfatin-1, was discovered. It has been reported that nesfatin-1 inhibits food intake after injection into the third ventricle as well as intraperitoneal (ip) injection. Cholecystokinin (CCK) is well established to play a role in the regulation of food intake. The aim of the study was to examine whether CCK-8S injected ip modulates neuronal activity in nesfatin-1 immunoreactive (ir) neurons localized in the PVN and in the nucleus of the solitary tract (NTS). Additionally, tyrosine hydroxylase-immunoreactivity (TH-ir) in the PVN was determined to assess the distribution of TH-ir fibers in relation to nesfatin-1-ir. Non-fasted male Sprague-Dawley rats received 6 or 10 µg CCK-8S/kg or vehicle solution (0.15 M NaCl; n = 4 all groups) ip. The number of c-Fos-ir neurons was determined in the PVN, arcuate nucleus (ARC), and NTS. Double staining procedure for nesfatin-1 and c-Fos revealed that CCK-8S increased significantly and in a dose-dependent manner the number of c-Fos positive nesfatin-1-ir neurons in the PVN ( 4-fold and 7-fold) and NTS ( 9-fold and 26-fold). Triple staining in the PVN showed a dose-dependent neuronal activation of nesfatin-1 neurons that were colocalized with CRF and oxytocin. Double labeling against nesfatin-1 and TH revealed that nefatin-1-ir neurons were encircled in a network of TH-ir fibers in the PVN. No effect on the number of c-Fos-ir neurons was observed in the ARC. These results suggest that the effects of CCK on the HPA axis and on food intake may, at least in part, be mediated by nesfatin-1-ir neurons in the PVN.     

Nesfatin-1及MCH对大鼠胃酸分泌和胃运动的影响

目的:本实验主要探究nesfatin-1对胃运动和胃酸分泌的影响,以及弓状核(ARC)-下丘脑外侧区(LHA)nesfatin-1神经通路在该过程中的作用。方法:采用逆行追踪和免疫组织化学染色实验观察ARC-LHA nesfatin-1神经通路的构成;在体胃运动实验观察nesfatin-1对胃运动的影响以电刺激ARC对胃运动的影响;采用幽门结扎法测量胃液和胃酸分泌量。结果:LHA微量注射nesfatin-1抑制胃运动和胃酸分泌,但是预先注射黑色素浓集激素(MCH)受体拮抗剂PMC-3881-PI减弱nesfatin-1对胃运动和胃酸分泌的抑制作用。电刺激ARC后,胃收缩幅度和频率显著增强,胃酸分泌明显增多。nesfatin-1抗体或PMC-3881-PI对电刺激ARC诱导的胃运动没有显著影响,但是能够改变电刺激ARC诱导的胃酸分泌。结论:ARC-LHA间nesfafin-1通路可调控大鼠胃运动和胃酸分泌,并且黑色素浓集激素也参与调节该过程。     

Nesfatin-1对大鼠摄食、胃酸分泌、胃运动及胃排空的影响

目的:观察Nesfatin-1对大鼠摄食、胃酸分泌、胃运动及胃排空的影响并探究其可能机制。方法:将大鼠随机分为摄食实验组、胃酸实验组、胃运动实验组以及胃排空实验组。大鼠经腹内侧核置管后给予nasfatin-1,检测大鼠摄食量,使用Na OH滴定法测定大鼠胃酸分泌,记录清醒大鼠胃运动,以比色法测定大鼠胃排空。结果:低剂量和高剂量nesfatin-1均减少2小时累积食物摄入量;高剂量组4小时累积食物摄入量仍显著低于NS对照组。Nesfatin-1能够抑制2-DG对胃酸分泌的促进作用。SHU9119能够部分阻断nesfatin-1对2-DG的抑制作用。Nesfatin-1能够抑制胃运动及胃排空,SHU9119可部分阻断nesfatin-1对胃运动及胃排空的抑制作用。结论:Nesfatin-1能够调控大鼠摄食、胃酸分泌、胃运动及胃排空,黑皮质素信号通路可能也参与该调控过程。     

Glucose and insulin induce Ca2+ signaling in nesfatin-1 neurons in the hypothalamic paraventricular nucleus

Nucleobindin-2 derived nesfatin-1 in the hypothalamic paraventricular nucleus (PVN) plays a role in inhibition of feeding. The neural pathways downstream of PVN nesfatin-1 have been extensively investigated. However, regulation of the PVN nesfatin-1 neurons remains unclear. Since starvation decreases and refeeding stimulates nesfatin-1 expression specifically in the PVN, this study aimed to clarify direct effects of meal-evoked metabolic factors, glucose and insulin, on PVN nesfatin-1 neurons. High glucose (10mM) and insulin (10(-13)M) increased cytosolic calcium concentration ([Ca(2+)](i)) in 55 of 331 (16.6%) and 32 of 249 (12.9%) PVN neurons, respectively. Post [Ca(2+)](i) measurement immunocytochemistry identified that 58.2% of glucose-responsive and 62.5% of insulin-responsive neurons were immunoreactive to nesfatin-1. Furthermore, a fraction of the glucose-responsive nesfatin-1 neurons also responded to insulin, and vice versa. Some of the neurons that responded to neither glucose nor insulin were recruited to [Ca(2+)](i) increases by glucose and insulin in combination. Our data demonstrate that glucose and insulin directly interact with and increase [Ca(2+)](i) in nesfatin-1 neurons in the PVN, and that the nesfatin-1 neuron is the primary target for them in the PVN. The results suggest that high glucose- and insulin-induced activation of PVN nesfatin-1 neurons serves as a mechanism through which meal ingestion stimulates nesfatin-1 neurons in the PVN and thereby produces satiety.     

Effects of restricted feeding on the activity of hypothalamic Orexin (OX)-A containing neurons and OX2 receptor mRNA level in the paraventricular nucleus of rats

We have examined the effects of 3 weeks of food restriction on both the activity of neurons containing hypothalamic orexin (OX)-A and the level of OX receptor type 2 (OX2R) mRNA in the paraventricular nucleus (PVN) of rats. Double immunohistochemistry was used to examine the expression of OX-A and Fos in the lateral hypothalamic area (LHA), and in situ hybridization histochemistry was used to measure levels of OX2R mRNA in the PVN. After the period of restricted feeding, 20-30% of OX-A-containing neurons exhibited Fos-like immunoreactivity (LI). The distribution of OX-A-LI/Fos-LI cells in the food-restricted rats was similar to that observed in glucose-deprived rats after intracerebroventricular (icv) administration of 2-deoxy-D-glucose (2-DG). In addition, 3 weeks of food restriction caused a significant decrease in the expression of the OX2R gene in the parvocellular division of the PVN. These results suggest that the activation of OX-A-containing neurons induced by restricted feeding may be involved in neuroendocrine responses to food restriction.     

Prepro-orexin and feeding-related peptide receptor expression in dehydration-induced anorexia

Food-restricted animals present metabolic adaptations that facilitate food-seeking behavior and decelerate energy utilization by reducing the hypothalamus–pituitary–thyroid (HPT) axis function. Stress by dehydration induces an anorexic behavior in rats, loss of weight and reduced food intake when compared to ad libitum fed animals, however these alterations are accompanied by HPT axis changes such as increased serum thyrotropin levels and enhanced expression of thyrotropin-releasing hormone (TRH) in the paraventricular nucleus of the hypothalamus, which is considered as anorexigenic peptide. In contrast, a pair-fed group conformed by forced-food-restricted animals (FFR) (eating the exact same amount of food as dehydration-induced anorexic rats—DIA rats) present decreased TRH mRNA levels. NPY synthesis in the arcuate nucleus and orexin-expressing neurons from the lateral hypothalamic area (LHA) are activated during food restriction. These brain structures project into PVN, suggesting that NPY and orexins are possible factors involved in TRHergic neuron activation in DIA rats. Leptin signaling is another likely factor to be involved in TRH differential expression. Therefore, to gain more insight into the regulation of the feeding behavior in the experimental models, we analyzed Y1, Y5, Ox1-R and Ob-R_b mRNA levels in PVN and prepro-orexin in LHA, since their signaling to the PVN might be altering TRH synthesis and feeding in DIA animals. Prepro-orexinergic cells were activated in FFR animals; Ox1-R and Y1 expression was reduced in FFR vs. controls or DIA group. Compensatory changes in PVN receptor expression of some feeding-related peptides in anorexic rats may alter TRHergic neural response to energy demands.     

The hypothalamus is involved in the anorexic effect of glucagon-like peptide-1 in chicks

The present study was carried out to investigate whether the hypothalamus is involved in the anorexic effect of glucagon-like peptide-1 (GLP-1) in chicks. To examine this, Fos expression in the chick hypothalamus were immunohistochemically detected after intracerebroventricular (ICV) injection of 30-pmol GLP-1. ICV injection of GLP-1 stimulated the expression of Fos-like immunoreactive (FLI) cells in the ventromedial hypothalamic nucleus (VMN). When 15-pmol GLP-1 was directly injected into the chick VMN, the chick's food intake was significantly decreased compared with the control treatment. Microinjection of GLP-1 into the (LHA) also inhibited feeding in chicks, although ICV injection of GLP-1 did not stimulate FLI expression in the brain area. These results suggest that VMN and some brain regions are involved in the anorexic effect of GLP-1 in chicks.     

Ghrelin is an orexigenic and metabolic signaling peptide in the arcuate and paraventricular nuclei

Ghrelin is a 28-amino acid acylated peptide and is the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). The GHS-R is expressed in hypothalamic nuclei, including the arcuate nucleus (Arc) where it is colocalized with neuropeptide Y (NPY) neurons. In the present study, we examined the effects of ghrelin on feeding and energy substrate utilization (respiratory quotient; RQ) following direct injections into either the arcuate or the paraventricular nucleus (PVN) of the hypothalamus. Ghrelin was administered at the beginning of the dark cycle at doses of 15-60 pmol to male and female rats. In feeding studies, food intake was measured 2 and 4 h postinjection. Separate groups of rats were injected with ghrelin, and the RQ (VCO(2)/VO(2)) was measured using an open circuit calorimeter over a 4-h period. Both Arc and PVN injections of ghrelin increased food intake in male and female rats. Ghrelin also increased RQ, reflecting a shift in energy substrate utilization in favor of carbohydrate oxidation. Because these effects are similar to those observed after PVN injection of NPY, we then assessed the impact of coinjecting ghrelin with NPY into the PVN. When rats were pretreated with very low doses of ghrelin (2.5-10 pmol), NPY's (50 pmol) effects on eating and RQ were potentiated. Overall, these data are in agreement with evidence suggesting that ghrelin functions as a gut-brain endocrine hormone implicated in the regulation of food intake and energy metabolism. Our findings are also consistent with a possible interactive role of hypothalamic ghrelin and NPY systems.     

Increased expression of hypothalamic NADPH-diaphorase neurons in mice with iron supplement

Iron deficiency is known as the most important nutritional problem in the world. The loss of appetite is a common characteristic of iron deficiency. Iron-containing heme is required as a cofactor for nitric oxide synthase (NOS) which produces nitric oxide (NO). NOS in the central nervous system has been suggested to regulate food intake. Hence, we examined the expression of hypothalamic NOS at various levels of dietary iron. ICR mice (n = 30) were randomly divided into three groups based on the level of dietary iron and fed experimental diets for 4 weeks: the normal-iron diet group (7 mg/kg diet, n = 10), the low-iron diet group (21 mg/kg diet, n = 10) and the high-iron diet group (42 mg/kg diet, n = 10). Expression of NOS in the paraventricular nucleus (PVN) and lateral hypothalamic area (LHA) of hypothalamus was examined by histochemistry for nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-diaphorase). The high-iron diet mice showed significantly higher staining intensity of NADPH-diaphorase-positive neurons in the PVN and LHA than the normal- and low-iron diet mice.     

The newly identified anorexigenic adipokine nesfatin-1 in hemodialysis patients: Are there associations with food intake, body composition and inflammation?

Nesfatin-1 is a recently identified anorexigenic peptide that has been implicated in appetite regulation, weight loss and/or malnutrition. Anorexia and malnutrition are common features of chronic kidney disease (CKD) that predispose patients to worse outcomes. However, the reasons for the occurrence of anorexia in CKD patients are not fully elucidated. The aim of this study was to investigate the association between nesfatin-1 and protein intake and body composition in patients undergoing hemodialysis (HD). Twenty five HD patients from a private Clinic in Rio de Janeiro, Brazil were studied and compared with 15 healthy subjects that were matched for body mass index (BMI), % body fat mass (by anthropometrics) and age. Appetite was measured using a specific questionnaire, and food intake was evaluated based on 3-day food records. Nesfatin-1 levels were measured by ELISA and leptin, TNF-α and IL-6 levels were determined by a multiplex assay kit. Serum nesfatin-1 levels did not differ between HD patients (0.16±0.07ng/mL) and healthy subjects (0.17±0.10ng/mL). Nesfatin-1 levels showed significant negative correlations with protein intake (r=-0.42; p=0.03), but did not associate with inflammatory markers or appetite scores. Combining patients and controls, we observed positive correlations with BMI (r=0.33; p=0.03), % body fat (r=0.35; p=0.03), leptin (r=0.45; p=0.006) and the triceps skinfold thickness (r=0.36; p=0.02). In multivariate analysis % body fat was the main determinant of nesfatin-1 variance. In conclusion, nesfatin-1 levels did not differ between HD patients and healthy subjects and negatively correlated with protein intake. This pathway is likely not dysregulated in uremia.     

Expression of NPY Y1 and Y5 receptors in the hypothalamic paraventricular nucleus of aged Fischer 344 rats

Many mammals, nearing the end of life, spontaneously decrease their food intake and body weight, a stage we refer to as senescence. The spontaneous decrease in food intake and body weight is associated with attenuated responses to intracerebroventricular injections of neuropeptide Y (NPY) compared with old presenescent or with young adult rats. In the present study, we tested the hypothesis that this blunted responsiveness involves the number and expression of hypothalamic paraventricular nucleus (PVN) Y(1) and/or Y(5) NPY receptors, both of which are thought to mediate NPY-induced food intake. We found no significant difference in mRNA levels, via quantitative PCR, for Y(1) and Y(5) receptors in the PVN of senescent vs. presenescent rats. In contrast, immunohistochemistry indicated that the number of PVN neurons staining for Y(1) receptor protein was greater in presenescent compared with senescent rats. We conclude that a decreased expression and number of Y(1) or Y(5) receptors in the PVN cannot explain the attenuated responsiveness of the senescent rats to exogenous NPY.