Early methyl donor deficiency produces severe gastritis in mothers and offspring through N-homocysteinylation of cytoskeleton proteins, cellular stress, and inflammation.

We examined the gastric mucosa structure and inflammatory status in control well-nourished Wistar dams and in Wistar dams deprived of choline, folate, and vitamin B12 during gestation and suckling periods, and in their offspring just before birth and at weaning. In this model of methyl donor deficiency (MDD), structural protein (E-cadherin and actin) N-homocysteinylation was measured through immunoprecipitation and proximity ligation assays. Cellular stress, inflammation, and apoptosis were estimated by the analysis of the NF-κB pathway, and the expression of superoxide dismutase, cyclooxygenase-2, tumor necrosis factor α, caspases 3 and 9, and TUNEL assay. Aberrant gastric mucosa formation and signs of surface layer erosion were detected in MDD fetuses and weanlings. E-cadherin and actin were N-homocysteinylated (+215 and +249% vs. controls, respectively; P<0.001). Expression of ß-catenin staining drastically decreased (-98%; P<0.01). NF-κB pathway was activated (+124%; P<0.01). Expressions of all inflammatory factors (+70%; P<0.01), superoxide dismutase (+55%; P<0.01), and caspases (+104%; P<0.01) were markedly increased. These changes were also observed in dams, to a lesser extent. Early MDD induced gastric mucosa injury similar to atrophic gastritis through structural protein N-homocysteinylation, marked inflammation, and apoptosis, despite activation of repair machinery.

Methyl donor deficiency affects fetal programming of gastric ghrelin cell organization and function in the rat.

Methyl donor deficiency (MDD) during pregnancy influences intrauterine development. Ghrelin is expressed in the stomach of fetuses and influences fetal growth, but MDD influence on gastric ghrelin is unknown. We examined the gastric ghrelin system in MDD-induced intrauterine growth retardation. By using specific markers and approaches (such as periodic acid-Schiff, bromodeoxyuridine, homocysteine, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling, immunostaining, reverse transcription-polymerase chain reaction), we studied the gastric oxyntic mucosa cellular organization and ghrelin gene expression in the mucosa in 20-day-old fetuses and weanling pups, and plasma ghrelin concentration in weanling rat pups of dams either normally fed or deprived of choline, folate, vitamin B6, and vitamin B12 during gestation and suckling periods. MDD fetuses weighed less than controls; the weight deficit reached 57% at weaning (P < 0.001). Both at the end of gestation and at weaning, they presented with an aberrant gastric oxyntic mucosa formation with loss of cell polarity, anarchic cell migration, abnormal progenitor differentiation, apoptosis, and signs of surface layer erosion. Ghrelin cells were abnormally located in the pit region of oxyntic glands. At weaning, plasma ghrelin levels were decreased (-28%; P < 0.001) despite unchanged mRNA expression in the stomach. This decrease was associated with lower body weight. Taken together, these data indicate that one mechanism through which MDD influences fetal programming is the remodeling of gastric cellular organization, leading to dysfunction of the ghrelin system and dramatic effects on growth.

Association of neuropeptide W, but not obestatin, with energy intake and endocrine status in Zucker rats. A new player in long-term stress-feeding interactions.

The aim of this study was to ascertain the roles of neuropeptide W (NPW) and obestatin in feeding and endocrine regulations and their interactions with leptin, corticosterone, and insulin, three key hormones involved in metabolic homeostasis. Plasma variations were measured in obese hyperphagic Zucker rats either following a one-day fast, or after chronic food restriction (one-third less food than normal for three weeks). Obestatin did not vary by feeding condition, and did not differ between lean and obese rats; it likely does not play any role in feeding regulation. NPW did not vary with one-day fasting, but was higher in obese rats than in lean rats under satiated (+38%) and fasting (+44%; P<0.01) conditions. In chronically food-restricted obese rats that lost about 10% of their initial body weight, NPW decreased by 18% (P<0.02), in parallel with a similar decrease in plasma insulin (P<0.03), and a 10% decrease of plasma leptin (P<0.001). Corticosterone levels in obese rats were much higher than in lean rats, and increased (P<0.0001) after chronic food restriction, but not after a short fast. Prolonged food restriction was therefore stressful for obese rats. Long-term food shortage associated with insulin, leptin and corticosterone changes is then a critical factor for the regulation of NPW. The NPW up-regulation in hyperphagic conditions and its down-regulation in hypophagic conditions, is compatible with an anorexigenic role of this peptide. NPW thus may be one of the regulatory factors involved in the complex long-term interactions between stress and feeding.

Suppression of QRFP 43 in the hypothalamic ventromedial nucleus of Long-Evans rats fed a high-fat diet.

QRFP 43 is a RFamide peptide present in the ventromedial nucleus (VMN) and lateral hypothalamus. It stimulates food intake in mice and its chronic infusion induces hyperphagia, reduced thermogenesis, and obesity. In this experiment, we measured it in the VMN and lateral hypothalamus of Long-Evans rats fed either a high-fat (HF), control, or low-fat (LF) diet in parallel with plasma leptin, adiposity, and energy intake. After 8weeks of ad libitum diet intake, energy intake of HF rats was similar to that of control rats. In the VMN, QRFP 43 was completely undetectable in HF rats and its tissue concentration in control rats was significantly lower than in LF rats (p<0.03). HF rats had higher levels of leptin than control rats (+24%; p<0.03) and than LF rats (+42%; p<0.002). The QRFP 43 concentration in the VMN was inversely correlated with plasma leptin (r=-0.34; P<0.04) and with the adipogenic index of the diet (p<0.02) but not with insulin. We conclude that the decrease of the orexigenic drive mediated by QRFP 43 could contribute to the normalization of caloric intake in HF diet fed rats. QRFP 43 might play a role downstream of leptin in the regulation of feeding behavior.

Hypothalamic galanin and plasma leptin and ghrelin in the maintenance of energy intake in the Brattleboro rat.

Galanin, ghrelin, and leptin are three peptides involved in feeding regulation and more particularly in fat intake. The Brattleboro (di/di) rat is a genetic model of diabetes insipidus characterized by a preference for fat when it is in a food choice situation. Here, we measured hypothalamic galanin concentrations, plasma ghrelin and leptin and dietary preferences of adult di/di Brattleboro rats, di/+ and Long-Evans controls. The Brattleboro rats weighed significantly less than the di/+ rats (-18%; P<0.001). The fat-to-carbohydrate intake ratio was significantly greater in Brattleboro rats than in di/+ (P<0.02) when the rats could choose between a high-fat diet and a high-carbohydrate diet. Galanin concentrations were significantly lower in di/di rats than in di/+ rats in the paraventricular nucleus (-56%; P<0.001), but not in the arcuate nucleus. Plasma leptin was significantly lower in the di/di rats than in the di/+ rats (3.49+/-0.20 vs. 6.94+/-0.49 ng/ml; P<0.001). Plasma ghrelin concentrations were significantly lower in Long-Evans rats than in the di/di rats (-21%; P< 0.01). Given that galanin mRNA is overexpressed in the paraventricular nucleus of Brattleboro rats, these data are consistent with increased release of the peptide. In the Brattleboro rat, this overactive galanin system and the variations of ghrelin and leptin maintain an orexigenic drive favoring a preferential intake of fat which provides the animal with enough energy for its metabolism.

Foetal programming by methyl donor deficiency produces steato-hepatitis in rats exposed to high fat diet.

Non-alcoholic steatohepatitis (NASH) is a manifestation of metabolic syndrome, which emerges as a major public health problem. Deficiency in methyl donors (folate and vitamin B12) during gestation and lactation is frequent in humans and produces foetal programming effects of metabolic syndrome, with small birth weight and liver steatosis at day 21 (d21), in rat pups. We investigated the effects of fetal programming on liver of rats born from deficient mothers (iMDD) and subsequently subjected to normal diet after d21 and high fat diet (HF) after d50. We observed increased abdominal fat, ASAT/ALAT ratio and angiotensin blood level, but no histological liver abnormality in d50 iMDD rats. In contrast, d185 iMDD/HF animals had hallmarks of steato-hepatitis, with increased markers of inflammation and fibrosis (caspase1, cleaved IL-1ß, α1(I) and α2(I) collagens and α-SMA), insulin resistance (HOMA-IR and Glut 2) and expression of genes involved in stellate cell stimulation and remodelling and key genes triggering NASH pathomechanisms (transforming growth factor beta super family, angiotensin and angiotensin receptor type 1). Our data showed a foetal programming effect of MDD on liver inflammation and fibrosis, which suggests investigating whether MDD during pregnancy is a risk factor of NASH in populations subsequently exposed to HF diet.

Orexins/hypocretins in the ob/ob mouse: hypothalamic gene expression, peptide content and metabolic effects.

Orexins (forms A and B) belong to a new family of peptides that, as neuropeptide Y (NPY), stimulate food intake when centrally injected. The ob/ob mouse is a well-characterized model of hyperphagia and obesity associated with strong metabolic disturbances and a central dysregulation of peptides involved in the control of feeding. In the present report, we investigated the hypocretin (Hcrt)/orexin (OX) peptide pathway in lean and ob/ob mice. Prepro-Hcrt/OX mRNA expression, measured by in situ hybridization was restricted to the lateral hypothalamus area. It was significantly decreased in ob/ob mice (-18%; p<0.01). When estimated by real time RT-PCR in the whole hypothalamus, this decrease amounted to 65% (p<0.001). Hcrt-1/OX-A peptide concentrations, measured by RIA in microdissected hypothalamic nuclei were high in the lateral hypothalamus (LH) and lower in the arcuate (ARC) and paraventricular nuclei (PVN). In ob/ob mice, OX-A levels were significantly lower than in lean mice in the LH (-34%; p<0.02) and in the PVN (-72%; p<0.005). Acute intracerebroventricular injection of Hcrt-1/OX-A (1-10 nmol) stimulated feeding in lean, but not in ob/ob mice, whereas Hcrt-2/OX-B (1-10 nmol) had the opposite effect. Acute third ventricle (i3vt) injections of Hcrt/OX peptides in ob/ob mice transiently increased their metabolic rate and stimulated lipid substrate utilization. These findings provide direct evidence that Hcrt/OX peptides are down-regulated in the hypothalamus of ob/ob mice, contrary to the NPY system. The present data argues that Hcrt/OX peptides are not primarily responsible for the metabolic syndrome of the ob/ob mice. The diminution in the OX tone might participate in a counterregulatory system necessary to limit the adverse effects of NPY on food intake and body weight.

Feeding response to a potent prolactin-releasing peptide agonist in lean and obese Zucker rats.

Prolactin (PRL)-releasing peptide (PrRP) is a new peptide present in the hypothalamus and in the circulation that may be involved in the regulation of feeding behavior. In the present experiment, we measured it in a well-known model of obesity, the Zucker rat. We also measured the reactivity of this animal in terms of food intake after the intraperitoneal (I.P.) or central injection of PrRP-13, a potent PrRP agonist. Plasma PrRP levels were 35% lower in obese fa/fa than in the lean rats (p<0.005). I.P. injections of PrRP-13 (10 mg/kg) stimulated food intake in lean and had no effect in obese rats (p<0.001). Intracerebral injections of PrRP-13 had no effects in both genotypes. Altogether, these results do not support a role for PrRP in the hyperphagia and obesity syndrome of the Zucker rat.

Ghrelin and body weight regulation in the obese Zucker rat in relation to feeding state and dark/light cycle.

Ghrelin is a new orexigenic peptide primarily produced by the stomach but also present in the hypothalamus. It has adipogenic effects when it is chronically injected in rodents but in obese humans, its plasma concentration is decreased. It can reverse the anorectic effects of leptin when it is co-injected with this peptide in the brain ventricles. The Zucker fa/fa rat is a genetic model of obesity related to a default in the leptin receptor. It is characterized by a large dysregulation of numerous hypothalamic peptides but the ghrelin status of this rat has not yet been determined. Through several experiments, we determine in lean and obese Zucker rats its circulating form in the plasma, its tissue levels and/or expression, and studied the influence of different feeding conditions and its light/dark variations. Ghrelin expression was higher in the obese stomach and hypothalamus (P < 0.05 and P < 0.02, respectively). The ratio of [Octanoyl-Ser3]-ghrelin (active form) to [Des-Octanoyl-Ser3]-ghrelin (inactive form) was approximately 1:1 in the stomach and 2:1 in the plasma in lean and obese rats (no differences). After fasting, plasma ghrelin concentrations increased significantly in lean (+ 64%; P < 0.001) and obese (+ 60%; P < 0.02) rats. After 24 hours of refeeding, they returned to their initial ad lib levels. Ghrelin concentrations were higher in obese rats by 69% (P < 0.005), 65% (P < 0.02), and 73% (P < 0.005) in the ad libitum, fast, and refed states respectively. These results indicate that the obese Zucker rat is characterized by increases in the stomach mRNA expression and in peptide release in the circulation. They clearly support a role for ghrelin in the development of obesity in the absence of leptin signaling.

Feeding response to ghrelin agonist and antagonist in lean and obese Zucker rats.

Ghrelin is a new orexigenic and adipogenic peptide primarily produced by the stomach and the hypothalamus. In the present experiment, we determined the circulating ghrelin levels in 60-week old fa/fa Zucker rats with a well-established obesity (n = 12) and in their lean (FA/FA) counterparts (n = 12). We also tested the feeding response of both groups to intra-peritoneal (I.P.) injection of ghrelin agonist and antagonist. Obese rats ate significantly more than the lean rats (21.7 +/- 1.1 vs. 18.3 +/- 0.3 g/day; p < 0.01). Their plasma ghrelin concentration was 35% higher than that in the lean homozygous rats (p < 0.025). GHRP-6 (1 mg/kg I.P, a GHS-R agonist) stimulated food intake in lean but not in obese rats (p < 0.01), whereas [D-Lys)]-GHRP-6 (12 mg/kg I.P., a GHS-R antagonist) decreased food intake in both groups (p < 0.0001). These results indicate that the obese Zucker rat is characterized by an increase in plasma ghrelin concentrations and by an attenuated response to a GHS-R agonist. They support a role for ghrelin in the development of obesity in the absence of leptin signaling.

Effects of long-term ingestion of aspartame on hypothalamic neuropeptide Y, plasma leptin and body weight gain and composition.

The aim of this study was to determine the effects of the chronic ingestion of aspartame (ASP) on brain neuropeptide Y (NPY) concentrations, plasma hormones, food intake and body fat. Two groups of male Long-Evans rats, fed on a control (C) well-balanced diet, had to drink either a 0.1% ASP solution or water for a period of 14 weeks starting at weaning. Food intake and body weight were weekly recorded. At the end of the experiment, fat pads were sampled, leptin and insulin were measured in the plasma and NPY in several microdissected brain areas. Substituting ASP for water led to lower body weight (-8%; P<.004) and lower fat depot weight (-20%; P<.01) with no differences in energy intake or plasma insulin concentrations. Plasma leptin was significantly reduced by 34% (P<.05). Leptin concentrations were well-correlated with final body weight (r=.47; P<.025) and fat pad mass (r=.53; P<.01). NPY concentrations were 23% lower (P<.03) in the arcuate nucleus of ASP rats with no differences in other brain areas. The beneficial effects on body composition could be related to the decreased effects of NPY on lipid and energy metabolism, independently of insulin. The reasons for the NPY decrease (regulatory or toxicological) are not obvious. The constitutive amino acids of the ASP molecule might participate in the NPY regulation.

Immunogenicity of booster vaccination with a virosomal hepatitis A vaccine after primary immunization with an aluminum-adsorbed hepatitis A vaccine.

BACKGROUND: Increasing numbers of individuals are traveling to areas of high hepatitis A endemicity and require immunization against the hepatitis A virus (HAV). The option of using a virosomal, aluminum-free, HAV vaccine (Epaxal) for booster immunization following primary vaccination with an aluminum-adsorbed vaccine has been assessed. METHODS: In total, 142 healthy subjects, 79 men and 63 women, aged 12 to 72 years, were injected intramuscularly with a booster dose of Epaxal (0.5 mL containing < or =500 RIA units of HAV antigen) 6 to 24 months after primary vaccination with Havrix (0.5 or 1.0 mL containing 720 or 1440 ELISA units of HAV antigen, respectively, adsorbed onto aluminum hydroxide). Anti-HAV antibody titers were measured on days 0 and 28 by an enzyme immunoassay. Adverse events were recorded for 1 month postinjection. RESULTS: Overall, 98/118 subjects (83%) with no serologic evidence of past HAV infection were still seroprotected at enrolment (anti-HAV antibody titer < or = 20 mIU/mL). The seroprotection rate was 87% in those primed with Havrix 1440 6 to 12 months earlier (n=93) and 60% in those primed < or =12 months before enrolment (n=20, mean 16 months). The geometric mean anti-HAV antibody titer increased from 65 mIU/mL at day 0 to 1,722 mIU/mL at day 28 after a single booster dose with Epaxal in evaluable subjects who were primarily vaccinated with either a single dose of Havrix 1440 (n=111) or two separate doses of Havrix 720 (n=4). All subjects were seroprotected at day 28, and 98% showed at least a four-fold increase in anti-HAV antibody titer. Epaxal was well tolerated and no serious adverse events were reported. At day 28, the tolerability of the vaccination was judged as either "very good" or "good" by 96% of vaccinees and by all investigators. CONCLUSION: Epaxal can be successfully used to boost immunization following primary vaccination with an aluminum-adsorbed vaccine, and is well tolerated.

Ghrelin, neuropeptide Y, and other feeding-regulatory peptides active in the hippocampus: role in learning and memory.

The hippocampus is a brain region of primary importance for neurogenesis, which occurs during early developmental states as well as during adulthood. Increases in neuronal proliferation and in neuronal death with age have been associated with drastic changes in memory and learning. Numerous neurotransmitters are involved in these processes, and some neuropeptides that mediate neurogenesis also modulate feeding behavior. Concomitantly, feeding peptides, which act primarily in the hypothalamus, are also present in the hippocampus. This review aims to ascertain the role of several important feeding peptides in cognitive functions, either through their local synthesis in the hippocampus or through their actions via specific receptors in the hippocampus. A link between neurogenesis and the orexigenic or anorexigenic properties of feeding peptides is discussed.

Ingestion of Carbohydrate-Rich Supplements during Gestation Programs Insulin and Leptin Resistance but not Body Weight Gain in Adult Rat Offspring.

Prenatal nutritional conditions can predispose to development of obesity and metabolic syndrome in adulthood. Gestation with its important modifications in hormonal status is a period of changes in normal feeding habits with pulses of consumption or avoidance of certain categories of food. We tried to mimic in an animal model some changes in food consumption patterns observed in pregnant women. For this purpose, Long-Evans female rats were fed during the dark period, their usual pre-gestational food quantity, and were allowed to complete their daily intake with either a restricted control (Cr), high-fat (HF), or high-carbohydrate (HC) diet available ad libitum during the light period. Dams fed a control diet ad libitum (Ca) served as controls. Body weight and composition, food intake, and metabolic hormones (insulin, leptin) were recorded in male offspring until 20 weeks after birth. Cr and HC females ate less than Ca females (-16%; p < 0.001) and their offspring presented a weight deficit from birth until 6 (HC group) and 10 (Cr group) weeks of age (p < 0.05 or less). Plasma leptin corresponded to low body weight in Cr offspring, but was increased in HC offspring that in addition, had increased plasma insulin, blood glucose, and subcutaneous adipose tissue mass. HF dams ate more than Ca dams (+13%; p < 0.001), but plasma leptin and insulin were similar in their offspring. Hypothalamic Ob-Rb expression was increased in Cr, HC, and HF offspring (+33-100% vs Ca; p < 0.05 or less). HC supplement ingestion during gestation therefore leads to insulin and leptin resistance in adult offspring independently of lower birth weight. These hormonal changes characterize obesity-prone animals. We therefore suggest that attention should be paid to the carbohydrate snacking and overall carbohydrate content in the diet during the last weeks (or months) preceding delivery to limit development of later metabolic disorders in offspring.

Early and persistent up-regulation of hypothalamic orexigenic peptides in rat offspring born to dams fed a high-carbohydrate supplement during gestation.

Maternal diet ingested during gestation can profoundly alter production and action of hypothalamic neuropeptides involved in feeding and body weight regulation. In this study, we set out to simulate, in a rat model, modifications to feeding habit often observed in pregnant women. Gestating dams were fed a restricted normal diet with the opportunity to complete their energy requirements with either a high-fat (HF) or a high-carbohydrate (HC) diet. Growth and hypothalamic feeding peptides were measured in the offspring at 3 (weaning) and 20 weeks of age. At weaning, body weight was lower in HC pups than in HF pups or control (Ca) pups born to dams fed control diet ad libitum. Expression of neuropeptide Y (NPY) and AgRP mRNA in the arcuate nucleus were increased in HC pups vs Ca and HF pups. By 20 weeks of age, body weight differentials had disappeared, and there was no differences in NPY and AgRP gene expression, although POMC expression was lower in HC rats than in HF rats. NPY and orexin peptide concentrations in the paraventricular nucleus at this age were higher in HC rats than in Ca and HF rats. In HC rats, there was also a greater positive gradient of peptide concentration between the zone of release and the zone of synthesis for NPY and orexin. The early up-regulation of orexigenic peptides in HC rats may be a compensatory adjustment to low body weight. This persisting overactive orexigenic drive might have deleterious metabolic effects in an obesogenic environment at adulthood.

Increased homocysteinemia is associated with beneficial effects on body weight after long-term high-protein, low-fat diet in rats.

OBJECTIVE: Diets rich in protein are often used for weight loss in obese patients, but their long-term effects are not fully understood. Homocysteine (Hcy) is considered to be a risk factor for cardiovascular diseases, and its levels are influenced by diet, particularly the protein and fat content. We studied the effect of diets with varying fat/protein content on body weight and composition, food intake, Hcy, B vitamins, leptin, and several pro-inflammatory cytokines. METHODS: For 2 mo, Long-Evans rats were fed either a low protein/high fat (LP), a standard control (C), or a high protein/low fat (HP) diet containing 5, 15, or 40% protein, respectively, and normal carbohydrate content (55% of total energy). RESULTS: The HP rats ingested 12 to 15% fewer calories (P < 0.001), gained less weight (P < 0.04), and were less fatty (P < 0.01) than the other groups. Plasma Hcy was increased in HP rats compared to C (+23%) and LP (+29%) rats (P < 0.03). It was positively correlated with protein intake (r = 0.386; P < 0.01). No obvious signs of inflammation were observed in any of the groups. Hcy increase was related directly to decrease in plasma folate (r = -0.372; P < 0.02). CONCLUSION: These data confirm the beneficial effects of HP diets on body weight but bring attention to the control of folate allowance to limit the adverse effects of elevated Hcy. Ingestion of folate-rich foods or even folate supplementation should be considered when using these HP diets over the long term for weight loss.

Differential long-term dietary regulation of adipokines, ghrelin, or corticosterone: impact on adiposity.

In the present experiment, we examined in Long-Evans rats the long-term effects of diets that differed in the energy provided by proteins (P) and fats (F) but provided a constant level of energy from carbohydrates (55%) on various hormones regulating feeding and metabolism. Sixty adult rats were fed for 2 months either a high-fat (protein-to-fat, PF 5/40), a control (PF 15/30), low-fat (PF 30/15), or high-protein (PF 40/5) diet ad libitum. Both the PF 30/15 and the PF 40/5 rats ate significantly less than their PF 5/40 and PF 15/30 counterparts throughout the experiment (P<0.001). PF 40/5 rats weighed less than PF 15/30 rats (PL=0.04). PF 40/5 and PF 30/15 rats had smaller epididymal and perirenal adipose tissue depots than PF 5/40 and PF 15/30 rats (P<0.05 or less). Adiponectin (+25-47%) and leptin levels in the PF 5/40 rats were higher than in the three other groups (P<0.0025 or less). Ghrelin concentration in the PF 30/15 group was also higher than in the three other groups (P<0.001 versus PF 5/40; P<0.05 versus PF 15/30 and PF 40/5). Corticosterone level was 2- to 2.5-fold higher in PF 40/5 rats than in the three other groups (P<0.01 or less). Immunoreactive insulin was not different between the four groups. Our current findings thus show that increases in the protein content resulted in a greater degree of leanness, but at sufficiently high levels, also activated the hypothalamo-pituitary axis. Ghrelin appeared to be down-regulated by increases in fat content and no obvious signs of insulin resistance were observed in any of the rats under study.

Neuropeptide Y in the arcuato-paraventricular pathway and diet selection in the vasopressin-deficient Brattleboro rat.

Neuropeptide Y (NPY) is one of the most important brain peptides involved in feeding behavior. It influences both food choice and fluid homeostasis. The paraventricular and arcuate nuclei belong to the main pathway through which NPY stimulates carbohydrate intake. In this study, we measured NPY in various hypothalamic microdissected areas in Brattleboro di/di rats, a rat model of diabetes insipidus with specific dietary preferences. We confirmed that this rat is characterized by an increased fat intake (+10%; p<0.001) and a decreased carbohydrate intake (-10%; p<0.001) leading to a completely different dietary profile than that of di/+ controls. This profile was associated with a decrease in NPY in the paraventricular nucleus (-33%; p<0.005) and in the ventromedial nucleus (-24%; p<0.002). Intake of carbohydrate was negatively correlated with the gradient of NPY concentration between the arcuate and paraventricular nuclei. NPY could therefore contribute to the qualitative changes of feeding behavior in the Brattleboro rat through altered transport/release of the peptide and participate in the balance of neuropeptides that determines food choice in this strain of rat.

Hypothalamic galanin and early state of hyperphagia in obese Zucker rats.

Galanin (GAL) stimulates food intake in normal rats when it is injected in different hypothalamic areas involved in feeding such as the paraventricular and ventromedial nuclei and the lateral hypothalamus. At adulthood, the hyperphagic obese Zucker rat is characterized by a general dysregulation of some important neuropeptides involved in the regulation of food intake including GAL. The aim of this study was to measure GAL in different microdissected brain areas in 2- and 4-week-old lean (FA/-) and obese (fa/fa) male Zucker rats in order to know if GAL actively participates in triggering abnormal feeding behavior in obese rats. There was a significant increase (40%-220%) in GAL concentration with age in the arcuate and dorsomedial nuclei and in the above areas except for the lateral hypothalamus. Genotype differences were observed in the arcuate and paraventricular nuclei only. GAL levels were globally lower in obese than in lean rats (-15% to -25%) and the difference was significant at 2 weeks of age in the paraventricular nucleus and at 4 weeks of age in the arcuate nucleus. In agreement with human observations, these data suggest that GAL is not an early player in the development of overeating.

Responsiveness of obese Zucker rats to [D-Trp34]-NPY supports the targeting of Y5 receptor for obesity treatment.

The increased synthesis and release of neuropeptide Y (NPY) in the hypothalamus participate in the development of overeating and obesity in the Zucker fa/fa rat. The orexigenic effects of NPY are mediated through the Y1 and Y5 receptors. The substitution of [D-Trp34] in the NPY amino-acid sequence increases selectivity without lowering potency at the Y5 receptor. In the present study, to address the role of the NPY Y5 receptor in obesity, we investigated the acute effect of [D-Trp 34]-NPY in lean and obese Zucker rats. Obese rats were markedly hyperphagic (27.1 +/- 0.6 vs. 18.7 +/- 0.4 (lean) g/day; p < 0.01). Injection of [D-Trp34]-NPY in the lateral brain ventricle at a dose of 16 microg stimulated food intake to the same extent in both lean (p < 0.01) and obese (p < 0.01) rats 1 h after injection. This effect was still observed after 6 h (p < 0.01). These results indicate, therefore, that the obese rats are responsive to [D-Trp34]-NPY. They support the role of the neuropeptide Y5 receptor in the regulation of food intake and suggest that NPY Y5 antagonism might be useful for treating obesity.