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Neuropeptide Y (NPY) is the most potent stimulant of feeding when administered by intracerebroventricular injection. Despite this, there is conflicting evidence as to its importance in the regulation of daily food intake and energy balance. It has been suggested that whilst it is important in the response to starvation it has little role in the regulation of daily food intake. To investigate the role of NPY in the regulation of food intake, anti-sense cRNA to NPY was expressed in the arcuate nucleus of adult male rats. The anti-sense NPY (AS-NPY) construct was initially tested in vitro and there was a decrease of approximately 50% in NPY release from anti-sense treated cells compared to controls (16.3 +/- 2.0 fmol/L [AS-NPY] vs 37.3 +/- 7.7 fmol/L [control], mean +/- SEM p < 0.05). NPY release from hypothalamic explants from anti-sense injected animals was decreased by over 50% compared to those from controls at both 15 and 20 days after AAV injection (15 days 42% +/- 6.5% [AS-NPY] vs 100% +/- 36% [control], 20 days 41% +/- 6% [AS-NPY] vs 100% +/- 27% [control] mean+/-SEM, p < 0.05). In a study lasting for 50 days, weight gain was significantly lower in anti-sense injected animals from day 16 (day 16: 6.25 +/- 1.10 g [AS-NPY] vs 9.42 +/- 0.65 g [control] mean +/- SEM, p < 0.05) and remained so until the end of the study when they had gained approximately 40% less weight than controls (day 50: 52.0 +/- 9.6 g [AS-NPY] vs 82.0 +/- 6.3 g [control] mean +/- SEM, p < 0.01). Cumulative food intake was significantly lower in the anti-sense injected animals from day 23 (day 23: 225.8 +/- 1.9 g [AS-NPY] vs 250.6 +/- 8.7 g [control], mean +/- SEM, p < 0.05) and remained so until the end of the study (day 50: 834.5 +/- 14.8 g [AS-NPY] vs 926.0 +/- 31.7 g [control], mean +/- SEM, p < 0.05). Similarly mean daily food intake was also reduced in the anti-sense injected animals (days 7-14: 24.9 +/- 0.4 g/day [AS-NPY] vs 27.2 +/- 0.4 g/day [control], mean +/- SEM, p < 0.01). These data are supportive of a role for NPY in the regulation of daily food intake as well as in response to starvation.

Plasma osteocalcin, a marker of osteoblastic activity, is reduced in starvation, malnutrition, and anorexia nervosa, resulting in low bone turnover osteoporosis. Contradictory findings about the role of leptin as a link between nutritional status and bone physiology have been reported. We demonstrate that leptin-deficient ob/ob and leptin-resistant db/db male mice have increased plasma osteocalcin, and that in male ob/ob mice osteocalcin is not decreased by starvation, unlike control mice. Intraperitoneal leptin administration increased plasma osteocalcin in male ob/ob mice, and prevented its fall during 24 h fasting and 5 days of food restriction in normal male mice. This effect may be mediated via actions on the hypothalamic–pituitary–testicular or –growth hormone axes, or a direct action on osteoblasts. These studies support the hypothesis that the fall in leptin during starvation and weight loss is responsible for the associated reduction in osteoblast activity, and suggest a role for leptin in regulating bone turnover.

Background: Keratinocyte growth factor (KGF) is a potent mitogen and may be of value for the treatment of conditions such as short bowel syndrome and chemotherapy-induced mucositis. However the most efficacious route and method of administration is unclear. Methods: Rats maintained by total parenteral nutrition (TPN) were given KGF (1 mg/kg/rat/day, iv) infused continuously or as a once-daily injection. The same dose was also given sc. to chow-fed rats. Changes in gut growth were assessed by measurement of wet weight, proliferation (vincristine induced metaphase arrest) and crypt branching index. Changes in gut hormone profile were also determined to examine if any trophic effects were mediated via this mechanism. Results: KGF caused a 70–100% increase in wet weight of the stomach, small and large intestine of TPN-fed rats (P

We have previously shown that intracerebroventricular BIBP 3226 inhibits NPY induced feeding in rats. However, this was associated with abnormal behaviour, likely to be due to interaction with Y1 receptors involved in mechanisms other than the control of food intake. In order to minimise such interactions we investigated the effects of paraventricular nucleus (PVN) injections of BIBP 3226 and its inactive enantiomer BIBP 3435. Intra-PVN injection of NPY (0.1-2.5 nmol/animal) increased food intake, with an EC50 of approximately 0.15 nmol/animal. Injections of BIBP 3226 and BIBP 3435 (0.25-25 nmol) reduced NPY-induced food intake in a dose responsive manner, with BIBP 3226 reducing food intake by 95%, and BIBP 3435 by 65% at the highest dose tested. The reversibility of the effect of BIBP 3226 was investigated by measuring the feeding response to NPY (0.5 nmol) in animals 1 week after BIBP 3226 injection. The response to NPY was less in animals which had received high doses of BIBP 3226. Animals previously injected with saline vehicle alone showed a normal NPY feeding response. These results suggest that BIBP 3226 may be inhibiting NPY-induced food intake in a non-specific manner, not secondary to inhibition of the Y1 receptor. This does not, however rule out a role for the Y1 receptor in the control of food intake by NPY.

This study set out to validate the use of 31P-NMR spectroscopy together with alanine +/- glucagon infusions to assess hepatic gluconeogenic flux in vivo. Bolus infusions of alanine (2.8 or 5.6 mmol/kg) +/- glucagon (250 microg/kg) were used. Maximal changes in the phosphomonoesters (PME), inorganic phosphate (Pi) and beta-NTP occurred 40 mins post infusion. PME increased 13.1% (p0.02) and 20.8% (P0.01) at 2.8 mmol/kg + glucagon and 5.6 mmol/kg +/- glucagon, respectively. Pi was unaltered at 2.8 mmol/kg but increased by 28.8% (P0.01) at 5.6 mmol/kg alanine + glucagon. beta-NTP decreased by 14.4% (P0.02) and 16.1% (P0.02) at 5.6 mmol/kg -/+ glucagon, respectively. This latter infusion showed slower recovery rates of NTP which remained 12.3% (P0.05) lower 70 min post infusion compared with pre-infusion values. 31 P-NMR analysis of liver extracts revealed that PME increases were partly due to 3-phosphoglycerate and corroborated reductions in beta-NTP and gamma-NTP: beta-NDP ratio upon infusion of 5.6 mmol/kg alanine +/- glucagon. Hepatic glucose output from perfused liver experiments showed no difference between alanine concentrations indicating maximal glucose output at the lower concentration. This study has shown that in vivo 31P-NMR in combination with alanine infusion, can be used to determine metabolic changes associated with gluconeogenesis.

Intracerebroventricular (i.c.v.) infusions of neuropeptide Y (NPY) (2500 pmol) induced c-fos protein in the paraventricular nucleus (PVN) of intact male rats 60 min later. The greatest expression was observed in the dorsal (parvicellular) region of the PVN; there were intermediate levels in the lateral (magnocellular) and lowest ones in the medial (parvicellular) regions. Allowing rats to eat during the post-infusion interval did not modify this pattern of c-fos expression. Depriving rats of food for either 24 or 48 h did not induce recognisable expression of c-fos in the PVN, and allowing 24 h-deprived rats to eat also had no effect on PVN c-fos. Plasma insulin was increased by i.c.v. NPY, and raised still further in rats that were allowed to eat following NPY infusions. However, plasma glucose was not altered by either treatment. Food-deprived rats had low levels of insulin, but unaltered blood glucose, compared to controls. These results show that NPY can induce c-fos expression in both parvicellular and magnocellular areas of the PVN. The pattern of expression within the PVN seems to differ from that induced by other peptides, such as angiotensin II, vasopressin and corticotropin-releasing factor, suggesting that distinct populations of neurons are activated by different peptides within the complex structure of the PVN. Food deprivation does not induce c-fos expression within the PVN, though other studies have shown that NPY levels and release are both increased, so there is no simple relation between current energy state, blood levels of either glucose or insulin and c-fos expression within the PVN.

Endothelin-1 (ET-1) is a 21-residue peptide isolated from the conditioned medium of cultured porcine endothelial cells and is widely distributed throughout the body, with relatively high levels in the kidney and lung. Animal studies have revealed that the lung appears to have the largest capacity for ET-1 removal from the blood stream. In this study we have examined the possible influence of thyroid status on immunoreactive endothelin (IR-ET) levels in the plasma and lung of the male rats. 3 weeks after the surgical removal of the thyroid gland from male rats, the IR-ET levels in the lung were reduced by 39%. Similarly, IR-ET levels were decreased 46% in the lung of rats rendered hypothyroid by treatment with 0.1% (w/w) PTU in the drinking water for 30 days, and replacement with daily L-thyroxine (T4) injections (5 micrograms/100 g) prevented this decrease. However, thyrotoxicosis induced by daily L-T4 injections (10 micrograms/100 g) also caused a decrease of the lung IR-ET levels by 49%. Nevertheless, the plasma IR-ET levels are similar in each group. Fast protein liquid chromatography study verified the presence of ET-1 immunoreactivity in both rat plasma and lung tissue extracts. This study demonstrates that euthyroid status is required for the maintenance of physiological concentrations of IR-ET in the lung of male rats.

Neuropeptide Y (NPY) is a powerful appetite stimulant, and hypothalamic concentrations rise after food deprivation and in experimental diabetes. Serotonergic drugs such as dexfenfluramine are inhibitors of feeding. We measured hyothalamic NPY and NPY mRNA, along with galanin, neurotensin, and somatostatin in chow-fed rats and in rats with dietary obesity, and examined the effect of dexfenfluramine on these peptides in this model. Sixty-five rats were fed a palatable diet (condensed milk, sucrose and chow) for 6 weeks, which produced significant weight gain compared to twenty fed standard chow ( 145.1 ± 2.3 g vs. 113.4 ± 3.2 g , p ). Groups of animals were treated for 7 days or 28 days with dexfenfluramine (1.8 mg/kg/day) or saline intraperitoneally via miniosmotic pumps. Hypothalami were dissected into medial and lateral blocks, and NPY, galanin, neurotensin, and somatostatin were measured by radioimmunoassay. Neuropeptide Y mRNA was measured by Northern blotting. Hypothalamic NPY was significantly higher in the palatable diet group compared to chow-fed controls (medial hypothalamus: 86.6 ± 7.6 vs. 65.7 ± 4.0 pmol/g tissue, p , lateral hypothalamus 71.2 ± 6.6 vs. 53.1 ± 3.6 pmol/g tissue, p ), but NPY mRNA was unchanged. Although dexfenfluramine was effective at reducing weight gain in the animals fed the palatable diet, this did not result in any changes in the hypothalamic neuropeptides measured. Neuropeptide Y may be of importance in diet-induced obesity but the weight loss produced by dexfenfluramine in such animals is not mediated by changes in hypothalamic NPY.

We have measured plasma histamine concentrations, systemic vascular resistance, cardiac output and arterial pressure during laparotomy in a patient with systemic mastocytosis. The patient developed vasodilatation and hypotension and hypotension during surgery, associated with a massive increase in plasma histamine concentration.

Peptide histidine valine (PHV) is a 42 amino acid polypeptide closely related to the neuropeptides VIP, PHI and PHM. We have performed a placebo-controlled, double-blind study to assess the hypothesis that the cardiovascular response to PHV infusion may be mediated via the sympathetic nervous system. Four subjects received atenolol or matched placebo 90 min prior to a controlled incremental infusion of PHV, with monitoring of heart rate, blood pressure and skin temperature. Following placebo all subjects showed a dose-related increase in heart rate and skin temperature with no effect on blood pressure during PHV infusion. β-Blockade had no effect on skin temperature response. Pre-treatment with atenolol reduced the resting blood pressure and the maximum heart rate achieved, but did not affect the percentage increase in heart rate during PHV infusion. This suggests that the action of PHV does not involve β-receptors. The lack of effect of PHV infusion on blood pressure, despite tachycardia and marked cutaneous vasodilatation, implies that PHV has a different effect on the resistance vessels from that of other peptides such as VIP.

Background Kisspeptin (encoded by the KISS1 gene) is a crucial regulator of normal reproductive function. In human beings, KISS1 deletion results in a failure to go through puberty whereas activating mutations result in central precocious puberty. Administration of kisspeptin induces ovulation in rodents and sheep, but whether exogenous kisspeptin can alter the menstrual cycle in healthy women is not known. This study aimed to determine the effects of kisspeptin administration on the menstrual cycle in healthy women. Methods A prospective, single-blinded, one-way crossover study at Imperial College, London, was performed. Five healthy female volunteers aged 24–37 years were recruited through adverts in the local press. They each received twice-daily subcutaneous injections of kisspeptin-54 or saline for 7 days during days 7 to 14 of their menstrual cycle. All women underwent serial assessments of basal reproductive hormones, ultrasound measurements, and luteinising hormone (LH) pulsatility, as well assessment of acute sensitivity to gonadotrophin-releasing hormone (GnRH) and kisspeptin injection. Because of the intensive protocol, women attended for assessments every 2–3 days throughout the cycle, rather than daily, to minimise stress and enhance compliance. Ethics approval was granted by the Hammersmith and Queen Charlotte's and Chelsea Hospitals Research Ethics Committee (registration number 05/Q0406/142). Findings Kisspeptin-54 treatment shortened the menstrual cycle (mean length of menstrual cycle: saline 28·6 days [SE 3·1] vs kisspeptin 26·8 [3·1], p=0·0043), advanced the onset of highest recorded serum LH (mean menstrual day of highest recorded LH 15·2 [SE 2·9] vs 13·0 [4·1], p=0·0372), and advanced the onset of the luteal phase of the menstrual cycle (mean menstrual day of progesterone increase 18·0 [SE 2·1] vs 15·8 [2·0], p=0·0402). On menstrual day 15, the largest ovarian follicle had a significantly higher diameter after kisspeptin-54 than after saline (mean diameter of largest follicle saline 10·0 mm [SE 4·4] vs kisspeptin 15·5 mm [2·2], p=0·04). LH pulsatility was maintained during kisspeptin-54 treatment. Sensitivity to exogenous kisspeptin-54 and exogenous GnRH was maintained during twice-daily kisspeptin-54 administration. Interpretation We have shown, for the first time to our knowledge using biochemical and radiological data, that exogenous kisspeptin-54 advances the menstrual cycle in healthy women. These data have important therapeutic implications for the use of kisspeptin in the treatment of women with reproductive disorders. Even though participants attended every 2–3 days rather than daily, statistical significance in key parameters was still achieved, confirming the strength of the data. In addition, use of both biochemical and radiological data allowed detailed analysis of the underlying physiological processes. Funding Wellcome Trust, National Institute for Health Research, UK Medical Research Council.

Ghrelin, a powerful appetite-stimulating hormone secreted by the stomach, is modified by an octanyl side chain on its third amino acid, a serine, which is essential for its activity. A recent study (Yang et al., 2008) reports identification of the enzyme catalyzing the addition of this octanyl, GOAT.

To investigate whether peptide YY (PYY) has a role in minimising fluid loss during diarrhoea, its effect on hypersecretion induced by vasoactive intestinal peptide (VIP) was studied in seven subjects with ileostomies. An isotonic electrolyte solution containing polyethylene glycol 4000 was infused directly into the duodenum and the effluent was collected for 40 min (baseline), then VIP was infused intravenously at 5 pmol.kg -1 .min -1 for 500 min. PYY was infused intravenously at low doses (0·4 and 0·2 pmol.kg -1 .min -1 ) for 100 min each during the continuous VIP infusion. Small-intestinal secretion was assessed by effluent weight and by polyethylene glycol dilution, which gave similar results. Plateau ileal output was 501 (SEM 33) ml/h during VIP infusion. PYY caused significant falls in secretion—to 404 (48) ml/h for the lower dose and to 323 (75) ml/h for the higher. It also prolonged small-bowel transit. These findings suggest that PYY is a natural inhibitor of diarrhoea and that its therapeutic potential merits investigation.

arterialized-venous plasma by LC-MS/MS. Fat-free mass was assessed by Dual-energy X-ray Absorptiometry. Statistics were done using Student’s t-Test. Results: Total ARG and CIT production were not different between COPD patients and healthy controls. However, de novo ARG production was reduced in COPD (7.12±0.6 vs. 10.6±1.5mmol/kg FFM/h, p = 0.027) and lower values were also found for whole body NO synthesis (0.31±0.1 vs. 0.74±0.1mmol/kg FFM/h, p < 0.01). Conclusion: Compromised NO synthesis is associated with a reduced de novo ARG production in patients with stable COPD. This suggests that in order to upregulate whole body NO synthesis in COPD, higher dietary intake of ARG or its precursor CIT is necessary.

Introduction The reported remission of type 2 diabetes in patients undergoing Roux-en-Y gastric bypass has brought the role of the gut in glucose metabolism in focus. We aimed to explore the role of the proximal gut on glucose handling.Methods A comparative controlled investigation of oral versus gastrostomy glucose loading in patients who had previously undergone gastric bypass and had a gastrostomy tube in the gastric remnant for feeding. A standard glucose load was administered either orally (day 1) or via the gastrostomy tube (day 2). Plasma levels of glucose, insulin, glucagon-like peptide 1 (GLP-1) and peptide YY (PYY) were measured pre and post glucose loading. Results Exclusion of the proximal small gut from glucose passage induced lower plasma glucose responses and higher plasma insulin, GLP-1 and PYY responses compared to glucose via a gastrostomy (p