Energy deficit is common during prolonged periods of strenuous physical activity and limited sleep, but the extent to which appetite suppression contributes is unclear. The aim of this randomised crossover study was to determine the effects of energy balance on appetite and physiological mediators of appetite during a 72-h period of high physical activity energy expenditure (about 9·6 MJ/d (2300 kcal/d)) and limited sleep designed to simulate military operations (SUSOPS). Ten men consumed an energy-balanced diet while sedentary for 1 d (REST) followed by energy-balanced (BAL) and energy-deficient (DEF) controlled diets during SUSOPS. Appetite ratings, gastric emptying time (GET) and appetite-mediating hormone concentrations were measured. Energy balance was positive during BAL (18 (sd 20) %) and negative during DEF (–43 (sd 9) %). Relative to REST, hunger, desire to eat and prospective consumption ratings were all higher during DEF (26 (sd 40) %, 56 (sd 71) %, 28 (sd 34) %, respectively) and lower during BAL (–55 (sd 25) %, −52 (sd 27) %, −54 (sd 21) %, respectively; P condition < 0·05). Fullness ratings did not differ from REST during DEF, but were 65 (sd 61) % higher during BAL (P condition < 0·05). Regression analyses predicted hunger and prospective consumption would be reduced and fullness increased if energy balance was maintained during SUSOPS, and energy deficits of ≥25 % would be required to elicit increases in appetite. Between-condition differences in GET and appetite-mediating hormones identified slowed gastric emptying, increased anorexigenic hormone concentrations and decreased fasting acylated ghrelin concentrations as potential mechanisms of appetite suppression. Findings suggest that physiological responses that suppress appetite may deter energy balance from being achieved during prolonged periods of strenuous activity and limited sleep.

Mounting evidence showed that bitter-tasting compounds modulate eating behaviour through bitter taste receptors in the gastrointestinal tract. This study aimed at evaluating the influence of microencapsulated bitter compounds on human appetite and energy intakes. A microencapsulated bitter ingredient (EBI) with a core of bitter Gentiana lutea root extract and a coating of ethylcellulose–stearate was developed and included in a vanilla microencapsulated bitter ingredient-enriched pudding (EBIP). The coating masked bitterness in the mouth, allowing the release of bitter secoiridoids in the gastrointestinal tract. A cross-over randomised study was performed: twenty healthy subjects consumed at breakfast EBIP (providing 100 mg of secoiridoids) or the control pudding (CP) on two different occasions. Blood samples, glycaemia and appetite ratings were collected at baseline and 30, 60, 120 and 180 min after breakfast. Gastrointestinal peptides, endocannabinoids (EC) and N-acylethanolamines (NAE) were measured in plasma samples. Energy intakes were measured at an ad libitum lunch 3 h after breakfast and over the rest of the day (post lunch) through food diaries. No significant difference in postprandial plasma responses of gastrointestinal hormones, glucose, EC and NAE and of appetite between EBIP and CP was found. However, a trend for a higher response of glucagon-like peptide-1 after EBIP than after CP was observed. EBIP determined a significant 30 % lower energy intake over the post-lunch period compared with CP. These findings were consistent with the tailored release of bitter-tasting compounds from EBIP along the gastrointestinal tract. This study demonstrated that microencapsulated bitter secoiridoids were effective in reducing daily energy intake in humans.

Adult Corrigia vitta (Trematoda: Dicrocoelidea) inhabit the pancreatic duct of the fieldmouse, Apodemus sylvaticus, where, in numbers, they may occlude the duct lumen and prevent the flow of pancreatic secretions. Enzyme histochemical and immunocytochemical techniques, in conjunction with confocal scanning laser microscopy, have been used to examine the localization and distribution of cholinergic. serotoninergic (5-HT, serotonin) and peptidergic components of the nervous system of the adult worm. All three classes of neuronal mediator showed a common pattern of staining, occurring throughout the central and peripheral nervous systems. Of the four peptide immunoreactivities (IR) demonstrated (pancreatic polypeptide (PP), peptide YY (PYY), substance P (SP), FMRFamide), PP-IR was the most predominant, occurring not only within the central ganglia and longitudinal nerve cords, but also in subtegumental plexuses and in fibres associated with the egg-forming apparatus. PYY and FMRFamide IRs were evident throughout the central and peripheral nervous systems; FMRFamide immunostaining, in particular, highlighted innervation of the ootype and immunoreactive cell bodies around the Mehlis' gland. Both SP- and 5-HT-IRs were restricted to the cerebral ganglia, ventral nerve cords and associated cell bodies. The distribution pattems of these peptides and 5-HT within the nervous system of C. vitta suggest they are likely to function as neuronal mediators. PP, PYY and FMRFamide may also serve in regulating egg production.

An electron microscopical examination has been made of the fine structure and disposition of pancreatic polypeptide immunoreactive cells associated with the egg-forming apparatus in Diclidophora merlangi. The cell bodies are positioned in the parenchyma surrounding the ootype and taper to axon-like processes that extend to the ootype wall. The terminal regions of these processes branch and anastomose and, in places, the swollen endings or varicosities form synaptic appositions with the muscle fibres in the ootype wall. The cells are characterized by an extensive GER-Golgi system that is involved in the assembly and packaging of dense-cored vesicles. The vesicles accumulate in the axons and terminal varicosities, and their contents were found to be immunoreactive with antisera raised to the C-terminal hexapeptide amide of pancreatic polypeptide. It is concluded that the cells are neurosecretory in appearance and that, functionally, their secretions may serve to regulate ootype motility and thereby help co-ordinate egg production in the worm.

The localization and distribution of neuropeptides in the nervous system of the liver fluke, Fasciola hepatica at different stages in the development of the adult fluke have been determined by an indirect immunofluorescence technique, using antisera to 19 vertebrate peptides and the invertebrate neuropeptide, FMRFamide. Positive immunoreactivity was obtained with antisera to pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), substance P (SP) and FMRFamide. Cell bodies and nerve fibres immunoreactive to the 4 peptides are present in the anterior ganglia and the 3 pairs of longitudinal nerve cords and their commissures in the central nervous system. In the peripheral nervous system, immunoreactivity occurs in the nerve plexuses supplying the subtegumental musculature, the oral and ventral suckers, and the muscular lining of the male and female reproductive ducts, including the ootype, uterus, cirrus pouch and gonopore. Cells displaying immunoreactivity to PYY and FMRFamide lie amongst the Mehlis' gland cells that surround the ootype. Processes from these cells extend into the wall of the ootype. One group of PP-immunoreactive cells occurs at the junction of the vitelline and ovovitelline ducts, whilst another group is situated at the entrance to the uterus from the ootype. The results are discussed in relation to the possible roles of the peptides in the neurophysiology and egg production of the fluke.

Using a C-terminally directed pancreatic polypeptide (PP) antiserum and immunocytochemical methods, PP-immuno-reactivity (IR) was localized throughout the central (CNS) and peripheral nervous systems (PNS) of the cestode, Moniezia expansa. In the CNS, immunostaining was evident in the paired cerebral ganglia (primitive brain), connecting commissure, and the paired longitudinal nerve cords that are cross-linked by numerous regular transverse connectives. The PNS was seen to consist of a fine anastomosing nerve-net of immunoreactive fibres, many of which were closely associated with reproductive structures. Radioimmunoassay of this peptide IR in acid-alcohol extracts of the worm measured 192·8 ng/g of PP–IR. HPLC analyses of the M. expansa PP–IR identified a single molecular form which was purified to homogeneity. Plasma desorption mass spectrometry (PDMS) of purified parasite peptide resolved a single peptide with a molecular mass of 4599±10 Da. Automated gas-phase Edman degradation identified a 39-amino acid peptide with a C-terminal phenyl-alaninamide. Examination of its primary structure shows that it displays significant sequence homology with the vertebrate neuropeptide Y superfamily, suggesting that this platyhelminth-derived peptide is the phylogenetic precursor. Neuropeptide F (M. expansa) is the first regulatory peptide to be fully sequenced from the phylum Platyhelminthes and may represent a member of an important new class of invertebrate neuropeptide.

A post-embedding immunogold technique has been used to examine the subcellular distribution of immunoreactivities to vertebrate pancreatic polypeptide (PP) and to the invertebrate peptide, FMRFamide within the central nervous system (CNS) of the nematode, Ascaris suum. Gold labelling of peptide was localized exclusively over dense-cored vesicles within nerve cell bodies, nerve axons and nerve terminals of the main ganglia and nerve cords in the CNS. Double-labelling of peptides demonstrated an apparent co-localization of PP and FMRFamide immunoreactivities in the same dense-cored vesicles, although populations of dense-cored vesicles that labelled solely for FMRFamide were also evident. Antigen preabsorption studies indicated little or no cross-reactivity between the two antisera.

Immunocytochemical techniques used in conjunction with confocal scanning laser microscopy (CSLM) and electron microscopy have been used to demonstrate, for the first time, the distribution of the parasitic platyhelminth neuropeptide, neuropeptide F (NPF) in the cestode, Moniezia expansa. Antisera were raised to intact NPF(1–39) and to the C-terminal decapeptide of NPF(30–39). These antisera were characterized and validated for use in both immunocytochemistry and radioimmunoassay (RIA). NPF immunoreactivity (IR) was detected using both antisera throughout all of the major components of the central and peripheral nervous systems of the worm. The pattern of NPF-IR was found to mirror the IR obtained using a C-terminally directed pancreatic polypeptide (PP) antiserum and FMRFamide antisera; blocking studies using these antisera revealed that FMRFamide and PP antisera cross-react with NPF(M. expansa). RIA of acid-alcohol extracts of the worm measured 114 ng/g using the C-terminal NPF antiserum and 56 ng/g using the whole-molecule-directed antiserum. While the C-terminally-directed NPF antiserum cross-reacts with NPF-related peptides from other invertebrates, the whole-molecule-directed NPF antiserum is specific for NPF(M. expansa). The C-terminal NPF antiserum has potential for use in the identification and purification of NPF analogues from other platyhelminth parasites.

Pancreatic polypeptide (PP) is a gut hormone released from the pancreas in response to food ingestion and remains elevated for up to 6 h postprandially. Plasma levels are elevated in patients with pancreatic tumours. An intravenous infusion of PP has been reported to reduce food intake in man, suggesting that PP is a satiety hormone. We investigated whether a lower infusion rate of PP would induce significant alterations in energy intake. The study was randomised and double-blinded. Fourteen lean fasted volunteers (five men and nine women) received 90 min infusions of PP (5 pmol/kg per min) and saline on two separate days. The dose chosen was half that used in a previous human study which reported a decrease in appetite but at supra-physiological levels of PP. One hour after the end of the infusion, a buffet lunch was served and energy intake measured. PP infusion was associated with a significant 11 % reduction in energy intake compared with saline (2440 (se 200) v. 2730 (se 180) kJ; P < 0·05). Preprandial hunger as assessed by a visual analogue score was decreased in the PP-treated group compared to saline. These effects were achieved with plasma levels of PP within the pathophysiological range of pancreatic tumours.

The ontogenesis, postnatal development and ageing of the endocrine pancreas in mammals have not been extensively studied. In order to improve understanding of this organ, we studied the buffalo pancreas during fetal and postnatal development. Glucagon, insulin and somatostatin immunoreactive cells (i.c.) were first seen in 2-mo-old embryos. Pancreatic polypeptide (PP) i.c. were observed during the 3rd month of gestation. The early embryo pancreas was almost totally composed of endocrine tissue. The endocrine portion only slightly increased in mass with animal growth, whereas the exocrine portion noticeably increased in mass during the late fetal and postnatal periods. In adults, therefore, the exocrine portion was more evident than the endocrine portion. Three types of islet were observed in fetal and young buffalos: small, large and PP-islets. The small islets were composed of insulin, glucagon, somatostatin and PP i.c. The large islets were primarily composed of insulin i.c. and a few glucagon, somatostatin and PP i.c. The PP islets were mostly composed of PP i.c. with a few somatostatin, insulin and glucagon i.c. The number of large islets greatly diminished by adulthood. Glucagon, insulin, somatostatin and PP i.c. were also seen scattered in the exocrine parenchyma and along the duct epithelium. In the duct epithelium, these cells were either single or grouped, and they sometimes formed a protrusion projecting towards the connective tissue. These morphological features were primarily observed in fetuses and young buffalos.

The endocrine pancreas of the toad consists of rounded islets of various sizes embedded in the exocrine tissue. Isolated cells are also present. At least 4 types of endocrine cell are distinguishable by shape, size and electrondensity of the secretory granules as well as by their immunoreactivity with different antisera: insulin, somatostatin, pancreatic polypeptide, and glucagon cells. Insulin cells can be divided into 2 types according to their cytoplasmic electrondensity. Colocalisation of different hormones in the same cell is rarely observed. The close contact between endocrine and exocrine cells and the scarcity of nerve supply is indicative of a paracrine control of hormone secretion.

The flow pattern of unilateral parotid saliva in sheep was compared when a total of 800 g lucerne (Medicago sativa) hay was offered as one, two, four or eight distinct meals. These patterns were related to changes in the tonicity of rumen fluid and plasma and to plasma concentrations of gastrin and pancreatic polypeptide. Sheep having ad lib access to hay overnight were offered fresh hay from 08.00 to 09.00 hours and were then given one, two, four or eight meals of fresh hay according to a schedule such that the mean deprivation period was 6.5 h for each meal frequency-size. Neither the peak in saliva flow rate nor the time of this peak differed among the different meal sizes. The flow rate decreased rapidly after reaching a maximum at 3.2 min into the meal. After 7 min of eating, the tonicity of plasma and rumen fluid had increased by only 2.2 and 8.2 mosmol/kg respectively. These increases would not cause the rapid decline in parotid flow observed after 3.2 min of eating. There was no postprandial change in the concentration of gastrin in jugular plasma. However, it did increase significantly (P = 0.0043) from 16 to 4 min before eating commenced. There was a postprandial peak in plasma pancreatic polypeptide concentration after 4.5 min of eating. However, the parotid flow rate remained low after the concentration of this peptide returned to prefeeding levels. The rapid decrease in parotid secretion rate observed early in the meal may be due to subsiding central excitation rather than to an inhibitory factor limiting production.