Neuropsychiatric Symptoms in Dementia: Considering a Clinical Role for Electroencephalography

OBJECTIVE

Degenerative dementia is characterized by progressive cognitive decline and neuropsychiatric symptoms. People with Alzheimer's disease (AD), the most common cause of dementia, show synaptic loss and disruption of functional brain networks along with neuritic plaques and neurofibrillary tangles. Electroencephalography (EEG) directly reflects synaptic activity, and among patients with AD it is associated with slowing of background activity. The purpose of this study was to identify associations between neuropsychiatric symptoms and EEG in patients with dementia and to determine whether EEG parameters could be used for clinical assessment of pharmacological treatment of neuropsychiatric symptoms in dementia (NPSD) with galantamine or risperidone.

METHODS

Seventy-two patients with EEG recordings and a score ≥10 on the Neuropsychiatric Inventory (NPI) were included. Clinical assessments included administration of the NPI, the Mini-Mental State Examination (MMSE), and the Cohen-Mansfield Agitation Inventory (CMAI). Patients underwent EEG examinations at baseline and after 12 weeks of treatment with galantamine or risperidone. EEG frequency analysis was performed. Correlations between EEG and assessment scale scores were statistically examined, as were EEG changes from baseline to the week 12 visit and the relationship with NPI, CMAI, and MMSE scores.

RESULTS

Significant correlations were found between NPI agitation and delta EEG frequencies at baseline and week 12. No other consistent and significant relationships were observed between NPSD and EEG at baseline, after NPSD treatment, or in the change in EEG from baseline to follow-up.

CONCLUSIONS

The limited informative findings in this study suggest that there exists a complex relationship between NPSD and EEG; hence, it is difficult to evaluate and use EEG for clinical assessment of pharmacological NPSD treatment.

Increased plasma hyaluronan in severe pre-eclampsia and eclampsia

Pre-eclampsia is a serious multi-system disorder with general endothelial disease, often with a component of hepatic dysfunction. The pathogenesis of preeclampsia is not fully understood, and no specific diagnostic tests are available for early and reliable diagnosis, or for monitoring of the disease process. Hyaluronan is an extracellular matrix polysaccharide present at low concentrations in plasma. Normally, it is rapidly eliminated from the blood by the liver. Increased concentrations of circulating hyaluronan are seen in conditions with impaired hepatic function such as liver cirrhosis, and hyaluronan concentrations have previously been used to evaluate hepatic function in other diseases. In the present study, 11 pregnant women admitted to the intensive care unit with severe pre-eclampsia or eclampsia were studied. As control 31 healthy pregnant women, 18 undergoing vaginal delivery and 13 caesarean section, were included. Plasma hyaluronan was measured before and after delivery. Increased concentrations of plasma hyaluronan were found in the pre-eclampsia group both before (171 (75-586) microg/L (p<0.01)) and after delivery (215 (124-768) microg/L (p<0.001)) (median and inter-quartile range), as compared to both caesarean section (13 (7-28) microg/L before and 28 (18-48) microg/L after delivery) and vaginal delivery healthy controls (12 (8-24) microg/L before and 30 (13 63) microg/L after delivery). In the control groups, a small increase in plasma hyaluronan was seen after delivery, after both caesarean section (p<0.05) and vaginal delivery (p<0.01). In conclusion, plasma hyaluronan is increased in severe pre-eclampsia and eclampsia. The cause of the increase is unknown.

Circulatory arrest in late pregnancy: caesarean section a vital decision for both mother and child

Circulatory arrest during pregnancy is extremely rare and there should be a well-planned strategy for its management in all hospitals. To consider the priority of the mother's life over the child's and an unwarranted pre-term delivery may lead to hesitancy and uncertainty and jeopardize both of them. In these situations, speed is a priority. Cardiopulmonary resuscitation should commence immediately. The anaesthesiologist should be well aware of the possible advantage of a caesarean section. Even if the obstetrician is responsible for the decision to perform the operation, the anaesthesiologist should strongly support the action. An 'emergency caesarean kit' with the essential surgical instruments should be immediately available in every labour ward and emergency department.

Generation of 2.8 ps pulses by mode-locking a Nd:GdVO4 laser with defocusing cascaded Kerr lensing in periodically poled KTP

A Nd:GdVO4 laser mode locked by self-defocusing cascaded Kerr lens in PPKTP is presented. A strong pulse shortening mechanism is produced by the interplay of group velocity mismatch and the cavity design. The cavity had a repetition rate of 200 MHz and the mode-locked output power was 350 mW. Pulses as short as 2.8 ps were obtained with a bandwidth of 0.6 nm.

Neurotrophin receptors and enteric neuronal development during metamorphosis in the amphibian Xenopus laevis

During metamorphosis, the frog intestine goes through a dramatic shortening with extensive apoptosis and regeneration in the epithelial layer and connective tissue. Our aim was to study changes in the enteric nervous system represented by one inhibitory (vasoactive intestinal polypeptide; VIP) and one excitatory (substance P, neurokinin A; SP/NKA) nerve population and concomitant changes in neurotrophin receptor occurrence during this development in the gut of Xenopus laevis adults and tadpoles at different stages of metamorphosis (NF stages 57-66). Sections were incubated with antibodies against the neurotrophin Trk receptors and p75NTR, and the neurotransmitters VIP and SP/NKA. Trk-immunoreactive nerves increased dramatically but transiently in number during early metamorphic climax. Nerves immunoreactive for p75NTR were present throughout the gut, decreased in number in the middle intestine during climax, and increased in the large intestine during late metamorphosis. The percentage of VIP-immunoreactive nerves did not change during metamorphosis. SP/NKA-immunoreactive nerves were first apparent at NF stages 61-62 in the middle intestine and increased in the stomach and large intestine during metamorphosis. Endocrine cells expressing SP/NKA increased in number in stomach, proximal, and middle intestine during metamorphic climax. Thus, neurotrophin receptors are expressed transiently in neurons of the enteric nervous system during metamorphosis in Xenopus laevis and SP/NKA innervation is more abundant in the intestine of the postmetamorphic frog than in the tadpole.

Simultaneous search for multiple QTL using the global optimization algorithm DIRECT

MOTIVATION

A simultaneous search is necessary for maximizing the power to detect epistatic quantitative trait loci (QTL). The computational complexity demands that the traditional exhaustive search be replaced by a more efficient global optimization algorithm.

RESULTS

We have the previously known algorithm adapted DIRECT, to the problem of simultaneous mapping of multiple QTL. We have compared DIRECT with standard exhaustive search and a genetic algorithm previously used for QTL mapping in two dimensions. In all two- and three-QTL test cases, DIRECT accurately finds the global optimum two to four orders of magnitude faster than when using an exhaustive search, and one order of magnitude faster than when using the genetic algorithm. Thus, randomization testing for determining empirical significance thresholds for at least three QTL is made feasible by the use of DIRECT.

AVAILABILITY

The code of the prototype implementation is available at http://user.it.uu.se/~kl/qtl_software.html

Occurrence of neurotrophin receptors and transmitters in the developing Xenopus gut

The ontogeny of gut innervation in the anuran amphibian Xenopus laevis was studied using immunohistochemistry on sections of whole larvae from NF stages 38-52. Immunoreactivity to acetylated tubulin confirmed the presence of nerve fibres as early as stages 38-39. Actin immunoreactivity was found at stage 41, indicating the presence of smooth muscle cells. Trk-like neurotrophin receptors were occasionally found in nerve fibres as soon as stages 38-39. Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) immunoreactivities coexisted in nerves innervating the gut wall from stages 40-41, and nitric oxide synthase (NOS) from stage 42. Substance P/neurokinin A (SP/NKA) occurred at stage 42. In all these cases, the first fibres were observed in the oesophagus. Calcitonin gene-related peptide (CGRP) was first observed in nerves at stage 48. In general, VIP/PACAP and NOS innervation was denser than the tachykinin innervation. In conclusion, the development of nerve fibres in the Xenopus gut is probably dependent on neurotrophins that may act via Trk-like receptors and occur before the gut wall is fully organised morphologically. Feeding in Xenopus larvae starts at NF stage 45. The study demonstrates that several of the transmitters investigated are expressed in the gut innervation (and in endocrine cells) prior to this stage.

Gastrin-releasing peptides from Xenopus laevis: purification, characterization, and myotropic activity

Two molecular forms of gastrin-releasing peptide (GRP) were isolated from an extract of the intestine of the tetraploid frog Xenopus laevis. The primary structure of GRP-1 (APTSQQHTEQ(10)LSRSNINTRG(20) SHWAVGHLM.NH(2)) differs from that of GRP-2 by a single amino acid substitution (Asn(15)--> Thr(15)). GRP-(20-29) peptide (neuromedin C) was also isolated from the extract. Synthetic GRP-1 produced concentration-dependent contractions of longitudinal smooth muscle strips from Xenopus cardiac stomach (pD(2) = 8.93 +/- 0.32; n = 6). The responses were unaffected by tetrodotoxin, atropine, and methysergide, indicating a direct action of the peptide on smooth muscle cells. GRP-1 elicited concentration-dependent relaxations of precontracted (5 microM carbachol) circular smooth muscle strips from the same region (pD(2) = 8.96 +/- 0.21; n = 8). The responses were significantly (P < 0.05) attenuated (71 +/- 24% decrease in maximum response; n = 6) by indomethacin, indicating mediation, at least in part, by prostanoids. Despite the fact that Xenopus GRP-1 differs from pig GRP at 15 amino acid sites, both peptides are equipotent and equally effective for both contractile and relaxant responses, demonstrating that selective evolutionary pressure has acted to conserve the functional COOH-terminal domain in the peptide. The data suggest a physiologically important role for GRP in the regulation of gastric motility in X. laevis.

Evolution of vertebrate neuropeptides

This review describes some of the most typical features in the evolution of neuropeptides. Neuropeptides are synthesized like other polypeptides and proteins, with an amino acid sequence determined by the DNA sequence of the corresponding gene. Mutations of bases in the coding regions of the DNA lead to changes in amino acid sequence, and explain the differences in amino acid sequence of a certain neuropeptide in different animal species. The more distantly related two species are, the more substitutions can be found in one and the same neuropeptide. The biologically active part of the neuropeptide is usually the most conserved part. Neuropeptides also form families of closely related peptides, where several members may occur in one animal species. This is due to gene or exon duplications followed by mutations. Gene splicing and posttranslational processing decides the gene product in a single cell. Difference in sequence may cause difference in function, but more often than not, members of a family appear to produce the same effect. Three neuropeptide families, the tachykinins, the neuropeptide Y family, and the vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating peptide family will be described in more detail.

Effects of trout endothelin on the motility of gastrointestinal smooth muscle from the trout and rat

Trout endothelin (ET), previously isolated from the kidney of the rainbow trout Oncorhynchus mykiss, contains four amino acid substitutions at residues 4-7 compared with rat ET-1. Trout ET produced sustained and concentration-dependent contractions of strips of longitudinal smooth muscle from trout stomach (pD(2) = 7.52 +/- 0.06) and proximal small intestine (pD(2) = 7.80 +/- 0.10) and from rat fundus (pD(2) = 7.78 +/- 0.14). Rat ET-1 was equipotent with trout ET for contraction of rat fundus and 2- to 3-fold more potent for contraction of trout gastrointestinal tissues. In contrast, rat ET-1 was 10- to 20-fold more potent than trout ET in constricting isolated rings of vascular tissue from trout efferent branchial artery and cardinal vein and from rat aorta (Y. Wang et al., 1999, Am. J. Physiol. 277, R1605-R1611). It is known that the contractile effects of ET-1 on rat fundus are mediated through the ET(B) receptor and effects on the rat aorta are mediated through the ET(A) receptor. We propose, therefore, that trout gastrointestinal tissues express an ET(B)-type receptor that differentiates poorly between trout ET and rat ET-1, whereas trout vascular tissues express an ET(A)-type receptor that is preferentially activated by rat ET-1. The rat ET-1-induced contractions of the trout gastrointestinal tissues are in part indirect, involving a serotoninergic neuronal pathway in the intestine and a noncholinergic, nonserotoninergic pathway in the stomach.

Large veins in the Atlantic cod (Gadus morhua) and the rainbow trout (Oncorhynchus mykiss) are innervated by neuropeptide-containing nerves

Previous studies have shown that fish veins are reactive to several hormones known to exist in the fish circulation. Besides this humoral control, another possible means of active regulation of venous return is by autonomic nervous control of venous tone. This study therefore investigated the presence of a perivascular innervation of major veins in the Atlantic cod (Gadus morhua) and the rainbow trout (Oncorhynchus mykiss) using immunohistochemical methods. Histological staining was employed to investigate the smooth muscle distribution in the vessel walls. Vasoactive intestinal polypeptide-immunoreactive nerve fibers were found to be widespread in the venous system of G. morhua and O. mykiss, while pituitary adenylate cyclase-activating polypeptide-immunoreactive fibers were demonstrated in the duct of Cuvier of both species. Fibers containing neurokinin A and/or substance P were found in the duct of Cuvier and the posterior cardinal vein of both species and in the hepatic portal vein of O. mykiss. Calcitonin-gene related peptide-immunoreactive fibers were present in the duct of Cuvier of both species and in the hepatic portal vein of O. mykiss. Galanin-immunoreactive fibers were found in the duct of Cuvier in O. mykiss and in the hepatic portal vein of both species. Co-existence of neuropeptides in the perivascular nerve fibers was investigated by double labelling. Vasoactive intestinal polypeptide/pituitary adenylate cyclase-activating polypeptide-immunoreactive fibers were found in both species. Vasoactive intestinal polypeptide/galanin-immunoreactive fibers and vasoactive intestinal polypeptide/calcitoningene related peptide-immunoreactive fibers were found in G. morhua but not in O. mykiss. This study gives further evidence for an active venoregulation by autonomic nerves in teleost fish.

Effects of cod bradykinin and its analogs on vascular and intestinal smooth muscle of the Atlantic cod, Gadus morhua

The effects of [Arg(0),Trp(5),Leu(8)]-BK (cod [Arg(0)]BK) on vascular preparations from branches of the cod celiac artery and on longitudinal smooth muscle preparations from the cod intestine were investigated. Cod [Arg(0)]BK (3 x 10(-8) M) caused a relaxation of the celiac artery precontracted with adrenaline. The relaxation was abolished by the cyclooxygenase inhibitor indomethacin, suggesting that the effect is mediated through the release of prostaglandins, but there was no evidence for the involvement of leukotrienes or nitric oxide in the response. In the intestinal preparations, cod [Arg(0)]BK produced concentration-dependent contractions (pD(2) = 8.28 +/- 0.16). Experiments with N-terminally and C-terminally truncated analogs and with alanine-substituted analogs of cod [Arg(0)]BK demonstrate that the central amino acid Gly(4) and the C-terminal amino acids Leu(8) and Arg(9) are the most important in determining the conformation of the peptide that interacts with the receptor. The results indicate that the ligand binding properties of the cod BK receptor are considerably different from the receptor present in trout tissues and may resemble those of the mammalian B(2) receptor more closely.

Nitric oxide, a potent vasodilator of the aortic anastomosis in the estuarine crocodile, Crocodylus porosus

The effects of five neuropeptides (CGRP, SOM, SP, NPY, VIP), L-NAME (nitric oxide synthase inhibitor), and adrenaline on the contractile tone of the aortic anastomosis in the estuarine crocodile, Crocodylus porosus, were investigated. None of the neuropeptides, which had previously been found to be present in the aortic anastomosis, had any direct effect on the tension developed by ring preparations. L-NAME itself significantly increased the basal tone of the vascular ring preparations, suggesting a tonic release of nitric oxide in the preparation. Adrenaline produced concentration-dependent vasoconstrictions that were counteracted by profound reflex vasodilatations that were susceptible to blockade by L-NAME. Immunohistochemistry revealed the presence of nitric oxide synthase and tyrosine hydroxylase-containing (indicating the presence of a adrenergic innervation) nerve fibres in the adventitia and adventitio-medial border of the aortic anastomosis. These data demonstrate opposing actions of adrenaline and nitric oxide on the vascular smooth muscle in the anastomosis of the C. porosus. The morphology of the anastomosis, with the extremely thick muscular vessel wall, suggests a sphincter-like function for this vessel that could be controlled mainly by adrenergic and nitrergic mechanisms.

The control of gut motility

Gut motility in non-mammalian vertebrates as in mammals is controlled by the presence of food, by autonomic nerves and by hormones. Feeding and the presence of food initiates contractions of the stomach wall and subsequently gastric emptying, peristalsis, migrating motor complexes and other patterns of motility follow. This overview will give examples of similarities and differences in control systems between species. Gastric receptive relaxation occurs in fish and is an enteric reflex. Cholecystokinin reduces the rate of gastric emptying in fish as in mammals. Inhibitory control of peristalsis is exerted, e.g. by VIP, PACAP, NO in fish and amphibians, while excitatory stimuli arise from nerves releasing tachykinins, acetylcholine or serotonin (5-HT). In crocodiles, we have found the presence of the same nerve types, although the effects on peristalsis have not been studied. Recent studies on signal transduction in the gut smooth muscle of fish and amphibians suggest that external Ca2+ is of great importance, but not the only source of Ca2+ recruitment in tachykinin-, acetylcholine- or serotonin-induced contractions of rainbow trout and Xenopus gastrointestinal smooth muscle. The effect of acetylcholine involves reduction of cAMP-levels in the smooth muscle cells. It is concluded that, in general, the control systems in non-mammalian vertebrates are amazingly similar between species and animal groups and in comparison with mammals.

The emetic reflex in a reptile (Crocodylus porosus)

The emetic (vomiting) reflex in a crocodilian, Crocodylus porosus, was characterised for the first time using the plant alkaloid veratrine (5 mg kg(−)(1) i.v. or i.p.) as an emetic stimulus. The latency to the onset of vomiting was 8.0+/−0.9 min (mean +/− s.e.m., N=5 animals). Vomiting was preceded by a clearly defined set of prodromal behaviours including, in temporal sequence, rhythmic contraction of the pharynx, sneezing and jaw snapping. Expulsion of vomitus was not particularly forceful and was accompanied by lateral shaking of the head. Physiological studies revealed that vomiting was accompanied by oscillatory (9.1+/−0.7 oscillations over 29.7+/−3. 6 s, N=9 episodes in three animals) increases in intraperitoneal pressure (7.0+/−0.9 kPa, cf. 0.7+/−0.1 kPa during respiration). The significance of these results is discussed in the context of the role(s) of vomiting as a protective reflex and as a mechanism for removal of indigestible food residues (e.g. fur, claws) from the gut.

PACAP and nitric oxide inhibit contractions in the proximal intestine of the atlantic cod, Gadus morhua

The possible inhibitory roles of pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal polypeptide (VIP) and nitric oxide in the control of intestinal motility were investigated in the Atlantic cod, Gadus morhua. Circular and longitudinal smooth muscle preparations developed spontaneous contractions that were inhibited by atropine (10(−)(5)mol l(−)(1)). PACAP 27 and PACAP 38 (10(−)(7)mol l(−)(1)) reduced the amplitude of the contractions but did not usually affect the resting tension. In the circular preparations, the mean active force developed (above resting level; +/− s.e.m.) was reduced from 0. 62+/−0.18 mN to 0.03+/−0.03 mN (N=10) by PACAP 27 and from 0.53+/−0. 20 mN to 0.31+/−0.13 mN (N=7) by PACAP 38, while neither cod nor mammalian VIP (10(−)(10)-10(−)(6)mol l(−)(1)) had any effect. In the longitudinal preparations, PACAP 27 reduced the force developed from 1.58+/−0.22 mN to 0.44+/−0.25 mN (N=8) and PACAP 38 reduced it from 1.61+/−0.47 mN to 0.75+/−0.28 mN (N=5). The nitric oxide donor sodium nitroprusside (NaNP) almost abolished the contractions in the circular preparations, reducing the mean force developed from 0. 47+/−0.05 mN to 0.02+/−0.06 mN (10(−)(6)mol l(−)(1); N=9) and 0+/−0. 07 mN (10(−)(5)mol l(−)(1); N=8). In the longitudinal preparations, NaNP reduced the force developed from 2.03+/−0.36 mN to 0.33+/−0.22 mN (10(−)(6)mol l(−)(1); N=8) and 0.19+/−0.30 mN (10(−)(5)mol l(−)(1); N=8). The L-arginine analogue N(G)-nitro-L-arginine methyl ester (L-NAME; 3×10(−)(4)mol l(−)(1)) enhanced the contractions in both circular and longitudinal preparations, increasing the mean force developed from 0.51+/−0.12 mN to 0.94+/−0.21 mN (N=8) and from 1.49+/−0.36 mN to 3.34+/−0.67 mN (N=7), respectively. However, preincubation with L-NAME before a second addition of PACAP 27 (10(−)(7)mol l(−)(1)) did not affect the response to PACAP, neither did preincubation with the guanylate cyclase inhibitor 6-anilinoquinoline-5,8-quinone (LY83583; 10(−)(5)mol l(−)(1)), while the inhibitory response to NaNP (3×10(−)(7)mol l(−)(1)) was abolished by LY83583. The PACAP analogue PACAP 6–27 (3×10(−)(7)mol l(−)(1)) had no effect on the response to either NaNP (3×10(−)(7)mol l(−)(1)) or PACAP 27 (10(−)(8)mol l(−)(1)) in the circular preparations. These findings indicate the presence of both a cholinergic and a nitrergic tonus in the smooth muscle preparations of the cod. Although PACAP and NaNP both inhibit contractions, there is no evidence of any interactions between the two substances. In addition, NaNP, but not PACAP, probably acts via stimulating the production of cyclic GMP. In conclusion, both PACAP and nitric oxide may act as inhibitory transmitters, using distinct signalling pathways, in the control of intestinal motility in the Atlantic cod.

Vasodilation of swimbladder vessels in the european eel (Anguilla anguilla) induced by vasoactive intestinal polypeptide, nitric oxide, adenosine and protons

The effects of β-adrenergic stimulation, vasoactive intestinal polypeptide (VIP), adenosine, the nitric oxide (NO)-releasing agent sodium nitroprusside and of metabolic end-products of gas gland cell metabolism on swimbladder blood flow were investigated using saline- or blood-perfused swimbladder preparations of the freshwater European eel Anguilla anguilla. While β-adrenergic vasodilation was not detectable, a bolus injection of adenosine (100 microl, 10(−)7 mol l-1) and application of VIP (10(−)7 mol kg-1) caused a significant decrease in perfusion pressure in saline-perfused swimbladder preparations. Immunohistochemical analysis revealed the presence of VIP-immunoreactive nerve fibres in the swimbladder artery and in the swimbladder vein (seawater-adapted eels were used for immunohistochemical studies). Application of sodium nitroprusside also elicited a small, but significant, decrease in perfusion pressure in saline-perfused swimbladder preparations, while preincubation of swimbladder tissue with N(ω)nitro-l-arginine, a non-selective inhibitor of nitric oxide synthase, significantly enhanced the flow-induced increase in perfusion pressure. Lactate, the major metabolic end-product of gas gland cell metabolism, had no effect on perfusion pressure. In contrast, an increase in proton concentration in both saline- and blood-perfused preparations induced a vasodilation, as indicated by a significant decrease in perfusion pressure. The results demonstrate that VIP, NO, adenosine and protons may induce a vasodilation of swimbladder blood vessels. None of these effects, however, compares in time span with the previously described immediate, short-lasting vasodilation of swimbladder vessels elicited by pulse stimulation of the vagus nerve.

Cholecystokinin affects gastric emptying and stomach motility in the rainbow trout Oncorhynchus mykiss

In this study, we describe new methods for recording gastric emptying and in vivo measurements of intragastric pressure in fish. Using these methods, we investigated the effects of the sulphated octapeptide of cholecystokinin (CCK8) on gastric emptying and on stomach motility in vivo and in vitro. Gastric emptying of 99Tcm-labelled food was measured in swimming fish by using a gamma camera, counting consecutive 2.5 min periods for 18–42 h. After 20 h, 55.3+/−4.0 % of the labelled food remained in the stomach of the control fish (mean s.e.m., N=9). Vascular infusion of CCK8 (25 pmol kg-1 h-1) delayed gastric emptying so that 70.4+/−4.8 % of the labelled food remained in the stomach after 20 h (N=8). Gastric pressure changes in vivo were measured using a balloon surgically fitted into the cardiac or pyloric part of the stomach. In the cardiac part, intra-arterial infusion of CCK8 at 0.1 nmol kg-1 h-1 resulted in a decrease in the frequency and amplitude of rhythmic contractions, while higher doses started/increased contractions. Atropine blocked much of the basal contractile activity, but did not influence the CCK8-induced inhibition of contractile activity. The pyloric part of the stomach was unaffected by intra-arterial infusion of CCK8 or atropine. In vitro perfusion of the stomach (with a balloon placed in the cardiac part to record motility) with CCK8 at high concentrations (10(−7)mol l-1 and above) augmented the spontaneous contractions, while lower concentrations had inconsistent effects. In addition, CCK8 (10(−7) to 10(−6)mol l-1) decreased the amplitude of spontaneous contractions in longitudinal strip preparations, usually in combination with an increase in the resting tension. The decrease in amplitude was not affected by the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester hydrochloride (L-NAME; 10(−4)mol l-1). Depending on the concentration and experimental arrangement, CCK8 had either inhibitory or excitatory effects on the cardiac stomach, suggesting the possible presence of different types of CCK receptor. We conclude that the predominant effect of CCK8 in vivo may be a slowing down of gastric emptying, presumably coinciding with a release of bile into the duodenum.

Gastrin and cholecystokinin of the bullfrog, Rana catesbeiana, have distinct effects on gallbladder motility and gastric acid secretion in vitro

Many regulatory peptides form families with at least two homologous members. For several such families the divergence of the individual members from a common ancestor can be dated to early in vertebrate history. Cholecystokinin (CCK) and gastrin were originally identified in mammals. Recently, two distinct members of the CCK/gastrin family were identified in the bullfrog (Rana catesbeiana), termed CCK and gastrin. Frog gastrin is very similar to CCK in the region defining biological activity. To evaluate whether the two endogenous peptides have distinct properties, their effects were studied in typical target organs. While porcine gallbladder responded equally to frog gastrin-8 and CCK-8, EC50 values for stimulation of bullfrog gallbladder contractions were 490 nM (gastrin) and 69 nM (CCK). In contrast, gastrin appeared to be a more potent stimulant of acid secretion than CCK; the estimated EC50 values are 3.1 and 17.2 nM, respectively. Furthermore, gastrin had a significantly higher efficacy than CCK-8s. Thus, in spite of their close structural resemblance, there are clear differences between the two endogenous peptides in their action on gallbladder and gastric mucosa. It is concluded that there are distinct gastrin and CCK functions already at the amphibian level of evolution.

Primary structure, distribution, and effects on motility of CGRP in the intestine of the cod Gadus morhua

Calcitonin gene-related peptide (CGRP) was isolated from an extract of the intestine of the cod Gadus morhua. The primary structure of this 37-amino acid peptide was established as follows: ACNTA TCVTH RLADF LSRSG GIGNS NFVPT NVGSK AF-NH2. The peptide shows close structural similarities to other nonmammalian (3-4 amino acid substitutions) and mammalian (5-8 amino acid substitutions) CGRPs, and it contains the two residues Asp14 and Phe15 that seem to be characteristic for CGRP in nonmammalian vertebrates. Cod CGRP (10(-9)-10(-7) M) inhibited the motility of spontaneously active ring preparations from the cod intestine and was significantly (P < 0.05) more potent than rat alpha-CGRP. Neither prostaglandins nor nitric oxide is involved in the inhibitory response produced by cod CGRP, and the lack of effect of tetrodotoxin suggests an action of CGRP on receptors on the intestinal smooth muscle cells. The competitive CGRP antagonist human alpha-CGRP-(8-37) significantly (P < 0.05) reduced the response to cod CGRP. Immunohistochemistry demonstrated CGRP-immunoreactive neurons intrinsic to the intestine, and a dense innervation with immunoreactive nerve fibers was observed in the myenteric plexus and the circular muscle layer. Myotomy studies show that CGRP-containing nerves project orally and anally in the myenteric plexus, whereas nerve fibers in the circular muscle layer project mainly anally, indicating a role for CGRP in descending inhibitory pathways of the cod intestine.

Projections and actions of tachykininergic, cholinergic, and serotonergic neurones in the intestine of the atlantic cod

The native tachykinins cod neurokinin A and cod substance P, serotonin and acetylcholine have excitatory effects on the circular smooth muscle of the cod intestine. Furthermore, immunoreactivities to the cod tachykinins, serotonin and two markers for cholinergic neurones, viz. choline acetyltransferase and vesicular acetylcholine transporter, have been demonstrated in myenteric neurones of the cod intestine. In order to elucidate whether the neurones containing these substances project orally and thus might be involved in the ascending excitatory reflex of peristalsis, myotomy operations have been performed on the cod intestine. The immunoreactive areas of the myenteric plexus immediately oral and anal to the myotomy operations have been measured by using confocal laser scanning microscopy. Large accumulations of immunoreactivity to the tachykinins are found on the anal side of the myotomies, indicating oral projections of tachykininergic neurones. The areas immunoreactive to serotonin and choline acetyltransferase are of equal size on the oral and anal sides. Since the tachykinin containing neurones of the intestine project orally, and since cod neurokinin A and cod substance P have excitatory effects on circular smooth muscle, we conclude that tachykininergic neurones are involved in the ascending excitatory reflex of peristalsis in the cod intestine.

Calcitonin gene-related peptide (CGRP), but not tachykinins, causes relaxation of small arteries from the rainbow trout gut

Possible vasoactive effects on small diameter arteries from the rainbow trout gut of calcitonin gene-related peptide (CGRP-chicken) and different fish tachykinins; substance P (SP-trout), neurokinin A (NKA-trout), scyliorhinin I and II (SCY I and SCY II-dogfish), were investigated. CGRP relaxed precontracted arteries with a pD2 value of 8.3+/-0.2. Relaxation to CGRP 10(-8) M was reduced by 86.4+/-5.2% by the CGRP-1 receptor antagonist CGRP8-37 (10(-6) M), but unaffected by NG-nitro-L-arginine (10(-4) M), indomethacin (10(-6) M) and by removal of the endothelium, suggesting no involvement of nitric oxide, prostaglandins or endothelium-derived factors. A low number of CGRP immunoreactive fibers were present in the arterial wall. The tachykinins (10(-12)-10(-6) M) occasionally contracted the relaxed vessel. No synergistic action of SP on the CGRP-induced response was found. A dense plexus of tachykinin-containing fibers without coexisting CGRP innervated the arterial wall. Tachykinins or CGRP had no effect on small diameter veins, and no such immunoreactivity was found in these vessels. In conclusion, CGRP- and tachykinin-containing fibers innervate trout gut arteries. CGRP probably is vasodilatory, while the function of the tachykinin fibers is unknown.

Nitric oxide in the fish gut

Nitric oxide synthase-positive nerve cells have been found in most vertebrate classes and also some invertebrates, indicating an early evolutionary origin for the enzyme and its function as a neurotransmitter. The general distribution and inhibitory effect on motility of nitric oxide in the fish gut agrees well with studies from other vertebrates, but details may vary between species, suggesting variations in function. The coexistence with vasoactive intestinal polypeptide (VIP)/pituitary adenylate cyclase-activating polypeptide (PACAP) suggests a co-function in fish as in mammals, but this remains to be confirmed.

Nitric oxide synthase- and neuropeptide Y-containing subpopulations of sympathetic neurons in the coeliac ganglion of the Atlantic cod, Gadus morhua, revealed by immunohistochemistry and retrograde tracing from the stomach

In this study retrograde tracing was used to locate sympathetic ganglion cells innervating the stomach of a teleost fish, Gadus morhua. A subpopulation of small neurons in the coeliac ganglion was retrogradely labelled after Fast Blue injection in the stomach wall. Neurons projecting to the myenteric plexus and muscle layers contained tyrosine hydroxylase immunoreactivity, and neurons projecting to submucosal layers and blood vessels contained neuropeptide Y immunoreactivity in addition to being tyrosine hydroxylase immunoreactive. A population of nitric oxide synthase containing tyrosine hydroxylase immunoreactive neurons was also found in the coeliac ganglion. These neurons were not frequently labelled after injection in any layer of the stomach. The presence of entero-enteric pathways was also surveyed, but too few enteric neurons were labelled with Fast Blue after injection in the coeliac ganglion to indicate a presence of an entero-enteric reflex. We conclude that in teleost fish, as previously reported in a variety of mammals, a pattern of target specific chemical coding of sympathetic neurons exists, but that all reflex systems of mammalian vertebrates are perhaps not present in fish.

Vip-induced relaxation of small arteries of the rainbow trout, Oncorhynchus mykiss, involves prostaglandin synthesis but not nitric oxide

Small arteries (internal diameter 376 +/- 69 microns) from the proximal intestine region of the rainbow trout were mounted in a myograph apparatus where changes in isometric tension could be recorded. VIP (vasoactive intestinal polypeptide) caused a concentration-dependent relaxation (10(-9)-3 x 10(-7) M) of vessels precontracted with the alpha-adrenoceptor agonist phenylephrine (10(-5) M). The nitric oxide synthase inhibitor L-NAME (10(-4) M) did not affect the VIP-relaxation, neither did the lipoxygenase inhibitor esculetin (10(-5) M). However, the cyclooxygenase inhibitor indomethacin (10(-6) M) shifted the concentration-response curve significantly to the right. The VIP-relaxation was still present after mechanical removal of the endothelium. Sodium nitroprusside (10(-9)-10(-6) M) caused a concentration-dependent relaxation of the precontracted vessel, indicating the presence of soluble guanylate cyclase in the vascular smooth muscle cells. VIP-immunoreactivity was found in varicose nerve fibers in these vessels, but nitric oxide synthase-immunoreactivity could not be demonstrated. These results suggest that in rainbow trout, as in mammals, VIP is an endogenous vasodilating neuropeptide. No endothelium-dependent mechanism seems to be involved, neither is production of nitric oxide. Instead the relaxation is mediated, at least in part, via prostaglandin synthesis.

Anally projecting neurons exhibiting immunoreactivity to galanin, nitric oxide synthase and vasoactive intestinal peptide, detected by confocal laser scanning microscopy, in the intestine of the Atlantic cod, Gadus morhua

The projections of enteric neurons showing immunoreactivity for vasoactive intestinal peptide (VIP), nitric oxide synthase (NOS) and galanin were investigated in the myenteric plexus of the intestine of the Atlantic cod, Gadus morhua. Quantification of immunoreactive material on the proximal and distal side of a myotomy was performed by means of confocal laser scanning microscopy. NOS immunoreactivity was reduced anal to the myotomy, whereas there was an accumulation of immunoreactivity for VIP and for galanin oral to the cut. These results suggest the presence of VIP, NOS and galanin in neurons with oral-to-anal projections along the intestine of the cod. Since descending neurons in the myenteric plexus of many other vertebrates also contain these substances, we conclude that the oral-to-anal projections of neurons containing VIP, NOS and galanin are highly conserved features and important for the descending phase of intestinal peristalsis on an evolutionary basis.

Involvement of nitric oxide in inhibitory innervation of urinary bladder of Atlantic cod, Gadus morhua

The aim of this study was to investigate the involvement of nitric oxide (NO) in the nonadrenergic, noncholinergic (NANC) relaxation of the urinary bladder of the Atlantic cod, Gadus morhua. NADPH diaphorase-reactive nerve cells, presumed to be able to produce NO, were found in the vesicular nerve. The cells occurred alone and in ganglia together with stained and unstained cells. The effect of inhibitors of NO synthesis on the relaxation was examined in vitro in isolated muscle preparations. NG-nitro-L-arginine methyl ester (10(-4) M) and NG-nitro-L-arginine (L-NNA; 10(-4) M) decreased the electrically induced relaxation to 32 +/- 6 (n = 8) and 28 +/- 6% (n = 8) of the control, respectively. L-Arginine (10(-3) M) increased the relaxation to 152 +/- 24% (n = 8), without affecting the inhibition by L-NNA. The beta-adrenoceptor antagonist propranolol together with L-arginine analogues abolished the relaxation in 7 of 11 preparations. The NO donor sodium nitroprusside (NaNP) caused a concentration-dependent relaxation of the bladder, with a maximal effect obtained at 10(-4) M. LY-83583 (10(-5) M), a guanylate cyclase inhibitor, decreased both the electrically (n = 8) and the NaNP (10(-6) M, n = 9)-induced relaxation to 69 +/- 5 and 20 +/- 4% of the control, respectively. Together these findings suggest that NO is involved in the NANC regulation of the motility of the urinary bladder of the Atlantic cod.

A preliminary investigation of the effects of vasoactive intestinal peptide on secretion from the lingual salt glands of Crocodylus porosus

Vasoactive intestinal peptide (VIP)-like immunoreactivity was demonstrated in the lingual salt glands of the estuarine crocodile, Crocodylus porosus. Varicose fibers showing VIP-like immunoreactivity ramified the salt glands, forming a dense network around the basal region of the exocrine cells. Secretions from the lingual salt glands were monitored in hatchling C. porosus. Spontaneous secretory activity was variable, ranging from 0.3 to 5.3 micromol Na 100 g(-0.7) bm hr(-1) (bm, body mass). Administration of a 100-microl bolus of 0.9% NaCl, via a cannulated femoral vein, did not affect the spontaneous secretory rate. However, injection of 100 pmol porcine VIP resulted in a massive increase in secretory activity, reaching a maximum of 58.2 micromol of Na 100 g(-0.7) bm hr(-1). The presence of VIP-like immunoreactivity and the positive secretory effect of administered VIP indicate a potential action of VIP on salt gland activity.

Vasoactivity and immunoreactivity of fish tachykinins in the vascular system of the spiny dogfish

Tachykinin control of gut blood flow (measured by pulsed Doppler technique), dorsal aortic pressure, and heart rate were studied in unrestrained spiny dogfish Squalus acanthias injected with the elasmobranch tachykinins scyliorhinin I and II (SCY I and SCY II), the trout tachykinins substance P (SP), and neurokinin A (NKA). Effects on somatic vasculature were measured by in vitro perfusion of the isolated tail. SCY I and trout SP produced hypotension due to a general vasodilation. This caused a transient increase in mesenteric blood flow and a prolonged increase in celiac blood flow. SCY II caused an initial hypertension induced by a general vasoconstriction, followed eventually by an elevated flow in both gut arteries due to dilation of the vascular beds. Trout NKA evoked a short-lasting increase in celiac blood flow due to a decrease in vascular resistance, a late decrease in mesenteric flow due to vasoconstriction, and no effect on the somatic vasculature. None of the peptides affected heart rate. The study demonstrates a significant vasoactive function of fish tachykinins in the vascular system of an elasmobranch species and, in addition, the occurrence of tachykinin receptor subtypes. Immunohistochemistry revealed a NKA/SCY II-like peptide in nerve fibers innervating many vessels, including the celiac and the mesenteric arteries, the gastrointestinal canal, and the heart.

Vasoconstrictive effects of native tachykinins in the rainbow trout, Oncorhynchus mykiss

The role of trout substance P (tSP) and neurokinin A (tNKA) in cardiovascular regulation was investigated in the rainbow trout, Oncorhynchus mykiss, in vivo and in vitro. In vivo, the coeliac arterial and ventral aortic relative blood flows were measured with Doppler flow probes, and blood pressure was measured via a cannula inserted into the dorsal aorta. tSP (0.1 and 1 nmol kg-1) and tNKA (1 nmol kg-1) increased both systemic and coeliac vascular resistances, leading to hypertension and bradycardia. In addition, cardiac output was decreased. The mammalian NK1 tachykinin receptor antagonist CP-96,345 did not affect the responses to tSP or tNKA. In vitro perfusions of the dorsal aortic and coeliacomesenteric vascular beds were performed using peristaltic pumps. The dorsal aortic vascular resistance was dose-dependently increased following infusion of the two peptides (pD2 values 7.6 +/- 0.1 and 7.3 +/- 0.1 for tSP and tNKA, respectively). Tetrodotoxin did not affect the tSP-induced hypertension. Increases in coeliac vascular resistance caused by tSP was correlated with stomach contractions when measurement of intragastric pressure was made using an inserted balloon. In conclusion, native SP and NKA are potent vasoconstrictors of rainbow trout vasculature, a property quite unusual to tachykinins compared with the vasodilation normally seen in mammals.

Neuropeptide control of the cardiovascular system in fish and reptiles

Accumulating evidence shows the involvement of neuropeptides in cardiovascular control in mammals as well as non-mammalian species. Our own immunohistochemical studies indicate a sparse innervation only in cyclostomes, holostean fish and lungfish, a more extensive variation and distribution in elasmobranchs and teleosts, and a rich and varied innervation of the cardiovascular system in crocodiles and lizards. Vasoactive intestinal polypeptide (VIP), neuropeptie Y (NPY), gastrin releasing peptide (GRP) and tachykinins are present in most vertebrate groups. VIP is vasodilatory in the Atlantic cod (Gadus morhua) as in most mammalian species, but increases gut vascular resistance in the spiny dogfish (Squalus acanthias). NPY potentiates the effect of noradrenaline on skate (Raja rhina) coronary vessels, suggesting an interaction between adrenergic mechanisms and NPY early in evolution, but studies in the spiny dogfish and the crocodile also demonstrate different mechanisms for the action of NPY and adrenaline in some species. Bombesin/GRP increases flow to the gut in the spiny dogfish by an increase in somatic vascular resistance, while visceral resistance remains unchanged. In the caiman (Caiman crocodylus crocodylus) bombesin causes a shunting of blood from the lung to the gut. Substance P and other tachykinins in general increase flow to the gut, and on some occasions also increase somatic blood flow. Flow in the anastomosis of the crocodile (Crocodylus porosus) gut is increased by substance P. The results presented here are a review of several published and unpublished studies.

Enteric reflexes and nitric oxide in the fish intestine

The aim of the present study was to elucidate the possible regulation of peristalsis in the intestine of the Atlantic cod Gadus morhua. For this purpose, the mid intestine was dissected out and placed in a partitioned bath. Balloon distension (0.1&shy;0.4 ml) and intramural field stimulation (8 Hz, 10 V) were carried out and the responses of the circular muscle were recorded 1.5 cm orally and anally to the stimulus using force transducers. The preparations developed spontaneous contractions propagating in the anal direction with a frequency of about one contraction per 2 min. Distension of the muscle wall with a balloon did not evoke any recordable peristaltic reflexes. Intramural stimulation caused a contraction oral to the stimulation and a relaxation anal to the stimulation in most cases. Tetrodotoxin abolished the responses to electrical stimulation in both directions. Atropine reduced and methysergide abolished the oral contractions caused by electrical stimulation. Administration of the nitric oxide synthesis inhibitor l-NG-nitro-arginine methyl ester (l-NAME) abolished the anal relaxation caused by electrical stimulation and augmented the oral contractions. The results indicate the presence in teleost fish intestine of an ascending excitatory peristaltic reflex which involves a cholinergic&shy;serotonergic pathway and a descending inhibitory reflex involving a nitrergic pathway. These observations suggest a high degree of conservation of peristaltic mechanisms during vertebrate evolution.

Intraduodenal fat and amino acids activate gallbladder motility in the rainbow trout, Oncorhynchus mykiss

The effects on gall bladder motility of intraduodenal injections of fat (cod liver oil) and amino acids were investigated in rainbow trout, Onchorhynchus mykiss, in vivo. Fat (1 ml/kg, 15 min) increased basic tonus of the gallbladder by 79% and frequency of contractions by 53%; both effects were antagonized by pretreatment with atropine (1.2 mg/kg). The amino acid mixture similarly increased tonus and frequency of contractions of the gallbladder smooth muscle by 63 and 109%, respectively. The effects were mimicked by intraarterial infusion of cholecystokinin (100 pmol-1 nmol/kg-hr). It is concluded that the presence of oil and amino acids in the duodenum stimulates rainbow trout gallbladder motility and tension, possibly by a release of cholecystokinin, and that the effect of oil, as for cholecystokinin, involves a cholinergic pathway.

Neuropeptide immunoreactivity and co-existence in cardiovascular nerves and autonomic ganglia of the estuarine crocodile, Crocodylus porosus, and cardiovascular effects of neuropeptides

The two aortas of the crocodile are in open connection at two sites, the foramen of Panizzae immediately outside the ventricles, and the arterial anastomosis at the level of the gut. The present study was performed to elucidate the innervation of the cardiovascular structures of the crocodile, in part to provide a further basis for the assumption that the apertures of the foramen and the anastomosis may be altered, possibly leading to changes in the flow profiles of the central vessels. The presence of smooth muscle arranged at the circumference of the foramen and in the walls of the anastomosis was demonstrated. The cardiovascular structures were innervated by nerves containing co-existing tyrosine hydroxylase, NPY and somatostatin immunoreactivities, which also occurred in neurons of the sympathetic ganglia. CGRP and substance P immunoreactive material co-existed in cardiovascular nerves, and in the nodose ganglion. In addition, bombesin, VIP and galanin immunoreactive nerves were found. Effects of neuropeptides on blood flows and blood pressures were studied in vivo. Substance P increased all blood flows measured, NPY increased the flow through the arterial anastomosis while neurotensin caused an initial decrease in the flow through the arterial anastomosis. In conclusion, there is a rich innervation of the heart and major vessels of the estuarine crocodile, including the foramen of Panizza and the arterial anastomosis. These nerves possibly regulate the distribution of blood in the cardiovascular system, which is further suggested by the results of the injection of neuropeptides.

Distribution of neurons reactive for NADPH-diaphorase in the branchial nerves of a teleost fish, Gadus morhua

The NADPH-diaphorase reaction was used to determine the distribution of postganglionic autonomic neurons in the branches of the glossopharyngeal and vagus nerves supplying the gill arches of the cod fish, Gadus morhua. Neurons were common in major nerve trunks in all gill arches, especially in the post-trematic rami of the branchial nerves. From about 55% to more than 85% of the neurons in any branchial nerve were reactive for NADPH-diaphorase. The results suggest that the presence of NADPH-diaphorase, and presumably the ability to synthesise nitric oxide, have been a property of cranial parasympathetic neurons from early in the evolution of the vertebrates.

Food selection in anorectics and bulimics: food items, nutrient content and nutrient density

OBJECTIVE

The food selection and nutrient intake were investigated in women with anorexia nervosa, bulimia nervosa and controls.

METHODS

Dietary data was obtained by 24-hour recall, and 7-day recording among eating disordered patients, and by 3-day registration among controls.

RESULTS

The intake of energy and nutrients differed from controls, as expected, while there were no differences between anorectics and bulimics in this respect, except for iron. There were only minor differences among the three groups studied with respect to nutrient density. Energy percentages of protein, fat, and carbohydrates, were similar in all groups, but a subdivision of the macronutrients into respective sources showed that bulimics had a lower relative and absolute intake of carbohydrates from bread and cereals than anorectics and controls.

CONCLUSION

Eating disorder patients, despite their marginal food intake, still met the minimum requirement for most nutrients according to the Nordic Nutrient recommendations.

Distribution of PACAP (pituitary adenylate cyclase-activating polypeptide)-like and helospectin-like peptides in the teleost gut

Pituitary adenylate cyclase-activating polypeptide (PACAP) and helospectin are two vasoactive intestinal polypeptide (VIP)-related neuropeptides that have recently been demonstrated in the mammalian gut; the aim of this study was to reveal their occurrence and localisation in the gastrointestinal tract, swimbladder, urinary bladder and the vagal innervation of the gut of teleosts, using immunohistochemical methods on whole-mounts and sections of these tissues from the Atlantic cod, Gadus morhua and the rainbow trout, Oncorhynchus mykiss. Both PACAP-like and helospectin-like peptides were present in the gut wall of the two species. Immunoreactive nerve fibres were found in all layers but were most frequent in the myenteric plexus and along the circular muscle fibres. Immunoreactivity was also demonstrated in nerves innervating the swimbladder wall, the urinary bladder and blood vessels to the gut. Immunoreactive nerve cell bodies were found in the myenteric plexus of the gut and in the muscularis mucosae of the swimbladder. In the vagus nerve, non-immunoreactive nerve cells were surrounded by PACAP-immunoreactive fibres. Double staining revealed the coexistence of PACAP-like and helospectin-like peptides with VIP in all visualized nerve fibres and in some endocrine cells. It is concluded that PACAP-like and helospectin-like peptides coexist with VIP in nerves innervating the gut of two teleost species. The distribution suggests that both PACAP and helospectin, like VIP, are involved in the control of gut motility and secretion.

CARDIOVASCULAR RESPONSES TO SCYLIORHININ I AND II IN THE RAINBOW TROUT, ONCORHYNCHUS MYKISS, IN VIVO AND IN VITRO

Changes in cardiac output, heart rate, dorsal aortic blood pressure and coeliac artery blood flow were measured in unrestrained rainbow trout, Oncorhynchus mykiss, following injections of the elasmobranch tachykinins scyliorhinin I and II. The resistance in the coeliac vascular bed and the total systemic vasculature were calculated from blood pressure and flow. In addition, isolated tails were perfused to investigate the effect of the peptides on the somatic vasculature. Scyliorhinin I (SCY I) produced a biphasic change in the coeliac vascular resistance: an initial decrease was followed by an increase. The decrease in coeliac vascular resistance was accompanied by a decrease in the total systemic vascular resistance, leading to an increased cardiac output. The ensuing increase in coeliac vascular resistance caused a slight increase in blood pressure. In the perfused tail, SCY I produced a marked increase in the somatic vascular resistance. Scyliorhinin II (SCY II) decreased the systemic vascular resistance, causing an increase in cardiac output. SCY II also caused a late increase in the coeliac vascular resistance, which led to hypertension and bradycardia. In vitro, SCY II produced a biphasic response in which an initial decrease in the somatic resistance was followed by a larger increase. The results demonstrate that exogenous SCY I and II are vasoactive peptides that act by different mechanisms in the rainbow trout cardiovascular system. Their actions also differ from the actions of substance P previously observed in the cod, Gadus morhua, and possibly involve a neural reflex.

Binge eating versus nonpurged eating in bulimics: is there a carbohydrate craving after all?

Food selection and macro nutrient content were evaluated in a group of bulimic subjects, both during the nonpurged intake and the bingeing. Dietary data was assessed by single 24-hour recall. As expected, energy distribution and food selection differed markedly between the nonpurged diet and the binges. The main differences were related to an inverse relationship in the order of macro nutrients, fat being the dominant and protein the least important source of macro nutrients during binge eating. The nutrient content during binges admittedly had a preponderance for fat. Nevertheless, the primary choice of food items during binges was carbohydrates, which was shown both by a greater quantity and by the subjects' own desires.

Neuropeptides in the Australian lungfish Neoceratodus forsteri: effects in vivo and presence in autonomic nerves

The Australian lungfish Neoceratodus forsteri is one of the few extant species of a phylogenetically ancient group. Immunohistochemistry showed the presence of galanin-, vasoactive intestinal polypeptide (VIP)-, neurotensin-, substance P-, and calcitonin gene-related peptide (CGRP)-like immunoreactivities in nerve fibers in the heart, lung, and gut, with a coexistence of VIP-, galanin-, and somatostatin-like immunoreactivity in the lung and galanin- and somatostatin-like immunoreactivity in the gut. About 20% of the substance P-immunoreactive fibers in gut and lung contained CGRP-like material. Major vessels showed a sparse innervation. In free-swimming unanesthetized fish, neurotensin (1 nmol/kg), galanin (1 nmol/kg), and bombesin (10 nmol/kg) reduced the heart rate. In two specimens tested, the effect of neurotensin was partially antagonized by atropine. Galanin and bombesin reduced and cholecystokinin 8 (CCK-8-S) increased blood flow to the lung. Neurotensin decreased, CCK-8-S increased, and substance P had no effect on dorsal aortic pressure, and all three decreased flow to the gut. It can be concluded from the present study that the general vertebrate pattern of cardiovascular and visceral nervous control by several neuropeptides is present also in Neoceratodus.

Involvement of the myenteric plexus in the cholera toxin-induced net fluid secretion in the rat small intestine

BACKGROUND

The enteric nervous system is responsible in vivo for most of the change in fluid transport induced by cholera toxin. The aim of the present study was to investigate the importance of the myenteric plexus in the Intramural reflex responsible for this secretion.

METHODS

Long-term ablation of the myenteric plexus was achieved by serosal application of benzalkonium chloride on jejunal segments in rats.

RESULTS

The treated segments without functioning myenteric plexus showed a normal net fluid absorption. Cholera toxin in this segment only induced a reduction of fluid absorption, whereas in a nontreated ileal segment it concomitantly induced a conspicuous net fluid secretion. Intravenous hexamethonium did not change the cholera toxin response in the treated jejunal segments, whereas vasoactive intestinal polypeptide elicited a marked secretion.

CONCLUSIONS

Benzalkonium chloride treatment eliminated the ability of cholera toxin to induce intestinal secretion. Thus, all afferent fibers in the intramural secretory reflex activated by cholera toxin are probably conveyed via the myenteric plexus, which functions as the integrating center in the enteric nervous system. The Ussing chamber technique using stripped intestinal preparations cannot be used when studying effects of luminal secretagogues.