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Biomedical subjects

S Holmgren

Publications and source records attributed to S Holmgren.

At least 55 records · Page 3Linked to original sources
PubMed1994

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.

Adult↗
PubMed1994

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.

Animals↗
PubMed1994

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.

Journal Article↗
PubMed1993

Galanin-like immunoreactivity in extrinsic and intrinsic nerves to the gut of the Atlantic cod, Gadus morhua, and the effect of galanin on the smooth muscle of the gut.

The presence of galanin-like immunoreactivity in nerves to the stomach of the Atlantic cod has been investigated by immunohistochemistry. The distribution of ganglion cells showing galanin-like immunoreactivity was compared with the total distribution in nerves and ganglia. Projection studies were made to determine the origin of the galanin neurons. The effect of galanin was studied in smooth muscle strip preparations of the gut wall and arteries. Galanin-like immunoreactive ganglion cells frequently occurred along the vagal branches to the stomach. Most of them projected cranially. Immunoreactive nerve fibers were present in all layers of the gut and around arterial branches on the surface of the stomach. Ligations of the vagus and splanchnic nerves produced accumulations of immunoreactive material on both sides of the ligature. Galanin produced weak contractile effects unaffected by tetrodotoxin on the gut wall and on gut arteries. It is concluded that a population of the ganglion cells along the vagus nerve in the Atlantic cod contains a galanin-like peptide. Some of these cells may be parts of autonomic parasympathetic pathways innervating the gut of the Atlantic cod, having direct excitatory effects on the smooth muscles of the gut wall and gut arteries.

Animals↗
PubMed1993

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.

Animals↗
PubMed1993

Respiratory and cardiovascular responses to hypoxia in the Australian lungfish.

Simultaneous measurements of pulmonary blood flow (qPA), coeliacomesenteric blood flow (qCoA), dorsal aortic blood pressure (PDA), heart rate (fH) and branchial ventilation frequency (fv) were made in the Australian lungfish, Neoceratodus forsteri, during air breathing and aquatic hypoxia. The cholinergic and adrenergic influences on the cardiovascular system were investigated during normoxia using pharmacological agents, and the presence of catecholamines and serotonin in different tissues was investigated using histochemistry. Air breathing rarely occurred during normoxia but when it did, it was always associated with increased pulmonary blood flow. The pulmonary vasculature is influenced by both a cholinergic and adrenergic tonus whereas the coeliacomesenteric vasculature is influenced by a beta-adrenergic vasodilator mechanism. No adrenergic nerve fibers could be demonstrated in Neoceratodus but catecholamine-containing endothelial cells were found in the atrium of the heart. In addition, serotonin-immunoreactive cells were demonstrated in the pulmonary epithelium. The most prominent response to aquatic hypoxia was an increase in gill breathing frequency followed by an increased number of air breaths together with increased pulmonary blood flow. It is clear from the present investigation that Neoceratodus is able to match cardiovascular performance to meet the changes in respiration during hypoxia.

Animals↗
PubMed1993

Neuropeptide Y potentiates contractile response to norepinephrine in skate coronary artery.

The skate is an extant representative of the first vertebrate group with a coronary circulation, the elasmobranch fish. Histochemical studies have revealed that skate coronary arteries are innervated by adrenergic nerves as well as by nerves showing neuropeptide Y (NPY)-like immunoreactivity. This study investigates the effect of NPY in the coronary system of an elasmobranch fish, a vertebrate that first evolved 450 million years before mammals and the mammalian coronary circulation. The responses of vascular ring preparations of the coronary artery from the longnose skate (Raja rhina) were measured using isometric force transducers. The main effect of NPY was a potentiation of the amplitude of the norepinephrine-induced contraction, leaving the pD2 value (-log 50% effective concentration) for norepinephrine unaffected. NPY per se occasionally contracted the coronary rings in higher concentrations. The potentiation response may not involve the endothelium and was abolished by pretreatment with tetrodotoxin. We conclude from this study that NPY potentiates norepinephrine-induced contraction in skate coronary artery via an indirect pathway.

Animals↗
PubMed1993

Distribution and activity of dogfish NPY and peptide YY in the cardiovascular system of the common dogfish.

Neuropeptide Y is present in sympathetic nerves in the mammalian cardiovascular system. This study has investigated the distribution of neuropeptide Y in the cardiovascular and gastrointestinal systems and the effect of dogfish neuropeptide Y and related peptides on cardiovascular tissue of an elasmobranch fish, the common dogfish (Scyliorhinus canicula). Neuropeptide Y-like immunoreactivity is present in varicose nerve fibers innervating dogfish gut and cardiovascular tissue and in endocrine cells of the dogfish spiral intestine. Dogfish neuropeptide Y, dogfish peptide YY, and porcine neuropeptide Y contract the dogfish afferent branchial artery in a concentration-dependent manner. The effect is not inhibited by the presence of tetrodotoxin or by removal of the endothelium. The mammalian Y1 receptor selective agonist [Leu31Pro34]NPY but not the mammalian Y2 receptor selective agonist neuropeptide Y-(13-36) peptide has vasoconstrictor properties in this system, suggesting that the receptor mediating the vasoconstriction resembles the mammalian Y1 receptor more than the Y2 receptor.

Absorption↗
PubMed1992

Galanin is more common than NPY in vascular sympathetic neurons of the brush-tailed possum.

The distribution of galanin (Gal) in sympathetic vascular neurons of adult and juvenile brush-tailed possums (Trichosurus vulpecula), was examined using double-labelling immunohistochemistry. This was compared with the distribution of neuropeptide Y (NPY) in the same tissues. Immunoreactivity (IR) to galanin was present in the majority (64-99%) of nerve cell bodies in paravertebral sympathetic ganglia, where it mostly co-existed with IR to the catecholamine-synthesizing enzyme, tyrosine hydroxylase (TH). Gal-IR also was present in most, if not all, TH-IR perivascular axons supplying systemic arteries and veins. NPY-IR was less common than Gal-IR in all sympathetic ganglia and perivascular axons examined. Some sympathetic, TH-IR axons supplying the abdominal aorta and renal artery contained both Gal-IR and NPY-IR, while TH-IR axons supplying cephalic and thoracic vessels contained Gal-IR but not NPY-IR. Limited observations on sympathetic neurons in two species of wallabies indicated that Gal-IR also was more common than NPY-IR in other marsupial species, but the incidence of NPY-IR was higher in these wallabies than in the brush-tailed possum. Together with previous studies, this work suggests that the coexistence of galanin and NPY may be the primitive condition for sympathetic neurons in tetrapods. The differential expression of these peptides in specific populations of sympathetic neurons may have important functional consequences in the autonomic control of the circulation.

Age Factors↗
PubMed1992

Release of substance P-like immunoreactive material from the stomach of the rainbow trout.

The release of substance P-like immunoreactive material (SPLI) from the vascularly perfused stomach of the rainbow trout, Oncorhynchus mykiss, was studied. In most cases, SPLI was detected in the collected vascular perfusate during experimental resting conditions. Distensions of the stomach, accomplished by a water-filled intragastric balloon, produced an initial rapid relaxation of the stomach, followed by a slow further relaxation and a stimulation of contractile activity. The amount of SPLI in the vascular perfusate was significantly elevated during the distension period. Tetrodotoxin had no effect on the response to distension or on the release of SPLI during distension, indicating release from tetrodotoxin-insensitive neurons or endocrine cells. The results suggest that a substance P-like peptide may be involved in the contractile response and/or in the maintenance of muscular tone during gastric distensions in the rainbow trout. Infusion of capsaicin had no effect on the release of SPLI. However, capsaicin caused an increase in vascular flow, an effect that could be repeated on a second infusion of capsaicin, indicating that the action may not be specific to sensory neurons.

Animals↗
PubMed1992

Duodenal acidification and intra-arterial injection of CCK8 increase gallbladder motility in the rainbow trout, Oncorhynchus mykiss.

A sensitive method for in vivo measurement of intra-gallbladder pressure in free swimming rainbow trout (Oncorhynchus mykiss) is described. The method gives information on changes in gallbladder pressure after either instillation of liquids into the duodenum or infusion/injection of agents into the circulatory system. Blood samples can also be taken. Duodenal acidification is a potent initiating factor for gallbladder motility in the rainbow trout. Intra-arterially injected sulfated octapeptide of cholecystokinin is also a potent excitatory agent for activating the gallbladder. Acidification of the upper intestine causes release of cholecystokinin, which affects gallbladder motility in trout as in mammals.

Animals↗
PubMed1992

Neurotensin, substance P, gastrin/cholecystokinin, and bombesin in the intestine of the tilapia (Oreochromis mossambicus) and the goldfish (Carassius auratus): immunochemical detection and effects on electrophysiological characteristics.

The distribution of neurotensin-, substance P-, gastrin/cholecystokinin/carerulein- and bombesin-like immunoreactivities has been studied in the gut of the tilapia (Oreochromis mossambicus) and the goldfish (Carassius auratus) using immunohistochemistry and radioimmunoassay; the electrophysiological effects of these peptides on the intestinal epithelium were also examined with the Ussing-type chamber technique. Neurotensin- and gastrin/cholecystokinin/caerulein-like immunoreactivities were present in endocrine cells in both species. Substance P- and bombesin-like immunoreactive endocrine cells were present in the intestine of the tilapia. Neurotensin-like immunoreactivity was observed in varicose fibers and nerve cell bodies in the muscle layers and myenteric plexus of both species, whereas nerve fibers showing substance P-like immunoreactivity were found in the goldfish only. Using radioimmunoassays, neurotensin- and gastrin/cholecystokinin/caerulein-like immunoreactive materials were detected in intestinal extracts of both species. The amounts of substance P- and bombesin-like material were below detection level. The ion selectivity of the intestinal epithelium of both species was modulated by exogenously applied neurotensin. This effect was blocked by tetrodotoxin in the tilapia but not in the goldfish. In the tilapia, neurotensin may act via stimulation of a cAMP-dependent increase of the Cl- conductance of the tight junctions, whereas in the goldfish, neurotensin induced, via an unknown messenger, a transient decrease of the cation selectivity without a decrease in the resistance. Substance P, cholecystokinin, and bombesin were without effect on the electrophysiological characteristics of the epithelium.

Animals↗
PubMed1992

VIP inhibits CCK-induced gallbladder contraction involving a beta-adrenoceptor mediated pathway in the rainbow trout, Oncorhynchus mykiss, in vivo.

The effects of VIP on CCK-induced contractions of the gallbladder were studied in the rainbow trout, Oncorhynchus mykiss, in vivo. Gallbladder pressures were measured via a catheter inserted into the gallbladder, and drugs were injected through a catheter in the dorsal aorta. CCK-induced contractions of the gallbladder wall were reduced in a dose-dependent manner by VIP. The effect of VIP was inhibited by the beta-adrenergic antagonist sotalol, indicating an adrenergic link in the VIP inhibition of the CCK-induced contraction. It is suggested that activation of VIP nerves could facilitate postprandial filling/refilling of the gallbladder despite the increased plasma levels of CCK during this period.

Animals↗
PubMed1991

Bombesin-like immunoreactivity in skates and the in vitro effect of bombesin on coronary vessels from the longnose skate, Raja rhina.

Bombesin-like immunoreactivity is present in nerve fibers projecting to the cardiovascular system, including the coronary arteries, and to the gastrointestinal canal, and in endocrine cells of the gut of skates belonging to the family Rajidae. Synthetic bombesin contracted isolated coronary rings from the longnose skate, Raja rhina, in a cumulative fashion. The contractile response was 84% of that of 60 mM potassium chloride. The pD2-value for bombesin was 8.83 (S.E.M. = 0.33; n = 15). Phentolamine, atropine and two substance P-antagonists increased the sensitivity to bombesin, while atenolol, sotalol, nifedipine, tetrodotoxin and two bombesin antagonists were devoid of significant effects. We conclude from this study that a bombesin-like peptide is present in nerves innervating the cardiovascular system and the gastrointestinal canal of skates of the family Rajidae, and that bombesin contracts coronary vessels in vitro via a direct mechanism and/or via mechanisms involving alpha-adrenergic and muscarinergic receptors.

Animals↗
PubMed1991

Tachykinins and intestinal motility in different fish groups.

The presence and function of tachykinins were studied in the intestine of hagfish (Myxine glutinosa), lamprey (Lampetra fluviatilis), starry ray (Raja radiata), lungfish (Lepidosiren paradoxa), bichir (Polypterus senegalensis), and rainbow trout (Oncorhynchus mykiss), which represent different systematic groups of fish. Immunohistochemistry revealed cells containing substance P (SP)-like material in the intestine of lamprey and lungfish, and in the stomach of the ray. The intestinal motility was studied using isolated muscle strip preparations. SP had no effect on hagfish or lamprey intestine. In the other four species SP produced intestinal contractions. In ray, bichir, and lungfish the tachykinins may be released from endocrine cells and act, at least in the bichir and lungfish, directly onto the smooth muscle cells. In the rainbow trout intestine, where SP-like material may be released from both nerve fibres and endocrine cells, it is indicated that the contractile effect is in part direct upon the smooth muscle and in part via stimulation of cholinergic and serotonergic neurons.

Animals↗
PubMed1991

Gut blood flow in the estuarine crocodile, Crocodylus porosus.

Simultaneous recordings of blood flow in the right and left aorta and carotid and coeliac artery were made in the crocodile, Crocodylus porosus at rest and during various stimuli. In resting animals the right aorta and carotid artery flow profiles resembled the recordings obtained in the caiman (Axelsson et al. 1989a), with an anterograde blood flow throughout the cardiac cycle. As in the caiman, the left aorta flow profile was complex with both anterograde and retrograde blood flow during the cardiac cycle, and a net left aorta blood flow near zero at rest. The coeliac artery blood flow profile did not show the complex pattern seen in the upper aorta, immediately suggesting that most of the coeliac artery blood originates elsewhere. We believe that coeliac artery blood flow in the resting animal derives from the right aorta via the abdominal anastomosis between the two aortas. Feeding induced an increase in the coeliac artery and left aorta blood flow, probably due to a decrease in visceral vascular resistance, and hence coeliac arterial and the left aorta blood pressure, which facilitates blood flow (from right to left aorta) through the foramen of Panizza. During short 'fright dives', heart rate fell and there was a decrease in the recorded blood flows: carotid artery blood flow did not decrease to the same extent as the RAo and coeliac artery flow, indicating some capacity for redistribution of blood to the cephalic circuits during diving. Similarly, a near-unimpaired carotid artery blood flow was maintained after adrenaline injection. Substance P increased the coeliac artery blood flow and produced a right-to-left cardiac shunt, probably by construction of the pulmonary vasculature.

Alligators and Crocodiles↗
PubMed1990

Bombesin potentiates the effect of acetylcholine on isolated strips of fish stomach.

The interaction between bombesin and acetylcholine acting on smooth muscle of the stomach wall was investigated in two species of teleost fish. Oncorhynchus mykiss (rainbow trout) and Gadus morhua (Atlantic cod). Acetylcholine or bombesin alone has an excitatory effect on the stomach muscle. The effect on contraction amplitude of acetylcholine (10(-6)-10(-5) M) alone is about 10-times greater than the effect of bombesin (10(-9)-10(-7) M). In molar terms however, bombesin is more potent than acetylcholine. Bombesin (10(-8)-10(-7) M) added 0.5-3 min prior to acetylcholine potentiates the effect of acetylcholine in a dose-dependent manner. The potentiation is most pronounced in circular muscle preparations, but is present also in longitudinal muscle preparations. Bombesin affects the response to carbachol (10(-6) M) with a similar potentiation, indicating that the potentiation is not caused by inhibition of choline esterase activity. Atropine (10(-6)-10(-5) M) abolishes the response to bombesin plus acetylcholine as well as the response to acetylcholine alone. Tetrodotoxin (10(-6) M) does not block the effect of acetylcholine, bombesin or the combination acetylcholine plus bombesin. Substance P (10(-9)-10(-7) M) which has a similar excitatory effect on the stomach muscle as bombesin, does not potentiate the effect of acetylcholine. Immunohistochemistry has shown the presence of strong bombesin-like immunoreactivity in stomach nerves of the cod and weak bombesin-like immunoreactivity in rainbow trout nerves. In addition, bombesin-like immunoreactivity was demonstrated in endocrine cells in the gastric and intestinal mucosa of both species. It is concluded that bombesin, contained either in nerve fibres or in mucosal endocrine cells, specifically potentiates the effect of acetylcholine in the fish stomach.

Acetylcholine↗