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Biomedical subjects

W Langhans

Publications and source records attributed to W Langhans.

At least 19 recordsLinked to original sources
PubMed1995

ACTH, cortisol and glucose responses after administration of vasopressin in cattle and sheep.

The present study compared the effects of vasopressin on plasma concentrations of corticotropin, cortisol and glucose in cattle and sheep. After intravenous injection of 1, 0.1 and 0.01 microgram vasopressin per kg body weight, the plasma vasopressin concentration increased proportionally to the injected dose, and this increase was similar in cattle and sheep. Doses of 1 and 0.1 microgram per kg body weight of vasopressin triggered significant responses of corticotropin, cortisol and glucose in cattle and sheep. The corticotropin response to both doses was significantly greater in sheep, whereas the glucose response was greater in cattle. The cortisol response did not differ between species. The lowest dose of vasopressin (0.01 microgram per kg body weight) still induced a significant cortisol response without a substantial effect on plasma corticotropin, suggesting that a direct action of vasopressin on the adrenals may contribute to the observed cortisol response. The results demonstrate that vasopressin increases plasma levels of corticotropin, cortisol and glucose in cattle, as it does in sheep, but the intensities of the corticotropin and glucose responses to vasopressin differ between cattle and sheep. The reasons for these differences remain to be clarified.

Adrenocorticotropic Hormone↗
PubMed1995

Limited importance of a learned aversion in the hypophagic effect of interleukin-1 beta.

This study addressed the possible role of a learned aversion in the hypophagic effect of interleukin-1 beta (IL-1 beta) in the rat. Two repetitive intraperitoneal injections of IL-1 beta (2 micrograms/kg body weight = b.wt.) progressively reduced intake of a novel-tasting saccharin diet (SD) presented immediately after injection. When SD and the familiar diet were offered some days after an injection, SD selection was in some but not all trials reduced by IL-1 beta pretreatment. When SD was offered alone several days after an injection, SD intake was not affected by the initial pairing of SD presentation with IL-1 beta injection. In further experiments, the novelty of a flavor added to the diet fed immediately after injection proved to be crucial for the aversive effect of IL-1 beta, and enhanced its hypophagic effect. Finally, lesion of the area postrema and the adjacent nucleus of the solitary tract failed to affect the hypophagia induced by IL-1 beta (1 microgram/kg b.wt.). The results indicate that, under certain conditions, IL-1 beta can induce an aversion to the taste and flavor of the food consumed after injection. This aversive effect of IL-1 beta appears to be rather weak and is presumably not involved in the hypophagic effect of IL-1 beta under normal feeding conditions. It may however enhance IL-1 beta's hypophagic effect under certain conditions, for instance after repeated injections.

Animals↗
PubMed1995

Feeding patterns of lactating cows of three different breeds fed hay, corn silage, and grass silage.

Feeding behavior of 35 lactating cows of three different breeds (Holstein-Friesian = HF, Simmental = SI, and Jersey = JER) was compared in the present study. The cows were kept in a loose housing system and fed hay, corn silage (CS) and grass silage (GS) ad lib. Within 7 consecutive days, 2918 meals were recorded and analyzed: 2503 meals were eaten during the light phase (0430-2200), and 57% of these diurnal meals consisted of only one feedstuff (43% hay, 9% CS, 5% GS). During the dark phase, only 23% of the 415 meals consisted of hay alone, but 16% of CS and 21% of GS alone. This circadian distribution showed no breed differences, yet meal patterns did: HF and SI cows ate 11 meals per day, and JER cows ate more than 13 meals/day. Meal size was 9.8MJ, 7.9MJ, and 5.8MJ for HF, SI, and JER cows, respectively. HF cows had the highest 24 h energy intake and JER cows the lowest, but the latter spent the most time feeding. During the light phase all three breeds obtained the most energy from hay, followed by CS and GS. In contrast, during the dark phase most energy was derived from GS, and hay contributed the least. A significant premeal correlation was observed for cows of all breeds, in particular during the time with the highest feeding activity (0800-1300). During the dark phase no premeal correlation could be detected; instead a significant postmeal correlation appeared, in particular in HF and SI cows.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1995

Hepatic portal insulin antibody infusion increases, but insulin does not alter, spontaneous meal size in rats.

To investigate the acute effects of pancreatic insulin on spontaneous feeding in rats fed ad libitum, insulin or insulin antibodies were infused into the hepatic portal vein during the first meal of either the light or dark phase. Infusions (3 min, 0.033 ml/min) were remotely controlled, and a computerized system recorded meal patterns. In separate crossover tests, 1, 2, 4, 8, and 16 mU insulin/meal did not affect meal size or subsequent intermeal interval (P > 0.10). In one test, nocturnal meal duration was decreased by 2 mU insulin/meal (19%, P < 0.05). Infusions of polyclonal antibodies to human insulin with in vitro rat insulin binding capacity of 20 or 50 mU increased the size of the first nocturnal meal by 24 and 29% (P < 0.05), respectively. Meal duration was reliably increased only by the smaller antibody dose. Subsequent intermeal interval was unaffected by either antibody dose. The stimulatory effect of insulin antibody infusion on meal size indicates that antagonism of circulating insulin during meals interferes with the control of meal termination. Thus insulin appears to play a role in the physiological control of nocturnal spontaneous feeding in rats. Exogenous insulin may have failed to decrease meal size because of a ceiling effect.

Animals↗
PubMed1994

Caprine arthritis encephalitis virus infection changes caprine blood monocyte responsiveness to lipopolysaccharide stimulation in vitro.

The effects of caprine arthritis encephalitis virus (CAEV) infection on cytokine activity of caprine monocytes stimulated with Escherichia coli lipopolysaccharide (LPS) were examined. Compared with supernatants from LPS-stimulated monocytes of CAEV-negative goats, supernatants from CAEV-positive goats stimulated less proliferation of murine thymocytes in the MTT (3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide) assay, showed about 50% less IL-1 activity on the IL-1-dependent cell line LBRM-33 1 A-5, and showed about 200% more tumor necrosis factor (TNF) activity on the TNF-sensitive murine fibroblast cell line L-929. These results indicate that CAEV infection changes caprine monocyte cytokine responsivity.

Animals↗
PubMed1993

Eating patterns of lactating dairy cows of three different breeds fed grass ad lib.

Eating behavior of lactating cows of three breeds (Holstein-Friesian = HF, Simmental = SI, and Jersey = JER) was compared in the present study. The cows were kept in a loose housing system and fed grass and hay ad lib along with concentrates. Within 11 days, 1396, 1504, and 1682 grass meals were recorded and analyzed for HF, SI, and JER cows, respectively. In cows of all three breeds, 89% of the grass meals (= 94% of the total grass intake) occurred during the light phase (0400-2200) and peaks of grass intake with large meals were always observed shortly after refilling the troughs. A similar diurnal distribution was evident for concentrate intake, but was less pronounced (28% eaten during the dark phase), and peaks of concentrate intake occurred also in the evening and after midnight. Hay intake was negligible and was not considered for meal pattern analysis. JER cows ate generally less than HF or SI cows, but spent more time eating. Grass meal frequency was higher, but grass meal size and mean eating rate within grass meals was smaller for JER cows than for HF and SI cows. Significant correlations between the size of grass meals and the duration of either the interval preceding or following that same meal were observed only for some animals (in particular JER and SI cows) during the main eating period in the morning (0800-1300), but barely in the afternoon (1300-1700). Thus, the short-term physiological control of meal-taking in dairy cows kept under normal farming conditions seems to be markedly influenced by external factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1993

Does a learned taste aversion contribute to the anorectic effect of bacterial lipopolysaccharide?

The present study addressed the possible role of a conditioned taste aversion in the anorectic effect of bacterial lipopolysaccharide (LPS) in the rat. Pairing an intraperitoneal (IP) injection of LPS (100 micrograms/kg b.wt.) with the subsequent presentation of a familiar diet (FD) or of a novel-tasting saccharin diet (SD) for several hours did not affect FD or SD intake when the same diet was offered several days later after 12 h of food deprivation. However, food intake during the second presentation of SD was reduced when food was not withheld prior to the test. In a similarly designed experiment, the antipyretic and antiinflammatory drug indomethacin (5 mg/kg b.wt., IP) attenuated the anorectic effect of LPS during the initial pairing, but did not affect the inhibition of SD intake in LPS-pretreated rats during the second feeding test. The antiemetic trimethobenzamide (5 mg/kg b.wt., IP) failed to influence the anorectic effect of LPS. Lesion of the area postrema (AP) and the adjacent nucleus of the solitary tract (NST) was found to enhance the anorectic effect of LPS, but the development of tolerance to this effect remained unchanged in AP/NST-lesioned animals. In spite of the ability of LPS to induce a taste aversion that inhibits feeding under certain conditions (novel-tasting diet, no food deprivation prior to the feeding test), the findings indicate that a learned taste aversion is not the only contributor to the anorectic effect of LPS.

Animals↗
PubMed1992

[Effect of carbohydrate intake during a long distance run on work capacity and metabolism].

The present study addressed the effects of carbohydrate consumption during endurance exercise on performance, energy turnover, and metabolism. Well-trained endurance runners consumed a beverage with (cho[+]) or without (cho[-]) carbohydrates during a long-distance run (46.6 km). The respiratory quotient (RQ), plasma levels of carbohydrate and fat metabolites, and of hormones (insulin, glucagon) were measured before, several times during, and after the run. The mean running speed for the entire distance was 13.6 and 13.4 km/h with the cho[+] and cho[-] beverage, respectively. The decrease in speed that was observed towards the end of the run was somewhat more pronounced with consumption of the cho[-] beverage. The RQ decreased during the run almost linearly. This decrease was independent of the consumed beverage. The changes in plasma levels of lactate, free fatty acids (FFA), glycerol, D-3-hydroxybutyrate (DHB), glucagon and insulin that occurred during the run were not affected by intake of the cho[+] beverage. However, intake of the cho[+] beverage prevented the decrease in plasma glucose observed towards the end of the run under control conditions, and eliminated the steep postexercise increase in plasma DHB. The intake of the cho[+] beverage also caused a rapid decrease in plasma levels of FFA and glucagon after the run, and slightly increased plasma insulin. The results demonstrate that ingestion of a carbohydrate-containing beverage during a long-distance run affects metabolism only during the final phase of the run and during the subsequent recovery period. Moreover, carbohydrate consumption improves performance only during the final phase of a long-distance run.

3-Hydroxybutyric Acid↗
PubMed1992

Enhancement or loss of the hypophagic effect of interleukin-1 upon chronic administration.

To further characterize the effect of interleukin-1 on food intake, we tested whether a tolerance to the hypophagic effect of recombinant human interleukin-1 beta (rhIL-1 beta) develops with repeated injections or continuous infusion in rats. Daily intraperitoneal (IP) injections of rhIL-1 beta (25,000 LAF units/kg b.wt.) for 4 days did not result in tolerance to rhIL-1 beta's hypophagic effect. The hypophagic effect of the same dose of rhIL-1 beta actually increased if injections were given every second day, when the hypophagic effect of the preceding injection had subsided. A dose of rhIL-1 beta that usually did not affect food intake (5000 LAF units/kg b.wt.) reduced food intake if injected repeatedly. Continuous infusion of rhIL-1 beta (25,000 LAF units/kg b.wt/day) via IP-implanted osmotic minipumps caused a strong initial suppression of feeding followed by the development of tolerance to the hypophagic effect of the infused rhIL-1 beta. Nevertheless, hypophagia caused by a subsequent IP injection of rhIL-1 beta (25,000 LAF units/kg b.wt.) was enhanced. As specific antibodies to rhIL-1 beta could be detected in sera of only three of 11 rhIL-1 beta-infused rats, the observed tolerance was probably not due to a humoral immune response. The results demonstrate that, dependent on test conditions, chronic administration of rhIL-1 beta in the rat can lead to an enhancement or to a loss of its hypophagic effect. The reasons for this difference remain unclear.

Animals↗
PubMed1991

Mechanisms of vasopressin's anorectic effect.

The present experiments investigated the effect of vasopressin (VP) on food intake in rats under various conditions. VP (1.25-10 micrograms/kg body weight = b.wt.) injected intraperitoneally (IP) at the onset of the dark phase of the lighting cycle inhibited feeding in a dose-dependent manner. The suppression of feeding induced by VP was primarily due to a delayed onset of the first meal after injection and was reversed by a V1-receptor antagonist (7 micrograms/kg b.wt., IP), by the Ca(++)-channel blocker verapamil (5 mg/kg b.wt., IP) and by the alpha-adrenergic receptor antagonist phentolamine (500 micrograms/kg b.wt.), but not by dissection of the hepatic branch of the vagus. In further experiments VP inhibited gastric emptying. This effect was not reversed by phentolamine. VP had also an aversive effect, but this effect was weaker than that of LiCl and probably not involved in VP-induced hypophagia. The results suggest that VP reduces feeding through a V1-receptor-mediated activation of an alpha-adrenergic mechanism. The inhibition of gastric emptying or a possible stimulation of hepatic oxidative metabolism by VP seems to be not essential for VP's effect on feeding. The results are consistent with a role of VP in stress-induced anorexia in rats.

Animals↗
PubMed1991

Hepatic and intestinal handling of metabolites during feeding in rats.

Changes in hepatic vein, hepatic portal vein and aortal plasma levels of glucose, lactate, nonesterified fatty acids, and D-3-hydroxybutyrate as well as changes in hepatic glycogen and lactate levels were studied during feeding after 12 h of food deprivation in rats. Feeding caused an increase in portal vein lactate concentration and a transient net hepatic lactate uptake that led to hepatic lactate accumulation. As in previous experiments, feeding was associated with hepatic glycogenolysis and net hepatic glucose release, despite a profound increase in portal vein plasma glucose. Net hepatic uptake of nonesterified fatty acids and net hepatic release of D-3-hydroxybutyrate declined during feeding but did not cease, suggesting that hepatic fatty acid oxidation continued throughout feeding. A prandial net intestinal uptake from arterial blood was observed for nonesterified fatty acids and D-3-hydroxybutyrate, while a net intestinal release was found for glucose and lactate. The results are consistent with the idea that under the conditions tested, glucose, lactate and nonesterified fatty acids jointly activate a hepatic metabolic mechanism of satiety.

3-Hydroxybutyric Acid↗
PubMed1991

Changes in feeding behavior and plasma vasopressin concentration during water deprivation in goats.

To further characterize the suppression of feeding that normally accompanies water deprivation and to test whether vasopressin contributes to this hypophagia, food intake, meal patterns and plasma vasopressin concentrations were measured during 24 h or 72 h of water deprivation in pygmy goats. The effects of exogenous vasopressin and of a V1-receptor antagonist on feeding during water deprivation were also assessed. The hypophagia during water deprivation was primarily due to decreases in meal size. The plasma vasopressin concentration increased about 2.5-fold and 10-fold after 24 and 72 h of water deprivation, respectively. Plasma osmolality also increased (measured only after 72 h of water deprivation). Intraperitoneally (ip) injected vasopressin (1.5 micrograms/kg b. wt.) that previously reduced food intake in goats with ad lib, access to water (Meyer et al., 1989), failed to affect cumulative food intake in water deprived goats, but led to a transient increase in meal size. The V1-receptor antagonist (2.5 micrograms/kg b. wt., ip) did not affect cumulative food intake or meal patterns either. These findings indicate that endogenous vasopressin is not crucially involved in the hypophagia during water deprivation. The results are in line with the hypothesis that an abnormal prandial increase in the osmolality of the ruminal fluid is a major contributor to the hypophagia during water deprivation.

Animals↗
PubMed1991

Differential feeding responses to bacterial lipopolysaccharide and muramyl dipeptide.

The present study was designed to test whether a tolerance to the hypophagic effects of bacterial lipopolysaccharide (LPS) and muramyl dipeptide (MDP) develops with repeated injections in rats and whether a relationship between the hypophagic effects of both compounds exists. Only the first of three subsequent intraperitoneal injection of LPS (100 micrograms/kg body wt each), given every 2nd day, led to a significant reduction of food intake. In contrast, MDP (1.6 mg/kg body wt) did not lose its hypophagic effect with four subsequent intraperitoneal injections. Furthermore, the LPS tolerance did not alter the hypophagic response to subsequently injected MDP. Likewise, MDP pretreatment did not alter the hypophagic response to LPS. Doses of MDP and LPS that were individually below the threshold for a reliable reduction of food intake (0.4 mg MDP/kg body wt + 25 micrograms LPS/kg body wt) reduced food intake synergistically when injected together. The hypophagia produced by combined injections of MDP plus LPS slowly diminished with repeated injections. The results indicate that separate but interacting mechanisms are involved in the feeding responses to MDP and LPS. The observed synergism between MDP and LPS suggests a synergistic role of bacterial muramyl peptides and LPS in the anorexia during bacterial infections.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

[Regulation of food intake].

Regulation of food intake is commonly treated as a negative feedback-loop. Hunger and/or appetite lead man and animals to ingest food. The subsequent meal-contingent activation of pre- and postabsorptive mechanisms then leads to satiety. The activation of oral and gastrointestinal chemo- and mechanoreceptors is important on the preabsorptive site. The gastrointestinal hormone cholecystokinin may also have a physiological satiety effect. Preabsorptive satiety mechanisms are influenced by the rate of gastrointestinal transit. The pancreatic hormone glucagon, which is released during meal taking, and various metabolites contribute to the postabsorptive regulation of food intake through activation of hepatic chemoreceptors, which are connected to the brain via predominantly vagal afferents. In addition, glucoreceptors in the brain, in particular in the nucleus of the solitary tract, contribute to food intake regulation by monitoring blood glucose concentration or, more specifically, glucose utilization. The nucleus of the solitary tract, which relays vagal afferents from gut and liver and also gustatory afferents, projects to the hypothalamus and to other forebrain structures. In this neural network the informations from the periphery are integrated by various neurotransmitters and neuropeptides, but the exact role of the substances involved is not fully understood yet. Body weight and, hence, body fat presumably affects feeding through modulation of a postabsorptive mechanism.

Animals↗
PubMed1990

Comparison of the effects of bacterial lipopolysaccharide and muramyl dipeptide on food intake.

For further characterization of the mechanism involved in the anorexia during bacterial infection, we investigated whether muramyl dipeptide (MDP), the minimal immunologically active structure of gram-positive bacterial cell walls, affects rats' food intake in the same way as lipopolysaccharide (LPS) from E. coli. MDP (1.6 mg/kg body weight = b.wt.) injected intraperitoneally (IP) reduced food intake by decreasing meal frequency without affecting meal size. Indomethacin (2.5 mg/kg b.wt., IP) but not verapamil (5 mg/kg b.wt., IP) attenuated the hypophagic effect of MDP. In further experiments, MDP and LPS (100 micrograms/kg b.wt., IP) both inhibited gastric emptying and indomethacin failed to block this effect of LPS. Hepatic vagotomy did not attenuate the hypophagic effects of MDP or LPS. LPS reduced water intake only when food was available, but reduced food intake also during water deprivation. MDP did not affect water intake. MDP and LPS both had an aversive effect, but LiCl, which was also aversive, failed to reduce feeding under the conditions tested. This questions the role of a conditioned taste aversion in the hypophagia induced by MDP or LPS. The results suggest that a stimulation of eicosanoid synthesis contributes to MDP-induced hypophagia and may therefore also contribute to the anorexia during infection. In contrast, an inhibition of gastric emptying, an activation of hepatic satiety signals or a reduction of water intake, does not seem to be crucial for the hypophagic effects of MDP or LPS.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1990

Meal patterns of pygmy goats fed hay and concentrate ad lib.

The meal patterns of pygmy goats fed hay and pelleted concentrate ad lib were recorded and analyzed. The pygmy goats consumed 8 hay meals [6 during the light phase (= light)/2 during the dark phase (= dark)] and 10 concentrate meals (7 during light/3 during dark) during 24 hr (12 hr light/12 hr dark). Sixty-two percent of hay and 74% of concentrate intake occurred during light. Total 24-hr hay (280 g) and concentrate (264 g) intakes were similar, but concentrate was preferred during dark. Concentrate meals were smaller during light than during dark. The mean feeding rate (g/min) within meals for both hay and concentrate was higher during dark than during light. Meal size and duration of postmeal interval were positively correlated for concentrate but not for hay. No significant positive correlation was found between meal size and duration of premeal interval. Separate analysis of diurnal and nocturnal meals indicated that the postmeal correlation for concentrate was evident primarily during dark. The results demonstrate that food intake in pygmy goats shows distinct diurnal variations and suggest that food intake in ruminants is regulated from meal to meal, with different factors prevailing during light and dark.

Animal Feed↗
PubMed1989

Verapamil and indomethacin attenuate endotoxin-induced anorexia.

To characterize the mechanism of the anorexia during infection, we investigated the effect of E. coli lipopolysaccharide (LPS) on feeding in rats under various conditions: LPS (125, 100, 75, and 50 micrograms/kg body weight = b. wt.) injected intraperitoneally (IP) reduced food intake by decreasing meal frequency without affecting meal size. The Ca++-channel blocker verapamil (5 mg/kg b. wt., IP) or the antipyretic and antiphlogistic drug indomethacin (2.5 mg/kg b. wt., IP), but not combined alpha- and beta-adrenergic receptor blockade by IP phentolamine plus propranolol (500 micrograms/kg b. wt., each) attenuated the anorectic effect of LPS (125 or 100 micrograms/kg b. wt.). The results suggest that a phospholipase A2-sensitive mechanism contributes to the anorexia during injection.

Animals↗