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Biomedical subjects

E Goñalons

Publications and source records attributed to E Goñalons.

At least 37 records · Page 2Linked to original sources
PubMed1994

Rhythmic oscillating complex: characterization, induction, and relationship to MMC in chickens.

Migrating myoelectrical complexes (MMCs) and rhythmic oscillating complexes (ROCs) have been investigated in chickens prepared for electromyography. Animals were chronically implanted with electrodes in stomach, duodenum, jejunum, ileum, ceca, and rectum. MMCs showing phases I-III were found in the jejunum and ileum both in fed and fasted states. Repetitive spike bursts were recorded in the duodenum (0.5-1/h), disrupting the gastroduodenal coordination and preceding a phase III in the jejunum. ROCs appeared spontaneously in fasted animals and in 75% of the recordings during the dark period. Four consecutive intestinal myoelectrical patterns have been described during a ROC. Briefly, they consisted in series of high-speed propagated abroad contractions of great amplitude that progressively changed into others of orad direction. In relation to the MMC, the ROC pattern appeared just after a phase III reached the distal ileum, and a pattern of duodenal repetitive spike bursts, followed by a migrating phase III in the jejunum, started at the duodenum after a ROC. No myoelectrical changes were recorded in cecorectal activity during ROC. Vagotomized animals showed the ROC pattern. Neither apomorphine (5-100 micrograms/kg iv) nor cholecystokinin (10(-9) mol/kg iv) induced ROCs. Naloxone (5 x 10(-7) mol/kg iv) and atropine (0.1 mg/kg iv) induced isolated orad contractions. Myoelectrical and functional similarities can be found between retrograde giant contractions, described in mammals, and ROCs. However, they differ in their origin and mechanism of induction.

Animals↗
PubMed1993

In vivo modulation of gastrointestinal motor activity by Met-enkephalin, morphine and enkephalin analogs in chickens.

The main objectives of this work have been to study (1) whether or not opioid effects on gastrointestinal motility in chicken are mediated through central or peripheral pathways; (2) the receptors involved; (3) the correlation of the motor response to the distribution of Met-enkephalin in the gastrointestinal tract and (4) to evaluate the physiological role of endogenous opioids in spontaneous MMCs. Intravenous infusion of Met-enkephalin and morphine (5 x 10(-7) mol/kg) induced gastric inhibition and a migrating intestinal hyperactivity. Induced intestinal activity was faster in vagotomized chickens. In the stomach there was a correlation between the duration of the inhibitory response and the affinity of the agonists for mu-receptors ([D-Ala2,N-Me-Phe4,Gly5-ol]-enkephalin (DAGO) > morphine > Met-enkephalin > Tyr-D-Pen-Gly-Phe-D-Pen (DPDPE)). DPDPE induced duodenal hyperactivity which was not propagated. Immunohistochemistry showed that Met-ENK like material is mainly located at the myenteric plexus and the outer circular muscle in stomach. In the intestine, it was found in the myenteric and the deep muscular plexuses. When endogenous MMCs were studied, i.v. infusion of naloxone lengthened significantly their duration. In conclusion, the fact that Met-enkephalin and their analogs induced a migrating activity in the intestine and the lengthening of MMC by naloxone, suggest a physiological role for opioids on induction of MMC in birds, acting at peripheral level.

Amino Acid Sequence↗
PubMed1993

Abnormalities of sympathetic sudomotor function in experimental acrylamide neuropathy.

The possible involvement of sympathetic sudomotor function by acrylamide intoxication was investigated in the mouse, and compared with nerve conduction studies and global motor tests. Acrylamide (40 mg/kg, 3 days per week, 8 weeks) was given per os to a group of mice (A1). Their motor ability to stand on the rotarod was impaired from day 11, reaching a minimum between 46 and 60 days. The number of pilocarpine reactive sweat glands (SG), evaluated by the silicone mold technique, was similar to controls at 40 days and slightly decreased at 54 days. Another group of mice (A2), given acrylamide at a higher dose (50 mg/kg, 5 days per week, 5 weeks), showed abnormalities on the rotarod by 11 days, a progressive decrease of muscle action potential (CMAP) amplitude, and significantly decreased number of reactive SG from 15 days, with respect to controls. Comparatively, sudomotor dysfunction was milder and appeared later in time than alphamotor involvement, being noticeable only after severe poisoning. The decrease in SG response is attributable to damage by acrylamide intoxication of postganglionic sudomotor nerve fibers, which are unmyelinated sympathetic efferents.

Acrylamides↗
PubMed1993

Effects of cholecystokinin and gastrin on gastroduodenal motility and coordination in chickens.

Cholecystokinin (CCK) has not been isolated from chicken gut yet and there has been no study on the effects of chicken gastrin (CG), the only gastrin/CCK peptide isolated from avian gut, on gastrointestinal motility. The main objective was to study the effects of CCK and CG on gastroduodenal motility and coordination in chickens. Electrodes for electromyography were implanted in the stomach and proximal and distal duodenum of 4 wk old chickens. Sulphated CCK-octapeptide (CCK8) (10(-10) to 10(-8) moles/kg), CCK-tetrapeptide (CCK4) (2 x 10(-10) to 2 x 10(-8) moles/kg) and CG (3 x 10(-10) to 10(-8) moles/kg) were given in a 10 min i.v. infusion. All these peptides induced a dose-dependent inhibition of gastric motility. CCK8 induced a duodenal hyperactivity whereas CCK4 and CG induced a duodenal inhibition. Neither the CCK-A receptor antagonist L364,718 nor the CCK-B receptor antagonist L365,260 (10(-9)-10(-7) moles/kg) antagonized CCK8 actions. From these results we suggest that the receptors mediating CCK effects are different from those of mammals. The site of action for these peptides is the same in the stomach whereas in the duodenum there are two different ones, one mediating excitation and the other inhibition. These results suggest a physiological role for CCK regulating gastroduodenal motility in birds.

Animals↗
PubMed1993

Receptors implicated in the actions of serotonin on chicken ileum longitudinal smooth muscle.

The presence of serotonin (5-HT) in the chicken gastrointestinal tract has been previously reported, but its motor effects have been poorly described. The aims of this work were: A) to define the effects of 5-HT on chicken longitudinal ileum; B) to explore the mechanisms by which such effects occur and C) to identify the subtype(s) of 5-HT-ergic receptors implicated. The motor responses to 5-HT were assayed in vitro using ileal strips taken from male White Leghorn chickens 7-9 week old. 5-HT elicited ileal contraction (EC50 9.6 x 10(-8) M), which was markedly decreased in the presence of tetrodotoxin (TTX). Repeated exposure of the tissue to supramaximal concentrations of 5-HT did not however lead to desensitization. Atropine (10(-6) M), ketanserin (10(-5) M), methysergide (10(-5) M) and methiothepine (10(-6) M) attenuated the response to 5-HT. Ketanserin was an effective inhibitor of the residual response to 5-HT obtained even in the presence of TTX. Several serotonergic agonists were assayed to further analyse the type of receptors involved in the response to 5-HT. 5-methoxytryptamine (5-MOT), a mixed 5-HT1, 5-HT2 and 5-HT4 agonist, reproduced all the effects of 5-HT. 8-OH-DPAT, a selective 5-HT1A agonist, trifluoromethylphenylpiperazine, a mixed 5-HT1B/C agonist, and m-chlorophenylbiguanide, a 5-HT3 agonist, did not induce any consistent contractile effects. Sumatriptan, a 5-HT1D agonist, exerted a slight agonistic effect which was blocked by methiothepine and decreased by TTX but not by atropine. Cisapride, a 5-HT4 partial agonist in mammals, decreased the effects of both 5-HT and 5-MOT. These results indicate that chicken ileum contains 5-HT1 receptors similar to the 5-HT1D mammalian subtype but not the 5-HT1A, 5-HT1B, 5-HT1C or 5-HT3 subtypes. 5-HT2 receptors are also present and would appear to be located on smooth muscle.

Animals↗
PubMed1993

Mechanism of action of CCK in avian gastroduodenal motility: evidence for nitric oxide involvement.

Our objective was to study the mechanism of action of cholecystokinin (CCK) on the motility of the gastroduodenal area. Chickens were implanted with five electrodes for electromyography in the stomach and duodenum. The effects of CCK (10(-9) mol.kg-1.10 min-1) were studied against the presence of several antagonists and in vagotomized animals. CCK caused inhibition of gastric motility and duodenal hyperactivity. Vagotomy blocked CCK responses in the stomach but not in the duodenum. Hexamethonium partially blocked gastric inhibition induced by CCK. NG-nitro-L-arginine methyl ester blocked the inhibitory response to CCK in the stomach but did not modify duodenum response. L-Arginine did not modify CCK actions. Opioid antagonists naloxone and naltrindole and adrenergic antagonists phentolamine and propranolol did not modify CCK response. Atropine did not modify duodenal response to CCK. Sodium nitroprusside (10(-8)-10(-6) mol/kg) inhibited gastroduodenal activity in a dose-related manner. We suggest that gastric response to CCK is vagally mediated, mainly by the nitric oxide system. Duodenal hyperactivity seems to be a direct action of CCK. Nitric oxide is a putative neurotransmitter in the chicken gut.

Animals↗
PubMed1993

Immunohistochemical differentiation of gastrin and cholecystokinin in gastrointestinal tract of chickens.

The presence of cholecystokinin (CCK) in the gastrointestinal tract of chickens has not been well demonstrated, although immunological and chromatographic techniques have shown the presence of intestinal gastrin-CCK-like factors. Recently, a new peptide, structurally related to mammalian CCK, but with a gastrin-like activity, has been isolated from the digestive tract of chickens. The objective of this work has been: 1) to study the presence of gastrin-CCK-like immunoreactivity (IMR) in the digestive tract of chickens; 2) to distinguish chicken gastrin from CCK; and 3) to establish their distribution using specific antibodies. Tissue specimens from the proventriculus, gizzard, pylorus, duodenum, jejunum, ileum, ceca, and rectum were studied using indirect immunofluorescence procedures. The antibodies used were: 1) an antibody specific against the C-terminal pentapeptide common to gastrin and CCK; 2) one specific against CCK-33; and 3) one specific against chicken gastrin. Their use allowed the differentiation of two cellular populations which showed different affinities for the antibodies, indicating the presence of a gastrin-like peptide in the antrum and another CCK-like peptide in the small intestine, with the highest concentration in the proximal ileum. Immunoreactivity was not found in any other studied area. Two different peptides of the gastrin-CCK family are present in the chicken's gastrointestinal tract. However their differentiation and identification are more difficult than in mammals due to the greater structural similarities of these peptides in birds.

Animals↗
PubMed1992

Opioid-induction of migrating motor activity in chickens.

Enkephalin and morphine initiation of phase III of MMC has been reported in dog and humans. In chickens, a similar migrating activity initiated at the duodenum occurs 7-9 times a day while the gastric activity ceases. The main objective was to determine whether this migrating activity could be induced by opioids. Electrodes for electromyography were implanted in the stomach, proximal and distal duodenum, jejunum and proximal and distal ileum of 4 wk old chickens. Met-enkephalin, morphine and beta-casomorphin-5 (5 x 10(-7) moles/Kg) were infused i.v.. All these substances initiated an intestinal migrating activity concurrent with gastric inhibition. The mean duration of gastric inhibition depended on the substance, lasting from 5 min (met-enkephalin) to 27 min (beta-casomorphin-5). The migrating activity started in the distal duodenum and propagated to the ileum in about 18 min. These effects were partially blocked by naloxone at equimolar doses. In conclusion, in chickens, as in dogs and humans, migrating myoelectrical activity can be initiated by opioids.

Animals↗
PubMed1992

A method of analysis of the electrical activity of the proximal gastrointestinal tract of the chicken.

The present paper describes a method of recording and analyzing electromyographical (EMG) signals from the digestive tract of the chicken. The EMG signals from the proventriculus, gizzard, and duodenum were recorded after implantation of Ni and Cr electrodes. The amplified EMG signals were digitized using a sampling frequency of 50 samples per second, and numerical data was stored immediately on the hard disk (1 datum = 1 byte). The software designed allowed: 1) detection of spike-bursts with a high accuracy; 2) analysis of maximum amplitude (with a maximum error of 6.7%), mean amplitude, duration, and frequency of the spike-bursts; the time of interval between spike-bursts, and the percentage of activity; 3) integration of the recorded data with a variable time set; and 4) a wave analysis by means of the Fourier algorithm. These methods, already used in EMG studies in mammals, are assembled and adapted for its application in birds.

Animals↗
PubMed1989

Factors determining gastrointestinal transit time of several markers in the domestic fowl.

The aim of this study was to find out how marker characteristics could affect digestive transit time in Gallus gallus. One soluble marker, Cr-EDTA, and two insoluble markers, Cr2O3 and chromium-mordanted plant cells of two sizes, were used. Three- to six-week-old chickens were killed in series after the oral administration of the markers at intervals of 0, 0.5, 1, 2, 3, 5, 7, and 9 h. The amount of chromium in each digestive segment was determined by atomic absorption. There were some differences in the initial distribution of markers; whereas almost the total amount of the chromium-mordanted rice husk of the largest size was found in the crop at time 0, less than half of the Cr-EDTA was found. Marker emptying out of the crop was fast and not related to either the type or size. In contrast, the emptying rate of the gizzard depended on marker particle size. As far as the caeca were concerned, the ileocaecal junction allowed the passage of soluble Cr-EDTA whereas solid markers were impeded (Cr2O3) or not allowed to pass through at all (vegetable fibre of any size). It can be concluded that marker selection is of major importance to transit time studies in chickens, since its characteristics can determine transit time in an absolute way.

Animals↗
PubMed1989

Age influence on digestive transit time of particulate and soluble markers in broiler chickens.

The gastrointestinal transit-time of two markers, Cr-mordanted bran, a solid marker, and Cr-EDTA, a soluble marker, have been studied in chickens (Gallus gallus) at 1, 2, and 3 wk of age. Mean retention time of the particular marker decreased as chicks grew. The excretion of Cr-EDTA took longer as birds grew; this soluble marker was retained in the ceca of the fowl. It was postulated that the ceca are not fully functional until total resorption of the yolk sac content occurs.

Aging↗
PubMed1987

Study of the rate of passage of food with chromium-mordanted plant cells in chickens (Gallus gallus).

Thirty broilers 8-10 weeks old were used to study the rate of food passage in chickens. Wheat bran and rice husks of three different sizes: more than 2 mm, between 1 and 1.5 mm, and less than 0.5 mm, mordanted with chromium, were used as markers. The suitability of these markers to study the rate of food passage in chickens and the possible influence of the size and hardness of the particle on the retention time was the objective of this study. Both T1, the time of first appearance of the marker, and Tm, the mean retention time, have been evaluated. Tm was a better parameter than T1 for studying transit time. Tm was longer with the biggest particles, especially with rice husk. The gizzard, with its grinding activity and pylorus, a selector of particle size, seems to be the transit regulator for solid particles in chickens. No chromium was found in the caecal contents of any case.

Animal Nutritional Physiological Phenomena↗
PubMed1982

Phenol red as indicator of the digestive tract motility in chickens.

Phenol red has been shown to produce no effects on intestinal motility of 24-hour-old chickens, allowing for quantitative measures of gastrointestinal transit and emptying. The results show that 1 hr after ingestion, the main digestive contents are stored in the crop with lesser amounts in the muscular part of the stomach, in the ileum, and in the rectum and caeca.

Animals↗
PubMed1979

3,3-Bis-(4-hydroxyphenyl)-7-methyl-2-indolinone (BHMI), the active metabolite of the laxative sulisatin.

The disodium salt of the sulphuric diester of 3,3-bis-(4-hydroxyphenyl)-7-methyl-2-indolinone (sodium sulisatin, Laxitex), a synthetic laxative with two phenolic groups esterified with sulfate, has been studied in order to find out if its laxative properties may be attributed to the unaltered compound or to its diphenolic derivative BHMI. We first studied the effect of homogenates of the gastrointestinal tract of rats and of rat cecal content of the hydrolysis of sulfate ester bonds of sulisatin. Results show that sulisatin can be hydrolyzed by cecal content while homogenates of stomach, small intestine and large intestine have no hydrolytic effect. Sulisatin is also a substrate of arylsulfate sulphohydrolase obtained from the snail Helix pomatia. The unaltered drug has no effect on the intestinal motility since it does not change the intestinal transit speed in rats pretreated with neomycin sulfate. Sulisatin (1.5, 3 and 6 mg) is unable to inhibit water absorption in rat colon while small amounts of BHMI (15 and 30 micrograms) may inhibit it significantly. It is concluded that sulisatin passes unaltered through the small intestine and is hydrolyzed in the large intestine by the intestinal microflora to its diphenolic derivative BHMI, which is responsible for the laxative activity of the drug.

Animals↗
PubMed1976

Study of the laxative properties of the disodium salt of the sulfuric diester of 3,3-bis-(4-hydroxyphenyl)-7-methyl-2-indolinone (DAN-603 in the rat.

The influence of DAN-603 (disodium salt of sulphuric diester of 3,3-bis-(4-hydroxyphenyl)-7-methyl-2-indolinone) on the propulsive motility of the rat digestive tract was studied by means of indicators (charcoal and pyrvinium pamoate) and radioactive tracers (133BaSO4). The results showed that DAN-603 increases selectively the colon motility without modifying the speed of gastric, intestinal (small intestine) and caecal emptying.

Animals↗