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Biomedical subjects

Y Ruckebusch

Publications and source records attributed to Y Ruckebusch.

At least 73 records · Page 4Linked to original sources
PubMed1985

Colonic motor responses in the pony: relevance of colonic stimulation by opiate antagonists.

The electrical and mechanical activity of the digestive tract and its response to the administration of opiate agonists and antagonists was assessed from electrodes and strain gauges chronically implanted on the jejunum and the cecocolonic segments in 3 ponies given a diet of hay and concentrates. Before the drugs were given, 10 to 17 migrating myoelectric complexes/day were recorded on the small intestine, and a rhythmic motor activity (base line) was observed on the proximal portion of the colon at the rate of 3.5 to 6.6/hour. Propagated contractions from the proximal to the distal portion of the colon occurred at the rate of 1.5 to 2.3/hour. Each pony was used as its own control and was given morphine (0.5 or 1 mg/kg of body weight, IV) or fentanyl (0.01 or 0.05 mg, IV) at weekly intervals. After an early phase of inhibition of the overall activity that lasted from 0.5 to 3 hours, depending on the dose, the resting muscle tone of the colonic activity was increased for a dose-dependent period. Propagated contractions only reappeared at the end of this 2nd phase. The opiate antagonist naloxone (0.5 mg/kg, IV) elicited a marked propulsive activity on the left replicated colonic segment, characterized by an increase in the number of propagated contractions. The N-methyl-quaternary analog of naloxone (methylnaloxone, which presumably entails selective action at opiate receptors outside the CNS) was also effective, indicating peripheral effects at the dosage level used (0.5 mg/kg, IV). Seemingly, an inhibitory opioid system exists in the control of colonic motor function in ponies and the possible usefulness of opiate antagonists to relieve hypomotility resulting in colonic impaction and constipation.

Animals↗
PubMed1985

Prednisolone succinate and prednisolone acetate in cattle: pharmacokinetics and action on the adrenal gland.

The pharmacokinetics of prednisolone were studied in a group of 6 cows given prednisolone 21-sodium succinate IV and IM (600 micrograms/kg of body weight expressed as prednisolone alcohol) and prednisolone acetate IM (600 micrograms/kg of body weight expressed as prednisolone alcohol). After IV administration of prednisolone 21-sodium succinate, the half-life of elimination was 3.6 +/- 1.177 hours. After IM administration of prednisolone 21-sodium succinate, absorption was rapid and complete. After IM administration of prednisolone acetate, absorption was very slow with an absorption half-life of 48 hours, but was still complete. Basal plasma hydrocortisone was about 7.5 ng/ml. After IV and IM administration of prednisolone 21-sodium succinate, plasma hydrocortisone returned to normal values within 48 hours. In contrast, after IM administration of prednisolone acetate, a long adrenal suppression lasting from 4 to 6 weeks was observed.

Adrenal Glands↗
PubMed1985

[Control of antroduodenal motility in sheep].

The continuous but cyclic delivery of contents through the pylorus in the adult ruminant is regulated by the initiation of the migrating myoelectric complexes on the duodenal bulb. The motor responses of the pyloric antrum to the volume of digestive contents, the presence of lipids and ulcerogenic agents revealed that the inhibition of the motor antral activity, whatever its origin, resulted in a higher frequency of the duodenal cyclic motor events. Conversely, stimulation of duodenal motor activity, for example the increased frequency of migrating myoelectric complexes, resulted in the inhibition of the antral motor activity. It is suggested that the motor profile of the antroduodenal junction corresponded to interactions which fulfill the regulation of gastric emptying motor functions, with the first part of the duodenum as an extremely sensitive and rapid controlling mechanism.

Animals↗
PubMed1984

Opioid control of the ruminant stomach motility: functional importance of mu, kappa and delta receptors.

In sheep, the subcutaneous (SC) or intracerebroventricular (ICV) administration of the mu-type opioid agonists, fentanyl and morphine, evokes a blockade of the cyclic contractions of the reticulum. A similar inhibition of forestomach motility was recorded following the administration of the two enkephalin analogs, D-Ala2-Met5-enkephalinamide (DAMA) and D-Ala2-D-Leu5-enkephalin (DADLE) which are mixed mu - delta opioid agonists. In contrast, the reticular contractions were enhanced by the SC or ICV administration of the kappa type agonist, ethylketazocine (EKC) and U - 50 488 H. The proximal duodenum motor activity was transiently increased resulting in the occurrence of a phase III-like activity by these opioid agonists, regardless of the subtypes. The effects of the opioid agonists on reticular motility were prevented by the injection of naloxone but not by the quaternary parent compound methylnaloxone which does not cross the blood-brain barrier. The duodenal motor effects elicited by the opioid agonists were antagonized by both naloxone and methylnaloxone. The results suggest that the inhibition of the ruminant stomach motility is centrally mediated by mu - delta type opioid agonists and are consistent with opposite effects from kappa type opioid agonists. The stimulatory effect of peptide and non-peptide opioid agonists on the duodenum may result in part from direct opioid receptor-mediated actions on smooth muscle.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1984

Opioid receptor agonists in the rabbit colon: comparison of in vivo and in vitro studies.

Myoelectrical activity was recorded in the proximal and distal colon of rabbits using chronically implanted electrodes. The motility in both the proximal and distal colon was inhibited by the intravenous (IV) administration of the following opioid agonists for mu receptors: morphine and fentanyl, kappa receptors: ethylketazocine (EKC) and U 50 488 H, and delta receptors: D-Ala2 D-Leu5-enkephalin (DADLE) and D-Ser2 Leu-enkephalin-Thr6 (DSLET). In contrast, the myoelectric activity in the distal colon was increased during the infusion of an endogenous kappa opioid agonist, dynorphin (DYN). All of these effects were prevented by naloxone pretreatment. During in vitro studies using extraluminal force transducers, fentanyl, U 50 488 H and DSLET inhibited spontaneous contractions of the proximal colon, but U 50 488 H and DSLET caused a substantial increase in the motility of the distal colon. The observed motor responses in the proximal and distal colon following opioid agonist administration indicate that the control of these two intestinal segments may be different. It is suggested that the stimulatory effect of dynorphin on the distal colon is peripherally-mediated while inhibition of the whole colon by opioid agonists regardless of subtypes seems to be centrally-mediated.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1984

The cyclic motor activity of the ovine gut: its reset at a faster rhythm.

In adult sheep, the frequency of the migrating motor complexes (MMC) was increased by the duodenal administration of methysergide, but not affected by other 5-HT1 or 5-HT2 antagonists. This reset of the MMC pattern at a faster rhythm suggests a selective action on the enteric neuronal serotoninergic mechanism modulating the pacing of the gut cyclic motor activity.

Animals↗
PubMed1984

Involvement of serotonergic mechanisms in initiation of small intestine cyclic motor events.

Continuous mechanical and electrical activity recordings of the gastroduodenal junction and duodenum were performed in conscious sheep receiving pharmacologic agents delivered intraduodenally before and after nerve section. Sheep on a normal diet regimen exhibited cyclic periods of maximal activity (phase III of the migrating myoelectric complex) on the duodenum or in-series contractions on the duodenal bulb recurring at a frequency of 13/24 hr and more after nerve section. Among the variety of agents triggering in intact animals premature phases of maximal activity, methysergide, when administered locally, was found to increase the number of complexes to a frequency of 24/24 hr, even when extrinsic nerve supply was removed. The results suggest that in the ovine model the mechanism of cycling of the motor events involved serotonergic myenteric neurons located in the duodenal bulb. The data were consistent with the regulation of the enteric biological clock via 5HT neural receptors mediating inhibition.

Animals↗
PubMed1984

In vivo modulation of intestinal motility and sites of opioid effects in the rat.

The effects of subcutaneous (s.c.), intrathecal (i.t.) and intracerebroventricular (i.c.v.) injection of fentanyl and D-Ala2,D-Leu5-enkephalin (DADLE) on intestinal myoelectrical activity were examined in fed rats. In rats with chronically implanted electrodes on the small and large bowel, i.c.v. fentanyl and DADLE restored the 'fasted' pattern of duodenal activity, i.e. the migrating myoelectric complex (MMC) for 8-12 h at a dose as small as 1 nM/kg. In addition, the colonic pattern of activity evaluated as the number of migrating spike bursts (MSB) per min was nearly halved for 1 h following i.c.v. fentanyl (10 nM/kg). Pretreatment with naloxone, but not methylnaloxone prevented these effects on the small and large bowel. Fentanyl (100 nM/kg s.c.) significantly reduced small and large bowel motility, but DADLE (100 nM/kg s.c.) which induced a transient 'fasted pattern' on the duodenum strongly stimulated colonic motor activity. Pretreatment with methylnaloxone prevented the inhibitory effects of s.c. fentanyl but not the colonic excitatory effects of DADLE. The i.t. administration of fentanyl and DADLE did not modify the activity pattern of the bowel. Again, i.t. DADLE stimulated the colon, even after methylnaloxone treatment and at doses 100 times less than the smallest active s.c. dose. The long-lasting changes in small bowel motility and the important delay following DADLE and fentanyl i.c.v., reinforces the hypothesis of a central opioid control of the gastrointestinal motor pattern with possible involvement of released substances.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Pattern of electrical activity of the ovine uterus and cervix from mating to parturition.

The electrical activity of the uterus, greater curvature and lesser curvature, and of the cervix were recorded throughout several oestrous cycles, matings and the entire course of pregnancy in a set of ewes. In cyclic ewes, all electrode sites were active during the periovulatory period, but during the luteal phase only the cervix and lesser curvature continued to present regular activity, i.e. episodes of 6-8 min duration. Matings failed to disrupt the oestrous activity pattern in 5 out of 6 ewes. During the subsequent pregnancy in 4 ewes, activity, when present, consisted of the cyclic occurrence of regular activity episodes in the gravid horn(s) (greater curvature) and in the cervix (and lesser curvature in 1 ewe). Three phases were recognized on the basis of the activity of the greater curvature of the gravid horn(s). The first phase corresponded to quiescence of the horn from Day 5 (Day 0 = mating) to about Day 41. The second phase was marked by the sudden onset of regular activity of the uterus; frequency rapidly increased and maximal values were reached around Day 49, after which frequency progressively decreased until around Day 66. The third phase was characterized by a steady state in genital tract activity until the peripartum period. The cervix and lesser curvature activity followed an almost similar development of regular activity episodes with only slight time differences.

Animals↗
PubMed1984

Short-term and long-term effects of ranitidine and oxmetidine on gastrointestinal motility in sheep.

Short-term and specific motor effects of ranitidine on gastrointestinal motility of conscious sheep were recorded. These effects were prevented by atropine, but tachyphylaxis was observed after a second injection. Short-term effects on motility were not obtained with oxmetidine. Long-term effects for both ranitidine and oxmetidine, at high doses, were reducing the frequency of reticular contractions and shortening the interval between MMCs in a similar manner.

Animals↗
PubMed1984

[The motoricity cycle of the small intestine].

The electrical spike activity of the small intestine at the gastroduodenal junction occurs as migrating myoelectric complexes (MMCs), initiated regularly at intervals of 90-100 min. in the adult sheep and of 20-30 min. in the neonate. This ultradian rhythm, generated by the enteric nervous system, may become identical in the adult and in the neonate, by the use of methysergide which interacts with 5-HT myenteric neurones. The results suggest a postnatal development of a serotoninergic inhibitory system, involved in the control of the basic rest-activity cycle of the small intestine.

5-Hydroxytryptophan↗
PubMed1984

Enhancement of the cyclic motor activity of the ovine small intestine by lysergic acid derivatives. Mechanism and significance.

The effects of a variety of substances influencing the initiation of cyclic motor events at the gastroduodenal junction were studied in conscious sheep. A significant and long-lasting decrease in the frequency of cyclic events from approximately 100 min to 30-40 min was elicited by the intraduodenal bulb administration of the lysergic acid derivatives methylergonovine and methysergide. This effect was dose-dependent and occurred with smaller dosages than those effective when administered parenterally or more distal in the jejunum. Intraluminal administration of cyproheptadine, fonazine, and metergoline into the duodenal bulb increased the interval between phase III activity. At higher dosages, however, cyproheptadine and metergoline reduced the spiking activity of the antroduodenal junction, without significantly changing the cycle duration of the migrating myoelectric complex on the duodenal bulb or jejunum. After administration of cyproheptadine, fonazine, and metergoline, the cycling activity of the duodenojejunum was irregular for 1-2 days. These findings are compatible with a resetting of the enteric biological clock at a faster rhythm and suggest a selective action via an enteric serotoninergic mechanism involved in the normal pacing of the cyclic motor events of the gut.

Action Potentials↗
PubMed1984

[Changes in electromyogram of the colon related to ingestion of undigestible particles in dogs].

The relationship between undigestible particle intake and myoelectric activity of the colon was examined in three dogs fed with a low-fiber diet alone or with polyethylene particles containing 10 p. 100 and 45 p. 100 of dry matter. When compared to controls colonic electromyograms of dogs fed on polyethylene revealed a 40 p. 100 reduction in long spike bursts (LSBs). The sequences of LSBs propagated over long distances, or MSBs (migrating spike bursts) were unchanged and only the myoelectric activity corresponding to LSBs propagated for very short distances was abolished by polyethylene diets. Concurrently, the percentage of water excreted in the feces was increased. Undigestible and inert particles were thus able to modify the colonic motor profile and to increase the fecal excretion of water. Such effects were similar to those observed with dietary fibers. It is suggested that dietary fiber effects on fecal excretion and colonic motility are partially induced by their mechanical action on the intestinal wall. In addition, the absence of LSBs propagated in both directions and for short distances on the canine proximal and transverse colons seems to be a limiting factor in the movements of water absorption.

Animals↗
PubMed1983

Antagonistic effects of naloxone on CCK-octapeptide induced satiety and rumino-reticular hypomotility in sheep.

Continuous intracerebroventricular (ICV) infusion of CCK-octapeptide (CCK8) was performed in ewes fitted with a permanent cannula into the lateral cerebral ventricle and Nichrome electrodes on the reticulum in order to record its electrical activity. In the first series of experiments, subsequently repeated in 12 h fasted animals, CCK8 was infused during the first hour of a 3 hour period of feeding at 2.5, 5 and 10 ng.kg-1.min-1. The same series of infusion were performed 20 min after ICV injection of 2.4 and 10 micrograms.kg-1 of naloxone. CCK8 reduced significantly in a dose related manner the food intake (r = 0.95; P less than 0.01) and the frequency of cyclic spike bursts associated to biphasic contractions of the reticulum observed during feeding (r = 0.89; P less than 0.01). At 5 and 10 ng.kg-1.min-1, the reduction of food intake reached 46.2 and 52.6% during the period of infusion; the basal and stimulated (feeding) frequency of reticular contractions were nearly halved. Previous ICV administration of naloxone (2.4 micrograms.kg-1) partially blocked the effects of CCK8 infusion on both food intake (72%) and reticular frequency (54% basal, 67% stimulated). The CCK8 induced effects on both food intake and frequency of reticular contraction were completely abolished after a previous 10 micrograms.kg-1 injection of naloxone. These results suggest that the central effects of CCK8 on feeding behavior and forestomach motility involve similar central structures and are mediated through opiate receptor structures.

Animals↗
PubMed1983

Are regular activity episodes of the genital tract controlled by pulsatile releases of oxytocin?

The possible control by endogenous oxytocin of the regular activity episodes which occur in the ovine genital tract was assessed in 3 cyclic ewes chronically fitted with intraparietal electrodes. Despite the existence of a pulsatile release of the hormone into plasma, no significant relationships were noticed between the motility events of genital tract and plasma concentrations of oxytocin.

Animals↗