ABSTRACT
AIMS: To investigate the effects of intrathecal morphine and fentanyl combined with low-dose naloxone on the expression of motilin and its receptor in a rat model of postoperative pain. MAIN METHODS: An intrathecal catheter was implanted, and saline, opioids (morphine and fentanyl) and naloxone were intrathecally administered 7 days later. An incisional pain model was established to induce pain behaviors in rats by unilateral plantar incision. Thermal hyperalgesia and mechanical allodynia were measured by using a radiant heat and electronic Von Frey filament, respectively. The expression of motilin in the hippocampus, stomach, duodenum, and plasma was determined by ELISA; and the expression of motilin receptor in the hippocampus was detected by Western blot assay. KEY FINDINGS: Motilin and its receptor were detected in the hippocampus. Acute incisional pain increased the motilin expression in the hippocampus and duodenum, while decreasing its expression in the gastric body and plasma. Postoperative analgesia with morphine+fentanyl upregulated the expression of motilin in the hippocampus; however, motilin was downregulated in peripheral sites. Naloxone at 1 ng/kg restored motilin to baseline levels. Acute pain, morphine+fentanyl, and naloxone all induced the expression of motilin receptor in the hippocampus. SIGNIFICANCE: Acute pain, postoperative analgesia with opioids, and naloxone significantly impacted the expression of hippocampal and peripheral motilin. Variation trends in all sites were not identical. Intrathecal injection of low-dose naloxone upregulated paw withdrawal thermal latency and enhanced the analgesic effects of opioids. The findings presented here provide a new basis for central and peripheral regulations in GI motility, clinical postoperative analgesia, and management of analgesic complications.
Subject(s)
Analgesics, Opioid/administration & dosage , Disease Models, Animal , Motilin/biosynthesis , Naloxone/administration & dosage , Pain, Postoperative/drug therapy , Receptors, Gastrointestinal Hormone/biosynthesis , Receptors, Neuropeptide/biosynthesis , Animals , Drug Therapy, Combination , Hippocampus/drug effects , Hippocampus/metabolism , Injections, Spinal , Motilin/antagonists & inhibitors , Motilin/metabolism , Pain Measurement , Pain, Postoperative/metabolism , Rats , Rats, Sprague-Dawley , Treatment Outcome , Up-Regulation/physiologyABSTRACT
BACKGROUND: Pancreatic polypeptide is released immediately after food ingestion. The release is operated by vagal-abdominal projections and has therefore been suggested as a test for vagal nerve integrity. Pathoanatomical and clinical studies indicate vagal dysfunction in early Parkinson's disease (PD). METHODS: We assessed the postprandial secretion of pancreatic polypeptide and motilin in healthy controls (n = 18) and patients with idiopathic rapid-eye-movement sleep behavior disorder (iRBD, n = 10), a potential premotor stage of PD, as well as in drug-naive (n = 19) and treated (n = 19) PD patients. RESULTS: The postprandial pancreatic polypeptide secretion showed a physiological pattern in all groups and even an enhanced response in drug-naive PD and iRBD. Motilin concentrations correlated with pancreatic polypeptide concentrations. CONCLUSIONS: Postprandial pancreatic polypeptide secretion is not a suitable test for vagal nerve integrity in PD. The unimpaired pancreatic polypeptide response in iRBD and PD might be explained by partially intact vagal-abdominal projections or compensatory mechanisms substituting a defective neuronal brain-gut axis.
Subject(s)
Pancreatic Polypeptide/biosynthesis , Parkinson Disease/metabolism , REM Sleep Behavior Disorder/metabolism , Aged , Female , Humans , Male , Middle Aged , Motilin/biosynthesis , Parkinson Disease/physiopathology , Postprandial Period/physiology , REM Sleep Behavior Disorder/physiopathologyABSTRACT
Motilin is an important endogenous regulator of gastrointestinal motor function, mediated by the class I G protein-coupled motilin receptor. Motilin and erythromycin, two chemically distinct full agonists of the motilin receptor, are known to bind to distinct regions of this receptor, based on previous systematic mutagenesis of extracellular regions that dissociated the effects on these two agents. In the present work, we examined the predicted intracellular loop regions of this receptor for effects on motilin- and erythromycin-stimulated activity. We prepared motilin receptor constructs that included sequential deletions throughout the predicted first, second, and third intracellular loops, as well as replacing the residues in key regions with alanine, phenylalanine, or histidine. Each construct was transiently expressed in COS cells and characterized for motilin- and erythromycin-stimulated intracellular calcium responses and for motilin binding. Deletions of receptor residues 63-66, 135-137, and 296-301 each resulted in substantial loss of intracellular calcium responses to stimulation by both motilin and erythromycin. Constructs with mutations of residues Tyr66, Arg136, and Val299 were responsible for the negative impact on biological activity stimulated by both agonists. These data suggest that action by different chemical classes of agonists that are known to interact with distinct regions of the motilin receptor likely yield a common activation state of the cytosolic face of this receptor that is responsible for interaction with its G protein. The identification of functionally important residues in the predicted cytosolic face provides strong candidates for playing roles in receptor-G protein interaction.
Subject(s)
Receptors, Gastrointestinal Hormone/genetics , Receptors, Neuropeptide/genetics , Amino Acid Sequence , Animals , COS Cells , Calcium/physiology , Calcium Signaling/physiology , Chlorocebus aethiops , DNA Mutational Analysis , GTP-Binding Proteins/metabolism , GTP-Binding Proteins/physiology , Humans , Kinetics , Molecular Sequence Data , Motilin/biosynthesis , Motilin/genetics , Mutagenesis , Radioligand AssayABSTRACT
Ghrelin is a novel gastrointestinal peptide that stimulates growth hormone secretion, food intake, and body weight gain. Increased ghrelin secretion has been reported in such negative energy states as starvation and low body weight. We investigated the dynamics of ghrelin in rats with streptozotocin-induced diabetes, because they present reduced body weight and hyperphagia. The plasma ghrelin levels and gastric preproghrelin mRNA expression levels of the diabetic rats increased significantly and their gastric ghrelin levels decreased significantly. Negative energy balance may enhance preproghrelin mRNA expression and ghrelin secretion into the bloodstream.
Subject(s)
Diabetes Mellitus, Experimental/blood , Peptide Hormones/blood , Animals , Body Weight , Diabetes Mellitus, Experimental/metabolism , Diabetes Mellitus, Experimental/pathology , Gastric Mucosa/metabolism , Ghrelin , Male , Motilin/biosynthesis , Motilin/genetics , Peptide Hormones/genetics , RNA, Messenger/biosynthesis , Rats , Rats, WistarABSTRACT
Motilin has never been isolated from rodents, the most frequently used laboratory animals, despite several attempts. We have isolated and sequenced the motilin precursor from duodenal mucosa of guinea pig (GenBank accession number AF323752) and studied its expression in several tissues. The percent homology with human motilin is the lowest yet observed due to several unique substitutions in the C-terminal end. As expected, the precursor was present in the gut mucosa with the exception of the gastric corpus. It was also present in medulla oblongata, nucleus of the solitary tract, hypophysis, spinal cord, hypothalamus, and cerebellum but not in the cerebral cortex. For the first time we demonstrated motilin expression in the thyroid.
Subject(s)
Motilin/biosynthesis , Motilin/chemistry , Protein Precursors/chemistry , Amino Acid Sequence , Animals , Brain/metabolism , Cloning, Molecular , DNA Primers/metabolism , DNA, Complementary/metabolism , Duodenum/metabolism , Guinea Pigs , Humans , Molecular Sequence Data , Motilin/genetics , Mucous Membrane/metabolism , Polymerase Chain Reaction , RNA, Messenger/metabolism , Sequence Homology, Amino Acid , Thyroid Gland/metabolism , Tissue DistributionABSTRACT
A 62-year-old man with a history of a resected rectal polyp was diagnosed 14 years later with right liver and multiple bone metastases. The liver biopsy showed a malignant epithelial tumor that was positive for neuron-specific enolase immunostaining and negative for chromogranin. Electron microscopy was characteristic of that for an endocrine tumor. Most circulating hormonal peptide levels were within normal ranges and only motilin level was elevated. On the right hepatectomy, the three large metastases had a histologic picture suggestive of an endocrine tumor. Immunohistochemistry revealed in some areas numerous tumor cells expressing motilin, and a few cells were strongly positive for pancreatic polypeptide and somatostatin. The retrospective analysis of the rectal polyp showed a similar histology and immunohistochemical profile, indicating that this lesion was the primary tumor. Motilin-positive cells from one of the hepatic lesions were identified on semithin sections and further processed for electron microscopy. Neurosecretory granules were numerous in all cells. Immunoelectron localization enabled us to characterize the motilin-containing neurosecretory granules, which had a mean diameter of 168.3x38.1 nm. Although not all tumor cells were motilin-positive, a diagnosis of motilinoma for the rectal polyp and its hepatic and bone metastases was proposed.
Subject(s)
Bone Neoplasms/metabolism , Carcinoid Tumor/metabolism , Liver Neoplasms/metabolism , Motilin/biosynthesis , Polyps/metabolism , Rectal Neoplasms/metabolism , Biopsy , Bone Neoplasms/pathology , Bone Neoplasms/secondary , Bone Neoplasms/ultrastructure , Carcinoid Tumor/pathology , Carcinoid Tumor/secondary , Carcinoid Tumor/surgery , Carcinoid Tumor/ultrastructure , Cytoplasmic Granules/metabolism , Cytoplasmic Granules/ultrastructure , Humans , Immunohistochemistry , Liver Neoplasms/pathology , Liver Neoplasms/secondary , Liver Neoplasms/ultrastructure , Male , Microscopy, Immunoelectron , Middle Aged , Polyps/pathology , Polyps/surgery , Polyps/ultrastructure , Rectal Neoplasms/pathology , Rectal Neoplasms/surgery , Rectal Neoplasms/ultrastructure , TimeSubject(s)
Male , Female , Humans , Pregnancy , Infant, Newborn , Child , Adult , Hormones/physiology , Androgens/biosynthesis , Androgens/physiology , Bombesin/biosynthesis , Calcitonin/biosynthesis , Calcitonin/physiology , Calcitriol/biosynthesis , Calcitriol/physiology , Menstrual Cycle , Cholecystokinin/biosynthesis , Cholecystokinin/physiology , Menstruation Disturbances/classification , Menstruation Disturbances/diagnosis , Calcium Metabolism Disorders/diagnosis , Calcium Metabolism Disorders/etiology , Phosphorus Metabolism Disorders/diagnosis , Phosphorus Metabolism Disorders/etiology , Enkephalins/biosynthesis , Enkephalins/physiology , Endorphins/biosynthesis , Endorphins/physiology , Estrogens/biosynthesis , Estrogens/physiology , Gastrins/biosynthesis , Gastrins/physiology , Glucagon/antagonists & inhibitors , Glucagon/biosynthesis , Glucagon/physiology , Glucagonoma/diagnosis , Glucagonoma/etiology , Glucocorticoids/biosynthesis , Thyroid Gland , Thyroid Gland/anatomy & histology , Parathyroid Glands , Adrenal Glands , Adrenal Glands/physiology , Gonadotropins/biosynthesis , Gonadotropins/physiology , Pregnancy/physiology , Hypothalamus , Hypothalamus/anatomy & histology , Pituitary Gland , Pituitary Gland/anatomy & histology , Adrenocorticotropic Hormone/biosynthesis , Adrenocorticotropic Hormone/physiology , Parathyroid Hormone , Growth Hormone/biosynthesis , Growth Hormone/physiology , Gastrointestinal Hormones/biosynthesis , Gastrointestinal Hormones/physiology , Hypothalamic Hormones/biosynthesis , Hypothalamic Hormones/physiology , Pituitary Hormone Release Inhibiting Hormones/physiology , Pituitary Hormone-Releasing Hormones/physiology , Insulin/biosynthesis , Insulin/physiology , Insulinoma/diagnosis , Insulinoma/etiology , Iodine/deficiency , Iodine/physiology , Iodine/metabolism , Placental Lactogen/biosynthesis , Placental Lactogen/physiology , Menopause/physiology , Menstruation , Motilin/biosynthesis , Motilin/physiology , Oxytocin/biosynthesis , Oxytocin/physiology , Ovary , Ovary/anatomy & histology , Ovary/physiology , Vasoactive Intestinal Peptide/biosynthesis , Vasoactive Intestinal Peptide/physiology , Glucagon-Like Peptides/biosynthesis , Glucagon-Like Peptides/physiology , Pancreatic Polypeptide/biosynthesis , Pancreatic Polypeptide/physiology , Progesterone/biosynthesis , Progesterone/physiology , Prolactin/biosynthesis , Prolactin/physiology , Pancreas/anatomy & histology , Pancreas/embryology , Relaxin/biosynthesis , Relaxin/physiology , Secretin/biosynthesis , Secretin/physiology , Somatostatin/biosynthesis , Somatostatin/physiology , Testosterone/biosynthesis , Testosterone/physiology , Testis/anatomy & histology , Testis/cytology , Testis/physiology , Thyroglobulin/biosynthesis , Thyroglobulin/physiology , Thyroglobulin/metabolism , Reference Values , Vasopressins/biosynthesis , Vasopressins/physiology , beta-Lipotropin/biosynthesisSubject(s)
Humans , Male , Female , Pregnancy , Infant, Newborn , Child , Adult , Hormones/physiology , Hypothalamic Hormones/biosynthesis , Hypothalamic Hormones/physiology , Hypothalamus/anatomy & histology , Hypothalamus , Pituitary Hormone-Releasing Hormones/physiology , Pituitary Hormone Release Inhibiting Hormones/physiology , Growth Hormone/biosynthesis , Growth Hormone/physiology , Prolactin/biosynthesis , Prolactin/physiology , Placental Lactogen/biosynthesis , Placental Lactogen/physiology , Adrenocorticotropic Hormone/biosynthesis , Adrenocorticotropic Hormone/physiology , beta-Lipotropin/biosynthesis , Endorphins/biosynthesis , Endorphins/physiology , Vasopressins/biosynthesis , Vasopressins/physiology , Oxytocin/biosynthesis , Oxytocin/physiology , Pituitary Gland/anatomy & histology , Pituitary Gland , Thyroid Gland/anatomy & histology , Thyroid Gland , Thyroglobulin/biosynthesis , Thyroglobulin/physiology , Thyroglobulin/metabolism , Iodine/deficiency , Iodine/physiology , Iodine/metabolism , Adrenal Glands/physiology , Adrenal Glands , Glucocorticoids/biosynthesis , Parathyroid Glands , Parathyroid Hormone , Calcitonin/biosynthesis , Calcitonin/physiology , Calcitriol/biosynthesis , Calcitriol/physiology , Calcium Metabolism Disorders/diagnosis , Calcium Metabolism Disorders/etiology , Phosphorus Metabolism Disorders/diagnosis , Phosphorus Metabolism Disorders/etiology , Ovary/anatomy & histology , Ovary/physiology , Ovary , Estrogens/biosynthesis , Estrogens/physiology , Progesterone/biosynthesis , Progesterone/physiology , Relaxin/biosynthesis , Relaxin/physiology , Gonadotropins/biosynthesis , Gonadotropins/physiology , Menstrual Cycle , Menstruation , Menstruation Disturbances/classification , Menstruation Disturbances/diagnosis , Menopause/physiology , Pregnancy/physiology , Testis/anatomy & histology , Testis/cytology , Testis/physiology , Androgens/biosynthesis , Androgens/physiology , Testosterone/biosynthesis , Testosterone/physiology , Pancreas/anatomy & histology , Pancreas/embryology , Glucagon/antagonists & inhibitors , Glucagon/biosynthesis , Glucagon/physiology , Insulin/biosynthesis , Insulin/physiology , Pancreatic Polypeptide/biosynthesis , Pancreatic Polypeptide/physiology , Insulinoma/diagnosis , Insulinoma/etiology , Glucagonoma/diagnosis , Glucagonoma/etiology , Somatostatin/biosynthesis , Somatostatin/physiology , Gastrointestinal Hormones/biosynthesis , Gastrointestinal Hormones/physiology , Secretin/biosynthesis , Secretin/physiology , Cholecystokinin/biosynthesis , Cholecystokinin/physiology , Gastrins/biosynthesis , Gastrins/physiology , Glucagon-Like Peptides/biosynthesis , Glucagon-Like Peptides/physiology , Enkephalins/biosynthesis , Enkephalins/physiology , Vasoactive Intestinal Peptide/biosynthesis , Vasoactive Intestinal Peptide/physiology , Motilin/biosynthesis , Motilin/physiology , Bombesin/biosynthesis , Reference ValuesSubject(s)
Gastrointestinal Hormones , Motilin , Animals , Blood Pressure/drug effects , Digestion/drug effects , Dogs , Duodenum/drug effects , Gastric Mucosa/metabolism , Gastrointestinal Hormones/metabolism , Gastrointestinal Hormones/pharmacology , Gastrointestinal Motility/drug effects , Humans , Motilin/analogs & derivatives , Motilin/biosynthesis , Motilin/pharmacology , Muscle, Smooth/drug effects , Protein Biosynthesis , Stomach/drug effectsABSTRACT
The semithin-thin technique applied to serial resin-embedded sections, using sequential immunocytochemistry, conventional electron microscopy and silver staining, indicates that a population of enterochromaffin cells in the intestine contain, and therefore presumably synthesize and secrete, the 22-amino acid residue peptide motilin.