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Molecular Medicine Reports Nov 2020Endometriosis (EMS) is a common disease in women aged 25‑45 years, and pain is the main clinical symptom. The primary clinical treatment is surgical excision and drug...
Endometriosis (EMS) is a common disease in women aged 25‑45 years, and pain is the main clinical symptom. The primary clinical treatment is surgical excision and drug therapy targeting the ectopic lesions, but these have not been very effective. Botulinum neurotoxin serotype A (BTX‑A) has been reported to be useful in the treatment of pain in a variety of diseases. Based on this, the aim of the present study was to explore the therapeutic effect and mechanism of BTX‑A on EMS. A model of nerve injury induced by oxygen glucose deprivation (OGD) was constructed in PC12 cells and EMS mice. Model cells and mice were treated with different concentrations of BTX‑A to observe the changes in pain behavior, to detect cell viability and the secretion of norepinephrine (NE) and methionine enkephalin (M‑EK) in cells and the spinal cord, and to evaluate the expression of apoptosis‑related molecules in spinal cord nerves. The results revealed that BTX‑A significantly reduced the amount of writhing in model mice, enhanced the activity of PC12 OGD cells, increased the secretion of NE and M‑EK in model cells and the spinal cord of mice, and decreased the apoptosis of neural cells in the spinal cord of the model mice. Therefore, it was hypothesized that BTX‑A may alleviate the pain induced by EMS by increasing the secretion of analgesic substances and promoting the repair of nerve injury. The present study provided a theoretical basis for the treatment of pain induced by EMS.
Topics: Adult; Animals; Botulinum Toxins, Type A; Cell Survival; Disease Models, Animal; Endometriosis; Enkephalin, Methionine; Female; Glucose; Humans; Mice; Mice, Inbred BALB C; Norepinephrine; PC12 Cells; Pain; Rats
PubMed: 33000241
DOI: 10.3892/mmr.2020.11501 -
Parasites & Vectors Jul 2015In vertebrates, the presence of enteric worms can induce structural changes to the alimentary canal impacting on the neuroendocrine system, altering the proper...
BACKGROUND
In vertebrates, the presence of enteric worms can induce structural changes to the alimentary canal impacting on the neuroendocrine system, altering the proper functioning of the gastrointestinal tract and affecting the occurrence and relative density of endocrine cells (ECs). This account represents the first immunohistochemistry and ultrastructure-based study which documents the intimate relationship between the intestinal mucous cells and ECs in a fish-helminth system, investigating the potential effects of enteric neuromodulators on gut mucus secretion/discharge.
METHODS
A modified dual immunohisto- and histochemical staining technique was applied on intestinal sections from both infected and uninfected fish. Sections were incubated in antisera to a range of neuromodulators (i.e. leu-enkephalin, met-enkephalin, galanin and serotonin) and the glycoconjugate histochemistry of the mucous cells was determined using a subsequent alcian blue - periodic acid Schiff staining step. Dual fluorescent staining on sections prepared for confocal laser scanning microscopy and transmission electron microscopy were also used to document the relationship between ECs and mucous cells.
RESULTS
From a total of 26 specimens of Squalius cephalus sampled from the River Paglia, 16 (i.e. 62 %) specimens were found to harbour an infection of the acanthocephalan Pomphorhynchus laevis (average intensity of infection 9.2 ± 0.8 parasites host(-1), mean ± standard error). When acanthocephalans were present, the numbers of mucous cells (most notably those containing acidic or mixed glycoconjugates) and ECs secreting leu-enkephalin, met-enkephalin, galanin, serotonin were significantly higher than those seen on sections from uninfected fish. The relationship between met-enkephalin-like or serotonin-like ECs and lectin DBA positive mucous cells was demonstrated through a dual fluorescent staining. The presence of tight connections and desmosomes between mucous and ECs in transmission electron micrographs provides further evidence of this intimate relationship.
CONCLUSIONS
The presence of P. laevis induces an increase in the number of enteric ECs that are immunoreactive to leu- and met-enkephalin, galanin, and serotonin anti-sera. The mucous cells hyperplasia and enhanced mucus secretion in the helminth-infected intestines could be elicited by the increase in the number of ECs which release these regulatory substances.
Topics: Acanthocephala; Animals; Cyprinidae; Enkephalin, Leucine; Enkephalin, Methionine; Fish Diseases; Helminthiasis, Animal; Intestinal Mucosa; Neurotransmitter Agents; Serotonin
PubMed: 26152567
DOI: 10.1186/s13071-015-0970-7 -
Organic & Biomolecular Chemistry Jun 2019Numerous studies demonstrate the promise of opioid peptides as analgesics, but poor oral bioavailability has limited their therapeutic development. This study sought to...
Numerous studies demonstrate the promise of opioid peptides as analgesics, but poor oral bioavailability has limited their therapeutic development. This study sought to increase the oral bioavailability of opioid peptides by cyclization, using Hantzsch-based macrocyclization strategies to produce two new series of cyclized DAMGO and Leu/Met-enkephalin analogs. Opioid receptor affinity and selectivity for compounds in each series were assessed in vitro with radioligand competition binding assays. Compounds demonstrated modest affinity but high selectivity for the mu, delta, and kappa opioid receptors (MOR, DOR and KOR), while selectivity for mu opioid receptors varied by structure. Antinociceptive activity of each compound was initially screened in vivo following intracerebroventricular (i.c.v.) administration and testing in the mouse 55 °C warm-water tail-withdrawal test. The four most active compounds were then evaluated for dose- and time-dependent antinociception, and opioid receptor selectivity in vivo. Cyclic compounds 1924-10, 1936-1, 1936-7, and 1936-9 produced robust and long- lasting antinociception with ED values ranging from 0.32-0.75 nmol following i.c.v. administration mediated primarily by mu- and delta-opioid receptor agonism. Compounds 1924-10, 1936-1 and 1936-9 further displayed significant time-dependent antinociception after oral (10 mg kg, p.o.) administration. A higher oral dose (30 mg kg. p.o.) of all four cyclic peptides also reduced centrally-mediated respiration, suggesting successful penitration into the CNS. Overall, these data suggest cyclized opioid peptides synthesized by a Hantzsch-based macrocyclization strategy can retain opioid agonist activity to produce potent antinociception in vivo while conveying improved bioavailability following oral administration.
Topics: Analgesics, Opioid; Animals; Cyclization; Dose-Response Relationship, Drug; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Enkephalin, Methionine; Injections, Intraventricular; Male; Mice; Mice, Inbred C57BL; Molecular Conformation; Receptors, Opioid; Respiratory Rate; Thiazoles
PubMed: 31094391
DOI: 10.1039/c9ob00882a -
Japanese Journal of Pharmacology Dec 1986Effects of methionine-enkephalin (ME) and 2-D-alanine-5-methionine-enkephalinamide (DAMEA) microinjected into the hypothalamic supraoptic (SON) and paraventricular (PVN)...
Antidiuretic effects of methionine-enkephalin and 2-D-alanine-5-methionine-enkephalinamide microinjected into the hypothalamic supraoptic and paraventricular nuclei in a water-loaded and ethanol-anesthetized rat.
Effects of methionine-enkephalin (ME) and 2-D-alanine-5-methionine-enkephalinamide (DAMEA) microinjected into the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei, which contain neurons synthesizing and releasing antidiuretic hormone, upon the outflow and the osmotic pressure of urine and the other visceral functions were studied in a rat which was loaded with water and anesthetized with ethanol. These opioid peptides when microinjected into the SON or PVN induced potent antidiuretic effects in dose-dependent and time-dependent manners with no significant effects on the other visceral functions. The approx. ED50 values for DAMEA were 1.3 (in the SON) and 0.7 (in the PVN) nmol, and the values for ME were 110 (in the SON) and 60 (in the PVN) nmol. The antidiuretic effects showed slow onset and long duration, with a minimal urine outflow at approx. 0.5 hr after microinjection and an approx. 2 hr-duration. The effects induced by the opioid peptides were inhibited by pretreatment with naloxone or atropine, without effects of pretreatment with alpha- or beta-adrenoceptor antagonists, suggesting that the antidiuretic effects were mediated through an opioid receptor having low sensitivity to naloxone and also possibly mediated through a muscarinic receptor which was stimulated probably by the ACh released by the opioid peptides.
Topics: Anesthesia; Animals; Atropine; Diuresis; Dose-Response Relationship, Drug; Enkephalin, Methionine; Ethanol; Male; Microinjections; Naloxone; Osmotic Pressure; Paraventricular Hypothalamic Nucleus; Phenoxybenzamine; Rats; Rats, Inbred Strains; Supraoptic Nucleus; Viscera
PubMed: 3807052
DOI: 10.1254/jjp.42.507 -
Eastern Mediterranean Health Journal =... 2007To address the role of the opioid system in the pathogenesis of hepatic encephalopathy (HE) we measured plasma met-enkephalin, beta-endorphin and leu-enkephalin in... (Comparative Study)
Comparative Study
To address the role of the opioid system in the pathogenesis of hepatic encephalopathy (HE) we measured plasma met-enkephalin, beta-endorphin and leu-enkephalin in patients with different grades of HE compared to control subjects and patients with cirrhosis. Plasma met-enkephalin levels were significantly higher in patients with cirrhosis and all grades of HE than controls. Plasma beta-endorphin levels were similar in the 3 groups. Plasma leu-enkephalin levels were significantly higher in HE grades II, III and IV than in controls, patients with cirrhosis and HE grade I patients. Our results support data on the involvement of met-enkephalin and leu-enkephalin in the pathogenesis of HE and provide a rationale for the use of opioid receptor antagonists in the treatment of HE.
Topics: Ammonia; Analysis of Variance; Case-Control Studies; Causality; Egypt; Enkephalin, Leucine; Enkephalin, Methionine; Hepatic Encephalopathy; Hepatitis B; Hepatitis C; Hepatitis, Autoimmune; Humans; Liver Cirrhosis; Metabolic Clearance Rate; Naltrexone; Narcotic Antagonists; Neurotransmitter Agents; Radioimmunoassay; Severity of Illness Index; Statistics, Nonparametric; beta-Endorphin
PubMed: 17684846
DOI: No ID Found -
The Journal of Experimental Medicine May 1990In this communication we show that T cell locomotion is affected by direct interaction with neurohormones. Opioid peptides, including beta-END, MET-ENK, LEU-ENK, and...
In this communication we show that T cell locomotion is affected by direct interaction with neurohormones. Opioid peptides, including beta-END, MET-ENK, LEU-ENK, and related enkephalin analogues enhanced migration of human peripheral blood T lymphocytes. Activity was dependent on the peptide NH2-terminal sequence, stimulated by enkephalin analogues with specificity for classical delta or mu types of opiate receptor, and inhibited by the opiate receptor antagonist naloxone. Our studies suggest that such neuropeptides stimulate T cell chemotaxis by interaction with sites analogues to classical opiate receptors. We propose that the endogenous opioids beta-END, MET-ENK, and LEU-ENK are potent immunomodulating signals that regulate the trafficking of immune response cells.
Topics: Amino Acid Sequence; Chemotaxis, Leukocyte; Enkephalin, Leucine; Enkephalin, Methionine; Enkephalins; Humans; In Vitro Techniques; Kinetics; Molecular Sequence Data; Structure-Activity Relationship; T-Lymphocytes
PubMed: 2332733
DOI: 10.1084/jem.171.5.1625 -
International Journal of Molecular... May 2019Ghrelin is an endogenous ligand for orphan growth hormone secretagogue receptors. Ghrelin receptors have been found in central nervous system (CNS) areas responsible for...
Effects of Intracerebroventricular and Intra-Arcuate Nucleus Injection of Ghrelin on Pain Behavioral Responses and Met-Enkephalin and β-Endorphin Concentrations in the Periaqueductal Gray Area in Rats.
Ghrelin is an endogenous ligand for orphan growth hormone secretagogue receptors. Ghrelin receptors have been found in central nervous system (CNS) areas responsible for pain modulation and transmission. This study investigated the effects of intracerebroventricular (ICV) and intra-arcuate nucleus (ARC) injection of ghrelin on pain behavioral responses and levels of β-endorphin (β-EP) and met-enkephalin (MENK) in the periaqueductal gray area (PAG) during the formalin test in rats. Thirty-five male rats were studied in five groups. Ghrelin was injected into the left lateral ventricle (ICV, 5 µL) or into the ARC (1 µL). After 15 min, formalin (2.5%) was subcutaneously injected into the left hind paw. Behavioral nociceptive scores were recorded for 60 min. MENK and β-EP were collected by microdialysis in the PAG and determined by high-performance liquid chromatography (HPLC). ICV and ARC injection of ghrelin significantly reduced pain in all phases of the formalin test ( < 0.001). Dialysate concentrations of MENK and β-EP in the PAG increased in all the phases ( < 0.01). In conclusion, the present study shows that the ARC nucleus and the endogenous opioid system are involved in ghrelin-induced pain modulation.
Topics: Animals; Arcuate Nucleus of Hypothalamus; Enkephalin, Methionine; Ghrelin; Injections; Male; Pain; Pain Measurement; Periaqueductal Gray; Rats; beta-Endorphin
PubMed: 31109149
DOI: 10.3390/ijms20102475 -
Japanese Journal of Pharmacology Aug 1989Substance P-like immunoreactivity (SPLI) and methionine-enkephalin-like immunoreactivity (MELI) were determined in salivary glands from rats by radioimmunoassay. In all...
Substance P-like immunoreactivity (SPLI) and methionine-enkephalin-like immunoreactivity (MELI) were determined in salivary glands from rats by radioimmunoassay. In all salivary glands investigated (submandibular gland, sublingual gland and parotid gland), SPLI and MELI were detected. The amount of both peptides is comparable to or relatively higher than those found in any other peripheral tissue. The level of SPLI showed a tendency to increase following chronic treatment with morphine: the enhancement in the submandibular gland and the sublingual gland was especially remarkable. The level of MELI was decreased, particularly in the submandibular gland.
Topics: Animals; Enkephalin, Methionine; In Vitro Techniques; Male; Morphine; Rats; Rats, Inbred Strains; Salivary Glands; Substance P
PubMed: 2476579
DOI: 10.1254/jjp.50.503 -
Proceedings of the National Academy of... May 1986The structures of [Met5]enkephalin (Tyr-Gly-Gly-Phe-Met) and [Leu5]enkephalin (Tyr-Gly-Gly-Phe-Leu) have been determined from single crystal x-ray diffraction data and...
The structures of [Met5]enkephalin (Tyr-Gly-Gly-Phe-Met) and [Leu5]enkephalin (Tyr-Gly-Gly-Phe-Leu) have been determined from single crystal x-ray diffraction data and refined to residuals of 0.100 and 0.092, respectively. The [Met5]enkephalin structure consists of dimers forming antiparallel beta-sheets extending in the monoclinic ac plane with 10.6 water molecules per dimer. The two molecules, related by pseudo two-fold axes, have similar backbone conformations and similar tyrosine and phenylalanine side-chain conformations. Both methionine residues are disordered and the disorder is different in the two independent molecules. Additional hydrogen bonds connect adjacent dimers to form infinite sheets normal to the b axis. The water molecules are found mainly in the interstices between the sheets. [Leu5]Enkephalin crystallizes as a monohydrate that is isomorphous with the [Met5]enkephalin structure with respect to the beta-sheet but different with respect to the tyrosine and phenylalanine side-chain conformations and water content. The peptide chains in both structures are fully extended and more nearly planar than pleated. The planes of the peptide chains in the dimers form an angle of 143.3 degrees with one another in [Met5]enkephalin and 156.0 degrees in [Leu5]enkephalin. This produces a zigzag pattern or pleat in the beta-sheets perpendicular to the direction of the peptide chains and, therefore, perpendicular to the normal beta-sheet pleat. The average repeat distance between Ni and Ni+2 in the peptide chains of both structures is 7.10 A, versus an ideal value of 6.68 A.
Topics: Crystallography; Enkephalin, Leucine; Enkephalin, Methionine; Humans; Hydrogen Bonding; Protein Conformation
PubMed: 3458181
DOI: 10.1073/pnas.83.10.3272 -
Blockade of OGFr delays the onset and reduces the severity of diabetic ocular surface complications.Experimental Biology and Medicine... Mar 2021The opioid growth factor (OGF)-OGF receptor (OGFr) pathway is present in the ocular surface and functions to maintain homeostasis of the epithelium. The OGF-OGFr pathway...
The opioid growth factor (OGF)-OGF receptor (OGFr) pathway is present in the ocular surface and functions to maintain homeostasis of the epithelium. The OGF-OGFr pathway has been reported to be dysregulated in diabetic individuals and animal models, and is reflected in elevations of the inhibitory growth factor, OGF, chemically termed [Met]-enkephalin. Recently, our laboratory reported elevated levels of OGF and OGFr in the serum and corneal epithelium of type 1 diabetic rats, suggesting that dysregulation of the OGF-OGFr axis may lead to dry eye, abnormal corneal surface sensitivity, and delayed re-epithelialization. Blockade of OGF-OGFr pathway using naltrexone, a potent opioid receptor antagonist, reverses dry eye symptoms and restores corneal surface sensitivity in diabetic rats when used as a therapy. Based on the evidence that both OGF and OGFr are elevated in type 1 diabetic rats, this study examined whether systemic or topical naltrexone treatment initiated at the time of induction of hyperglycemia could protect against the development of diabetic ocular surface complications. Diabetic male Sprague-Dawley rats treated systemically or topically with naltrexone had a delayed onset of dry eye and altered corneal surface sensitivity, and an improved healing rate for corneal wounds, that were comparable to non-diabetic rats. Serum levels of OGF were normal for rats receiving systemic naltrexone, and OGF tissue levels were normal for type 1 diabetic rats receiving twice daily naltrexone drops. OGFr levels remained elevated. These data support the role of the OGF-OGFr axis in regulation of ocular surface complications, and suggest that naltrexone therapy may be beneficial for pre-diabetic and early diabetic individuals.
Topics: Animals; Blood Glucose; Body Weight; Cornea; Diabetes Complications; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Enkephalin, Methionine; Eye; Male; Naltrexone; Rats, Sprague-Dawley; Receptors, Opioid; Severity of Illness Index; Time Factors; Rats
PubMed: 33203224
DOI: 10.1177/1535370220972060