Response of colonic motility to dopaminergic stimulation is subverted in rats with nigrostriatal lesion: relevance to gastrointestinal dysfunctions in Parkinson's disease.

BACKGROUND: Constipation is extremely common in patients with Parkinson's disease (PD) and has been described in PD animal models. In this study, we investigated whether a PD-like degeneration of dopaminergic neurons of the substantia nigra can influence peristalsis in colonic segments of rats by impacting on enteric dopaminergic transmission. METHODS: Male, Sprague-Dawley rats received a unilateral injection of neurotoxin 6-hydroxydopamine (6-OHDA), or saline, into the medial-forebrain-bundle. Peristaltic activity was recorded in isolated colonic segments, in baseline conditions and following exposure to combinations of D2 receptor (DRD2) agonist sumanirole and antagonist L-741626. Dopamine levels and DRD2 expression were assessed in the ileum and colon of animals. We also investigated the involvement of the dorsal motor nucleus of the vagus (DMV) - a potential relay station between central dopaminergic denervation and gastrointestinal (GI) dysfunction - by analyzing cytochrome c oxidase activity and FosB/DeltaFosB expression in DMV neurons. KEY RESULTS: We observed profound alterations in the response of colonic segments of 6-OHDA lesioned animals to DRD2 stimulation. In fact, the inhibition of colonic peristalsis elicited by sumanirole in control rats was absent in 6-OHDA-lesioned animals. These animals also showed reduced DRD2 expression in the colon, along with elevation of dopamine levels. No significant changes were detected within the DMV. CONCLUSIONS & INFERENCES: Our results demonstrate that selective lesion of the nigrostriatal dopaminergic pathway subverts the physiological response of the colon to dopaminergic stimulation, opening new perspectives in the comprehension and treatment of GI dysfunctions associated with PD.

Colonic mucosal mediators from patients with irritable bowel syndrome excite enteric cholinergic motor neurons.

BACKGROUND: Mediators released in the mucosal milieu have been suggested to be involved in visceral hypersensitivity and abdominal pain in patients with irritable bowel syndrome (IBS). However, their impact on myenteric neurons remains unsettled. METHODS: Mucosal biopsies were obtained from the descending colon of patients with IBS and controls. Mucosal mast cells were identified immunohistochemically. The impact of spontaneously released mucosal mediators on guinea pig electrically stimulated longitudinal muscle myenteric plexus (LMMP) preparations was assessed in vitro by means of selective receptor antagonists and inhibitors. KEY RESULTS: Patients with IBS showed an increased mast cell count compared with controls. Application of mucosal mediators of IBS to LMMPs potentiated cholinergic twitch contractions, an effect directly correlated with mast cell counts. Enhanced contractions were inhibited by 50.3% with the prostaglandin D2 antagonist BW A868C, by 31.3% and 39% with the TRPV1 antagonists capsazepine and HC-030031, respectively, and by 60.5% with purinergic P2X antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid. Conversely, the serotonin1-4, histamine1-3, tachykinin1-3 receptor blockade, and serine protease inhibition had no significant effect. CONCLUSIONS & INFERENCES: Colonic mucosal mediators from patients with IBS excite myenteric cholinergic motor neurons. These effects were correlated with mast cell counts and mediated by activation of prostanoid receptors, TRPV1, and P2X receptors. These results support the role of mucosal inflammatory mediators and mast cell activation in altered motor function of IBS.

Inhaled ammonium persulphate inhibits non-adrenergic, non-cholinergic relaxations in the guinea pig isolated trachea.

BACKGROUND: Persulphates can act both as irritants and sensitizers in inducing occupational asthma. A dysfunction of nervous control regulating the airway tone has been hypothesized as a mechanism underlying bronchoconstriction in asthma. OBJECTIVES: It was the aim of this study to investigate whether inhaled ammonium persulphate affects the non-adrenergic, non-cholinergic (NANC) inhibitory innervation, the cholinergic nerve-mediated contraction or the muscular response to the spasmogens, carbachol or histamine, in the guinea pig epithelium-free, isolated trachea. METHODS: Male guinea pigs inhaled aerosols containing ammonium persulphate (10 mg/m(3) for 30 min for 5 days during 3 weeks). Control animals inhaled saline aerosol. NANC relaxations to electrical field stimulation at 3 Hz were evaluated in whole tracheal segments as intraluminal pressure changes. Drugs inactivating peptide transmission, nitric oxide synthase, carbon monoxide production by haem oxygenase-2 and soluble guanylyl cyclase were used to assess the involvement of various inhibitory neurotransmitters. Carbachol and histamine cumulative concentration-response curves were obtained. RESULTS: In both groups, nitric oxide and carbon monoxide participated to the same extent as inhibitory neurotransmitters. In exposed animals, the tracheal NANC relaxations were reduced to 45.9 +/- 12.1% (p < 0.01). The cholinergic nerve-mediated contractions to electrical field stimulation and the muscular response to histamine were not modified by ammonium persulphate exposure. The muscular response to carbachol was unaffected up to 1 microM. Conversely, the response to the maximal concentration of carbachol (3 microM) was increased (p < 0.01). CONCLUSION: Ammonium persulphate inhalation at high concentrations impairs the nervous NANC inhibitory control in the guinea pig airways. This may represent a novel mechanism contributing to persulphate-induced asthma.

Functional and neurochemical changes of the gastrointestinal tract in a rodent model of Parkinson's disease.

Patients with Parkinson's disease develop motor disturbances often accompanied by peripheral autonomic dysfunctions, including gastrointestinal disorders, such as dysphagia, gastric stasis and constipation. While the mechanisms subserving enteric autonomic dysfunctions are not clearly understood, they may involve the enteric dopaminergic and/or nitrergic systems. In the present study, we demonstrate that rats with unilateral 6-hydroxydopamine lesion of nigrostriatal dopaminergic neurons develop a marked inhibition of propulsive activity compared to sham-operated controls, as indicated by a 60% reduction of daily fecal output at the 4th week of observation. Immunohistochemical data revealed that 6-hydroxydopamine treatment did not affect the total number of HuC/D-positive myenteric neurons in both the proximal and distal segments of ileum and colon. Conversely, in the distal ileum and proximal colon the number of nitrergic neurons was significantly reduced. These results suggest that a disturbed distal gut transit, reminiscent of constipation in the clinical setting, may occur as a consequence of a reduced propulsive motility, likely due to an impairment of a nitric oxide-mediated descending inhibition during peristalsis.

Effects of esomeprazole on glutathione levels and mitochondrial oxidative phosphorylation in the gastric mucosa of rats treated with indomethacin.

Proton pump inhibitors exert their preventive and healing effects on gastropathy induced by nonsteroidal anti-inflammatory drug (NSAIDs) by a dual action: the antisecretory and the antioxidant effect. The latter was investigated by using esomeprazole against indomethacin-induced gastric mucosa lesions in rats and assessed by a histomorphometric analysis. Treatment by intragastric gavage were 1% methocel as vehicle; esomeprazole 10, 30, or 60 micromol/kg; indomethacin 100 micromol/kg; and esomeprazole 10, 30, or 60 micromol/kg plus indomethacin 100 micromol/kg. The evaluation of glutathione (GSH) levels and respiratory chain complex activities [nicotinamide adenine dinucleotide, reduced (NADH)-ubiquinone oxidoreductase, succinate dehydrogenase, cytochrome C reductase, cytochrome oxidase] was performed in the isolated gastric mucosa. Esomeprazole (10-60 micromol/kg) dose dependently reversed, up to complete recovery, the inhibitory effect of indomethacin on GSH levels (approximately 60% inhibition) and mitochondrial enzyme activities (inhibition ranging from 60% to 75%). Indomethacin-induced mucosal injuries were reduced by esomeprazole. Thus, in addition to inhibiting acid secretion, the gastroprotective effect of esomeprazole can be ascribed to a reduction in gastric oxidative injury.

[Exposure to ammonium persulphate by inhalation: effect on the NANC inhibitory neurotransmitters in the guinea pig trachea]. / Esposizione inalatoria a persolfato d'ammonio: effetto sulle componenti del sistema NANC inibitorio della trachea di cavia.

To evaluate the effect of ammonium persulphate (AP) inhalation on NANC inhibitory (i-NANC) neurotransmitters of guinea pig airways, we exposed eight guinea pigs to AP (1 mg/m3), by aerosol inhalation for 30 minutes daily for three weeks. Control animals inhaled saline aerosol. After the last exposure, the isolated trachea was mounted in an organ bath and electrically stimulated in the presence of hyoscine, piperoxane and propranolol. The i-NANC responses were evaluated as decreases in intraluminal pressure and expressed as area under the curve (AUC, Pa x seconds). The isolated tracheae were treated with a-chymotrypsin, L-NAME, zinc protoporphyrin IX and ODQ, that inhibit the production or action of the single neurotransmitters, like peptides, NO and CO. In the exposed individuals, the NANC relaxations were below 50%, as compared to controls (P < 0.01). NO and CO were the neurotransmitters responsible for all the i-NANC responses, in similar proportions either in exposed individuals or in controls. In conclusion, ammonium persulphate exposure impairs the i-NANC control of airway tone without specifically affecting any neurotransmitter.

Role of galanin receptor 1 in peristaltic activity in the guinea pig ileum.

Galanin effects are mediated by distinct receptors, galanin receptor 1 (GAL-R1), GAL-R2 and GAL-R3. Here, we analyzed 1) the role of GAL-R1 in cholinergic transmission and peristalsis in the guinea-pig ileum using longitudinal muscle-myenteric plexus preparations and intact segments of the ileum in organ bath, and 2) the distribution of GAL-R1 immunoreactivity in the myenteric plexus with immunohistochemistry and confocal microscopy. Galanin inhibited electrically stimulated contractions of longitudinal muscle-myenteric plexus preparations with a biphasic curve. Desensitization with 1 microM galanin suppressed the high potency phase of the curve, whereas the GAL-R1 antagonist, RWJ-57408 (1 microM), inhibited the low potency phase. Galanin (3 microM) reduced the longitudinal muscle contraction and the peak pressure, and decreased the compliance of the circular muscle. All these effects were antagonized by RWJ-57408 (1 or 10 microM). RWJ-57408 (10 microM) per se did not affect peristalsis parameters in normal conditions, nor when peristalsis efficiency was reduced by partial nicotinic transmission blockade with hexamethonium. In the myenteric plexus, GAL-R1 immunoreactivity was localized to neurons and to fibers projecting within the plexus and to the muscle. GAL-R1 was expressed mostly by cholinergic neurons and by some neurons containing vasoactive intestinal polypeptide or nitric oxide synthase. This study indicates that galanin inhibits cholinergic transmission to the longitudinal muscle via two separate receptors; GAL-R1 mediates the low potency phase. The reduced peristalsis efficiency could be explained by inhibition of the cholinergic drive, whereas the decreased compliance is probably due to inhibition of descending neurons and/or to the activation of an excitatory muscular receptor. Endogenous galanin does not appear to affect neuronal pathways subserving peristalsis in physiologic conditions via GAL-R1.

5-HT4 receptors contribute to the motor stimulating effect of levosulpiride in the guinea-pig gastrointestinal tract.

BACKGROUND: The dopamine D2 receptor antagonist levosulpiride is a substituted benzamide derivative, whose gastrokinetic properties are exploited clinically for the management of functional dyspepsia. However, for other benzamide derivatives, such as cisapride and mosapride, agonism towards serotonin 5-HT4 receptors is considered the main mechanism leading to gastrointestinal prokinesia. AIMS: To assess whether levosulpiride is able to activate 5-HT4 receptors in the guinea-pig isolated gastrointestinal tract. MATERIALS AND METHODS: Circular muscle strips from gastric antrum, and colonic longitudinal muscle strips were used to detect electrically stimulated neurogenic contractions. The effect of levosulpiride was assessed in the absence and presence of GR125487, a selective 5-HT4 receptor antagonist. Furthermore, potential interaction of levosulpiride with 5-HT3 receptors and tissue cholinesterases was assessed in unstimulated ileal longitudinal muscle-myenteric plexus preparations. RESULTS: Antral and colonic strip contractions were cholinergic/tachykinergic in nature. Micromolar concentrations of levosulpiride potentiated submaximal responses, through a mechanism competitively antagonized by GR125487 (pKB=9.4). In LMMPs, levosulpiride slightly affected contractions caused by the 5-HT, receptor agonist 2-methyl-5-HT, and had no effect on contractions to exogenous acetylcholine. CONCLUSIONS: Our results indicate that levosulpiride acts as a moderate agonist at the 5-HT4 receptor. This property, together with antagonism at D2 receptors, may contribute to its gastrointestinal prokinetic effect.

[A case of pseudophlebitis of the great saphenous vein: focal nodular myositis of the gracilis muscle]. / A propos d'un cas de pseudophlébite de la grande veine saphène: une myosite nodulaire focale du muscle gracilis.

A case of focal myositis in a healthy 68-year-old woman is described. The patient was admitted for evaluation of a painful soft-tissue mass localised on the medial side of the left thigh, initially misdiagnosed as thrombophlebitis of the v. saphena magna. Laboratory data were normal, in particular sedimentation rate and muscle enzyme levels. After exclusion of venous thrombosis, the mass localised in the left m. gracilis was surgically removed. Histologic examination of the biopsy specimen showed muscle cell necrosis and severe inflammation, with lymphocytic infiltration leading to the diagnosis of focal myositis. This is a rare benign inflammatory pseudotumour of skeletal muscle. The aetiology and pathogenesis of the disease remain unclear. It is most commonly seen in the lower extremities and may mimic thrombophlebitis or soft-tissue neoplasm. Ultrasound and magnetic-resonance scans are helpful, but definitive diagnosis is obtained only by histology. Because recurrent lesions in other skeletal muscles are possible, and a third of patients develop polymyositis, a follow-up of several years is recommended.

Mycotic aneurysms of the aorta caused by infection with Pasteurella multocida.

We evaluated a patient for mycotic aneurysms caused by Pasteurella multocida. We treated Pasteurella aortitis medically with ciprofloxacin, and the patient has had long-term survival.

Chick optic lobe contains a developmentally regulated alpha2alpha5beta2 nicotinic receptor subtype.

The most widely expressed neuronal nicotinic acetylcholine receptor subtype in chick brain is that containing the alpha4 and beta2 subunits. However, immunoprecipitation and localization studies have shown that some brain areas also contain the alpha2 and/or alpha5 subunits, whose role in the definition of receptor properties is still intriguing. Using subunit-specific polyclonal antibodies, we found that the optic lobe is the chick central nervous system region that expresses the highest level of alpha2-containing receptors. Immunoprecipitation studies of these immunopurified alpha2-containing receptors labeled with the nicotinic agonist [(3)H]epibatidine showed that almost all of them contained the beta2 subunit and that more than 66% contained the alpha5 subunit. Western blot analyses of the purified receptors confirmed the presence of the alpha2, alpha5, and beta2 subunits and the absence of the alpha3, alpha4, alpha6, alpha7, alpha8, beta3, and beta4 subunits. The alpha2-containing receptors are developmentally regulated: their expression increases 25 times from embryonic day 7 to posthatching day 1 in the optic lobe, compared with an increase of only 5-fold in the forebrain. The alpha2-containing optic lobe receptors bind [(3)H]epibatidine (K(d) = 29 pM) and a number of other nicotinic agonists with very high affinity and have a pharmacological profile very similar to that of the alpha4beta2 subtype. They form functional cationic channels when reconstituted in lipid bilayers, with pharmacological and biophysical properties different from those of the alpha4beta2 subtype. These channels are activated by nicotinic agonists in a dose-dependent manner and are blocked by the nicotinic antagonist d-tubocurarine.

[Acute necrotizing hepatitis: an unusual side effect of oral anticoagulants]. / Akute nekrotisierende Hepatitis: eine ungewöhnliche Nebenwirkung oraler Antikoagulantien.

We report the case of a severe relapsing phenprocoumon-induced hepatitis. The first episode of hepatitis was thought to be caused by another drug (Verapamil). The anticoagulation with Phenprocoumon was therefore continued after healing of liver inflammation. The relapse typically developed after a shorter exposition-time supporting the hypothesis of an allergic etiology. Fortunately we didn't find any cross-reaction between Phenprocoumon and Acenocoumarol. The patient could thus be anticoagulated orally without complications. If long term anticoagulation is absolutely essential, it is reasonable to prescribe a different Coumarin-derivate. In the case of a cross-reaction, the therapy should be continued with low-molecular weight heparin.

Role of agonist-dependent receptor internalization in the regulation of mu opioid receptors.

Organotypic cultures and ileal neuromuscular preparations were used to determine (i) whether endogenous release of opioids by electrical stimulation induces mu receptor endocytosis, and (ii) whether and under which conditions ligand-induced mu receptor endocytosis influences the responsiveness of neurons expressing native mu receptors. In longitudinal muscle-myenteric plexus preparations, electrical stimulation at 20 Hz induced a prominent endocytosis of mu receptors in enteric neurons, indicating endogenous release of opioids. A similar massive endocytosis was triggered by exogenous application of the mu receptor agonist, [D-Ala(2),MePhe(4), Gly-ol(5)] enkephalin, whereas exogenous application of morphine was ineffective. [D-Ala(2),MePhe(4),Gly-ol(5)] enkephalin and morphine induced a concentration-dependent inhibition of neurogenic cholinergic twitch contractions to electrical stimulation at 0.1 Hz. beta-Chlornaltrexamine shifted to the right the inhibitory curve of both agonists with a concentration-dependent reduction of the maximum agonist response, which is consistent with the existence of spare mu opioid receptors. Under these conditions, the induction of mu receptor endocytosis by exogenously applied [D-Ala(2), MePhe(4),Gly-ol(5)] enkephalin diminished the inhibitory effect of this agonist on twitch contractions and tritiated acetylcholine release. In contrast, there was no reduction of the inhibitory effect of morphine, which failed to induce mu receptor endocytosis, on neurogenic cholinergic response. These results provide the first evidence for the occurrence of mu receptor endocytosis in neurons by endogenously released opioids and show that agonist-dependent mu receptor endocytosis could serve as a mechanism to regulate mu opioid receptor responsiveness to ligand stimulation when the opioid receptor reserve is reduced.

[An "exotic" lymphadenopathy: Kikuchi-Fujimotor histiocytic necrotizing lymphadenitis. Case report and discussion]. / Eine "exotische" Lymphadenopathie: Die histiozytäre nekrotisierende Lymphadenitis Kikuchi-Fujimoto. Fallbericht und Diskussion.

The case of a 25 year old women with isolated inguinal lymphadenopathy and persistent fever caused by necrotizing inguinal lymphadenitis Kikuchi-Fujimoto is reported. Diagnostic and differential diagnostic aspects of this self-limited disorder with unclear pathogenesis are discussed.

beta3 subunit is present in different nicotinic receptor subtypes in chick retina.

Although the neuronal nicotinic beta3 subunit was cloned several years ago, it has only recently been shown to form heteromeric channels when associated with other nicotinic subunits, and very little information is available concerning its assembly in the native nicotinic receptors of the nervous system. Using subunit-specific antibodies and immunoprecipitation experiments, we have identified the retina as being the chick central nervous system (CNS) area that expresses the highest level of the beta3 subunit. Sequential immunopurification experiments showed that there are at least two populations of beta3-containing receptors in chick retina: in one, the beta3 subunit is associated with the alpha6 and beta4 subunits; in the other more heterogeneous population, the beta3 subunit is associated with the alpha2, alpha3, alpha4, beta2 and beta4 subunits. Both of these receptor populations bind [3H]epibatidine and a number of nicotinic receptor agonists with high affinity (nM) and nicotinic receptor antagonists with a lower affinity (microM). The greatest pharmacological difference between the two populations is the affinity for the alpha-conotoxin MII, which inhibits binding to alpha6-containing receptors and not that to beta3-containing receptors. We also searched for the presence of the beta3 subunit associated with the alpha-bungarotoxin binding subunits alpha7 and/or alpha8 in retina and chick brain. Immunoprecipitation studies using anti-beta3 antibodies did not detect any specific alpha-bungarotoxin labeled receptors, thus, indicating that the beta3 subunit is not present in the alpha-bungarotoxin receptors of these areas.

Prejunctional muscarinic inhibitory control of acetylcholine release in the human isolated detrusor: involvement of the M4 receptor subtype.

1. Experiments were carried out in human detrusor strips to characterize muscarinic receptor subtypes involved in the prejunctional regulation of acetylcholine (ACh) release from cholinergic nerve terminals, and in the postjunctional smooth muscle contractile response. 2. In detrusor strips preincubated with [3H]-choline, electrical field stimulation (600 pulses) delivered in six trains at 10 Hz produced a tritium outflow and a contractile response. In the presence of 10 microM paraoxon (to prevent ACh degradation) the tritium outflow was characterized by HPLC analysis as [3H]-ACh (76%) and [3H]-choline (24%). 3. Electrically-evoked [3H]-ACh release was abolished by tetrodotoxin (TTX: 300 nM) and unaffected by hexamethonium (10 microM), indicating a postganglionic event. It was reduced by physostigmine (100 nM) and the muscarinic receptor agonist, muscarone (10 nM-1 microM), and enhanced by atropine (0.1-100 nM). These findings indicate the presence of a muscarinic negative feedback mechanism controlling ACh release. 4. The effects of various subtype-preferring muscarinic receptor antagonists were evaluated on [3H]-ACh release and muscle contraction. The rank potency (-log EC50) orders at pre- and postjunctional level were: atropine > or = 4-diphenyl-acetoxy-N-piperidine (4-DAMP) > mamba toxin 3 (MT-3) > tripitramine > para-fluorohexahydrosiladiphenidol (pF-HHSiD) > or = methoctramine > or = pirenzepine > tripinamide, and atropine > or = 4-DAMP > pF-HHSiD >> pirenzepine = tripitramine > tripinamide > methoctramine >> MT-3, respectively. 5. The comparison of pre- and post-junctional potencies and the relationship analysis with the affinity constants at human cloned muscarinic receptor subtypes indicates that the muscarinic autoreceptor inhibiting ACh release in human detrusor is an M4 receptor, while the receptor involved in muscular contraction belongs to the M3 subtype.

Antibodies against neuronal nicotinic receptor subtypes in neurological disorders.

Patients with myasthenia gravis (MG) have antibodies to the muscle nicotinic acetylcholine receptor (mAChR) which are responsible for their muscle weakness: but some patients with MG and other neuroimmunological disorders have autonomic symptoms. We characterised the neuronal forms of AChRs (nAChRs) into two neuroblastoma cell lines and developed immunoprecipitation assays to test for antibodies to the alpha7- and alpha3-containing nAChR subtypes, present in the autonomic ganglia. We then tested 70 sera samples from MG patients, 38 from subjects with other neurological diseases, and 30 from healthy individuals, for antibodies to these two forms of neuronal AChR subtypes. We used the alpha7 subtype extracted from the human neuroblastoma IMR32 cell line labeled with 125IalphaBungarotoxin (alphaBgtx), and the alpha3-containing subtype extracted from the human neuroblastoma SY5Y cell line labeled with 3H-Epibatidine (Epi). Nine subjects (five MG, one GBS, one CIPD and two LEMS) were positive for the alpha7 subtype; and four for the alpha3-containing subtype (two MG patients, one LEMS and the same GBS patient). None of the MG patients with undetectable levels of antibodies against muscle AChR were positive. The patients with serum antibodies to alpha7 or alpha3-containing neuronal AChRs showed a range of clinical features including autonomic symptoms and thymoma in two MG patients. These results indicate that patients with MG and other immune-mediated disorders can have antibodies to neuronal AChRs, and that these may contribute to the clinical characteristics of the diseases.

Functional alpha6-containing nicotinic receptors are present in chick retina.

Despite the fact that the neuronal chick alpha6 subunit was first cloned several years ago and recently has been shown to form acetylcholine (ACh)-activated channels in heterologous systems, no information is yet available concerning the structure and function of the alpha6-containing nicotinic receptors in neuronal tissues. Using subunit-specific antibodies directed against two different epitopes of the chick alpha6 subunit, we performed immunoprecipitation experiments on immunopurified alpha6-containing receptors radiolabeled with the nicotinic agonist [3H]epibatidine (Epi): almost all of the alpha6 receptors contained the beta4 subunit, 51% the beta3 subunit, 42% the alpha3 subunit, and 7.5% the beta2 subunit. Western blot analyses of the purified receptors confirmed the presence of the alpha3, beta3, beta2, and beta4 subunits, and the absence of the alpha4, alpha5, and alpha7 subunits. The alpha6-containing receptors bind [3H]Epi (Kd = 35 pM) and a number of other nicotinic agonists with very high affinity, the rank order being Epi >> cytisine > nicotine > 1, 1-dimethyl-4-phenylpiperazinium > acetylcholine > carbamylcholine. The alpha6 receptors also have a distinct antagonist pharmacological profile with a rank order of potency of alpha-conotoxin MII > methyllycaconitine > dihydro-beta-erythroydine > MG624 > d-tubocurarine > decamethonium > hexamethonium. When reconstituted in lipid bilayers, the alpha6-containing receptors form functional cationic channels with a main conductance state of 48 pS. These channels are activated by nicotinic agonists in a dose-dependent manner, and blocked by the nicotinic antagonist d-tubocurarine.

[Recurrent subacute encephalopathy in the framework of idiopathic hypereosinophilic syndrome]. / Subakute rekurrierende Enzephalopathie im Rahmen eines idiopathischen hypereosinophilen Syndroms.

HISTORY: An 81-year-old man, previously good health, suddenly developed confusion and rapidly progressive severe tetraparesis. INVESTIGATIONS: Peripheral blood and bone marrow revealed marked eosinophilia: allergic, parasitic, neoplastic or vasculitic causes were excluded. Magnetic resonance imaging demonstrated multiple lesions in the cortical and subcortical white matter. DIAGNOSIS, TREATMENT AND COURSE: The findings indicated idiopathic hypereosinophilic syndrome involving the central nervous system and treatment with high doses of glucocorticoids was started. After a stormy course almost complete recovery occurred. CONCLUSION: Idiopathic hypereosinophilic syndrome can rarely manifest itself a an isolated severe subacute encephalopathy.

Activation and internalization of the mu-opioid receptor by the newly discovered endogenous agonists, endomorphin-1 and endomorphin-2.

The multiple effects of opiate alkaloids, important therapeutic drugs used for pain control, are mediated by the neuronal miro-opioid receptor. Among the side effects of these drugs is a profound impairment of gastrointestinal transit. Endomorphins are opioid peptides recently isolated from the nervous system, which have high affinity and selectivity for micro-opioid receptors. Since the miro-opioid receptor undergoes ligand-induced receptor endocytosis in an agonist-dependent manner, we compared the ability of endomorphin-1, endomorphin-2 and the micro-opioid receptor peptide agonist, [D-Ala2,MePhe4,Gly-ol5]-enkephalin (DAMGO), to induce receptor endocytosis in cells transfected with epitope-tagged micro-opioid receptor complementary DNA, and in myenteric neurons of the guinea-pig ileum, which naturally express this receptor. Immunohistochemistry with antibodies to the FLAG epitope or to the native receptor showed that the micro-opioid receptor was mainly located at the plasma membrane of unstimulated cells. Endomorphins and DAMGO induced micro-opioid receptor endocytosis into early endosomes, a process that was inhibited by naloxone. Quantification of surface receptors by flow cytometry indicated that endomorphins' and DAMGO stimulated endocytosis with similar time-course and potency. They inhibited with similar potency electrically induced cholinergic contractions in the longitudinal muscle-myenteric plexus preparation through an action antagonized by naloxone. The apparent affinity estimate of naloxone (pA2 approximately 8.4) is consistent with antagonism at the micro-opioid receptor in myenteric neurons. These results indicate that endomorphins directly activate the micro-opioid receptor in neurons, thus supporting the hypothesis that they are ligands mediating opioid actions in the nervous system. Endomorphin-induced micro-opioid receptor activation can be visualized by receptor endocytosis.