RESUMO
Neurolysin oligopeptidase (E.C.3.4.24.16; Nln), a member of the zinc metallopeptidase M3 family, was first identified in rat brain synaptic membranes hydrolyzing neurotensin at the Pro-Tyr peptide bond. The previous development of C57BL6/N mice with suppression of Nln gene expression (Nln-/-), demonstrated the biological relevance of this oligopeptidase for insulin signaling and glucose uptake. Here, several metabolic parameters were investigated in Nln-/- and wild-type C57BL6/N animals (WT; n = 5-8), male and female, fed either a standard (SD) or a hypercaloric diet (HD), for seven weeks. Higher food intake and body mass gain was observed for Nln-/- animals fed HD, compared to both male and female WT control animals fed HD. Leptin gene expression was higher in Nln-/- male and female animals fed HD, compared to WT controls. Both WT and Nln-/- females fed HD showed similar gene expression increase of dipeptidyl peptidase 4 (DPP4), a peptidase related to glucagon-like peptide-1 (GLP-1) metabolism. The present data suggest that Nln participates in the physiological mechanisms related to diet-induced obesity. Further studies will be necessary to better understand the molecular mechanism responsible for the higher body mass gain observed in Nln-/- animals fed HD.
Assuntos
Dieta , Obesidade , Ratos , Camundongos , Animais , Masculino , Feminino , Camundongos Knockout , Obesidade/genética , Obesidade/metabolismo , Dieta/efeitos adversos , Metaloendopeptidases/genéticaRESUMO
INTRODUCTION: Mast cells are involved in not only inducing, but also maintaining neurogenic inflammation and neuropathic pain. In previous work, we have demonstrated that dehydroleucodine, xanthatin and 3-benzyloxymethyl-5H-furan-2-one inhibit rat peritoneal and human LAD2 mast cell degranulation induced by compound 48/80 and calcium ionophore A23187. However, the effect of these molecules on neuropeptide-induced mast cell activation has not been studied so far. OBJECTIVE: The aim of this study was to determine whether dehydroleucodine, xanthatin, and 3-benzyloxymethyl-5H-furan-2-one inhibit neuropeptide-induced mast cell activation. METHODS: This work is based on in vitro simulation of a neurogenic inflammation scenario involving neuropeptides and mast cells, to subsequently analyze potential therapeutic strategies for neuropathic pain. RESULTS: Neuromedin-N did not stimulate mast cell serotonin release but substance P and neurotensin did induce serotonin release from peritoneal mast cells in a dose-dependent manner. Mast cell serotonin release induced by substance P and neurotensin was inhibited by dehydroleucodine and xanthatin, but not by 3-benzyloxymethyl-5H-furan-2-one. The inhibitory potency of dehydroleucodine and xanthatin was higher than that obtained with the reference compounds, ketotifen and sodium chromoglycate, when mast cells were preincubated with dehydroleucodine before substance P incubation, and with dehydroleucodine or xanthatin before neurotensin incubation. CONCLUSIONS: These results are the first strong evidence supporting the hypothesis that dehydroleucodine and xanthatin inhibit substance P- and neurotensin-induced serotonin release from rat peritoneal mast cells. Our findings suggest, additionally, that these α,ß-unsaturated lactones could be of value in future pharmacological research related to inappropriate mast cell activation conditions such as neurogenic inflammation and neuropathic pain.
Assuntos
Lactonas/farmacologia , Mastócitos/efeitos dos fármacos , Inflamação Neurogênica/metabolismo , Neurotensina/farmacologia , Fragmentos de Peptídeos/farmacologia , Serotonina/metabolismo , Substância P/farmacologia , Animais , Células Cultivadas , Mastócitos/metabolismo , Ratos WistarRESUMO
BACKGROUND: Abnormal activity of two enzymes relevant to neurodevelopment, namely nuclear-distribution element-like 1 (Ndel1) and angiotensin I-converting enzyme (ACE), was reported in individuals with schizophrenia; to our knowledge, these oligopeptidases were never measured in bipolar disorder (BD). AIMS: Evaluate the enzyme activity of Ndel1 and ACE in euthymic individuals with BD type 1 which was compare to healthy control (HC) group. METHODS: Ndel1 and ACE activities were assessed in the serum of individuals with BD type 1 according to DSM-IV criteria (nâ¯=â¯70) and a HC group (nâ¯=â¯34). The possible differences between BD type 1 and HC groups were evaluated using Analysis of Covariance (ANCOVA), and the results were adjusted for age, gender and body mass index. RESULTS: We observed a positive correlation between Ndel1 activity and the total YMRS score in BD group (pâ¯=â¯0.030) and a positive correlation between ACE activity and Ham-D score (pâ¯=â¯0.047). ANCOVA analysis showed lower Ndel1 activity in BDs compared to HCs. Interestingly, we did not observe between-groups differences in ACE activity, despite the recognized correlation of ACE activity levels with cognitive functions, also described to be worsened in psychiatric patients. CONCLUSION: Oligopeptidases, especially Ndel1, which has been strongly correlated with neurodevelopment and brain formation, are potentially a good new target in the study of the neurobiology of BD. LIMITATIONS: The relatively small sample size did not permit to examine the cause-effect relationship of clinical dimensions of BD and the enzymatic activity.
Assuntos
Transtorno Bipolar/sangue , Transtorno Bipolar/enzimologia , Proteínas de Transporte/sangue , Peptidil Dipeptidase A/sangue , Adolescente , Adulto , Estudos de Casos e Controles , Manual Diagnóstico e Estatístico de Transtornos Mentais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Silk fibroin (SF) films containing a peptide, neurotensin (NT), stimulated by iontophoresis were developed aiming to modulate the inflammatory process and prevent the growth of microorganisms typical of wounds. NT-loaded SF films composition shows predominance of ß-sheet structures that conferred adequate mechanical properties, transparency, moderate roughness and low swelling index to fibroin films. Infrared spectroscopy and thermal analysis suggested the presence of non-covalent interactions between NT and fibroin. Using the MALDI imaging technique, it was possible to visualize the homogeneous NT distribution throughout the film surface, in addition to its prolonged release for up to 72â¯h. In vitro studies in E. coli liposaccharide-stimulated macrophages showed a significant reduction of interleukins production after NT-loaded film application, whereas NT solution did not reduce them. Bi-laminated NT-loaded fibroin films containing silver electrodes provided a burst release of NT when anodic iontophoresis was applied, enabling a rapid onset of drug action. In addition, anodic iontophoresis presented a bacteriostatic effect against gram-positive microorganisms. Different iontophoresis densities, from 0.2 to 0.6â¯mA/cm2, did not significantly reduce fibroblast viability after 30â¯min of application. In conclusion, iontophoretic-stimulated peptide-loaded fibroin films could be a promising platform for the treatment of wounds.
Assuntos
Antibacterianos/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Fibroínas/química , Neurotensina/administração & dosagem , Cicatrização/efeitos dos fármacos , Animais , Antibacterianos/química , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Bombyx/química , Sobrevivência Celular , Fibroblastos , Interleucinas/metabolismo , Iontoforese/métodos , Lipopolissacarídeos/farmacologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Testes de Sensibilidade Microbiana , Neurotensina/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
Neurotensin is known to inhibit neuronal Na+ , K+ -ATPase, an effect that is rescued by nitric oxide (NO) synthase inhibition. However, whether the neurotensinergic and the nitrergic systems are independent pathways, or are mechanistically linked, remains unknown. Here, we addressed this issue and found that the administration of low affinity neurotensin receptor (NTS2) antagonist, levocabastine (50 µg/kg, i.p.) inhibited NO synthase (NOS) activity by 74 and 42% after 18 h in synaptosomal and mitochondrial fractions isolated from the Wistar rat cerebral cortex, respectively; these effects disappeared 36 h after levocabastine treatment. Intriguingly, whereas neuronal NOS protein abundance decreased (by 56%) in synaptosomes membranes, it was enhanced (by 86%) in mitochondria 18 h after levocabastine administration. Levocabastine enhanced the respiratory rate of synaptosomes in the presence of oligomycin, but it failed to alter the spare respiratory capacity; furthermore, the mitochondrial respiratory chain (MRC) complexes I-IV activities were severely diminished by levocabastine administration. The inhibition of NOS and MRC complexes activities were also observed after incubation of synaptosomes and mitochondria with levocabastine (1 µM) in vitro. These data indicate that the NTS2 antagonist levocabastine regulates NOS expression and activity at the synapse, suggesting an interrelationship between the neurotensinergic and the nitrergic systems. However, the bioenergetics effects of NTS2 activity inhibition are likely to be independent from the regulation of NO synthesis.
Assuntos
Encéfalo/efeitos dos fármacos , Antagonistas não Sedativos dos Receptores H1 da Histamina/farmacologia , Mitocôndrias/efeitos dos fármacos , Óxido Nítrico/biossíntese , Piperidinas/farmacologia , Animais , Encéfalo/metabolismo , Masculino , Óxido Nítrico Sintase/metabolismo , Ratos , Ratos Wistar , Receptores de Neurotensina/antagonistas & inibidoresRESUMO
Evidences indicate the relationship between neurotensinergic and dopaminergic systems. Neurotensin inhibits synaptosomal membrane Na+, K+-ATPase activity, an effect blocked by SR 48692, antagonist for high affinity neurotensin receptor (NTS1) type. Assays of high affinity [3H]-ouabain binding (to analyze K+ site of Na+, K+-ATPase) show that in vitro addition of neurotensin decreases binding. Herein potential interaction between NTS1 receptor, dopaminergic D2 receptor and Na+, K+-ATPase was studied. To test the involvement of dopaminergic D2 receptors in [3H]-ouabain binding inhibition by neurotensin, Wistar rats were administered i.p.with antipsychotic drugs haloperidol (2mg/kg) and clozapine (3, 10 and 30mg/kg). Animals were sacrificed 18h later, cerebral cortices harvested, membrane fractions prepared and high affinity [3H]-ouabain binding assayed in the absence or presence of neurotensin at a 10 micromolar concentration. No differences versus controls for basal binding or for binding inhibition by neurotensin were recorded, except after 10mg/kg clozapine. Rats were administered with neurotensin (3, 10y 30µg, i.c.v.) and 60min later, animals were sacrificed, cerebral cortices harvested and processed to obtain membrane fractions for high affinity [3H]-ouabain binding assays. Results showed a slight but statistically significant decrease in binding with the 30µg neurotensin dose. To analyze the interaction between dopaminergic D2 and NTS1 receptors, [3H]-neurotensin binding to cortical membranes from rats injected with haloperidol (2mg/kg, i.p.) or clozapine (10mg/kg) was assayed. Saturation curves and Scatchard transformation showed that the only statistically significant change occurred in Bmax after haloperidol administration. Hill number was close to the unit in all cases. Results indicated that typical and atypical antipsychotic drugs differentially modulate the interaction between neurotensin and Na+, K+-ATPase. At the same time, support the notion of an interaction among dopaminergic and neurotensinergic systems and Na+, K+-ATPase at central synapses.
Assuntos
Córtex Cerebral/efeitos dos fármacos , Receptores de Dopamina D2/metabolismo , Receptores de Neurotensina/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Córtex Cerebral/metabolismo , Clozapina/administração & dosagem , Dopamina/metabolismo , Haloperidol/administração & dosagem , Neurotensina/química , Neurotensina/metabolismo , Ouabaína/química , Ouabaína/metabolismo , Ligação Proteica/efeitos dos fármacos , Pirazóis/administração & dosagem , Quinolinas/administração & dosagem , Ratos , Sinaptossomos/efeitos dos fármacos , Sinaptossomos/metabolismoRESUMO
The aim of the present article is to review experimental evidence which suggest joint involvement of both the dopaminergic and neurotensinergic systems in stress conditions. At present, the concept of stress refers to an environmental demand exceeding the normal regulatory ability of an organism, particularly during unpredictable and uncontrollable situations. Chronic stress yields devastating effects including cognitive and working memory dysfunctions, for which neurotransmission mediated by the catecholamines dopamine and noradrenaline is crucial. Catecholamine synthesis depends on the rate-limiting enzyme, tyrosine hydroxylase, whose expression is associated with working memory and the response to chronic stress. Neurotensin is a tridecapeptide widely distributed in the nervous system, at both central and peripheral levels, which behaves as a neurotransmitter or neuromodulator. It mediates diverse biological actions including reward, locomotion, pain modulation and stress. Neurotensin and its high affinity NTS1 receptor are densely localized in areas that process emotion (amygdala nucleus), cognition (such as hippocampal nuclei and cortical areas) and the response to stress (hypothalamic nucleus). Experimental evidence indicates a crosstalk between the dopaminergic and the neurotensinergic systems either from an anatomical or a biochemical point of view. It is suggested that a concomitant alteration of dopaminergic and neurotensinergic systems takes place in diverse stress conditions.
Assuntos
Dopamina/metabolismo , Neurotensina/metabolismo , Estresse Fisiológico , Animais , HumanosRESUMO
Neurotensin behaves as a neuromodulator or as a neurotransmitter interacting with NTS1 and NTS2 receptors. Neurotensin in vitro inhibits synaptosomal membrane Na(+), K(+)-ATPase activity. This effect is prevented by administration of SR 48692 (antagonist for NTS1 receptor). The administration of levocabastine (antagonist for NTS2 receptor) does not prevent Na(+), K(+)-ATPase inhibition by neurotensin when the enzyme is assayed with ATP as substrate. Herein levocabastine effect on Na(+), K(+)-ATPase K(+) site was explored. For this purpose, levocabastine was administered to rats and K(+)-p-nitrophenylphosphatase (K(+)-p-NPPase) activity in synaptosomal membranes and [(3)H]-ouabain binding to cerebral cortex membranes were assayed in the absence (basal) and in the presence of neurotensin. Male Wistar rats were administered with levocabastine (50 µg/kg, i.p., 30 min) or the vehicle (saline solution). Synaptosomal membranes were obtained from cerebral cortex by differential and gradient centrifugation. The activity of K(+)-p-NPPase was determined in media laking or containing ATP plus NaCl. In such phosphorylating condition enzyme behaviour resembles that observed when ATP hydrolyses is recorded. In the absence of ATP plus NaCl, K(+)-p-NPPase activity was similar for levocabastine or vehicle injected (roughly 11 µmole hydrolyzed substrate per mg protein per hour). Such value remained unaltered by the presence of 3.5 × 10(-6) M neurotensin. In the phosphorylating medium, neurotensin decreased (32 %) the enzyme activity in membranes obtained from rats injected with the vehicle but failed to alter those obtained from rats injected with levocabastine. Levocabastine administration enhanced (50 %) basal [(3)H]-ouabain binding to cerebral cortex membranes but failed to modify neurotensin inhibitory effect on this ligand binding. It is concluded that NTS2 receptor blockade modifies the properties of neuronal Na(+), K(+)-ATPase and that neurotensin effect on Na(+), K(+)-ATPase involves NTS1 receptor and -at least partially- NTS2 receptor.
Assuntos
Piperidinas/farmacologia , Receptores de Neurotensina/antagonistas & inibidores , Receptores de Neurotensina/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Masculino , Ouabaína/metabolismo , Ouabaína/farmacologia , Ligação Proteica/fisiologia , Ratos , Ratos WistarRESUMO
La fisiología gástrica constituye una compleja y dinámica interacción entre estructuras anatómicas, sus secreciones, el ambiente circundante y los factores exígenos aportados por el individuo. Este trabajo pretende hacer una breve revisión actualizada sobre fisiología de la secreción y la motilidad gástricas. Se expondrá la función de las principales células de la mucosa gástrica, sus secreciones y aquellas sustancias, hormonas y neurotransmisores que las estimulan, modulan o inhiben, haciendo especial énfasis en los mecanismos de prducción del acido gástrico. Además, se tratar específicamente el tema de la mortalidad gástrica con idéntica metodología...