RESUMEN
In 2002 the Gard was subjected to exceptional flooding, as much by their size as by the number of affected community victims, more than the Nimes floods in October 1988. No community was spared and more than 800 families had to be rapidly re-located. As the medical bibliography of the impact of the floods on respiratory heath was not conclusive we have proposed to the CHU of Nimes a hospital clinical research project undertaken by the members of RNSA, the Institute of Public Health of Brussels and the European Centre for Medical Bioclimate Research and Teaching, who have accepted to share their knowledge with the Gard. It seems to us to be indispensable, considering the certifications made by the professionals on the health on the department, to validate the study methods for the evaluation of the health impact of the floods, with regard to the development of moulds in the environment, so as to recognise the risk to health, in the very special circumstances, and so allow the mobilisabion of useful resources more rapidly than previously. The new floods to which the department was subjected in December 2003 made us regret that we had not developed this project more quickly.
Asunto(s)
Desastres , Encuestas Epidemiológicas , Enfermedades Respiratorias/etiología , Academias e Institutos , Contaminación del Aire Interior , Conducta Cooperativa , Exposición a Riesgos Ambientales , Francia/epidemiología , Hongos/fisiología , Humanos , Humedad , Hipersensibilidad Respiratoria/epidemiología , Hipersensibilidad Respiratoria/etiología , Enfermedades Respiratorias/epidemiología , Estudios Retrospectivos , Esporas FúngicasRESUMEN
PURPOSE: To examine whether magnetic fields (MF) affect N-acetyltransferase (NAT) and hydroxy-indole-O-methyltransferase (HIOMT) activity directly or exert their effect through a cellular pathway that indirectly regulates the activity of these enzymes and melatonin release. MATERIALS AND METHODS: The pineal glands from Wistar rats were isolated at 10:00 h and exposed to MF (50 Hz, 1 mT) for 4 h in vitro, with or without 1 micro M norepinephrine. An additional group of pineals was exposed to MF 30 min before norepinephrine addition. The direct effect of MF on the activity of the enzymes was studied in sonicated glands exposed to MF. NAT activity, HIOMT activity and melatonin release were determined. RESULTS: In pineal glands isolated in the morning, 4-h in vitro exposure did not affect the basal release of melatonin from the pineal gland as well as the basal NAT and HIOMT activities. Pineal gland exposure to MF 30 min before norepinephrine addition significantly (p<0.05) increased NAT activity, HIOMT activity and melatonin release (p<0.05). These effects were not observed in pineals co-treated with MF and norepinephrine or in sonicated glands exposed to MF. CONCLUSIONS: The results suggest that in pineals isolated in the morning, 4-h MF exposure changes melatonin release by affecting the signal transduction pathway leading from the norepinephrine receptor to NAT and HIOMT and not via a direct effect at the enzyme levels.
Asunto(s)
Acetilserotonina O-Metiltransferasa/biosíntesis , Arilamina N-Acetiltransferasa/biosíntesis , Campos Electromagnéticos , Melatonina/metabolismo , Animales , Masculino , Melatonina/sangre , Norepinefrina/farmacología , Glándula Pineal/enzimología , Glándula Pineal/metabolismo , Radioinmunoensayo , Ratas , Ratas Wistar , Transducción de Señal , Factores de TiempoRESUMEN
The Internet SPRING site has been created by five pollen european nets in relation with the spanish telephony firm: SADIEL. The aim of this project is to propose different services for persons concerned by pollen allergy (patients, scientists, pharmaceutical firms...) and to provide forecasts across Europe. The project validation was done during four months, comparing forecasts, announced on the site, with the real data obtained weekly by the analysts. Each country was divided in several zones and each zone controlled by three or four analysis sites. For France, six zones were identified and controlled. Others european nets want to joint now the SPRING project and everybody concerned by pollens could be informed daily (by phone or wap) of the pollen concentrations and the allergenic risk in each part of Europe.
Asunto(s)
Monitoreo del Ambiente , Internet , Polen , Rinitis Alérgica Estacional , Teléfono Celular , Monitoreo del Ambiente/estadística & datos numéricos , Predicción , Francia , Difusión de la Información , EspañaRESUMEN
Pollens of Poaceae remain the major concern of all those which are concerned with the allergies. The grasses in question are ubiquitaires, but the variations due to climate and the relief influence much on the statements. Our country, from its geographical richness and by the number of sites of collecting, allows an interesting synthesis and a better comprehension of the metabolism of the plant. We are interesting here in the sites of Nimes, Aixen-Provence, Gap and Briançon, included in the National Network. Moreover, one sensor placed temporarily at 2,000 meters of altitude, meadows of Briançon, gives one further information.
Asunto(s)
Poaceae , Polen , Altitud , Monitoreo del Ambiente/estadística & datos numéricos , Monitoreo Epidemiológico , Francia/epidemiología , Rinitis Alérgica Estacional/epidemiologíaRESUMEN
It was previously suggested that exposure to magnetic fields (MFs) could generate dysfunction of the CNS. The physiological manifestations described lead us to postulate that these symptoms might be related to a dysfunction of the serotonergic system and particularly of the 5-HT(1B) receptors. Accordingly, MFs could modify the conformation of these receptors altering their functional activities. In rat brain membrane preparations, we showed that the affinity constant of 5-HT for 5-HT(1B) receptors was modified under exposure to MFs since K(d) varied from 4.7+/-0.5 to 12+/-3 nM in control and exposed (2.5 mT) membranes, respectively. This effect was intensity-dependent (the sigmoidal dose-response curve was characterized by an EI(50) of 662+/-69 microT and a maximal increase of 321+/-13% of the control K(d)), reversible, temperature-dependent and specific to the 5-HT(1B) receptors. Similar results have also been obtained with the human 5-HT(1B) receptors. In parallel assays, the functional activity of 5-HT(1B) receptors was investigated. The capacity of a 5-HT(1B) agonist to inhibit the cAMP production was reduced by 37% (53.7+/-3.5% to 33.7+/-4.1%) following exposure to MFs and the cellular activity of the receptors (inhibition of the synaptosomal release of 5-HT) also was markedly reduced (66.5+/-3.2% to 28.5+/-4.2%). These results clearly show that in in vitro assays, MF specifically interacts with 5-HT(1B) receptors, inducing structural changes of the protein that result in a functional desensitization of the receptors. Thus, in vivo, exposure to MFs may lead to physiological changes, particularly in the field of mood disorders where the 5-HT system is strongly involved.
Asunto(s)
Corteza Cerebral/efectos de la radiación , Campos Electromagnéticos/efectos adversos , Receptores de Serotonina/efectos de la radiación , Animales , Unión Competitiva/efectos de la radiación , Células CHO , Membrana Celular/metabolismo , Membrana Celular/efectos de la radiación , Corteza Cerebral/metabolismo , Colforsina/farmacología , Cricetinae , AMP Cíclico/biosíntesis , AMP Cíclico/efectos de la radiación , Relación Dosis-Respuesta a Droga , Relación Dosis-Respuesta en la Radiación , Guanosina Trifosfato/metabolismo , Guanosina Trifosfato/farmacología , Cobayas , Humanos , Técnicas In Vitro , Ligandos , Conformación Proteica/efectos de los fármacos , Conformación Proteica/efectos de la radiación , Piridinas/farmacología , Pirroles/farmacología , Ratas , Receptor de Serotonina 5-HT1B , Receptores de Serotonina/efectos de los fármacos , Receptores de Serotonina/genética , Receptores de Serotonina/metabolismo , Serotonina/farmacología , Agonistas de Receptores de Serotonina/farmacología , Sinaptosomas/efectos de los fármacos , Sinaptosomas/metabolismo , Temperatura , TransfecciónRESUMEN
5-Hydroxytryptamine-moduline is an endogenous cerebral tetrapeptide that regulates the activity of 5-hydroxytryptamine1B receptors. Direct binding of 5-[3H]hydroxytryptamine-moduline on rat brain homogenate evidenced the existence of two interacting sites for the peptide, very likely corresponding to different conformations of the 5-hydroxytryptamine1B receptor: The peptide first binds to a low-affinity state of the receptor (pIC50 = 7.68+/-0.14) and then induces (or stabilizes) a high-affinity complex (pIC50 = 11.62+/-0.18). This work focuses on the ability of 5-hydroxytryptamine-moduline analogues to recognize the high- and low-affinity sites for 5-hydroxytryptamine-moduline. The results obtained show that the two conformers of the 5-hydroxytryptamine1B receptor have similar but not identical binding pockets for 5-hydroxytryptamine-moduline. These two sites proved to be stereoselective and selective for tetrapeptides and favored the binding of peptides with hydrophobic amino acids in positions 1 and 4, serine in position 2, and a short amino acid in position 3. However, the serine in position 2 seems to be more important for the interaction of the peptide with the low-affinity site than the high-affinity one, which only needs a short hydrophobic amino acid in position 2.
Asunto(s)
Neuropéptidos/química , Oligopéptidos/química , Receptores de Serotonina/metabolismo , Animales , Sitios de Unión , Unión Competitiva , Fenómenos Químicos , Química Física , Masculino , Neuropéptidos/metabolismo , Oligopéptidos/metabolismo , Unión Proteica , Conformación Proteica , Ratas , Ratas Wistar , Receptor de Serotonina 5-HT1B , Receptores de Serotonina/química , Receptores de Serotonina/efectos de los fármacos , Relación Estructura-ActividadRESUMEN
Lithium ion is widely used to treat depressive patients, often as an initial helper for antidepressant drugs or as a mood stabilizer; however, the toxicity of the drug raises serious problems, because the toxic doses of lithium are quite close to the therapeutic ones. Thus, precise characterization of the target(s) involved in the therapeutic activity of lithium is of importance. The present work, carried out at molecular, cellular, and in vivo levels, demonstrates that 5-HT1B receptor constitutes a molecular target for lithium. Several reasons suggest that this interaction is more likely related to the therapeutic properties of lithium than to its undesirable effects. First, the observed biochemical and functional interaction occurs at concentrations that precisely correspond to effective therapeutic doses of lithium. Second, 5-HT1B receptors are well characterized as controlling the activity of the serotonergic system, which is known to be involved in affective disorders and the mechanism of action of various antidepressants. These findings represent progress in our knowledge of the mechanism of action of lithium that may facilitate clinical use of the ion and also open new directions in the research of antidepressant therapies.
Asunto(s)
Litio/farmacología , Trastornos del Humor/metabolismo , Receptores de Serotonina/metabolismo , Células 3T3 , Animales , Antidepresivos/farmacología , Antidepresivos/uso terapéutico , Unión Competitiva , Plaquetas/metabolismo , Células CHO , Cationes/metabolismo , Cricetinae , Relación Dosis-Respuesta a Droga , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Cobayas , Humanos , Litio/uso terapéutico , Ratones , Trastornos del Humor/tratamiento farmacológico , Desempeño Psicomotor/efectos de los fármacos , Ratas , Receptor de Serotonina 5-HT1B , Receptores de Serotonina/efectos de los fármacos , Serotonina/metabolismo , Antagonistas de la Serotonina/farmacología , Antagonistas de la Serotonina/uso terapéutico , Radioisótopos de Azufre , Sinaptosomas/efectos de los fármacos , Sinaptosomas/metabolismoRESUMEN
The effect of the selective r5-HT1B agonist 3-(1,2,5,6-tetrahydro)-4-pyridil-5-pyrrolo [3,2-b] pyril-5-one (CP93,129) on the K(+)-evoked overflow of [3H]dopamine was studied in rat striatal synaptosomes loaded with [3H]dopamine. The aim of the study was to investigate the participation of 5-HT1B receptors in the serotonergic modulation of striatal dopaminergic transmission. The Ca2(+)-dependent, tetrodotoxin-resistant K(+)-evoked overflow of [3H]dopamine was inhibited by CP93,129 (0.01-100 microM) in a concentration-dependent manner (IC50=1.8 microM; maximal inhibition by 35.5% of control). [+/-]8-OH-DPAT, a 5-HT(1A) receptor agonist, [+/-]DOI, a 5-HT2 receptor agonist, and 2-methyl-5-hydroxytryptamine, a 5-HT3 receptor agonist, at concentrations ranging from 0.01 microM to 100 microM did not show any significant effect. Neither ketanserin (1 microM and 5 microM), a selective 5-HT2/5-HT1D receptor antagonist, nor ondansetron (1 microM), a 5-HT3 receptor antagonist, changed the inhibitory effect of CP93,129. SB224289, GR55562, GR127935, isamoltane and metergoline, selective and non-selective 5-HT1B receptor antagonists, in contrast, used at a concentration of 1 microM, antagonized the inhibitory effect of CP93,129 (3 microM and 10 microM). SB224289, a selective 5-HT1B receptor antagonist, inhibited the effect of CP93,129 in a concentration-dependent manner; the calculated K(i) value was 1.8 nM. Our results indicate that in rat striatal axon terminals the K(+)-evoked release of dopamine is regulated by the presynaptic 5-HT1B heteroreceptors.
Asunto(s)
Dopamina/metabolismo , Neostriado/metabolismo , Receptores de Serotonina/efectos de los fármacos , Sinaptosomas/metabolismo , Animales , Masculino , Neostriado/efectos de los fármacos , Piridinas/farmacología , Pirroles/farmacología , Ratas , Ratas Wistar , Receptor de Serotonina 5-HT1B , Agonistas de Receptores de Serotonina/farmacología , Sinaptosomas/efectos de los fármacosRESUMEN
5-Hydroxytryptamine-moduline (5-HT-moduline) is an endogenous tetrapeptide (Leu-Ser-Ala-Leu) recently isolated and characterized from mammalian brain. This compound interacts with 5-HT1B receptors as a non-competitive, high-affinity antagonist and has the properties of an allosteric modulator. 5-HT-moduline could play an important role in the regulation of serotonergic transmission and also, through heteroreceptors, dopaminergic transmission. The aim of this work was to examine the potential ability of 5-HT-moduline to modify the basal extracellular concentration of dopamine and its metabolites (3-methoxytyramine, dihydroxyphenylacetic acid and homovanillic acid), in the rat striatum and to determine its potential interaction with the stimulating activity of a specific 5-HT1B receptor agonist, 3-(1,2,5,6-tetrahydropyrid-4-yl) pyrrolo [3,2-b] pyrid-5-one (CP-93,129), on the release of dopamine. The technique is based on in vivo microdialysis using probes implanted in the striatum of the conscious rat. Results showed that the perfusion of 5-HT-moduline directly into this structure (1.25 mM) increased the striatal level of dopamine by two-fold (104% of the absolute basal release values, P = 0.0015) and that of 3-methoxytyramine by 3-fold (293%, P = 0.0001) without any change in the terminal metabolite concentrations. The intrastriatal administration of CP-93,129 induced a statistically significant, dose-dependent increase of dopamine levels (P < 0.0001). Coperfusion of 5-HT-moduline did not significantly alter the effect of CP-93,129 at 0.1 and 0.5 mM, but appeared to have an additive effect on the lowest dose (P = 0.0406). The results obtained show that 5-HT-moduline directly administered into the striatum increases the release of dopamine in this area. Presumably, this effect results from the desensitization of 5-HT1B receptors located on dopamine terminals. However, the fact that a 5-HT1B receptor agonist (CP-93,129) also increased the release of dopamine in the striatum and that 5-HT-moduline exhibited a slight additive effect with that of a low concentration of CP-93,129 suggests that the two substances interact with different mechanisms.
Asunto(s)
Encéfalo/efectos de los fármacos , Dopamina/metabolismo , Neuropéptidos/farmacología , Oligopéptidos/farmacología , Animales , Encéfalo/metabolismo , Interacciones Farmacológicas , Masculino , Microdiálisis , Piridinas/farmacología , Pirroles/farmacología , Ratas , Ratas Sprague-Dawley , Receptor de Serotonina 5-HT1B , Receptor de Serotonina 5-HT1D , Receptores de Serotonina/efectos de los fármacos , Agonistas de Receptores de Serotonina/farmacologíaRESUMEN
5-HT1B receptors are the predominant auto- and heteroreceptors located on serotonergic and non-serotonergic terminals where they regulate the neuronal release of neurotransmitters. 5-HT-moduline (Leu-Ser-Ala-Leu) has been shown to specifically interact with a very high apparent affinity and in a non-competitive manner with 5-HT1B receptors (Massot et al. 1996; Rousselle et al. 1996). Using transfected cells expressing either 5-HT1B or 5-HT1D receptors, it was shown that 5-HT-moduline prevents the binding of [3H]5-HT to 5-HT1B as well as to 5-HT1D receptors with similar biochemical characteristics: the IC50 of the peptide was 1.2x10(-12) M for 5-HT1B and 9x10(-13) M for 5-HT1D receptors. The observed effect corresponds to a marked decrease of the maximal binding for [3H]5-HT on 5-HT1B (-51.2 +/- 1%) as well as 5-HT1D binding (-47.2 +/- 7.7% of the control binding) whereas the affinity of 5-HT is increased by a factor close to 3. No effect is observed using the "scrambled" peptide (Ala-Leu-Leu-Ser). Parallel assays using transfected cells expressing 5-HT1A or 5-ht6 receptors did not show any significant change induced by the peptide under similar assay conditions. The interaction of the peptide was also studied on the functional activity related to the stimulation of the receptors as measured by the increase in [35S]GTPgammaS binding reflecting the coupling of the receptor to the G-protein. 5-HT-moduline yields an antagonistic effect on the 5-HT induced coupling with a corresponding IC50 = 1.2 +/- 0.7x10(-12) M for 5-HT1B and 9.8 +/- 4.0x10(-12) M for 5-HT1D receptors, respectively. The present results demonstrate that 5-HT-moduline interacts with 5-HT1D as well as 5-HT1B receptors and possesses a non-competitive antagonistic activity, likely corresponding to its role of endogenous allosteric modulator, specific for both 5-HT1B and 5-HT1D receptors.
Asunto(s)
Neuropéptidos/farmacología , Oligopéptidos/farmacología , Receptores de Serotonina/efectos de los fármacos , Regulación Alostérica/efectos de los fármacos , Animales , Sitios de Unión/efectos de los fármacos , Células Cultivadas , Relación Dosis-Respuesta a Droga , Depuradores de Radicales Libres/metabolismo , Proteínas de Unión al GTP/metabolismo , Humanos , Neuroglía/efectos de los fármacos , Neuroglía/metabolismo , Ratas , Receptor de Serotonina 5-HT1B , Receptor de Serotonina 5-HT1D , Receptores de Serotonina/metabolismo , Serotonina/metabolismo , Transfección/efectos de los fármacosRESUMEN
5-HT-moduline is a cerebral tetrapeptide [Leu-Ser-Ala-Leu] that was recently isolated from bovine brain tissue and shown to interact specifically with 5-HT1B receptors, particularly in rodents. The pharmacological properties of 5-HT1B receptors in rodents are different from those in other species. In order to better understand the role of this peptide in non-rodent species, we determined the distribution of 5-HT-moduline binding sites in guinea-pig brain using both the film autoradiography and digital autoradiography with a newly developed high resolution beta-imaging techniques. We found that 5-HT-moduline binding sites were expressed in various brain regions. Quantitative analysis showed that densities of binding sites were similar to those observed previously in rat brain. Regions with the highest labelling included cortex, septum, hippocampus and some regions of basal ganglia. Our results extend previous data and show that 5-HT-moduline interacts with the two forms of 5-HT1B receptors that are distinct pharmacologically. By this interaction, 5-HT-moduline may play an important role in regulating the functional activity of 5-HT1B receptors, thereby contributes to the pathophysiology of serotonergic transmission.
Asunto(s)
Encéfalo/metabolismo , Neuropéptidos/metabolismo , Oligopéptidos/metabolismo , Animales , Autorradiografía/métodos , Sitios de Unión/fisiología , Cobayas , Procesamiento de Imagen Asistido por Computador , Técnicas In Vitro , Distribución TisularRESUMEN
The serotonergic transmission is considered as a neuromodulatory system in the Central Nervous System. 5-HT1B receptors play an important role in this modulatory activity. We have purified from mammalian brain an endogenous peptide, LSAL, we called 5-HT-moduline, interacting specifically with 5-HT1B receptors. This interaction is characterized by a high affinity (Ki = 10(-10) M) and a non-competitive mechanism. Direct [3H]5-HT-moduline binding revealed a single population of sites having an apparent affinity constant close to 10(-10) M. Autoradiographic studies showed a brain distribution of [3H]5-HT-moduline binding sites closely related to the 5-HT1B receptors. In functional studies, the peptide is able to reverse the activity of a 5-HT1B agonist in the nanomolar range. Furthermore, this antagonist effect is also observed in vivo on mice behavior. Immunocytochemistry revealed an heterogeneous distribution of 5-HT-moduline in mouse brain. The labeled structures correspond to cellular profiles with axon-like prolongations. Moreover, in vitro, LSAL is released in a Ca++, K(+)-dependent manner. Therefore, 5-HT-moduline behaves as a neurotransmitter. The fact that 5-HT-moduline induces the desensitization of 5-HT1B receptors reflects the existence of a novel and efficient mechanism able to rapidly modulate the serotonergic activity.
Asunto(s)
Encéfalo/metabolismo , Neuropéptidos/fisiología , Oligopéptidos/fisiología , Receptores de Serotonina/fisiología , Animales , Humanos , Cinética , Ratones , Neuropéptidos/química , Neuropéptidos/metabolismo , Oligopéptidos/química , Oligopéptidos/metabolismo , Receptor de Serotonina 5-HT1BAsunto(s)
Encéfalo/fisiopatología , Linfocitos/fisiología , Neuropéptidos/inmunología , Neuropéptidos/farmacología , Oligopéptidos/inmunología , Oligopéptidos/farmacología , Receptores de Serotonina/fisiología , Animales , Formación de Anticuerpos , Encéfalo/inmunología , Línea Celular , Ventrículos Cerebrales/efectos de los fármacos , Ventrículos Cerebrales/fisiología , Ventrículos Cerebrales/fisiopatología , Regulación de la Expresión Génica/inmunología , Regulación de la Expresión Génica/fisiología , Humanos , Inyecciones Intraventriculares , Ratones , Ratas , Receptor de Serotonina 5-HT1B , Estrés Psicológico/inmunologíaRESUMEN
5-HT-moduline is an endogenous tetrapeptide [Leu-Ser-Ala-Leu (LSAL)] that was first isolated from bovine brain tissue. To understand the physiological role of this tetrapeptide, we studied the localization of 5-HT-moduline binding sites in rat and mouse brains. Quantitative data obtained with a gaseous detector of beta-particles (beta-imager) indicated that [3H]-5-HT-moduline bound specifically to rat brain sections with high affinity (Kd = 0.77 nM and Bmax = 0. 26 dpm/mm2). Using film autoradiography in parallel, we found that 5-HT-moduline binding sites were expressed in a variety of rat and mouse brain structures. In 5-HT1B receptor knock-out mice, the specific binding of [3H]-5-HT-moduline was not different from background labeling, indicating that 5-HT-moduline targets are exclusively located on the 5-HT1B receptors. Although the distribution of 5-HT-moduline binding sites was similar to that of 5-HT1B receptors, they did not overlap totally. Differences in distribution patterns were found in regions containing either high levels of 5-HT1B receptors such as globus pallidus and subiculum that were poorly labeled or in other regions such as dentate gyrus of hippocampus and cortex where the relative density of 5-HT-moduline binding sites was higher than that of 5-HT1B receptors. In conclusion, our data, based on autoradiographic localization, indicate that 5-HT-moduline targets are located on 5-HT1B receptors present both on 5-HT afferents and postsynaptic neurons. By interacting specifically with 5-HT1B receptors, this tetrapeptide may play a pivotal role in pathological states such as stress that involves the dysfunction of 5-HT neurotransmission.
Asunto(s)
Encéfalo/metabolismo , Neuropéptidos/metabolismo , Oligopéptidos/metabolismo , Receptores de Serotonina/metabolismo , Animales , Autorradiografía , Sitios de Unión , Bovinos , Masculino , Ratones , Ratas , Ratas Wistar , Receptores de Serotonina/análisis , TritioRESUMEN
The localization of 5-HT-moduline, an endogenous cerebral tetrapeptide (LSAL) which specifically interacts with 5-HT1B receptors (Rousselle et al., 1996; Massot et al., 1996) was examined in mouse brain using an immunocytochemistry technique with a polyclonal anti-peptide antibody highly specific for this tetrapeptide. Highest levels of 5-HT-moduline immunoreactivity were observed in the cerebral cortex including cingulate, retrosplenial, parietal and pyriform cortical areas and in the basal ganglia. Intense immunoreactivity also occurred in the hippocampus, subiculum, various hypothalamic and thalamic nuclei and in some midbrain regions such as the substantia nigra and the superior colliculi. Immunoreactive neurons generally showed intense and extensive labelling of the perikarya and dendritic arborizations with moderate to heavy characteristic deposits of reaction product along plasma membranes and within cytoplasm while the nuclei were devoid of reaction product. The results obtained indicated that 5-HT-moduline immunoreactivity was heterogenously distributed in neuronal structures of mouse brain. The distribution of 5-HT-moduline immunoreactivity closely correlated with that of 5-HT-moduline specific binding sites as visualized by autoradiography (Massot et al., 1996). Moreover, it seems to overlap with the distribution of serotonergic innervation and also with that of 5-HT1B receptors in mouse brain (Boschert et al., 1994; Bruinvels et al., 1994; Chopin et al., 1994; Langlois et al., 1995). These data provide evidence that 5-HT-moduline immunoreactivity is located in cells with the morphological appearance of neurones. Its localization in brain areas which also contain 5-HT1B receptors, is in good agreement with previous demonstrations that this peptide specifically interacts with 5-HT1B receptors to regulate their functional activity and accordingly controls the modulatory activity of the serotoninergic system on various CNS functions.
Asunto(s)
Encéfalo/metabolismo , Neuronas/metabolismo , Neuropéptidos/metabolismo , Oligopéptidos/metabolismo , Animales , Anticuerpos/inmunología , Encéfalo/anatomía & histología , Inmunohistoquímica , Ratones , Neuropéptidos/inmunología , Oligopéptidos/inmunologíaRESUMEN
The serotonergic system controls the activity of neurotransmissions involved in numerous physiological functions. It is also thought to be crucially implicated in various pathologies, including psychiatric disorders such as depression, anxiety, and aggressiveness. The properties of 5-hydroxytryptamine (5-HT)-moduline, a novel endogenous peptide, have been tested in vitro and in vivo. Binding studies have shown that the peptide specifically interacts with 5-HT1B/1D receptors via a noncompetitive mechanism corresponding to a high apparent affinity (EC50 = 10(10) M). The interaction was shown in rat and guinea pig brain tissues and in cells transfected with either 5-HT1B or 5-HT1D beta receptor gene. [3H]5-HT-moduline binds to a single population of sites in mammalian brain (Kd = 0.4 nM in rat, Kd = 0.8 nM in guinea pig) as well as in transfected cells expressing the 5-HT1B or the 5-HT1D beta receptors (Kd = 0.2 and 0.6 nM, respectively). Furthermore, the binding is clearly specific of the LSAL sequence. Autoradiographic studies showed an heterogeneous brain distribution of this site. The interaction of 5-HT-moduline with the 5-HT1B/1D receptor corresponds to a decrease in the functional activity of the receptor (i.e., a decrease in the inhibitory effect of a 5-HT1B agonist on the evoked release of [3H]5-HT from synaptosomal preparation). It was also shown that 5-HT-moduline possess an in vivo effect in the social interaction test in mouse. Finally, it was demonstrated that 5-HT-moduline was released from brain synaptosomal preparation by a K+/Ca(2+)-dependent mechanism. In conclusion, 5-HT-moduline is a novel endogenous peptide regulating the serotonergic activity via a direct action at presynaptic 5-HT receptor. It may play an important role in the physiological mechanisms involving the serotonergic system, particularly in mechanisms corresponding to the elaboration of an appropriate response of the central nervous system to a given stimulus.
Asunto(s)
Neurotransmisores/fisiología , Receptores de Serotonina/metabolismo , Serotonina/fisiología , Animales , Autorradiografía , Conducta Animal/efectos de los fármacos , Sitios de Unión , Encéfalo/metabolismo , Células CHO/metabolismo , Células CHO/fisiología , Cricetinae , Estabilidad de Medicamentos , Cobayas , Masculino , Ratones , Neurotransmisores/metabolismo , Ratas , Ratas Wistar , Receptor de Serotonina 5-HT1D , Receptores de Serotonina/genética , Sensibilidad y Especificidad , Serotonina/metabolismo , Sinaptosomas/metabolismo , Transfección , TritioRESUMEN
5-HT-Moduline (Leu-Ser-Ala-Leu) is a new endogenous peptide purified from rat brain which interacts specifically with 5-HT1B/1D receptors. The binding interaction of 5-HT-Moduline with 5-HT1B/1D receptors appeared to be a non-competitive process, since the Bmax value of [125I] cyanopindolol binding on rat brain cortical membranes was decreased without modification of the Kd. This interaction was conserved on NIH 3T3 cells expressing the 5-HT1B receptor (IC50 = 10(-11)M) suggesting that the binding site for 5-HT-Moduline is localized on the 5-HT1B receptor protein. The observed interaction may lead to functional alterations of 5-HT1B/1D receptors known to play an important role in regulating the release of 5-HT from serotonergic nerve terminals (autoreceptors) as well as the release of other neurotransmitters (heteroreceptors).
Asunto(s)
Química Encefálica/fisiología , Neuropéptidos/farmacología , Oligopéptidos/farmacología , Receptores de Serotonina/efectos de los fármacos , Secuencia de Aminoácidos , Animales , Sitios de Unión/efectos de los fármacos , Línea Celular , Corteza Cerebral/efectos de los fármacos , Corteza Cerebral/metabolismo , Cromatografía Líquida de Alta Presión , Técnicas In Vitro , Membranas/efectos de los fármacos , Membranas/metabolismo , Ratones , Datos de Secuencia Molecular , Neuropéptidos/aislamiento & purificación , Oligopéptidos/aislamiento & purificación , Pindolol/análogos & derivados , RatasRESUMEN
The existence of endogenous compounds interacting with the serotonergic system was previously postulated. In the present work, rat brain tissues were extracted by acidic and organic procedures. The resulting extract was tested for its capacity to interact with the binding of [3H]5-hydroxytryptamine ([3H]5-HT) to 5-HT1 receptors. Compounds responsible for the observed inhibitory activities were isolated and purified by high pressure liquid chromatography. A tetrapeptide corresponding to a novel amino acid sequence Leu-Ser-Ala-Leu (LSAL) was identified. It reduces the binding of [3H]5-HT to 5-HT1 receptors at low concentration (IC50 = 10(-10) M). This effect corresponds to a specific interaction at 5-HT1B receptors since LSAL does not significantly affect other neurotransmitter bindings. LSAL appears heterogeneously distributed throughout the brain (hippocampus > cerebellum > striatum > brain stem) and in peripheral tissues (kidney > lung > stomach > blood > liver > spleen). Two other peptides, Leu-Ser (LS) and Ala-Leu (AL), were also purified. They hardly affected [3H]5-HT binding compared with LSAL. They presumably represent degradation products of the functional peptide LSAL. The fact that LSAL interacts specifically with 5-HT1B receptors that inhibit the release of neurotransmitters and particularly that of 5-HT itself suggests that this peptide may be involved in mechanisms controlling 5-HT neurotransmission and, accordingly, may play an important role in pathophysiological functions related to 5-HT activity.
Asunto(s)
Encéfalo/metabolismo , Péptidos/aislamiento & purificación , Receptores de Serotonina/metabolismo , Serotonina/metabolismo , Secuencia de Aminoácidos , Animales , Sitios de Unión , Unión Competitiva , Bovinos , Cromatografía , Masculino , Datos de Secuencia Molecular , Especificidad de Órganos , Péptidos/metabolismo , Ensayo de Unión Radioligante , Ratas , Ratas Wistar , Análisis de SecuenciaRESUMEN
The presence in whole blood of circulating endothelial cells (EC) has been a subject of debate for many years. It could represent a good marker of vessel injury. We demonstrate here that human endothelial cells can be directly isolated and identified in circulating blood by means of an endothelial cell specific monoclonal antibody, S-Endo1, coupled to micromagnetic beads. The specificity and efficacy of the assay were established using normal blood samples with cultured EC added. Specific rosettes formed between EC and beads could subsequently be isolated with a magnet. The rosetted cells were recovered with a yield greater than 80%. Their endothelial origin was confirmed by the positive labelling of von Willebrand factor and thrombomodulin, as well as the presence of Weibel-Palade bodies. We applied this method to demonstrate significantly increased levels of EC in venous and arterial human blood samples in patients undergoing heart catheterization. This new whole blood immuno-separation method may be useful in determining endothelial cell injury in vascular disorders.
Asunto(s)
Anticuerpos Monoclonales , Células Sanguíneas/citología , Células Sanguíneas/inmunología , Separación Celular/métodos , Endotelio Vascular/citología , Endotelio Vascular/inmunología , Cateterismo Cardíaco/efectos adversos , Células Cultivadas , Enfermedad Coronaria/sangre , Endotelio Vascular/lesiones , Humanos , MagnetismoRESUMEN
It has long been debated whether endothelial cells are present at very low frequency in peripheral blood. Elevated concentrations of such circulating cells may represent a good marker of vascular injury. We have therefore designed an immunocytometric assay for the detection of rare endothelial cells in whole blood. This assay is based on a new monoclonal antibody (MAb) S-Endo 1, made against human umbilical vein endothelial cells (HUVEC) and specific for endothelial cells of various origins without detectable reactivity with blood cells. First, the sensitivity of the assay was established by using normal blood samples with admixed HUVEC as an in vitro model. A good correlation was obtained between added and counted endothelial cells; the recovery was greater than 90% and the minimum detectable concentration of HUVEC was about 0.2 cells/microliters whole blood. Using this rapid counting technique, no detectable levels of endothelial cells were found in the blood of normal individuals (CE less than or equal to 0.1 cells/microliters) while elevated concentrations (up to 8 cells/microliters) were detected in a human model of vascular injury corresponding to a traumatic venepuncture. Thus, this new whole blood immunocytometric assay using S-Endo 1 MAb may be useful in determining the levels of circulating endothelial cells in vascular disorders.