5-HT1B receptors: a novel target for lithium. Possible involvement in mood disorders.

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.

Cytofluorometric detection of human endothelial cells in whole blood using S-Endo 1 monoclonal antibody.

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.

Immunocytochemical localization of neurons expressing 5-HT-moduline in the mouse brain.

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.

Rapid isolation of human endothelial cells from whole blood using S-Endo1 monoclonal antibody coupled to immuno-magnetic beads: demonstration of endothelial injury after angioplasty.

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.

The estrogen-regulated 52 K protein adn plasminogen activators released by MCF7 cells are different.

In the MCF7 human breast cancer cell line, estradiol stimulates the synthesis of a 52 K secretory glycoprotein and has been reported to increase the plasminogen activator (PA) activity in the culture medium. Since one PA isozyme has a molecular weight close to 52 000 daltons under denaturing conditions, we asked whether the 52 K protein was a PA. The PA activity released in serum-free conditioned medium was evaluated by the increase in [125I]casein digestion observed in the presence of plasminogen. The 52 K protein was estimated by analysing the released proteins on SDS-polyacrylamide gel electrophoresis. When the conditioned medium was chromatographed on concanavalin A-Sepharose, the 52 K protein was retained on the gel, but not the PA. The two proteins also appeared different on the basis of their competing efficiency in a radioimmunoassay developed to quantify the 52 K protein. An antiserum against human urokinase failed to immunoprecipitate the 52 K protein. Under our culture conditions estradiol increased 52 K, but not PA, production. These results clearly indicate that the estradiol-regulated 52 K protein is not a plasminogen activator.

Estradiol increases the production of alpha 1-antichymotrypsin in MCF7 and T47D human breast cancer cell lines.

alpha 1-Antichymotrypsin (Achy) is an antiprotease of the acute inflammation phase, which is also released by MCF7 human breast cancer cells in culture. Using a fluorimetric assay with the synthetic substrate L-Seryl-L-Tyrosyl-2-N-naphthylamide, we have shown that a medium conditioned by MCF7 cells treated by estradiol inhibits the activity of alpha-chymotrypsin. This inhibition increased when physiological concentrations of estradiol were added to the cells for 2 days. It was due to an increased production of Achy and not to a direct effect of estradiol on alpha-chymotrypsin activity as shown by double immunoprecipitation with an antiserum against human alpha 1-antichymotrypsin. An increased accumulation by estradiol of an antigen located in the cytoplasm of MCF7 cells, which was revealed by immunoperoxidase staining with antibodies to Achy, also indicated that estradiol increased the production of Achy in these cells. Similar immunostaining was observed in a breast cancer tissue. Most of the estrogen regulated 60-68 kDa protein secreted by T47D cells (Chalbos et al. (1982) J. Clin. Endocrinol. Metab. 55, 276-283) was also specifically immunoprecipitated by the antibodies to Achy. Thus, alpha 1-antichymotrypsin is the first protein to be identified which is induced by estradiol and secreted by breast cancer cells.

Molecular, cellular and physiological characteristics of 5-HT-moduline, a novel endogenous modulator of 5-HT1B receptor subtype.

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.

A new peptide, 5-HT-moduline, isolated and purified from mammalian brain specifically interacts with 5-HT1B/1D receptors.

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).

Mapping of 5-HT-moduline binding sites in guinea-pig brain by film and digital autoradiography.

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.

Magnetic field desensitizes 5-HT(1B) receptor in brain: pharmacological and functional studies.

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.

5-HT-moduline, a 5-HT(1B/1D) receptor endogenous modulator, interacts with dopamine release measured in vivo by microdialysis.

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.

5-HT1B receptors modulate release of [3H]dopamine from rat striatal synaptosomes.

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.

Specific interaction of 5-HT-moduline with human 5-HT1b as well as 5-HT1d receptors expressed in transfected cultured cells.

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.

Magnetic field (50 Hz) increases N-acetyltransferase, hydroxy-indole-O-methyltransferase activity and melatonin release through an indirect pathway.

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.

[Creation and validation of the SPRING Internet site]. / Création et validation du site Internet SPRING.

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.

[Evaluation of the health inpact of the floods in the Gard on respiratory health of disaster victims]. / Evaluation de l'impact sanitaire des inondations dans le Gard sur la santé respiratoire des sinistrés.

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.

[Poaceae pollens. Comparison of Poaceae pollens in 1999 among Marseille, Gap, and Briançon 2000 meters]. / Comparaison des pollens de Poaceae en 1999 à Marseille, Gap, Briançon et Briançon 2000 mètres.

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.

Isolation and characterization of an endogenous peptide from rat brain interacting specifically with the serotonergic 1B receptor subtypes.

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.