Biomedical subjects

R Cespuglio

Publications and source records attributed to R Cespuglio.

At least 19 recordsLinked to original sources

PubMed1999

Voltammetric measurement of blood nitric oxide in irradiated rats.

UNLABELLED: PURPOSE. To investigate the effect of blood nitric oxide (NO) as a mediator of the neurovascular syndrome in rats following gamma-irradiation. MATERIAL AND METHODS: Using a voltametric method together with a carbon fibre based sensor, NO measurements were carried out in sham-irradiated and irradiated animals either in blood from the abdominal aorta or in blood samples from the heart. RESULTS: In in vitro conditions, properties of the probe were not altered by the ionizing radiation. Significant increases of +17% and +25.6% were observed in the voltametric signal height at 90 min and 24 h respectively after a 15 Gy gamma-ray exposure. These effects were followed on days 3 and 4 by a progressive decrease in the signal height of 7% and 18% respectively. Dose-effect relationships were observed at 90 min and 24 h after exposure to gamma-rays in the range of 3-15 Gy. Finally, the NO dependence on the measured voltametric signal was controlled by using inhibitors of the NO synthase (NOS) and by performing nitrate assays. CONCLUSIONS: Specific blood NO voltametric measurements are possible. Functional changes associated with NO after gamma-ray exposure are discussed.

Animals↗

PubMed1998

Localization of nitric oxide-synthesizing neurons sending projections to the dorsal raphe nucleus of the rat.

The origin of the nerve fibers immunoreactive for neuronal nitric oxide synthase (nNOS) in the rat dorsal raphe nucleus (DRN) was determined by combining the use of cholera toxin subunit b (CTb) as a retrograde tracer and nNOS immunohistochemistry with a monoclonal anti-nNOS antibody. Double labeled CTb-nNOS cell bodies were distributed from the rostral diencephalon to the caudal medulla oblongata, in about 20 areas of the brain. Several of the areas displaying double labeled cells are known for their involvement in the control of the sleep-wake cycle and/or transmission of nociception.

Activity Cycles↗

PubMed1998

In vivo voltammetric detection of rat brain lactate with carbon fiber microelectrodes coated with lactate oxidase.

To allow rat brain lactate measurement in vivo, a specific sensor based on a carbon fiber (phi = 30 microns) microelectrode coated with lactate oxidase was prepared. Combined with the differential normal pulse voltammetry measurement method, such a sensor, with a sensitivity of 9.15 +/- 0.91 mA.M-1.cm-2, provided a lactate linear response in concentrations ranging from 0.1 to 2.0 mM. The measurements performed appeared to be essentially insensitive to usual interference caused by the electroactive compounds present in the brain (ascorbic acid and peptides). In vivo detection performed in the cortex of the anesthetized rat led to the determination of a lactate concentration of 0.41 +/- 0.02 mM. Moreover, to validate the results obtained in vivo, an ex vivo determination of the lactate level was also performed in samples of brain tissue, plasma, and cerebrospinal fluid, using both voltammetry and a clinical analyzer with colorimetric-based detection. A good correlation was observed between the sets of data established by both methods.

Animals↗

PubMed1998

Comparative distribution of nitric oxide synthase- and serotonin-containing neurons in the raphe nuclei of four mammalian species.

Monoclonal antibodies were generated against serotonin (5-HT) and the C-terminal portion of the neuronal form of nitric oxide synthase (nNOS), the enzyme producing nitric oxide in neurons. These antibodies were used to compare the distribution of 5-HT- and nNOS-containing neurons in the raphe nuclei of four animal species (rat, mouse, guinea pig, and cat). It was found that the rat was the only species in which the raphe nuclei contain a substantial number of nNOS-immunoreactive (IR) cell bodies. In this species and as observed by other authors, all mesencephalic raphe nuclei contained nNOS-IR cells, the largest group being located in the nucleus raphe dorsalis. The coexistence of nNOS and 5-HT immunoreactivities in these nuclei was visualized by double labeling. In the medulla, the nuclei raphe magnus and obscurus displayed a rather low number of nNOS-IR neurons. In the other species, nNOS-IR cell bodies were found in very low numbers, whatever raphe nucleus was considered. The rostral pole of the nucleus raphe dorsalis and the nuclei raphe magnus and obscurus contained a few nNOS-IR neurons which did not show any coincidence with the 5-HT neurons. In addition, nNOS-IR axons were rare. It is concluded that in the mouse, guinea pig, and cat the involvement of nitric oxide in functions subserved by 5-HT within the raphe nuclei might be minimal.

Animals↗

PubMed1998

5-Hydroxyindoles compounds and nitric oxide voltammetric detection in the rat brain: changes occurring throughout the sleep-wake cycle.

The release of serotonin may occur throughout the sleep-wake cycle according to 2 different modalities: - by the axonal nerve endings during waking; - by the dendrites and/or the soma of the nucleus raphe dorsalis (nRD) during sleep. Neuronal nitric oxide (NO), synthesised by constitutive NO synthase (NOS), is colocalized with neurotransmitters such as GABA, acetylcholine, somatostatin, serotonin, etc. In order to evaluate its modalities of release throughout the rat sleep-wake cycle, a sensor allowing its specific detection in freely moving animals was prepared. In the cortex, the highest NO signal occurs during the waking state (W=100%) versus slow wave sleep (SWS=-6%) and paradoxical sleep (PS=-9%). The mild variations observed might reflect a mean of the individual sleep-wake cycle variations attached to each NO source (GABAergic interneurons, cholinergic and serotoninergic axonal nerve endings, etc.).

Animals↗

PubMed1998

Sleep and stress in man: an approach through exercise and exposure to extreme environments.

In this paper, the effects of exercise on human sleep (in temperate, cold, and hot climates) are compared with those of exposure to extreme environments (tropical, polar climates). Exercise has two effect: (i) when the exercise load is too heavy or if the subject is not trained to the exercise conditions, the hypothalamo-pituitary-adrenocortical axis (HPA) is strongly activated (somatic stress reaction), and a diachronic (delayed) decrease in total sleep time and slow-wave sleep (SWS) occurs with a synchronic (concomitant) sleep disruption (such as a decrease in REM sleep); (ii) a diachronic enhancement of SWS and (or) REM sleep occurs during moderate training and in athletes, with a moderate HPA activation (neurogenic stress reaction). Heat acclimatization (neurogenic stress response) results in a diachronic increase in SWS, contrary to acute heat exposure (somatic stress) which leads to a diachronic decrease in SWS. Nocturnal cold exposure (somatic and (or) neurogenic stress) provokes a synchronic decrease in REM sleep with an activation of stress hormones, which are reduced by previous acclimation (neurogenic pathway); SWS remains undisturbed in the cold, as it occurs at the beginning of the night before body cooling. In conclusion, when the brain can deal with the stressor (neurogenic stress), diachronic increases in SWS and (or) REM sleep occur. When these "central" mechanisms are overloaded, the classical "somatic" stress reaction occurs with diachronic and synchronic disruptions of the sleep structure.

Acclimatization↗

PubMed1997

Voltametric assessment of brain nitric oxide during heatstroke in rats.

Anesthetized rats exposed to a high ambient temperature develop heatstroke with brain ischemia. Since nitric oxide (NO) plays an important role during normothermic ischemia, its cortical and cerebellar production were continuously assessed in pentobarbital anesthetized rats exposed to heat by using differential pulsed voltammetry. After 60 min at thermoneutrality, the rats were submitted to an ambient temperature of 40 degrees C until death. After 60 min in the heat, the rats were injected intraperitoneally with saline, MK801 (1 mg.kg(-1)), an antagonist of N-methyl-D-aspartate (NMDA) receptors, or L-arginine p-nitroanilide (L-ANA; 100 mg.kg(-1)), an inhibitor of NO synthase. Just before death, a 70% increase in NO production was observed in both the cerebellum and the cortex of saline-treated rats. The cortical increase in NO was not modified by MK801 while the NO signal was suppressed by L-ANA.

Animals↗

PubMed1997

Voltammetric detection of nitric oxide (NO) in the rat brain: its variations throughout the sleep-wake cycle.

A sensor allowing the specific detection of nitric oxide (NO) is reported. Together with differential pulsed voltammetry, it allows the detection of a 650 mV signal either in NO solutions or in the rat frontal cortex. The intraperitoneal (i.p.) administration of a NO donor (S-nitrosoglutathione, 20 mg/kg i.p.) increases the signal height (+30%) while that of a nitric oxide synthase (NOS) inhibitor like L-nitro-arginine-p-nitro-anilide (100 mg/kg i.p.), produces its complete disappearance in the cortex of anesthetized rats. These results suggest that the 650 mV signal might be NO-dependent. Some other NOS inhibitors have been found either inefficient (L-nitro-arginine-methyl-ester) or partially efficient (7-nitro-indazole) on the signal height. In freely moving rats, also equipped with polygraphic electrodes, the signal measured in the frontal cortex exhibits the highest height during waking. It decreases during slow-wave sleep (-6%) and paradoxical sleep (-9%).

Activity Cycles↗

PubMed1997

Monitoring nitric oxide (NO) in rat locus coeruleus: differential effects of NO synthase inhibitors.

A porphyrinic microsensor combined with in vivo voltammetry was used to monitor extracellular nitric oxide (NO) in the locus coeruleus (LC) of anaesthetized rats. Administration of N omega-nitro-L-arginine p-nitro-anilide (100 mg/kg, i.p) or 7-nitro indazole (30 mg/kg, i.p.), which both inhibit preferentially neuronal NO synthase (NOS), induced a marked decrease in the NO oxidation peak height. On the other hand, N omega-nitro-L-arginine methyl ester (L-NAME) (200 mg/kg, i.p.), a less selective NOS inhibitor, failed to decrease the NO signal. Moreover, intra LC administration of NMDA, known to activate LC noradrenergic neurones, increased the NO signal. This study demonstrates the usefulness of in vivo voltammetry to monitor basal levels of NO and their changes in the LC. Differential effects of NOS inhibitors show that their central activity need to be assessed through in situ measurement of NO before using these inhibitors as neuropharmacological tools.

Anilides↗

PubMed1997

Brain glucose: voltammetric determination in normal and hyperglycaemic rats using a glucose microsensor.

Pulsed voltammetry applied to glucose oxidase-coated carbon fibre electrodes (glucose sensor) was used for brain glucose determination in normal and streptozotocin-treated rats (experimental diabetes mellitus). Glucose levels increased in the frontal cortex of diabetic animals compared with the controls (+262%). Glucose levels were also increased in their CSF (+48%) and plasma (+64%), determined in ex vivo conditions. The validity of the glucose sensor determinations, as well as that of the experimental model of diabetes used, was checked using the Beckman glucose analyser and a radioimmunoassay for plasma insulin. Insulin, unlike glucose, was decreased in diabetic animals. The sensor described here ensures precise determinations and is suitable for use in experimental models where alterations in glucose metabolism occur.

Animals↗

PubMed1997

Influence of a 1 h immobilization stress on sleep states and corticotropin-like intermediate lobe peptide (CLIP or ACTH18-39, Ph-ACTH18-39) brain contents in the rat.

A 1 h immobilization stress (IS) was imposed to rats at the beginning of the dark period, i.e., when the animals start to be active. The IS was accompanied by an intense polygraphic waking and followed, over 12 h of the dark period, by a significant rebound of slow-wave sleep (SWS, +17%) and paradoxical sleep (PS, +57%). In order to estimate the IS-related changes in the endogenous concentrations of corticotropin-like intermediate lobe peptide (CLIP, ACTH18-39) and related compounds, a specific radioimmunoassay (RIA) was used. Assays performed in cerebral biopsies taken from arcuate (AN) and raphe dorsalis (nRD) nuclei led to the obtention of 2 main immunoreactive peaks, corresponding to CLIP and its phosphorylated form Ph-CLIP. Just after end of the IS and within the nRD. Ph-CLIP immunoreactivity increased by about 95%. Four hours later, i.e., when PS rebound was maximal, a 37% increase in Ph-CLIP immunoreactivity was measured in the AN. These observations have never been described before. In the blood, at the end of the restraint, CLIP/ACTH1-39 total immunoreactivity was increased by 330%. It returned to baseline level 4 h later. Blood concentration of corticosterone was also increased by 56% at the end of the IS and was close to baseline level 4 h later. Data reported here indicate that the IS first triggers an increase in Ph-CLIP within the nRD. Since the nRD contains sleep permissive components, this increase might be determinant for the SWS and PS rebound induction. The changes observed in the blood as regards CLIP/ACTH1-39 total immunoreactivity and corticosterone concentration testify to the efficacy of the IS and are part of the conventional picture accompanying such a situation. Finally, the increase in Ph-CLIP, occurring in the AN 4 h after the end of the restraint, might be part of the restorative processes necessary to compensate the stress overshoot.

Adrenocorticotropic Hormone↗

PubMed1997

Ultrastructural relationships of the pro-opiomelanocortin axons with the serotoninergic neurons in the dorsal raphe nucleus of the rat.

The relationships of the corticotropin-like intermediate lobe peptide (CLIP)/ACTH-immunoreactive axons with the serotoninergic and non-serotoninergic neurons in the dorsal raphe nucleus of the rat were examined by means of a double label immunocytochemical method. It is suggested that the rare contacts established by the CLIP/ACTH-immunoreactive fibers with serotoninergic neurons (cell bodies and dendrites) are not under a synaptic from. In contrast, the contacts with non-serotoninergic neurons were predominantly formed with dendrites and showed a substantial number of synapses.

Adrenocorticotropic Hormone↗

PubMed1997

Prevention of ACTH- and adrenalectomy-induced muricidal behavior: by benzodiazepinic ligands.

We investigated the effect of treatment with central (neuronal and glial) benzodiazepine binding site-active molecules on ACTH- or adrenalectomy (ADX)-induced muricidal behavior in male Wistar rats. Pretreatment (IP) with either flumazenil or clonazepam prevented the subsequent induction of ADX-induced behavior, but only flumazenil protected against ACTH-induced behavior; posttreatment in both cases induced no significant modifications. Using 4'-chloro-diazepam or PK 11195, both pre- and posttreatment afforded protection, the effect lasting longer (> 1 week) than that induced by flumazenil or clonazepam (2 days). Pretreatment with the GABAA agonist, muscimol, also resulted in complete protection, whereas posttreatment had only a slight effect.

Adrenalectomy↗

PubMed1997

Determination of NADH in the rat brain during sleep-wake states with an optic fibre sensor and time-resolved fluorescence procedures.

The present paper reports a nanosecond time-resolved fluorescence derived from the cortex and the area of the periaqueductal gray including the nucleus raphe dorsalis (PAG-nRD) in unanaesthetized freely moving rats. The measurements were acquired through a single optic fibre transmitting a subnanosecond nitrogen laser pulse (337 nm, 15 Hz) and collecting the brain fluorescence occurring at 460 nm which might depend on mitochondrial NADH (reduced form of nicotinamide adenine dinucleotide). The fluorometric method was combined with polygraphic recordings, and this procedure allowed us to define, for the first time, variations of the 460 nm signal occurring throughout the sleep-wake cycle. In the PAG-nRD, the signal exhibited moderate heterogeneous variation in amplitude during slow-wave as compared to the waking state. Constant increases were observed during paradoxical sleep as compared to the waking state. For this state of sleep the magnitude of the variations depended on the optic fibre location. In the cortex and during either slow-wave sleep or paradoxical sleep, the signal presented moderate increases which were significant during paradoxical sleep. The magnitude of the redox variations observed either in the PAG-nRD or in the cortex might be ascribed to the oxidative energy balance which is related to sleep states.

Animals↗

PubMed1996

In vivo brain glucose measurements: differential normal pulse voltammetry with enzyme-modified carbon fiber microelectrodes.

The enzyme glucose oxidase was immobilized on the surface of carbon fiber microelectrodes (CFMEs) either by cross-linking in glutaraldehyde vapor or by enzyme entrapment in electropolymerized films of m-phenylenediamine or resorcinol. The cross-linked enzymatic layer was, in the given conditions, covered with an additional membrane of Nafion or cellulose acetate. The prepared glucose sensors were tested using differential normal pulse voltammetry (DNPV, in which the scan comprises successive double pulses ("prepulse and pulse"), the prepulses are of increasing amplitude, and the current measured is the differential of the current existing between each prepulse and pulse). With properly chosen DNPV parameters, the response to glucose presented a peak at a potential of about 1 V versus an Ag/AgC1-reference, owing to the oxidation of enzymatically produced hydrogen peroxide. The calibration curves obtained (peak height/glucose concentration) were linear from 0.3-0.5 up to 1.5-6.5 mM and showed a sensitivity ranging from 1.4 up to 34.5 mA M-1 cm-2, depending on the sensor type. The DNPV response to glucose exhibited an essential insensitivity toward easily oxidizable interfering substances such as ascorbic acid and acetaminophen present at physiological concentrations. Peptides, the interfering species typical of the cerebral medium, were effectively retained by the above additional membranes. Concentration values of glucose in plasma and cerebrospinal fluid, determined in vitro from the DNPV peak height, agreed well with those measured by standard procedures. In the anesthetized rat, extracellular brain concentration of glucose was also monitored during administration of either insulin or glucagon. Under such pharmacological conditions, the changes observed in the peak height were in perfect agreement with the known effects induced by both substances.

Acetaminophen↗

PubMed1996

Effects of tianeptine, sertraline and clomipramine on brain serotonin metabolism: a voltammetric approach in the rat.

Tianeptine is a substance enhancing the serotonir uptake while sertraline and clomipramine inhibit it. By means of 5-hydroxyin-doleacetic acid (5-HIAA) voltammetric measurements, this study investigated their influence on serotonin metabolism which depends mainly upon the activity of monoamine oxidase type A. After tianeptine injection the 5-HIAA signal increased by about 60%. This effect was maintained when the animals were pre-treated with MDL 72145 (an inhibitor of monoamine oxidase type B) but reduced when clorgyline (an inhibitor of monoamine oxidase type A) was administered after tianeptine. Administration of sertraline or clomipramine reduced the 5-HIAA signal by about 30-50%, whether the animals were pre-treated with MDL 72145 or not. It is to be concluded that tianeptine, sertraline and clomipramine can regulate the 5-HT fraction present in the synaptic cleft, not only by acting at the level of the serotoninergic neurons, but also by favoring or reducing the access of the amine to monoamine oxidase type A which is synthesized within non-serotoninergic neurons and glial cells.

1-Naphthylamine↗

PubMed1996

[Voltametric detection of cerebral NO in rats. Variations of the signal throughout the sleep-wakefulness cycle].

Nitric oxide (NO) is synthesized in the neurons by constitutive NO synthase (NOS). Within given neuronal sets, this enzyme is colocalized with different other neurotransmitters such as, for example, GABA, acethylcholine or serotonin. Our attention has been focused on the fact that serotoninergic neurons, well known for their involvement in sleep triggering and maintenance, synthesize also NO. In order to evaluate the modalities of release of this compound throughout the rat sleep-waking cycle, we prepared a sensor allowing its specific detection in freely moving animals. The active part of this sensor is a carbon fiber (phi = 30 microns) successively coated with porphyrin nickel and nafion. In vitro, together with differential normal pulse voltammetric measurements, it allows the detection of a 650 mV signal varying linearly in NO solutions ranging from 5.10(-7) to 10(-4) M. At physiological concentrations, L-arginine, L-citrulline, nitrites and nitrates do not yield a signal at 650 mV. Similarly, the compounds administered to the animals, hydroxylamine, L-arginine p-nitroanilide (L-ANA) and L-N omega-nitro arginine methyl ester (L-NAME) are not electroactive at 650 mV. L-ANA and L-NAME, also appear to be trapping agents for NO while leaving the electrochemical properties of the sensor untouched. In vivo, in the frontal cortex of the anesthetized rat, a signal is measured at 650 mV. The administration of hydroxylamine (40 mg/kg, i.p.) induces a 100% increase in its height. The administration of L-ANA (100 mg/kg, i.p.) produces its complete disappearance within 50 min. Finally, the administration of L-NAME (100 mg/kg, i.p.) is without effect. This last aspect might be dependent upon the inability of L-NAME to cross the blood brain barrier. On the contrary, the increase in the signal height obtained with hydroxylamine and its disappearance with L-ANA support that it might depend upon NO. In vivo, and in animals also equipped with polygraphic electrodes, the signal measured in the same area of the cortex exhibits the highest height during the waking state and decreases during either slow-wave sleep (-6%) or paradoxical sleep (-9%). These mild variations might represent the mean of several NO sources (cortical GABAergic interneurons, cholinergic and serotoninergic axonal nerve endings), each of them varying differently throughout the sleep-waking cycle.

Animals↗

PubMed1996

[Action duality of nitrogen oxide (NO) in experimental African trypanosomiasis].

Patients with human African trypanosomiasis present a major dysruption of the circadian rhythmicity of the sleep-wake cycle, which was also found in rats infected with Trypanosoma brucei brucei (T.b.b.). The alterations in the immune function and nervous system in African trypsanosomiasis led us to investigate the involvement of nitric oxide (NO), a key molecule in immune and neurophysiological mechanisms, in experimental trypanosomiasis. NO was measured in 35 Sprague Dawley rats using differential impulsional voltammetry with a carbon fiber coated with porphyrin-nickel and nafion, ex vivo in the blood and in vivo in the brain. The rats were anaesthetized with sodium chlorate. Infection was performed intraperitoneally (i.p.) with 0.2 ml of a T.b.b. cryostabilate (clone AnTat 1.1E). Blood was collected by an intracardiac puncture with immediate replacement of blood volume (1 ml) in 7 control rats and 8 rats infected since 15 days, before and after i.p. administration of L-ANA (L-arginine-p-nitro-anilide, 100 mg.kg-1, an inhibitor of NO synthase). Brain measures were done in 20 rats (8 controls, and 12 rats infected since 15 or 21 days), in the cortex (H, -0.5 mm; AP, -0.8 mm; L, 1.2 mm) and the lateral ventricle (H,-3.2 mm). In infected rats, blood NO was at 70% of control values (p < 0.001), and L-ANA suppressed the NO signal in all animals (p < 0.0001), demonstrating that the signal originated from NO. Cortical NO was higher than in the ventricle in both control (p < 0.0001) and infected rats (p < 0.001). NO was more elevated in both structures in 15-day-infected rats than in control rats (p < 0.0001), the difference being enhanced in 21-day-infected rats (p < 0.001). L-ANA suppressed the NO signal in 30 to 60 min. These data suggest that NO intervenes in the development of trypanosomiasis in different manners. It is increased in the brain, which remains unexplained, where it may be involved in blood-brain barrier permeation. Conversely, it is decreased in the blood, may be because of macrophage function impairment, which would explain why trypanosomes can multiply in the host.

Animals↗