Biomedical subjects

Raymond Cespuglio

Publications and source records attributed to Raymond Cespuglio.

At least 19 recordsLinked to original sources

PubMed2006

Regional age-related changes in neuronal nitric oxide synthase (nNOS), messenger RNA levels and activity in SAMP8 brain.

BACKGROUND: Nitric oxide (NO) is a multifunctional molecule synthesized by three isozymes of the NO synthase (NOSs) acting as a messenger/modulator and/or a potential neurotoxin. In rodents, the role of NOSs in sleep processes and throughout aging is now well established. For example, sleep parameters are highly deteriorated in senescence accelerated-prone 8 (SAMP8) mice, a useful animal model to study aging or age-associated disorders, while the inducible form of NOS (iNOS) is down-regulated within the cortex and the sleep-structures of the brainstem. Evidence is now increasing for a role of iNOS and resulting oxidative stress but not for the constitutive expressed isozyme (nNOS). To better understand the role of nNOS in the behavioural impairments observed in SAMP8 versus SAMR1 (control) animals, we evaluated age-related variations occurring in the nNOS expression and activity and nitrites/nitrates (NOx-) levels, in three brain areas (n = 7 animals in each group). Calibrated reverse transcriptase (RT) and real-time polymerase chain reaction (PCR) and biochemical procedures were used. RESULTS: We found that the levels of nNOS mRNA decreased in the cortex and the hippocampus of 8- vs 2-month-old animals followed by an increase in 12-vs 8-month-old animals in both strains. In the brainstem, levels of nNOS mRNA decreased in an age-dependent manner in SAMP8, but not in SAMR1. Regional age-related changes were also observed in nNOS activity. Moreover, nNOS activity in hippocampus was found lower in 8-month-old SAMP8 than in SAMR1, while in the cortex and the brainstem, nNOS activities increased at 8 months and afterward decreased with age in SAMP8 and SAMR1. NOx- levels showed profiles similar to nNOS activities in the cortex and the brainstem but were undetectable in the hippocampus of SAMP8 and SAMR1. Finally, NOx- levels were higher in the cortex of 8 month-old SAMP8 than in age-matched SAMR1. CONCLUSION: Concomitant variations occurring in NO levels derived from nNOS and iNOS at an early age constitute a major factor of risk for sleep and/or memory impairments in SAMP8.

Age Factors↗

PubMed2006

Recombinant human erythropoietin prevents the death of mice during cerebral malaria.

Cerebral involvement during malaria is a complication that leads to seizure, coma, and death. The effect of new neuroprotective therapies has not yet been investigated, although cerebral malaria shares some features with neurological stroke. Erythropoietin (EPO) is one of the more promising drugs in this area. We measured the effect of EPO on the survival of mice infected with Plasmodium berghei ANKA and demonstrated that inoculations of recombinant human EPO at the beginning of the clinical manifestations of cerebral malaria protect >90% of mice from death. This drug has no effect on the course of parasitemia. The effect of EPO was not related to either the inhibition of apoptosis in the brain or the regulation of the increase and decrease of nitric oxide production in the brain and blood, respectively. Tumor necrosis factor-alpha and interferon-gamma mRNA overexpression was inhibited by EPO, and treated mice had fewer brain hemorrhages. EPO has been used in patients with chronic diseases for years, and more recently it has been used to treat acute ischemic stroke. The data presented here provide the first evidence indicating that this cytokine could be useful for the symptomatic prevention of mortality during the acute stage of cerebral malaria.

Animals↗

PubMed2005

Acute administration of the novel serotonin and noradrenaline reuptake inhibitor, S33005, markedly modifies sleep-wake cycle architecture in the rat.

RATIONALE: The interrelationship between depressive states and sleep-wake cycle architecture is characterised by a decreased latency to the first paradoxical sleep (PS) episode, together with an enhancement of PS during the first part of the night. Conversely, slow-wave sleep (SWS) is decreased and intermittent awakenings increased. Notably, antidepressant treatment is generally associated with a diminution of PS. OBJECTIVES: In light of these observations, we examined the influence of acute administration of the novel mixed serotonin-noradrenaline reuptake blocker, (-)1-(1-dimethylaminomethyl 5-methoxybenzocyclobutan-1-yl)-cyclohexanol HCl (S33005), upon sleep-wake architecture in rats. METHODS: Animals were injected with vehicle or incremental doses of S33005 at the onset of either the dark or light periods. Digitised polygraphic recordings were performed, and changes evoked by S33005 were determined over 24-h recording periods, i.e., number and duration of sleep-wake episodes, latencies to PS and SWS, power band spectra of the electroencephalogram (EEG) and circadian changes. RESULTS: At 0.04 mg/kg, S33005 was inactive, whereas at 0.63 mg/kg, it modestly increased PS latencies and diminished PS duration during the light period. At 10 mg/kg, S33005 reduced markedly PS duration for about 4-h when injected prior to both light and dark periods. Latency to PS was prolonged, and the circadian acrophase was delayed. These effects are in keeping with previous studies of monoamine reuptake inhibitors, but, notably, SWS duration was increased when S33005 was injected at the onset of the light phase (+4%). These changes occurred without marked modifications in circadian rhythmicity or EEG spectral band power. Finally, even at the highest dose of S33005, only a limited rebound of SWS (+5%) and PS (+10%) was apparent. Amongst antidepressant to date examined, this is an original profile of influence upon sleep patterns. CONCLUSIONS: These results demonstrate a pattern of influence of S33005 upon sleep-wake architecture in rats which is globally consistent with antidepressant properties, but with a distinctive enhancement of restorative slow-wave sleep.

Adrenergic Agonists↗

PubMed2005

Sleep structure: a new diagnostic tool for stage determination in sleeping sickness.

Human African trypanosomiasis (HAT), due to the transmission of Trypanosoma brucei (T. b.) gambiense and T. b. rhodesiense by tsetse flies, is re-emerging in inter-tropical Africa. It evolves from the hemolymphatic Stage I to the meningo-encephalitic Stage II. The latter is generally treated with melarsoprol, an arseniate provoking often a deadly encephalopathy. A precise determination of the HAT evolution stage is therefore crucial. Stage II patients show: (i) a deregulation of the 24-h distribution of the sleep-wake alternation; (ii) an alteration of the sleep structure, with frequent sleep onset rapid eye movement (REM) periods (SOREMPs). Gambian HAT was diagnosed in eight patients (four, Stage II; three, Stage I; one, "intermediate" case) at the trypanosomiasis clinic at Viana (Angola). Continuous 48-h polysomnography was recorded on Oxford Medilog 9000-II portable systems before and after treatment with melarsoprol (Stage II) or pentamidine (Stage I and "intermediate" stage). Sleep traces were visually analyzed in 20-s epochs using the PRANA software. Stage II patients showed the complete sleep-wake syndrome, partly reversed by melarsoprol 1 month later. Two Stage I patients did not experience any of these alterations. However, the "intermediate" and one Stage I patients exhibited sleep disruptions and/or SOREMPs, persistent after pentamidine treatment. Polysomnography may represent a diagnostic tool to distinguish the two stages of HAT. Especially, SOREMPs appear shortly after the central nervous system invasion by trypanosomes. The reversibility of the sleep-wake cycle and sleep structure alterations after appropriate treatment constitutes the basis of an evaluation of the healing process.

Adolescent↗

PubMed2005

Clinical assessment of the entry into neurological state in rat experimental African trypanosomiasis.

Human African trypanosomiasis, caused by Trypanosoma brucei (T.b.) gambiense or rhodesiense, evolves in two stages: haemolymphatic stage and meningo-encephalitic stages, the latter featuring numerous neurological disorders. In experimental models infected with diverse T.b. sub-species, body weight (BW) loss, drop in food intake (FI), and hypo-activity after an asymptomatic period suggest the occurrence of a similar two-stage organization. In addition to daily measurement of BW and FI, body core temperature (T(co)) and spontaneous activity (SA) were recorded by telemetry in T.b. brucei-infected rats. After a 10--12-day symptom-free period, a complex clinical syndrome occurred suddenly. If the animal survived the access, the syndrome re-occurred at approximately 5-day intervals until death. The syndrome was made of a drop in FI and BW, a sharp decrease in T(co) and a loss of SA, suggesting a brisk alteration of the central nervous system functioning. Such events confirm the existence of a two-stage disease development in experimental trypanosomiasis. The entry into the second stage is marked by the occurrence of the first access, BW follow-up being essential and often sufficient its determination.

Animals↗

PubMed2005

Sleep wake profile and EEG spectral power in young or old senescence accelerated mice.

Changes occurring with age in cortical EEG and sleep-wake states architecture were examined in senescence accelerated prone (SAMP8) or senescence resistant (SAMR1) mice (age: 2 and 12 months) under baseline conditions or after a 4 h sleep deprivation (SD). In baseline conditions, an increase in slow wave sleep (SWS) amount (21-24%) occurs at the expense of the wakefulness (W) in old SAMP8 and SAMR1 mice versus young animals. In these conditions, SWS latency is reduced (67-72%). Moreover, in SAMP8 and SAMR1 mice, aging deteriorates paradoxical sleep (PS) architecture with more pronounced changes in SAMP8 (amount: -63%; episode duration: -44%; latency: +286%; circadian component loss; and EEG theta (theta) peak frequency (TPF): -1 Hz). During the 4 h recovery subsequent to a 4 h sleep deprivation, old SAMP8 mice exhibit an enhanced sensitivity resulting in SWS (+62%) and PS (+120%) rebounds, a characteristic of this inbred strain. Results obtained are discussed in line with the age-related learning and memory impairments existing in SAMP8 animals. In particular, the reduced cognitive performances described in old SAMP8 might be linked to the TPF deterioration during PS.

Age Factors↗

PubMed2005

Nitric oxide and sleep.

Nitric oxide (NO) is a biological messenger synthesized by three main isoforms of NO synthase (NOS): neuronal (nNOS, constitutive calcium dependent), endothelial (eNOS, constitutive, calcium dependent) and inducible (iNOS, calcium independent). NOS is distributed in the brain either in circumscribed neuronal sets or in sparse interneurons. Within the laterodorsal tegmentum (LDT), pedunculopontine tegmentum and dorsal raphe nucleus, NOS-containing neurons overlap neurons grouped according to their contribution to sleep mechanisms. The main target for NO is the soluble guanylate cyclase that triggers an overproduction of cyclic guanosine monophosphate. NO in neurons of the pontine tegmentum facilitates sleep (particularly rapid-eye-movement sleep), and NO contained within the LDT intervenes in modulating the discharge of the neurons through an auto-inhibitory process involving the co-synthesized neurotransmitters. Moreover, NO synthesized within cholinergic neurons of the basal forebrain, while under control of the LDT, may modulate the spectral components of the EEG instead of the amounts of different sleep states. Finally, impairment of NO production (e.g. neurodegeneration, iNOS induction) has identifiable effects, including ageing, neuropathologies and parasitaemia.

Brain↗

PubMed2005

Chloramphenicol decreases brain glucose utilization and modifies the sleep-wake cycle architecture in rats.

We studied the effects of chloramphenicol on brain glucose utilization and sleep-wake cycles in rat. After slightly anaesthetized animals were injected with [18F]fluoro-2-deoxy-D-glucose, we acquired time-concentration curves from three radiosensitive beta microprobes inserted into the right and left frontal cortices and the cerebellum, and applied a three-compartment model to calculate the cerebral metabolic rates for glucose. The sleep-wake cycle architecture was analysed in anaesthetic-free rats by recording electroencephalographic and electromyographic signals. Although chloramphenicol is a well-established inhibitor of oxidative phosphorylation, no compensatory increase in glucose utilization was detected in frontal cortex. Instead, chloramphenicol induced a significant 23% decrease in the regional cerebral metabolic rate for glucose. Such a metabolic response indicates a potential mismatch between energy supply and neuronal activity induced by chloramphenicol administration. Regarding sleep-wake states, chloramphenicol treatment was followed by a 64% increase in waking, a 20% decrease in slow-wave sleep, and a marked 59% loss in paradoxical sleep. Spectral analysis of the electroencephalogram indicates that chloramphenicol induces long-lasting modifications of delta-band power during slow-wave sleep.

Animals↗

PubMed2004

REM sleep control during aging in SAM mice: a role for inducible nitric oxide synthase.

Evidence that nitric oxide (NO) is involved in the regulation of rapid-eye-movement sleep (REMS) is supported by recent studies. During aging, NO generation encounters marked changes mainly related to the activation of the inducible NO-synthase (iNOS). To investigate links existing between iNOS and REMS impairments related to aging, we examine the age-related variations occurring in: mRNA and activity of iNOS in brainstem and frontal cortex; sleep parameters under baseline and after treatment by a selective iNOS inhibitor (AMT) in Senescence Accelerated Mice (SAM). SAMR1 (control) mice are a model of aging while SAMP8 are adequate to study neurodegenerative processes. RT-PCR analysis does not reveal significant variation in iNOS mRNA expression in both strains. However, significant age-related increases in iNOS activity occur in SAMR1 but such variation is not observed in SAMP8. In baseline conditions, aging induces a slight increase in slow-wave sleep (SWS) amounts in both groups and deteriorates greatly REMS architecture in SAMP8 compared to SAMR1. AMT reduces REMS amounts for 4-6h after treatment in a dose and age-dependent manner in SAMR1. Almost no changes occur in SAMP8. Data reported suggest that NO derived from iNOS contributes to trigger and maintain REMS during aging.

Age Factors↗

PubMed2004

Twenty-four-hour disruption of the sleep-wake cycle and sleep-onset REM-like episodes in a rat model of African trypanosomiasis.

STUDY OBJECTIVES: Patients with human African trypanosomiasis (sleeping sickness) due to the inoculation of Trypanosoma brucei gambiense or rhodesiense show a major disruption of the 24-hour sleep-wake distribution, accompanied by the occurrence of sleep-onset rapid-eye-movement (REM) sleep episodes, proportional to the severity of the illness. Although animal models of human African trypanosomiasis have been developed to understand the pathogenic mechanisms leading to immune alterations, the development of an animal model featuring the alterations of endogenous biologic rhythms remains a necessity. ANIMALS: Sprague-Dawley rats (N = 10) entrained to a 12:12-hour dark-light regimen. INTERVENTIONS: Rats were infected with Trypanosoma brucei brucei AnTat 1.1E and instrumented with electrocorticographic and electromyographic electrodes. Polysomnography was recorded continuously from 2 days before infection until the animal's death. MEASUREMENTS AND RESULTS: The analysis of the spontaneous sleep-wake architecture revealed an increased proportion of slow-wave sleep (SWS) and a decreased amount of wakefulness 2 days before death. Considerable sleep fragmentation was observed in the infected rats, with numerous changes in sleep-wake stages and an increased number of episodes of wakefulness and SWS. Infected rats presented a fragmented pattern of SWS and a marked reduction in the mean paradoxical-sleep (PS) latency, resulting in a considerable disruption of the PS-SWS sequences. Abnormal transitions, particularly the appearance of sleep-onset REM episodes, marked the disruption of the internal sleep structure. The electrocorticogram traces were modified during SWS, with the occurrence of abnormal hypersynchronic slow waves and a disappearance of spindles. CONCLUSION: The Trypanosoma brucei brucei-infected rat is a good model of the syndrome seen in human African trypanosomiasis, ie, the 24-hour disruption of the sleep-wake cycle and the occurrence of sleep-onset REM-like sleep episodes.

Animals↗

PubMed2004

Sleep-wake architecture in mouse models for Down syndrome.

Sleep-wake homeostasis is crucial for behavioral performances and memory both in the general population and in patients with learning disability, among whom were Down syndrome (DS) patients. We investigated, in mouse models of DS, cortical EEG and sleep-wake architecture under baseline conditions and after a 4-h sleep deprivation (SD). Young hemizygous mice (hSODwt/+) transgenic for the human CuZn superoxide dismutase (hSOD1) or for the human amyloid precursor protein (HuAPP(695); hAPPwt/+) were obtained on the same FVB/N inbred background. Baseline records for slow wave sleep (SWS) and wake (W) parameters were unchanged, whereas paradoxical sleep (PS) episode numbers were decreased and PS latency increased after lights off in hSODwt/+ mice versus controls. hSODwt/+ mice did not experience SWS or PS rebounds after SD but EEG activity in the delta-SWS activity (SWA) was enhanced. hAPPwt/+ mice exhibited no change in PS but an increase in W and a decrease in SWS before light transition as well as an increase in theta-power in PS and W. After SD, hAPPwt/+ mice exhibited SWS and PS rebounds as well as enhancement of SWA. We investigated also the nitrite/nitrate levels in all mice and found an increase in the brainstem of hSODwt/+ mice only versus control ones. These preliminary data provide useful results to investigate other genetically manipulated mice and to better understand the biochemical basis of sleep disorders in DS patients.

Animals↗

PubMed2004

In vivo measurement of glucose utilization in rats using a beta-microprobe: direct comparison with autoradiography.

A new beta-microprobe (betaP) has been used to locally measure the time-concentration curve of a radiolabeled substance. The betaP, analogous to positron emission tomography methodology, is useful for in vivo animal studies because it can acquire time-concentration curves with high temporal and spatial resolution. Using [18F]fluoro-2-deoxy-D-glucose and betaP, we evaluated the reliability of the biologic parameters and we compared this method with the [14C]2-deoxy-D-glucose autoradiography. BetaP time-concentration curves in three regions of the brain were obtained from 24 rats. Four kinetic parameters (K1-k4) were estimated from 60-minute experimental periods using a three-compartment model. Best fits were obtained when the vascular fraction (Fv) was estimated simultaneously with the four kinetic parameters (K1-k4). The mean estimated Fv values were about 5.5% for the frontal cortex regions and 8.0% for the cerebellum. Correlation coefficients higher than 0.830 were observed between regional cerebral metabolic rates for glucose (rCMRglc) values obtained by betaP and autoradiography. In addition, the betaP-derived input function was similar to that obtained by manual sampling. Our findings show that reliable rCMRglc values can be obtained using betaP.

Animals↗

PubMed2004

Changes occurring in cortical NO release and brain NO-synthases during a paradoxical sleep deprivation and subsequent recovery in the rat.

Variations occurring in cortical nitric oxide (NO) release were analysed with a voltametric method in rats (i) placed in control conditions, (ii) while being paradoxical sleep deprived (PSD), or (iii) recovering from a PSD. Activities of neuronal (nNOS) and inducible (iNOS) NO-synthases as well as nNOS expression were also determined in several brain regions. In baseline conditions, circadian variations in nNOS expression and activity were maximal during the dark period and minimal during the light one for all the structures analysed (frontal cortex, pons and medulla). In the same way, cortical NO release occurred through a circadian rhythm exhibiting maxima and minima during dark and light periods, respectively. In the same experimental conditions, iNOS activity did not exhibit time-dependent changes. The correlative changes observed in baseline conditions between NO release, nNOS expression and activity within the frontal cortex were disrupted during PSD and subsequent recovery. Still again, iNOS activity remained unchanged. Results obtained point out that the tight coupling existing in control conditions between nNOS expression-activity and NO release is disrupted by a PSD and remains affected during the subsequent 24 h recovery. Their significance is discussed.

Animals↗

PubMed2003

Behavioural changes after an acute stress: stressor and test types influences.

Behavioural consequences of different acute stressors (30 min of restraint, 20 min of forced swim stress, 15 min of inescapable footshocks) applied at the beginning of the active period were assessed in using two behavioural tests: a 20 min light extinction test 24 h after the stressor exposure in order to explore the psychomotor ability and a 10 min open field session within the dark period 48 h after the stressor exposure to estimate the emotional status and the locomotor activity of the rat. Different behavioural responses were observed depending on the nature of the applied stressor. In the light extinction test, the footshock-stressed rats developed a very low activity independent on light conditions whereas the rats submitted to forced swim and restraint exhibited an activity level depending on the strain. Moreover, restrained rats had a higher transient activity than forced swim rats under light condition. In the open field test, none of the stressed rats did develop differences in behaviour. The efficacy of a 24 h recovery period on the behavioural response to an acute stressor exposure depends on the intensity of the applied stressor and the behavioural demands.

Adaptation, Psychological↗

PubMed2003

Effects of a thermal injury on brain and blood nitric oxide (NO) content in the rat.

In the present study, the effects of a thermal injury on the nitric oxide (NO)-ergic system was investigated in freely moving rats. Using a voltammetric method allowing direct and in situ NO measurements, a significant decrease in cortical NO concentration was observed during the 24h following burning procedure. Since in the burning procedure halothane was employed, it was verified that this anaesthetic did not induce significant effect on cortical NO level. Experiments conducted in ex vivo conditions showed that blood NO and nitrites (NO(2)(-)) + nitrates (NO(3)(-)) concentrations increased strongly after burn injury while hypothalamic inducible NO-synthase (NOS(2)) mRNA level decreased significantly. A thermal injury was thus accompanied by a rapid impairment of the NO-ergic pathways, which might partly have been responsible for numerous changes occurring after burn injury.

Animals↗

PubMed2003

Inhibition of NADH oxidation by chloramphenicol in the freely moving rat measured by picosecond time-resolved emission spectroscopy.

Owing to the lack of methods capable to monitor the energetic processes taking place within small brain regions (i.e. nucleus raphe dorsalis, nRD), the neurotoxicity of various categories of substances, including antibiotics and psycho-active drugs, still remains difficult to evaluate. Using an in vivo picosecond optical spectroscopy imaging method, we report that chloramphenicol (CAP), besides its well-known ability to inhibit the mitochondria protein synthesis, also influences the NADH/NAD+ redox processes of the respiratory chain. At a 200-mg/kg dose, CAP indeed produces a marked increase in the fluorescent signal of the nRD which, according to clear evidence, is likely to be related to the NADH concentration. This effect also implies an efficient inhibition of complex I of the respiratory chain by CAP. It refers to the mechanism through which the adverse effects of the antibiotic may take place. It could explain why paradoxical sleep, a state needing aerobic energy to occur, is suppressed after CAP administration. The present approach constitutes the first attempt to determine by fluorescence methods the effects of substances on deep brain structures of the freely moving animal. It points out that in vivo ultrafast optical methods are innovative and adequate tools for combined neurochemical and behavioural approaches.

Animals↗

PubMed2003

Hepatic ischemia is associated with an increase in liver parenchyma nitric oxide that is in part enzyme-independent.

BACKGROUND: Nitric oxide (NO) might be involved in liver response to local ischemia-reperfusion injury. METHODS: A specific NO-sensitive electrode was inserted into liver parenchyma of anesthetized rabbits. After a 45-min period of stable NO signal, the vascular pedicle of the caudal lobe of the liver was clamped for 45 min, then the clamp was removed. Perfusion of the right upper lobe was left unchanged. The same procedure was applied in other animals after administration of a long-acting nonspecific NO synthase inhibitor NAPNA. RESULTS: Occlusion of the caudal pedicle was associated with a mean threefold increase in NO signal measured in the caudal lobe. After unclamping, this signal returned within 8 min to baseline value and remained stable for the next 6 h. In the right upper lobe, NO signal was unaffected by caudal lobe ischemia. By the end of the 6-h reperfusion period, administration of the NO inhibitor l-NAME led to a suppression of the NO signal, thus demonstrating the specificity of the measurement. Plasma nitrate and nitrite concentrations remained almost unchanged during the study period in all groups. In animals whose NO synthases had been previously inhibited by NAPNA, clamping the caudal pedicle for 45 min was still associated with a significant increase in caudal lobe NO signal. CONCLUSION: Nitric oxide is present in liver parenchyma, and its generation is dramatically affected by an ischemia injury. The increased NO generation during local ischemia is, at least in part, independent of NO synthases.

Alanine Transaminase↗

PubMed2002

Neurokinin NK1- and NK3-immunoreactive neurons in serotonergic cell groups in the rat brain.

Interactions are known to occur in the brain between serotonin (5-HT) and substance P (SP). To investigate whether SP can directly influence serotonergic neurons, double immunohistochemical labelings were performed on rat brain sections with NK1 or NK3 affinity-purified antibodies and a 5-HT monoclonal antibody. It was found that the vast majority of serotonergic cell bodies do not colocalize NK1 or NK3 labeling. Only in the central linear nucleus and ventral part of the dorsal raphe nucleus were a few serotonergic neurons double-labeled for NK1 receptors (15 and 0.8% of serotonergic neurons, respectively). It is suggested that serotonergic neurons are not major direct targets for SP in the rat brain.

Animals↗