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Biomedical subjects

Marc Ansseau

Publications and source records attributed to Marc Ansseau.

12 recordsLinked to original sources
PubMed2006

Nitrous oxide and xenon prevent amphetamine-induced carrier-mediated dopamine release in a memantine-like fashion and protect against behavioral sensitization.

BACKGROUND: Amphetamine administration induces stimulation-independent dopamine release in the nucleus accumbens (NAcc) through reverse dopamine transport, a critical neurochemical event involved in its psychostimulant action, and furthermore decreases stimulation-dependent vesicular dopamine release. These effects may involve possible indirect glutamatergic mechanisms. METHODS: We investigated the effects of nitrous oxide and xenon, which possess antagonistic action at the N-methyl-D-aspartate (NMDA) receptor, on brain slices ex vivo on amphetamine-induced changes in carrier-mediated and KCl-evoked dopamine release in the NAcc, and in vivo on amphetamine-induced locomotor sensitization. RESULTS: Like the low-affinity NMDA receptor antagonist memantine, but not the prototypical compound MK-801, nitrous oxide and xenon at appropriate concentrations blocked both the increase in carrier-mediated dopamine release and locomotor sensitization produced by amphetamine. CONCLUSIONS: In contrast to what has generally been found using prototypical NMDA receptor antagonists, these data regarding the effect of memantine, nitrous oxide, and xenon support the hypothesis that activation of certain NMDA receptors (possibly those containing the NR1a/NR2D subunit) in the NAcc is involved in the amphetamine-induced increase in carrier-mediated dopamine release and the development of behavioral sensitization to amphetamine. Nitrous oxide, xenon, and memantine may be of therapeutic interest for treating drug dependence.

Amphetamine↗
PubMed2005

Dopamine-glutamate reciprocal modulation of release and motor responses in the rat caudate-putamen and nucleus accumbens of "intact" animals.

Functional interactions between dopaminergic neurotransmission and glutamatergic neurotransmission are well known to play a crucial integrative role in the striatum, the major input structure of the basal ganglia now widely recognized to contribute to the control of motor activity and movements but also to the processing of cognitive and limbic functions. However, the nature of these interactions is still a matter of debate and controversy. This review (1) summarizes anatomical data on the distribution of dopaminergic and glutamatergic receptors in the striatum-accumbens complex, (2) focuses on the dopamine-glutamate interactions in the modulation of each other's release in the striatum-accumbens complex, and (3) examines the dopamine-glutamate interactions in the entire striatum involved in the control of locomotor activity. The effects of dopaminergic and glutamatergic receptor selective agonists and antagonists on dopamine and glutamate release as well on motor responses are analyzed in the entire striatum, by reviewing both in vitro and in vivo data. Regarding in vivo data, only findings from focal injections studies in the nucleus accumbens or the caudate-putamen of "intact" animals are reviewed. Altogether, the available data demonstrate that dopamine and glutamate do not uniformly interact to modulate each others' release and postsynaptic modulation of striatal output neurons. Depending on the receptor subtypes involved, interactions between dopaminergic and glutamatergic transmission vary as a multiple and complex combination of tonic, phasic, facilitatory, and inhibitory properties.

Animals↗
PubMed2005

5-Hydroxytryptamine 1A receptors, major depression, and suicidal behavior.

BACKGROUND: Several lines of evidence suggest a clear relationship between serotonin (5-hydroxytryptamine, 5-HT) hypoactivity and suicidal behavior across several psychiatric diagnoses. Few data are available, however, regarding the possible specific role of 5-HT1A receptors in the biology of suicidality. Therefore, the aim of our study was to use a neuroendocrine strategy to test the hypothesis of a role for 5-HT1A receptors in the biology of suicidal behavior. METHODS: Hormonal (adrenocorticotropic hormone [ACTH], cortisol, prolactin [PRL]) and temperature responses after administration of flesinoxan, a highly potent and selective 5-HT1A receptor full agonist, were assessed in 40 inpatients with major depression, divided into two subgroups (20 suicide attempters and 20 nonattempters), compared with 20 normal control subjects matched for gender and age. RESULTS: Compared with nonattempters, suicide attempters exhibited significantly lower PRL (p = .01), cortisol (p = .014), and temperature (p = .0002) responses. Prolactin (p = .007), cortisol (p = .04), and temperature (p = .00003) responses were also decreased in suicide attempters compared with normal control subjects. In contrast, we did not observe any significant differences in hormonal or temperature responses to flesinoxan between depressed patients without a history of suicide attempt and normal control subjects. CONCLUSIONS: The present study tends to confirm the role of 5-HT and more specifically 5-HT1A receptors in the biology of suicidal behavior in major depression.

Adrenocorticotropic Hormone↗
PubMed2005

Prevalence and impact of generalized anxiety disorder and major depression in primary care in Belgium and Luxemburg: the GADIS study.

PURPOSE: GADIS aims at determining the prevalence of generalized anxiety disorder (GAD) and major depression (MD) in primary care and their impact on the patient's functioning in Belgium and Luxemburg. METHOD: A large scale screening program was conducted at the consultation of general practitioners to detect patients with GAD and MD according to DSM-IV criteria. We collected additional data regarding the use of hypnotic, tranquilizer, antidepressant and analgesic medications. Impact on the patient was assessed with the Sheehan disability scale. RESULTS: Three hundred GP's in Belgium and Luxemburg were asked to screen 50 consecutive patients. Of the 13,677 analyzed patients, 8.3% were diagnosed to have GAD and 6.3% MD. Comorbidity was observed in 4.2% of patients. The prevalence was much higher in the French-speaking part of Belgium. GAD and MD were associated with impairment in social, familial and professional functioning. Only a minority of patients with GAD and/or MD was treated with an antidepressant and almost half of subjects with GAD and/or MD were treated with a tranquilizer. CONCLUSION: Prevalence rates of GAD and MD in primary care in Belgium are comparable to other countries. GAD and MD are disabling conditions. Antidepressants are still used only in a minority of subjects with GAD and/or MD in primary care in Belgium and Luxemburg. The prevalence of GAD and MD appears to be much higher in French-speaking parts of Belgium.

Analgesics, Non-Narcotic↗
PubMed2004

Impact of low frequency transcranial magnetic stimulation on event-related brain potentials.

Contradictory findings exist concerning the inhibitory function of low frequency repetitive transcranial magnetic stimulation (rTMS). Therefore, the study examines the impact of different duration of low frequency rTMS on ERPs. In 17 subjects, auditory ERPs were measured before and after 1 Hz rTMS delivered over the left prefrontal cortex during 10 min (600 pulses) and 15 min (900 pulses). Results showed that 15 min of 1 Hz rTMS induced a significant increase of P300 latency. There was no effect for early ERP components (N100, P200 and N200). This study confirms and extends that 1 Hz rTMS produces a real inhibitory effect only when the duration of the stimulation is about 15 min. The data suggest that rTMS modifies the speed of cognitive processing rather than the energetical aspect of information processing, and that cortical inhibition induced by the magnetic stimulation affects principally the controlled cognitive processes and not the automatic ones.

Adolescent↗
PubMed2004

Hormonal and temperature responses to flesinoxan in normal volunteers: an antagonist study.

RATIONALE: Flesinoxan is a highly potent and selective 5-HT1A agonist. In a recent study, in normal volunteers, flesinoxan induced a significant and dose-dependent increase in adrenocorticotropic hormone (ACTH), cortisol, prolactin (PRL), growth hormone (GH) and a decrease in body temperature. OBJECTIVES: In order to better define the role of 5-HT receptor subtypes in response to flesinoxan, we assessed the influence of 5-HT1A and 5-HT2 antagonists on hormonal and temperature responses to flesinoxan. METHODS: Hormonal and temperature responses were studied in 6 volunteers with or without pretreatment with pindolol (30 mg p.o.), a 5-HT1A antagonist, or ritanserin (10 mg p.o.), a selective 5-HT2 antagonist, using a double-blind crossover design. RESULTS: Pindolol significantly antagonized ACTH, PRL, GH and temperature responses to flesinoxan and ritanserin exhibited similar activity on PRL and ACTH responses. CONCLUSIONS: These results show the role of 5-HT1A mechanisms in the PRL, ACTH, GH, and temperature responses to flesinoxan, and the role of 5-HT2 mechanisms in PRL and ACTH responses. Therefore, they confirm the interest of flesinoxan as a 5-HT neuroendocrine probe.

Adrenocorticotropic Hormone↗
PubMed2003

Polymorphisms in the CYP 2D6 gene: association with plasma concentrations of fluoxetine and paroxetine.

Most antidepressants are metabolized by cytochrome P450 (CYP) 2D6, and it is well known that there may be significant interindividual variation in the capacity to metabolize xenobiotics. About 7 to 10% of whites are poor metabolisers (PM), and, on the contrary, about 5% are ultrarapid metabolizers (UM), inducing very different rates in the transformation of antidepressants extensively metabolized by CYP 2D6. CYP 2D6 polymorphism can be a potential risk factor for the development of side effects or a reason for the poor efficacy of the treatment. Various probe drugs may be used for phenotyping CYP 2D6, but genotyping is now available using leukocyte DNA and is independent of concomitant drug use. In this study, we used PCR-based methods for the identification of CYP 2D6 genotypes in 49 patients receiving standard doses of fluoxetine or paroxetine and found that plasma concentration of the antidepressant drugs was significantly correlated with genetic status. In one patient who displayed CYP 2D6 gene duplication (UM), paroxetine plasma concentration was extremely low. In PM fluoxetine-treated patients, drug plasma concentration was significantly higher than that seen in extensive metabolizers.

Adult↗
PubMed2003

Catecholamine and HPA axis dysfunction in depression: relationship with suicidal behavior.

A large body of evidence suggests a potential role for catecholaminergic function as a possible biological factor in the control of suicidal behavior. Recently, we have used a neuroendocrine strategy to study dopaminergic and noradrenergic activities in depressed suicide attempters. However, some problems are associated with the use of growth hormone (GH) response to catecholaminergic challenge, because GH release could be decreased by a direct effect of corticosteroids at the pituitary level. Therefore, the purpose of the present study was to assess GH response to both apomorphine, a dopaminergic agonist, and clonidine, an alpha2-adrenergic agonist, according to the dexamethasone suppression test (DST) status in a sample of 20 major depressed inpatients with a history of suicide attempt compared with nonattempters. Our results tended to show that hypercortisolemia as assessed by post-DST cortisol values did not inhibit GH response to apomorphine or clonidine, suggesting that hypothalamo-pituitary-adrenal axis overactivity does not explain the impaired GH response to apomorphine in major depressed patients with a history of suicide attempt.

Adrenergic alpha-Agonists↗
PubMed2003

Event-related potentials to emotional and neutral stimuli in alcoholism.

Several studies have demonstrated that the emotional value of stimuli affects P300 amplitude. In the present study, the influence of alcohol-related stimuli in alcoholic patients was investigated. Subjects were 10 alcoholic inpatients (3 female) and 10 age- and sex-matched controls. Eight alcohol-related and 8 neutral words served as stimuli in a visual oddball paradigm. Acohol-related words were targets (48 stimuli, 33%) and neutral words were standard stimuli (96 stimuli, 66%). Results showed that P300 amplitude for targets did not differ significantly between the two groups. However, P300 latency for targets as well as reaction time were significantly shorter in male alcoholic patients. In contrast, P300 latency was increased in female alcoholic patients but reaction time did not differ. These results suggest that male alcoholics process information linked to alcohol cues more rapidly than neutral cues, probably because a specific semantic network is activated in these patients. The decreased reaction time confirms the impulsive behavior frequently found in male alcoholism, as it has been described in type II alcoholism. Besides, the results imply that information processing was delayed in female alcoholic patients. Therefore this study demonstrates a gender-dependent impact of alcohol-related stimuli on information processing.

Adult↗
PubMed2002

Hormonal and temperature responses to the 5-HT1A receptor agonist flesinoxan in normal volunteers.

RATIONALE: Flesinoxan is a highly potent and selective 5-HT(1A) agonist and appears to be a potentially interesting neuroendocrine serotonergic probe. OBJECTIVES: We assessed hormonal (ACTH, cortisol, prolactin and growth hormone) and temperature responses to flesinoxan in normal volunteers. METHODS: In a double-blind placebo-controlled study, single doses of 0.5 mg and 1 mg were injected over 10 min into 12 healthy male volunteers at 1-week intervals. Temperature and hormonal responses were measured at times -30, 0, 15, 30, 60, 90, and 120 min. RESULTS: Flesinoxan induced a significant and dose-dependent increase in adrenocorticotropic hormone (ACTH), cortisol, prolactin (PRL), growth hormone (GH) and a decrease in body temperature. Tolerance to flesinoxan was excellent. CONCLUSIONS: These results showed the role of 5-HT(1A) mechanisms in the PRL, ACTH, cortisol, GH, and temperature responses to flesinoxan. In the present study, flesinoxan appears a very promising serotonergic neuroendocrine probe.

Adult↗
PubMed2001

Tianeptine and paroxetine in major depressive disorder, with a special focus on the anxious component in depression: an international, 6-week double-blind study dagger.

Tianeptine (37.5 mg/day) and paroxetine (20 mg/day) were compared in a population of depressive patients without past or current history of co-morbid anxiety and/or important anxiolytic treatment. In a 6-week, double blind trial, the special focus was on anxious symptoms.Both drugs showed good efficacy on depressive symptomatology, assessed with MADRS and HDRS, but no difference was detected between tianeptine and paroxetine, for any assessment criterion. Despite the choice of selected depressive patients, without any co-morbid anxious disorder, anxiety scale scores at inclusion (HAMA and BAS) were appreciable but correlated poorly with depressive scores. Both tianeptine and paroxetine improved the apparent anxious component in depression. Tolerability of both drugs was good, although significantly better with tianeptine.Thus tianeptine and paroxetine are effective and safe treatments for major depression and may also act directly on the anxious component of the psychopathology. Copyright 2001 John Wiley & Sons, Ltd.

Journal Article↗