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A Deslandes

Publications and source records attributed to A Deslandes.

11 recordsLinked to original sources
PubMed2000

Effects of acute and chronic tianeptine administration on serotonin outflow in rats: comparison with paroxetine by using in vivo microdialysis.

Using in vivo microdialysis, we compared the effects of tianeptine (an antidepressant drug which, in marked contrast with other antidepressants, is thought to increase the uptake of serotonin (5-hydroxytryptamine, 5-HT) on extracellular 5-HT concentrations ([5-HT](ext)) in the frontal cortex and raphe nuclei of freely moving rats with those of paroxetine, a potent selective serotonin reuptake inhibitor. A single paroxetine dose (1 mg/kg, i.p.) increased [5-HT](ext) over baseline in the frontal cortex and raphe nuclei, respectively. A single administration of tianeptine (10 mg/kg, i.p.) did not change [5-HT(ext)] in the two brain regions studied. Repeated exposure to paroxetine (0.5 mg/kg) b.i.d. for 14 days induced a sixfold significant increase in basal [5-HT](ext) in the raphe nuclei. Administration of tianeptine (5 mg/kg) b.i.d. for 14 days did not affect 5-HT baseline concentrations. In rats chronically treated with either paroxetine or tianeptine, drug challenge did not alter area under the curve values. Thus, our in vivo data indicate that tianeptine and paroxetine do not exert a similar in vivo effect on the serotonergic system in rat brain.

Animals↗
PubMed1999

Effects of antidepressants and benzodiazepine treatments on the dendritic structure of CA3 pyramidal neurons after chronic stress.

Both repeated stress and corticosterone administration induce remodeling of apical dendrites of hippocampal CA3 pyramidal neurons. Circulating glucocorticoids are involved in the mechanism that produces atrophy, along with excitatory amino acids and serotonin (5-hydroxytryptamine, 5-HT). We used 5-HT-related antidepressants and a benzodiazepine in order to explore indirectly the role of serotonin and GABA(A)-benzodiazepine receptors in the stress-induced structural changes visualized by the Golgi impregnation of the rat hippocampus. The 5-HT reuptake enhancer (+/-)-tianeptine prevented the dendritic atrophy caused by repeated restraint stress in a non-stereoselective fashion and two 5-HT reuptake antagonists, fluoxetine and fluvoxamine, failed to block dendritic atrophy. Tianeptine also functions as a therapeutic tool since it reversed the already established hippocampal atrophy caused by treatment with corticosterone for 3 weeks. Finally, the benzodiazepine agonist adinazolam was effective in preventing the stress-induced dendritic atrophy. These findings suggest that the synaptic availability of 5-HT is involved in the mechanism leading to stress-induced dendritic remodeling and supports the idea that the hippocampal inhibitory GABAergic tone may play a regulatory role.

Animals↗
PubMed1999

Although chemically related to amineptine, the antidepressant tianeptine is not a dopamine uptake inhibitor.

We investigated whether the antidepressant tianeptine shares the dopamine uptake inhibitory properties of the chemically related antidepressant amineptine. Tianeptine dose dependently (5, 10, 20, 40 mg/kg IP) increased locomotor activity in mice. This stimulant effect (20 mg/kg IP) was dose dependently prevented not only by the D1 dopamine receptor antagonist SCH 23390 (7.5. 15, 30 microg/kg SC), but also by the D2 dopamine receptor antagonist haloperidol (50, 100, 200 microg/kg IP), in contrast to that elicited by dopamine uptake inhibitors. Where the latter prevent dexamphetamine-induced (3 mg/kg SC) reversion of akinesia in mice pretreated with reserpine (4 mg/kg SC, 5 h before test), tianeptine (20 mg/kg IP, 30 min before test) did not. Tested up to a concentration of 10-4 M, tianeptine did neither inhibit the [3H]dopamine uptake into mouse striatal synaptosomes nor compete in vitro with the specific binding of [3H]WIN 35,428 at dopamine transporters from striatal membranes. Finally, in mice injected IV with a tracer dose of [3H]WIN 35,428 (1 microCi), the highest tested dose of tianeptine (40 mg/kg IP) did not reduce the specific binding of the radioligand to striatal dopamine transporters. It is concluded that the antidepressant effect of tianeptine does not depend upon a blockade of the neuronal dopamine transporter.

Animals↗
PubMed1996

Effects of nifedipine and diltiazem on pharmacokinetics of cefpodoxime following its oral administration.

We compared the effects of nifedipine and diltiazem on the uptake of cefpodoxime proxetil (CP). The study was aimed at establishing the impact of increased mesenteric blood flow due to calcium channel blockers on passive transport. Twelve volunteers were given CP (200 mg) orally in a crossover design. The absorption, disposition, and elimination parameters of cefpodoxime were compared among the following three treatment groups: CP alone, CP following oral administration of diltiazem (60 mg), or CP following oral administration of nifedipine (20 mg). No statistically significant difference in pharmacokinetic parameters was observed between the three treatment groups.

Administration, Oral↗
PubMed1994

High-performance liquid chromatographic method for the determination of cefpodoxime levels in plasma and sinus mucosa.

A selective HPLC method is described for the determination of cefpodoxime levels in plasma and sinus mucosa. Sample preparation included solid-phase extraction with a C8 cartridge. Cefpodoxime and cefaclor (internal standard) were eluted with methanol and analyzed on an optimised system consisting of a C18 stationary phase and a ternary mobile phase (0.05 M acetate buffer pH 3.8-methanol-acetonitrile, 87:103, v/v) monitored at 235 nm. Linearity and both between- and within-day reproducibility were assessed for plasma and sinus mucosa samples. Inter-assay coefficients of variation were lower than 13.6% (n = 10) for plasma (0.2 micrograms/ml) and lower than 12.4% (n = 5) for sinus mucosa (0.25 micrograms/g). The quantification limit was 0.05 micrograms/ml for plasma and 0.13 micrograms/g for tissue. The method was used to study the diffusion of cefpodoxime in sinus mucosa.

Ceftizoxime↗
PubMed1992

Adaptive computer program for determination of absorption profiles by numerical deconvolution: application to amoxicillin absorption.

We have developed a specific numerical deconvolution program for the Apple Macintosh microcomputer. After comparison with other methods, we used the program to evaluate the influence of nifedipine on the absorption and bioavailability of amoxicillin. The technique provided a model-independent approach. This study shows that the simultaneous administration of nifedipine with amoxicillin leads to a significant increase in both the total quantity of amoxicillin absorbed (+22%) and the rate of absorption. Parameters of clearance, volume of distribution, and elimination were unaffected. Numerical deconvolution analysis showed that nifedipine did not modify the absorption kinetics of amoxicillin, which are characterized by a lag time followed by a constant rate of absorption, suggesting zero-order kinetics with first-order kinetics at the end of the process. The results suggest the existence of a specialized, saturable transport molecule for this antibiotic.

Adult↗
PubMed1992

Modification of cefixime bioavailability by nifedipine in humans: involvement of the dipeptide carrier system.

We studied the action of nifedipine on the bioavailability of cefixime, a molecule absorbed via the gut wall dipeptide carrier system in the rat, and on the bioavailability of D-xylose, which is absorbed via a pH (and Na(+)-)-dependent transporter. Each compound was administered alone or in combination with 20 mg of nifedipine to eight healthy male volunteers. Nifedipine significantly increased the absorption rate of cefixime (20.7 +/- 4.3 versus 16 +/- 3.5 mg/h in the absence of nifedipine). The absolute bioavailability of cefixime alone was 31% +/- 6% compared with 53% +/- 1% (P < 0.01) in the presence of nifedipine. The observed peak concentrations in serum were significantly different (2.5 +/- 0.3 mg/liter without nifedipine and 3.7 +/- 1.1 mg/liter with nifedipine; P < 0.02). In contrast, nifedipine induced no significant differences in the pharmacokinetic profile of xylose following oral administration. We conclude that (i) cefixime is absorbed in humans by an apparently active process which can be enhanced by a calcium channel blocker, in this case, nifedipine; and (ii) nifedipine does not modify the activity of the pentose transporter.

Administration, Oral↗
PubMed1991

Reappraisal of amoxycillin absorption kinetics.

Interest in the intestinal absorption mechanisms of drugs has increased because transepithelial passage across the gut does not necessarily follow a passive diffusion process. Amoxycillin, like other amino-beta-lactam antibiotics, has been demonstrated in vitro to use the dipeptide carrier-mediated system in rodent small intestine. In order to assess the in-vivo relevance of these data, we applied the Loo-Riegelman method for a reappraisal of amoxycillin absorption kinetics in healthy human volunteers. The results showed evidence of a saturable carrier-mediated uptake of this antibiotic. With respect to the in-vitro data previously published, the dipeptide carrier system would appear to be the most likely transport mechanism.

Administration, Oral↗
PubMed1990

Nifedipine enhances amoxicillin absorption kinetics and bioavailability in humans.

Intestinal absorption of aminopenicillins in vitro uses the dipeptide carrier system. Recent experiments have reported calcium ion to be a cellular mediator of the regulation of electrolyte transport through the enterocyte membrane, especially the Na/H exchange which is partly responsible for the proton gradient energizing the carrier system. In order to assess the in vivo relevance of these data, we studied, in healthy volunteers, the influence of nifedipine, a calcium channel blocking agent, on the intestinal uptake of amoxicillin, a commonly prescribed and well-absorbed aminopenicillin. Results obtained show that 1) intestinal absorption kinetics of amoxicillin follows a zero-order process, which further substantiates the existence of a saturable carrier-mediated process for this antibiotic in humans and 2) calcium channel blockade significantly enhances both absorption rate (by 70%) and bioavailability of amoxicillin (by 21.4%) without modifying its distribution or elimination. These findings might suggest that nifedipine could enhance amoxicillin intestinal uptake by stimulating its active transport.

Adult↗
PubMedDate not supplied

[Comparison of the effects of tianeptine and paroxetine on amnesic deficits induced by prolonged alcohol drinking in mice].

Previous experiments have shown that chronic ethanol consumption in mice for 12 months produced memory deficits associated with both alterations in diencephalic structures (ie, cellular loss, hypometabolism, particularly in mamillary bodies) and with hippocampal and cortical cholinergic hypofunction (Béracochéa et al., Pharmacol Biochem Behav 1992; 42: 749-53). The present study was aimed at comparing the effects of tianeptine and paroxetine (10 mg.kg-1, i.p.), that have opposite properties on serotoninergic transmission, on this alcohol-induced memory deficits. For this purpose, animals were submitted to a T-maze sequential alternation task in which they were given daily series of 6 successive trials separated by a 30-second interval. Behavioural testing began following a 4-week complete withdrawal period. The experiment was conducted in two steps. In the first part, animals received no treatment. Results showed that, as compared to the control group (pair-fed, n = 7), alcohol-treated mice (n = 20) displayed a trial-specific impairment of alternation rates. Specifically, they were impaired on the last three trials (4-6) of the series (52.2 vs 81.0%, p < 0.001), but performed normally on the first ones (2-3), suggesting thereby an increased sensitivity to proactive interference (Béracochéa et al., Behav Brain Res 1987; 25: 63-74). In the second part of the experiment the alcohol group was divided into three homogeneous groups according to the treatment they received 30 minutes before each daily session (ie, placebo, tianeptine, paroxetine).(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Amnestic Disorder↗