Biomedical subjects

A Adell

Publications and source records attributed to A Adell.

27 records · Page 2Linked to original sources

PubMed1991

Regional distribution of extracellular 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in the brain of freely moving rats.

The extracellular concentrations of 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) have been determined in six brain areas of awake rats (frontal cortex, striatum, hypothalamus, hippocampus, inferior colliculus, and raphe nuclei) using intracerebral microdialysis. The extracellular levels of 5-HT showed no significant differences among the brain regions studied. The tissue levels of 5-HT and 5-HIAA as well as the extracellular concentration of 5-HIAA were significantly higher in raphe nuclei. The regional distribution of tissue and extracellular 5-HIAA were very similar, suggesting that extracellular 5-HIAA depends mainly on the output from the intracellular compartment. On the other hand, extracellular 5-HT and tissue 5-HT showed a different distribution pattern. The tissue/extracellular ratio for 5-HT ranged from 739 in frontal cortex to 2,882 in raphe, whereas it only amounted to 1.8-3.6 for 5-HIAA. The relationship between the present results and the density of 5-HT uptake sites in these areas is discussed.

Animals↗

PubMed1990

Non-specific inhibition of imipramine binding argues against an endogenous ligand.

We have attempted to characterize the product(s) inhibiting [3H]imipramine binding from rat cortical membranes. Fractions inhibiting [3H]imipramine binding were analysed by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography-mass spectrometry (HPLC-MS). Tissue extracts showed marked inhibitory activity (two different peaks); however, extracts containing no brain tissue (blanks) also exhibited inhibitory activity (one peak after HPLC pre-purification). The chemical composition of the compound that inhibited [3H]imipramine binding was identical in both cases (tissue and blank extracts) and consisted of zinc chelates, probably formed by the use of zinc sulfate during the extraction procedure. The second inhibitory peak in the tissue extracts was 5-hydroxytryptamine (serotonin, 5-HT). These results suggest that the inhibitory activity on [3H]imipramine binding attributed to a low-molecular weight putative endacoid is non-specific and due to ions introduced in the sample during purification.

Animals↗

PubMed1989

Chronic administration of clomipramine prevents the increase in serotonin and noradrenaline induced by chronic stress.

The effects of chronic clomipramine administration (15 mg/kg daily for 23 days) on changes in serotonin (5-hydroxytryptamine, 5-HT), 5-hydroxyindoleacetic acid (5-HIAA) and noradrenaline (NA) induced by chronic stress have been studied in the rat brain. Chronic stress increased 5-HT in midbrain, pons and hippocampus, 5-HIAA in frontal cortex, midbrain, pons and hippocampus, and NA in midbrain and striatum. Chronic clomipramine significantly decreased the levels of 5-HT in most regions. In hypothalamus, hippocampus and perhaps in frontal cortex this effect possibly reflects decreased synthesis caused by an action on presynaptic 5-HT receptors. However, in midbrain, pons and striatum decreased 5-HT could not be attributed to a decrease in its synthesis since 5-HIAA also increased. This drug treatment also reduced NA in all regions except the striatum. Nevertheless, conclusions on NA synthesis or turnover cannot be drawn since only NA levels were measured. When administered concurrently, chronic clomipramine prevented the increases in 5-HT, 5-HIAA and NA produced by chronic stress. These results are in good accordance with previous findings showing that chronic antidepressant treatment also prevented behavioural disturbances induced by chronic stress.

Animals↗

PubMed1989

An in vivo dialysis and behavioural study of the release of 5-HT by p-chloroamphetamine in reserpine-treated rats.

1. Reserpine (2.5 mg kg-1 i.p.) decreased rat brain 5-hydroxytryptamine (5-HT) by 86% 24 h later but most components of the 5-HT-dependent behavioural syndrome induced by p-chloroamphetamine (PCA, 5 mg kg-1 i.p.) or 5-methoxy-N,N-dimethyltryptamine (5-MeODMT, 5 mg kg-1 i.p.) over 1 h after administration were unaffected. However, Straub tail was increased after giving PCA or 5-MeODMT and head weaving was decreased after giving 5-MeODMT. 2. Frontal cortex extracellular 5-HT concentrations of vehicle pretreated rats before injection of PCA, as calculated from dialysate 5-HT concentrations, were about 1/1000th of corresponding brain values. Extracellular 5-hydroxyindoleacetic acid (5-HIAA) and brain values were comparable with each other. Dialysate 5-HT increased after PCA with peak values at 20-40 min. 3. Reserpine pretreatment reduced dialysate 5-HT concentration before PCA was given but the net increase (AUC) over the 1 h after PCA did not differ significantly from that seen in animals pretreated with vehicle. Dialysate 5-HIAA values slowly decreased after PCA injection in both reserpine and vehicle pretreated groups. 4. The results suggest that PCA causes the 5-HT syndrome by releasing 5-HT from the neuronal cytoplasm but that physiological release of 5-HT occurs from vesicular stores.

Amphetamines↗

PubMed1988

Time course of changes in serotonin and noradrenaline in rat brain after predictable or unpredictable shock.

The effects of predictable and unpredictable shock on concentrations of serotonin (5-hydroxytryptamine, 5-HT), 5-hydroxyindoleacetic acid (5-HIAA), tryptophan (TP) and noradrenaline (NA) have been studied in 7 regions of rat brain. Two separate experiments have been carried out determining these substances both at 30 min and 2 h after the stress session. Unpredictable shock depleted NA levels in all brain regions except the striatum. However, at 2 h poststress NA in these regions increased significantly in comparison with both controls and predictably shocked rats. Predictable shock also decreased NA in locus coeruleus, brainstem and hypothalamus, which was not observed 2 h later. Both predictable and unpredictable shock decreased 5-HT in brainstem and hypothalamus. At 2 h poststress, 5-HT levels in these regions were still decreased in predictably shocked rats, but had attained control values in unpredictably shocked rats. 5-HT metabolism expressed as the 5-HIAA/5-HT ratio, was significantly increased 30 min after predictable shock in all regions except the locus coeruleus and hippocampus. Unpredictable shock produced a much more marked increase in 5-HIAA/5-HT ratio. At 2 h poststress 5-HT metabolism returned to control values in most of the brain regions of predictably shocked animals, but it remained high after unpredictable shock. The activation of serotonergic metabolism following each type of shock is different according to the nucleus in which the 5-HT nerve endings originate. Only slight increases in tryptophan were observed after both types of shock. Our results suggest that unpredictable shock is perceived as a more anxiogenic situation and that under this condition both 5-HT and NA levels are more effectively normalized with time.

Animals↗

PubMed1988

Chronic stress increases serotonin and noradrenaline in rat brain and sensitizes their responses to a further acute stress.

The effects of 1 h/day restraint in plastic tubes for 24 days on the levels of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), tryptophan (TP), and noradrenaline (NA) in six regions of rat brain 20 h after the last restraint period were investigated. The levels of 5-HT, 5-HIAA, and NA but not TP increased in several regions. The effects of 1 h of immobilization on both control and chronically restrained rats were also studied. Immobilization per se did not alter brain 5-HT, 5-HIAA, and TP levels, but decreased NA in the pons plus medulla oblongata and hypothalamus. However, immobilization after chronic restraint decreased 5-HT, increased 5-HIAA, and decreased NA in most brain regions in comparison with values for the chronically restrained rats. We suggest that chronic restraint leads to compensatory increases of brain 5-HT and NA synthesis and sensitizes both monoaminergic systems to an additional acute stress. These changes may affect coping with stress demands.

Animals↗

PubMed1986

Quantitation of total MHPG in the rat brain using a non enzymatic hydrolysis procedure. Effects of drugs.

An acid-catalyzed procedure has been used to hydrolyze MHPG-sulfate in homogenates of rat brain. The samples (in 0.4 mol/L perchloric acid) are treated for 3 min. at 100 degrees C in a water bath and aliquots are injected into a reversed phase HPLC system. Detection is achieved fluorimetrically. The absolute detection limit for MHPG is 150 pg, which allows the reliable determination of either free or total MHPG in rat brain in concentrations down to 15 ng/g, using the described procedure. The concentration of total MHPG found in the brains of saline-treated rats are 101 +/- 21 ng/g (mean +/- S.D.) which is in a good accordance with the concentration value for the same samples obtained using a GC-MS method (115 +/- 19 ng/g). Rats treated with clonidine (300 micrograms/Kg, i.p.) or yohimbine (10 mg/Kg, i.p.) showed brain concentrations of total MHPG of 68 +/- 22 ng/g and 299 +/- 85 ng/g, respectively. The utility of this method for the analysis of brain regions or brain nuclei (e.g. locus coeruleus) is also shown.

Animals↗

PubMedDate not supplied

Comparative study in the rat of the actions of different types of stress on the release of 5-HT in raphe nuclei and forebrain areas.

The effects of several stress procedures on the release of 5-HT in the dorsal and median raphe nuclei (DRN and MRN, respectively) and in forebrain structures of the rat brain innervated by both nuclei have been studied using intracerebral microdialysis. Handling for 30 sec, a saline injection and forced swimming for 5 min elevated significantly the 5-HT output in the MRN. The 5-HT output in the DRN was also enhanced by a saline injection. With regard to the forebrain structure examined, handling and forced swimming increased dialysate 5-HT in the amygdala. The injection of saline induced a slight, but significant, elevation of 5-HT in the medial prefrontal cortex. In contrast, the outflow of 5-HT was significantly reduced in the ventral hippocampus and medial prefrontal cortex following forced swimming and this effect persisted well beyond the cessation of the swim session. These results indicate that the efflux of 5-HT in the MRN appears to respond to different forms of stress, whereas that in the DRN only increases after the injection of saline. The release of 5-HT in the forebrain structures is also dependent on the type of stress procedure and the region studied.

Animals↗

PubMedDate not supplied

Communication during prosthodontic treatment--dentist, patient, and dental nurse.

PURPOSE: This study described and explored verbal communication during prosthodontic treatment. MATERIALS AND METHODS: Sixty-one patients and 15 dentists participated. Sixty-one prosthetic treatment periods, during which fixed tooth- or implant-supported prostheses were placed, were followed. One visit during each treatment period was audio recorded. The recorded verbal communication was analyzed with the Roter Interaction Analysis System-dental. The inter-rater reliability was 95% to 97% for utterance classification and kappa = 0.71 to 0.78 for categorization definition. RESULTS: There were 43,663 utterances available for analysis. Of those, 59% was dentist communication, 28% was patient communication, and 10% was dental nurse communication. Other persons, e.g., dental technicians, contributed with 3%. The dentist-patient communication contained more task-focused than socioemotional behaviors. Female patients used socioemotional talk to a greater extent than did the male patients. Dentists and patients of different genders communicated more overall, especially male dentists with female patients. The age difference between dentist and patient had no effect on the amount or type of communication. The dental nurse talked slightly more with male patients. CONCLUSION: When different genders met there was more communication, and the talk was more socioemotional when the patient was female.

Adult↗