Biomedical subjects

G Giannaccini

Publications and source records attributed to G Giannaccini.

At least 19 recordsLinked to original sources

PubMed2006

Peripheral benzodiazepine receptors on platelets of fibromyalgic patients.

OBJECTIVE: The aim of the present study was to analyze if alterations of peripheral-type benzodiazepine receptor (PBR) characteristics occurred in platelet membranes of patients affected by primary fibromyalgia (FM). DESIGN AND METHODS: Platelets were obtained from 30 patients with FM. Evaluation of kinetic parameters of PBR was performed using [(3)H] PK11195 as specific radioligand compared with 16 healthy volunteers. RESULTS: The results showed a significant increase of PBR binding sites value in platelet membranes from FM patients (B(max) was 5366+/-188 fmol/mg vs. controls, 4193+/-341 fmol/mg, mean+/-SEM) (**p<0.01) but not for affinity value (K(d) was 4.90+/-0.39 nM vs. controls, 4.74+/-0.39 nM, mean+/-SEM) (p>0.05). Symptom severity scores (pain and tiredness) were positively correlated with B(max). CONCLUSIONS: Our results showed an up-regulation of PBR in platelets of FM patients, and this seems to be related to the severity of fibromyalgic symptoms.

Blood Platelets↗

PubMed2006

Common alterations in the serotonin transporter in platelets and lymphocytes of psychotic patients.

INTRODUCTION: Given the controversial data concerning the role of the serotonin (5-HT) transporter in psychosis, our study was aimed to investigate this structure by means of the measurements of the re-uptake kinetics and of the protein density, in both platelets and lymphocytes of 25 out- and inpatients with different psychotic disorders. METHODS: Diagnoses, according to DSM-IV criteria, were bipolar 1 disorders with mood incongruent psychotic features (14), mixed states (7) and schizophrenia (4). Twenty-five matched healthy subjects were also selected as the control group. Platelet and lymphocyte membranes were prepared according to standardized protocols, as were the [3H]5HT re-uptake and [3H]paroxetine ([3H]Par) binding. RESULTS: The results of this study showed a decreased density of the [3H]Par binding sites coupled with a reduced velocity of [3H]5-HT re-uptake in both platelets and lymphocytes of psychotic patients, as compared with healthy control subjects. CONCLUSION: These findings would suggest a general abnormality of the 5-HT system in psychotic patients, probably not confined only to the brain.

Adult↗

PubMed2004

In vitro effects of lead ions on peripheral benzodiazepine receptors and adenylyl cyclase activity in the mantle of Mytilus galloprovincialis.

As an extension of our previous work, where the density of peripheral benzodiazepine receptors (PBR) increased in mantle mitochondria of the marine mollusk Mytilus galloprovincialis Lmk. under chronic exposure to lead, the present study investigates the in vitro effects of an exogenous source of lead ions on PBR and on adenylyl cyclase (AC) complex in mantle membranes of mussels collected from a non-polluted coastal area. PBR binding experiments used the specific isoquinoline carboxamide derivative [3H]PK 11195, and AC activity was measured using a modified procedure adapted to M. galloprovincialis. Lead ions (Pb2+) dose-dependently decreased either the [3H]PK 11195 specific binding in mitochondria or basal AC velocity in plasma membranes of mussel mantle. The IC50 values for lead ions were 10 microM with [3H]PK 11195 binding and 25 microM with AC activity, with maximal inhibition values of 60% and 70%, respectively. Moreover, lead behaved as a non-competitive inhibitor on [3H]PK 11195 binding and as a 'mixed' inhibitor on AC activity. The present results suggest that some of the early effects induced by lead in mussel cell metabolism consist in significant changes of the PBR density and cyclic AMP production in the mantle of M. galloprovincialis.

Adenylyl Cyclases↗

PubMed2001

Decreased platelet [3H]paroxetine binding sites in suicide attempters.

Research to date would suggest the possible involvement of the serotonin (5-HT) system in the pathophysiology of suicide. With this study, we aimed to investigate the platelet 5-HT transporter, by means of the specific binding of tritiated paroxetine ([3H]Par), in a sample of 20 suicide attempters recruited at a first-aid service, as compared with healthy control subjects and psychiatric patients with no current or previous history of suicide attempt. The results, showing a decreased number of [3H]Par binding sites in suicide attempters, would suggest the involvement of the presynaptic 5-HT transporter in self-aggressive behavior.

Adolescent↗

PubMed2001

Synthesis, biological evaluation, and pharmacophore generation of new pyridazinone derivatives with affinity toward alpha(1)- and alpha(2)-adrenoceptors.

A series of new pyridazin-3(2H)-one derivatives (3 and 4) were evaluated for their in vitro affinity toward both alpha(1)- and alpha(2)-adrenoceptors by radioligand receptor binding assays. All target compounds showed good affinities for the alpha(1)-adrenoceptor, with K(i) values in the low nanomolar range. The polymethylene chain constituting the spacer between the furoylpiperazinyl pyridazinone and the arylpiperazine moiety was shown to influence the affinity and selectivity of these compounds. Particularly, a gradual increase in affinity was observed by lengthening the polymethylene chain up to a maximum of seven carbon atoms. In addition, compound 3k, characterized by a very interesting alpha(1)-AR affinity (1.9 nM), was also shown to be a highly selective alpha(1)-AR antagonist, the affinity ratio for alpha(2)- and alpha(1)-adrenoceptors being 274. To gain insight into the structural features required for alpha(1) antagonist activity, the pyridazinone derivatives were submitted to a pharmacophore generation procedure using the program Catalyst. The resulting pharmacophore model showed high correlation and predictive power. It also rationalized the relationships between structural properties and biological data of, and external to, the pyridazinone class.

Adrenergic alpha-Antagonists↗

PubMed2001

Simultaneous analysis of clozapine, clomipramine and their metabolites by reversed-phase liquid chromatography.

1. The authors present here a sensitive and rapid reversed-phase liquid chromatographic method which enables the simultaneous analysis in plasma of two different drugs and their metabolites: the atypical neuroleptic clozapine and the tricyclic antidepressant clomipramine. 2. Samples and the internal standard (dibenzepine) were extracted through automated solid-phase procedure, evaporated dryness and injected into the chromatograph. Mobile phase was a mixture of water and acetonitrile (63:37, v:v) containing TEMED and triethylamine. The total chromatographic time was of 14 min and analyte peaks were detected by means of an ultraviolet spectrophotometer preset at 254 nm. 3. Results revealed an assay sensitivity of 5 microg/L for clozapine or norclozapine and of 10 microg/L for clomipramine and desmethylclomipramine. Recoveries for these drugs and their metabolites were more than 60% and their coefficient of variation (within day and day-to-day) ranged from 1.3 % to 2.5 %. In spiked plasma, within day and day-to-day coefficients of variability (CV) were less than 5%. The simultaneous evaluation of these two drugs with adequate sensitivity and precision makes it particularly useful for therapeutic drug monitoring during mono- or polypharmacotherapy.

Antidepressive Agents, Tricyclic↗

PubMed2001

Structure-activity relationships in a series of 8-substituted xanthines as A1-adenosine receptor antagonists.

A series of 8-substituted xanthines were synthesized and their affinity in vitro towards A1, A2A-adenosine receptors was evaluated by radioligand receptor binding assays. All compounds showed a greater affinity and selectivity towards the A1-adenosine receptor than theophylline. The compounds in which the n-proyl group is in 1-position of the xanthine nucleus and the pyridazinone system in 8-position is linked through a chain of two or four carbon atoms, showed the highest affinity and selectivity.

Animals↗

PubMed2001

[3H]Ro 15-1788 binding sites to brain membrane of the saltwater Mugil cephalus.

The equilibrium binding parameters of the benzodiazepine antagonist [3H]Ro 15-1788 (8-fluoro-3-carboethoxy-5,6-dihydro-5-methyl-6-oxo-4H-imidazol-[1,5-a]-1,4 benzodiazepine) were evaluated in brain membranes of the saltwater teleost fish, Mugil cephalus. To test receptor subtype specificity, displacement studies were carried out by competitive binding of [3H]Ro 15-1788 against six benzodiazepine receptor ligands, flunitrazepam [5-(2-fluoro-phenyl)-1,3-dihydro-1-methyl-7-nitro-2H-1,4-benzodiazepin-2-one], alpidem [N,N-dipropyl-6-chloro-2-(4-chlorophenyl)imidazo[1,2-a]pyridine-3-acetamide], zolpidem [N,N-6 trimethyl-2-(4-methyl-phenyl)imidazo[1,2-a]pyridine-3-acetamide hemitartrate], and beta-CCM (methyl beta-carboline-3-carboxylate). Saturation studies showed that [3H]Ro 15-1788 bound saturatably, reversibly and with a high affinity to a single class of binding sites (Kd value of 1.18-1.5 nM and Bmax values of 124-1671 fmol/mg of protein, depending on brain regions). The highest concentration of benzodiazepine recognition sites labeled with [3H]Ro 15-1788 was present in the optic lobe and the olfactory bulb and the lowest concentration was found in the medulla oblongata, cerebellum and spinal cord. The rank order of displacement efficacy of unlabelled ligands observed suggested that central-type benzodiazepine receptors are present in one class of binding sites (Type I-like) in brain membranes of Mugil cephalus. Moreover, the uptake of 36Cl- into M. cephalus brain membrane vesicles was only marginally stimulated by concentrations of GABA that significantly enhanced the 36Cl- uptake into mammalian brain membrane vesicles. The results may indicate a different functional activity of the GABA-coupled chloride ionophore in the fish brain as compared with the mammalian brain.

Animals↗

PubMed2001

Distribution of [3H]GR65630 binding in human brain postmortem.

We investigated the distribution of serotonin (5-HT) receptors of type 3 (5-HT3) in human brain areas, by means of the the specific binding of [3H]GR65630. The brains were obtained during autoptic sessions from 6 subjects. Human brain membranes and the binding of [3H]GR65630 were carried out according to standardized methods. The highest density (Bmax +/- SD, fmol/mg protein) of [3H]GR65630 binding sites was found in area postrema (13.1+/-9.7), followed at a statistically lower level, by nucleus tractus solitarius (6.7+/-3.4), nervus vagus (5.5+/-2.1), striatum (4.8+/-2.4) with a progressive decrease in amygdala, olivar nuclei, hippocampus, olfactory bulbus and prefrontal cortex, and then by the other cortical areas and the cerebellum, where no binding was detected. These observations extend previous findings on the distribution of 5-HT3 receptors and confirm interspecies variations that might explain the heterogeneous properties of 5-HT3 receptors in different animals.

Aged↗

PubMed2001

Pharmacological characterization of the serotonin transporter in young and elderly subjects.

The potency of some tricyclics (imipramine and clomipramine) and selective 5-HT reuptake inhibitors (fluoxetine, paroxetine, and citalopram) in displacing the [(3)H]paroxetine binding to platelet membranes was measured in young and elderly subjects of both sexes. The results showed that the most potent compound in all subjects was paroxetine, followed by clomipramine, citalopram, fluoxetine, and imipramine, with no differences between male and female subjects. All drugs, except paroxetine and clomipramine, showed significantly lower pKi values in the elderly subjects of both sexes. These findings would suggest that although the pharmacological profile of the 5-HT transporter is not modified qualitatively by age, quantitative changes in its affinity do perhaps occur which would justify more careful studies on this topic in order to get optimal dosages of drugs acting at this level.

Adult↗

PubMed2001

Correlation between platelet alpha(2)-adrenoreceptors and symptom severity in major depression.

BACKGROUND: Abnormalities in different parameters of the norepinephrine system have been widely described in major depression. The presence of alpha(2)-adrenoreceptors in blood platelets, similar to those in the brain, prompted us to evaluate them in depressed patients, as compared with healthy controls. METHODS: Fifteen outpatients affected by major depression, according to DSM IV criteria, and 15 comparable healthy control subjects, were included in the study. The alpha(2)-adrenoreceptors were measured by means of the specific binding of [(3)H]rauwolscine, a highly selective antagonist for this receptor subtype. The severity of depression was assessed by means of the Hamilton Rating Scale for Depression (HRSD). RESULTS: The results did not show any difference in [(3)H]rauwolscine binding parameters (B(max) and K(d)) between patients and controls. However, in the patients, a significant and positive correlation between B(max), which measures the density of the receptors, and HRSD total score was detected. CONCLUSIONS: Therefore, although no change in alpha(2)-adrenoreceptors seems to occur in major depression, the density of these receptors would seem to be related to the severity of depressive symptoms.

Adult↗

PubMed2000

A novel class of highly potent and selective A1 adenosine antagonists: structure-affinity profile of a series of 1,8-naphthyridine derivatives.

A series of 1,8-naphthyridine derivatives (12-36), bearing a phenyl group in position 2 and various substituents in positions 4 and 7, were synthesized in an attempt to obtain potent, selective antagonists for the A1 adenosine receptor subtype. The compounds were tested to evaluate their affinity for A1 compared with A2A and A3 adenosine receptor subtypes. In binding studies in bovine brain cortical membranes, most of the compounds showed an affinity for A1 receptors in the low nanomolar range and two in the subnanomolar range with an interesting degree of A1 versus A2A and A3 selectivity. Comparison of the 4-substituted derivatives indicated that 4-OH substitution, with a 4-quinoid structure, causes an increase in the A1 and A2A affinity and generally also in A1 selectivity. The kind of substitution in position 7 can greatly modulate the affinity: the most interesting substituents in this position seemed to be electron-withdrawing groups; in particular the 7-chloronaphthyridine 25d showed a remarkable selectivity (A2A/A1 ratio of 670, A3/A1 ratio of 14,000) associated with a higher A1 affinity (Ki = 0.15 nM). NMR studies on these compounds 12-36 indicated that the 4-OH-substituted ones prefer the tautomer in which the oxygen in position 4 is in the quinoid form and the nitrogen in position 1 is protonated. Theoretical calculations are in agreement with the NMR data.

Adenylyl Cyclases↗

PubMed2000

Effect of noise exposure on rat cardiac peripheral benzodiazepine receptors.

Noise is an environmental physical agent, which is regarded as a stressful stimulus: impairment and modifications in biological functions are reported, after loud noise exposure, at several levels in human and animal organs and apparatuses, as well as in the endocrine, cardiovascular and nervous system. In the present study equilibrium binding parameters of peripheral benzodiazepine receptors (PBRs) labelled by the specific radioligand [3H]PK 11195, were evaluated in cardiac tissue of rats submitted to 6 or 12 h noise exposure and of rats treated "in vivo" with PBR ligands such as PK 11195, Ro54864, diazepam and then noise-exposed. Results revealed a statistically significant decrease in the maximum number of binding sites (Bmax) of [3H]PK 11195 in atrial membranes of 6 or 12 h noise exposed rats, compared with sham-exposed animals, without any change in the dissociation constant (Kd). The "in vivo" PBR ligand pre-treatment counteracted the noise-induced modifications of PBR density. As PBRs are mainly located on mitochondria we also investigated whether noise exposure can affect the [3H]PK 11195 binding parameters in isolated cardiac mitochondrial fractions. Results indicated a significant Bmax value decrease in right atrial mitochondrial fractions of rats 6 or 12 h noise-exposed. Furthermore, as PBR has been suggested to be a supramolecular complex that might coincide with the not-yet-established structure of the mitochondrial permeability transition (MPT)-pore, the status of the MPT-pore in isolated heart mitochondria was investigated in noise- and sham-exposed rats. The loss of absorbance associated with the calcium-induced MPT-pore opening was greater in mitochondria isolated from hearts of 6 h noise- than those of sham-exposed rats. In conclusion, these findings represent a further instance for PBR density decrease in response to a stressful stimulus, like noise; in addition they revealed that "in vivo" administration of PBR ligands significantly prevents this decrease. Finally, our data also suggest the involvement of MPT in the response of an organism to noise stress.

Animals↗

PubMed2000

Autoradiographic distribution of peripheral benzodiazepine receptors in the retina of the albino rabbit, Lepus cunicula.

The distribution of peripheral benzodiazepine receptors (PBRs) in the retina of the albino rabbit, Lepus cunicula, was studied by autoradiography using [3H]-PK11195, a isoquinoline carboxamide, as a tracer. Autoradiograms obtained by directly placing the slides containing the retina sections on tritium-sensitive film provide evidence for the presence of PBRs in rabbit retina. Furthermore, the dark field examination of photomicrographs taken from autoradiograms showed two dense horizontal bands corresponding to the outer and inner photoreceptor segments, and to the inner plexiform layer. The retinal regions where [3H]-PK11195 binding was more dense are rich in mitochondria, suggesting that as in other neuronal tissues, retinal PBRs are involved in the mitochondrial activity.

Animals↗

PubMed2000

Gender and age-related variation in adenylyl cyclase activity in the human prefrontal cortex, hippocampus and dorsal raphe nuclei.

The influence of gender and age on adenylyl cyclase activity was investigated, through a Dowex-alumina double step chromatographic procedure, in the prefrontal cortex, hippocampus and dorsal raphe nuclei obtained from autopsy cadavers. Results showed that forskolin-stimulated enzyme activity in raphe nuclei was greater in men than in women; a region-dependent rank order of basal, forskolin-induced adenylyl cyclase activity and percentage forskolin-stimulation was observed in women only. Lastly, basal values correlated positively with forskolin-stimulated adenylyl cyclase activity in all areas except the prefrontal cortex of the male subjects. Positive significant correlations were also found between both forskolin-stimulated enzyme activity and percentage forskolin stimulation and aging in the prefrontal cortex. Overall, the findings suggest that sex and/or age-related differences in brain adenylyl cyclase vary from one cerebral region to the other.

Adenylyl Cyclases↗

PubMed2000

Peripheral-type benzodiazepine receptors in human blood cells of patients affected by migraine without aura.

The kinetic parameters at equilibrium of peripheral benzodiazepine receptors in platelets, lymphocytes and granulocytes of 15 patients affected by migraine without aura were tested using [3H]PK 11195, a specific radioligand for this receptor and compared with the same number of healthy controls: a statistically significant increase (platelets 212%, lymphocytes 203%, granulocytes 171%, as absolute percentage) in the maximal number of binding sites (B(max)) in all three patient samples, compared with healthy controls was detected; on the contrary, the values of the dissociation constant (K(d)) at equilibrium do not show any statistically significant variations between the two groups. These data further confirm the presence of peripheral biochemical alterations in migraine without aura. As peripheral benzodiazepine receptors appear to be involved in the regulation of the mitochondrial respiratory chain, the observed increase in B(max) might be related to the mitochondrial anomalies found in migraine disorders.

Adult↗

PubMed2000

Lack of stereoselectivity of 8-hydroxy-2(di-N-propylamino)tetralin-mediated inhibition of forskolin-stimulated adenylyl cyclase activity in human pre- and post-synaptic brain regions.

The stereoselectivity of the serotonin1A (5-HT1A) receptor compound 8-hydroxy-2(di-N-propylamino)tetralin (8-OH-DPAT) on forskolin-stimulated adenylyl cyclase activity was investigated in membranes from human 5-HT pre-synaptic (raphe nuclei) and post-synaptic (hippocampus and prefrontal cortex) regions of autopsy brains. After sample incubation with agonists and antagonists, results showed that both the racemic mixture of 8-OH-DPAT or its (+) and (-) enantiomers behaved as full agonists in the tested brain regions. Enantiomer potency (EC50, nM) and efficacy (percentage of maximal inhibition, %) values were similar in all regions under investigation. However, some inter and intra-region variations in racemic 8-OH-DPAT potency and efficacy have been observed. In particular, the potency of racemic 8-OH-DPAT was higher in the prefrontal cortex and raphe nuclei than in the hippocampus, where it was in fact lower than either single enantiomers. Agonist effects were competitively reversed by 5-HT1A antagonists, although once again a different profile was revealed in the hippocampus. The data underscores the lack of stereospecificity of 8-OH-DPAT-mediated inhibition of adenylyl cyclase activity in either pre- or post-synaptic human brain regions. Moreover, such results have significant implication, as they support the notion that human 5-HT1A receptors might vary from one brain region to the other.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed2000

Substituted 1,2,3-triazolo[1,5-a]quinazolines: synthesis and binding to benzodiazepine and adenosine receptors.

This paper reports the synthesis and evaluation of the biological affinity towards benzodiazepine and A(1) and A(2A) adenosine receptors of some 3-ethoxycarbonyl or 3-phenyl-substituted 1,2, 3-triazolo[1,5-a]quinazolines. Starting from the appropriate chloro-substituted phenylazides, the series of 7 or 8 chloro-substituted triazoloquinazolines were prepared. Nitration reactions of the triazoloquinazoline ring and chlorination reactions of the hydroxyl group in the 5 position of the same ring are also reported. By nucleophilic displacement of halogen, the corresponding 5-amino derivatives and some analogous derivatives bearing cyclohexylamino and p-toluidino substituents were obtained. The binding assays showed a generalized decrease in the affinity towards the benzodiazepine receptors and confirmed a moderate affinity towards the A(1) adenosine receptors in comparison with the previously studied triazoloquinazoline derivatives.

Animals↗