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Biomedical subjects

J Marcusson

Publications and source records attributed to J Marcusson.

At least 19 recordsLinked to original sources
PubMed1992

[3H]nipecotic acid binding to GABA uptake sites in human brain.

The binding of [3H]nipecotic acid to frozen post-mortem human brain tissue has been characterized. Competition experiments with gamma-aminobutyric acid (GABA), GABA uptake inhibitors, ligands active at post-synaptic GABA receptors and receptors for other neurotransmitter systems, suggest that [3H]nipecotic acid binds to the neuronal (but not glial) GABA uptake site. Competition and kinetic experiments suggest that 85% of the binding is to a high affinity site. The dissociation constants (Kd) measured in kinetic and equilibrium experiments were in the same range (0.5-0.6 microM). The regional distribution was studied in 19 brain regions and the binding was relatively homogenous. It is concluded that [3H]nipecotic acid binding can be used as a marker for neuronal GABA uptake sites in post-mortem human brain tissue.

Aged↗
PubMed1992

Alterations in brain cholecystokinin receptors in suicide victims.

Cholecystokinin (CCK) and benzodiazepine receptor binding characteristics were analyzed in the brain tissue samples from 19 suicide victims and 23 control cases. In the frontal cortex, significantly higher apparent number of CCK receptors and affinity constants were found in the series of suicide victims. These differences between suicides and controls were present in similar proportions when the suicide cases with depressive syndrome or violent or non-violent means of self-killing were compared to matched controls. However, when the samples were split into subgroups consisting of persons either below or over the age of 60 years, significant differences in the CCK receptor characteristics in the frontal cortex were observed only between younger suicides and controls. Furthermore, the younger suicide victims had a higher density of CCK receptors in the cingulate cortex, whereas in older suicides the value was lower as compared to age-matched controls. No difference in benzodiazepine receptor binding was found between control and suicide groups. The results of this investigation suggest that CCK-ergic neurotransmission is linked to self-destructive behaviour, probably through its impact on anxiety and adaptational deficits.

Adolescent↗
PubMed1992

Gamma-aminobutyric acid-B (GABAB) binding sites in postmortem suicide brains.

Gamma-aminobutyric acid-B (GABAB) binding sites labelled with [3H]GABA were determined in postmortem frontal cortex samples of 20 control subjects and 16 suicides. The suicide group was further subdivided according to the method of suicide and the existence of depressive symptoms prior to death. No significant differences in GABAB binding were found either between overall suicide and control groups or between the control group and the other subgroups (violent suicide, nonviolent suicide, nondepressed and depressed suicide victims). A significant increase in GABAB binding was observed in those individuals dying from carbon monoxide poisoning. It is concluded that although GABAB binding sites are not altered in our suicide group, a presynaptic dysfunction might account for the increased GABAB binding found in the carbon monoxide subgroup.

Adult↗
PubMed1992

Age stability of human brain 5-HT terminals studied with [3H]paroxetine binding.

The effect of age on serotonin uptake sites labeled with [3H]paroxetine was studied in two sets of brains. The first set included 28 subjects (19 males and 9 females) between the ages 0 and 100 years. The cortex of cingulate gyrus and the amygdala were studied. No age-related changes in binding capacity (Bmax) or binding affinity (Kd) were noted. In the second set, the frontal cortex and hypothalamus from 22 subjects (18 males and 4 females) between 16 and 75 years were studied. No age-related changes in the binding were observed. The interval between death and freezing of the tissue did not influence the binding. Regarding the [3H]paroxetine binding as an indirect marker for 5-HT terminals, the data suggest a stability of 5-HT terminals with increasing age in the human brain.

Adolescent↗
PubMed1991

Brain gamma-aminobutyrate transaminase and monoamine oxidase activities in suicide victims.

The activity of gamma-aminobutyrate amino-transferase (GABA-T) and monoamine oxidase (MAO-A and -B) was measured in 42 postmortem human brains. Three brain regions (frontal cortex, cingulate cortex and hypothalamus) from 23 controls without known neurological or psychiatric disorder and from 19 suicide victims were analysed. The suicide victims were classified according to the use of violent and non-violent methods and to the presence or absence of a known history of depressive disorder. No difference was found between the series of suicide victims and the control subjects with regard to GABA-T activity. Carbon monoxide poisoning and death by drug overdose, however, were found to reduce the activity. The MAO-B activity did not differ between the groups. With MAO-A, however, a significant elevation (t = 2.01; P less than 0.05) was found in the hypothalamic region of the suicide victims. The difference seemed to be confined to the subgroup of suicides with a record of depressive disorder.

4-Aminobutyrate Transaminase↗
PubMed1989

High affinity [3H]paroxetine binding to serotonin uptake sites in human brain tissue.

[3H]Paroxetine binding to human brain tissue was characterized. Competition studies in the putamen and frontal cortex revealed single-site binding models for binding sensitive to 5-hydroxytryptamine (5-HT) (Ki 1-3 microM) and citalopram (Ki 0.6 nM), which displaced the same amount of binding. However, desipramine, norzimeldine and fluoxetine displaced additional binding (10-20%) and these competitors fitted two-site binding models with high affinity components in the nanomolar range and low affinity components in the micromolar range. The high affinity components approximated the 5-HT- and citalopram-sensitive binding fraction. Most of the [3H]paroxetine binding sites were protease-sensitive, but the low-affinity (microM) sites appeared to be protease-resistant. Based on these findings, only the [3H]paroxetine binding representing the fraction sensitive to 30 microM 5-HT (or e.g. 0.3 microM norzimeldine), was regarded as specific binding. This binding fraction was saturable with an apparent binding affinity (Kd) of 0.03-0.05 nM throughout the brain. The highest binding densities were obtained in the hypothalamus and substantia nigra (Bmax 500 fmol/mg protein). The basal ganglia reached intermediate densities (Bmax 200 fmol/mg protein), whereas cortical areas had low Bmax values (less than 100 fmol/mg protein). The lowest B max value was noted in cerebellar cortex (30 fmol/mg protein). The [3H]paroxetine binding was competitively inhibited by low concentrations of 5-HT, imipramine and norzimeldine, suggesting that the substrate recognition site for 5-HT uptake was labeled. Compounds active at dopaminergic, noradrenergic, histaminergic, 5-HT1, 5-HT2 and cholinergic muscarinic sites did not affect the binding at 100 microM concentrations. It is concluded that [3H]paroxetine is a marker for the 5-HT uptake site in the human brain, provided that an adequate pharmacological definition of specific binding is performed.

Aged↗
PubMed1989

Inhibition and dissociation of [3H]-paroxetine binding to human platelets.

Previous data on dissociation studies of [3H]-imipramine and [3H]-paroxetine binding to the human platelet 5-hydroxytryptamine (5-HT, serotonin) transporter have suggested that the binding is heterogeneous in nature and/or is subject to allosteric modifications through a separate low affinity site. The platelet 5-HT transporter is often used as a biological marker in psychiatric conditions. Therefore, it was of interest to further characterize the 5-HT uptake site by using [3H]-paroxetine. The 5-HT uptake inhibitors tested (citalopram, clomipramine, imipramine, norzimeldine and paroxetine) and 5-HT itself produced competitive inhibition patterns in saturation experiments, suggesting that these agents bind to the same site. In dissociation experiments in the presence of the 5-HT uptake inhibitors, the half-time values for dissociation were the same, whereas 5-HT slowed the dissociation. These data suggest that with the concentrations used of the 5-HT uptake inhibitors, they do not modify the 5-HT transporter. However, in the presence of 5-HT, the [3H]-paroxetine dissociation is decreased, suggesting an allosteric modification of the [3H]-paroxetine binding site.

Antidepressive Agents↗
PubMed1988

[3H]GBR-12935 binding to dopamine uptake sites in the human brain.

The binding of the selective dopamine uptake inhibitor [3H]GBR-12935 to post-mortem human brain membranes was studied. Competition experiments indicated the presence of multiple binding sites, but when a binding fraction that could be discriminated by either 0.3 microM mazindol or 1 mM dopamine was regarded as specific binding, a single-site binding model was obtained. The [3H]GBR-12935 binding was of protein nature since it was abolished after protease treatment and the binding appeared to label the dopamine uptake site. This was supported by the findings that dopamine uptake inhibitors inhibited the binding with high affinity (Ki 30-130 nM), whereas substances active at dopamine D1, D2 or autoreceptor sites revealed much lower affinities (Ki greater than 10 microM or inactive). Moreover, dopamine was the neurotransmitter with the highest affinity for the [3H]GBR-12935 binding site (Ki 30 microM). The dopaminergic nature of the [3H]GBR-12935 binding was further indicated by its regional distribution, which largely corresponds the known distribution of the dopamine system in the rat brain. The highest binding densities were obtained in the caudate nucleus and putamen (Bmax 1500-2000 fmol/mg protein), followed by the olfactory tubercle (Bmax 900 fmol/mg protein) and the substantia nigra (Bmax 300 fmol/mg protein). The apparent binding affinity (Kd) was the same in all brain regions (Kd 1-1.5 nM). Detectable specific [3H]GBR-12935 binding was obtained also in the globus pallidus, amygdala and cortices of orbital/rectus and cingulate gyri. Drug inhibition studies with the addition of low concentrations of dopamine and mazindol produced only alterations in the apparent Kd values, suggesting a competitive inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Unaltered 5-HT- and desipramine-sensitive [3H]imipramine binding and [3H]5-HT uptake in rat brain after chronic imipramine and norzimeldine treatment.

Several reports have shown heterogeneity of [3H]imipramine binding to brain membranes. Recently, a high affinity and 5-HT sensitive [3H]imipramine binding site of protein nature, that was suggested to be identical to the substrate recognition site for 5-HT uptake, was demonstrated. Since most studies on the regulation of the [3H]imipramine binding sites by antidepressants have used desipramine displaceable binding, which is heterogenous in nature and contains binding not related to 5-HT uptake sites, the present report studies the possible effects of chronic (3 weeks) administration of imipramine or norzimeldine (10 mg/kg intraperitoneally twice daily) on 5-HT sensitive [3H]imipramine binding sites. For comparison, desipramine sensitive binding was also studied, as well as the physiological correlate 5-HT uptake. There were no changes in either [3H]imipramine binding or 5-HT uptake after the antidepressant treatment.

Animals↗
PubMed1988

Dissociation kinetics of [3H]paroxetine binding to rat brain consistent with a single-site model of the antidepressant binding/5-hydroxytryptamine uptake site.

The effects of 5-hydroxytryptamine (5-HT) and 5-HT uptake inhibitors on the dissociation of [3H]paroxetine from rat brain membrane binding sites have been investigated. The dissociation induced by 5-HT (100 microM), paroxetine (0.15 microM), clomipramine (1 microM), citalopram (1 microM), imipramine (1 microM), or norzimeldine (1 microM) was consistent with first-order dissociation kinetics with half-life values of dissociation (t1/2) between 130 and 140 min. The dissociation induced by the combination of 5-HT (100 microM) with either citalopram (1 microM) or imipramine (1 microM) was not different from that initiated by either agent alone. These dissociation data, which are at variance with previous data on the 5-HT transporter labeled with [3H]imipramine, support a single-site model of the antidepressant binding/5-HT uptake site.

Animals↗
PubMed1988

[3H]imipramine binding of protein nature in human platelets: inhibition by 5-hydroxytryptamine and 5-hydroxytryptamine uptake inhibitors.

The nature of [3H]imipramine binding to human platelets was investigated. Desipramine and 5-hydroxytryptamine (5-HT) displaced the same amount of binding and the binding was sensitive to protease treatment. The nature of pharmacological inhibition of [3H]imipramine binding was investigated in saturation experiments. Increases in KD without changes in Bmax were noted with the addition of 5-HT, desipramine, norzimeldine, or 5-methoxytryptoline. Reductions in Bmax without alterations in KD were obtained when citalopram or clomipramine was added. It is concluded that the [3H]imipramine binding site in human platelets is of protein nature and that this binding site contains the substrate recognition site for 5-HT uptake. In addition, [3H]imipramine and other 5-HT uptake inhibitors have bonds to other parts of the 5-HT uptake carrier or to the surrounding lipid membrane. This additional binding outside the substrate recognition site is not one single site but most likely represents sites that are specific for the chemical structure of each uptake inhibitor, respectively.

Binding Sites↗
PubMed1979

HLA antigens in a psoriatic family: comparative studies with MLC, HTC, PLT and serological HLA-DR determinations.

HLA genotypes were characterized in a large family of 48 individuals in three generations. In this family, carriers of the proband's disease-predisposing haplotype commonly expressed clinical signs of illness, manifested as psoriasis and/or arthritic lesions. From these data, and from other family studies, presented previously, we have concluded that cutaneous and/or joint lesions may be signs of disease in carriers of the predisposing HLA haplotype. We have investigated HLA-A, B, C and D/DR antigens in the family members. This gave us the opportunity to evaluate the validity of different assays for the determination of HLA-D alleles in a family material where the MLC tests formed the basis for a correct assignment of HLA-D determinants. The HTC method and the PLT assay were both afflicted with specific typing problems, partly due to the existence of cellular cross-reactions between HLA-D determinants, which seemed to be reminiscent of serological DR crossreactions.

Alleles↗
PubMed1978

Psoriasis and arthritic lesions in relation to the inheritance of HLA genotypes: a family study.

This family consists of forty-eight subjects, all of whom have been examined with regard to the presence of psoriasis and nearly all for the presence of arthritic lesions (sacroiliitis and peripheral arthritis). All the members have been tissue-typed not only for HLA-A, B and C locus products but also for D locus products. This has enabled us to study the entire HLA chromosomal region. In the family concerned we have found that those subjects haploidentical with the proband have, to a very large degree, either one or all clinical manifestations, which demonstrates a close genetic relationship between joint (especially sacroiliitis) and cutaneous manifestations. These findings prompt us to repeat our previously made proposal about different phenotypic expressions of the same genotype. In this family study the disease-associated haplotypes did not contain the genes for B13, 17 or 37 antigens which are known to occur frequently in psoriatic patients. However, not all psoriasis patients have these antigens. Despite that, we believe that the gene(s) which increase the likelihood of developing psoriasis are identical in all patients and therefore family studies where the proband does not carry the particular psoriasis associated B-alleles are equally illuminating as to the inheritance pattern of disease.

Adolescent↗
PubMed1976

Psoriasis, sacro-iliitis and peripheral arthritis occurring in patients with the same HLA haplotype. A preliminary family report and a hypothetical explanation of the interaction between MHS products.

The present family investigation has shown that genes within the MHS are mainly responsible for the development of psoriasis or psoriasis-associated arthritic lesions (peripheral arthritis and sacroiliitis). We have hypothetically discussed the possibility that multiple genes, all located within the MHS, act in concert to increase the risk of developing disease to very high levels. This implies that at least two MHS linked genes act in complementary fashion for the development of disease, these genes seem to be able to operate both in the cis and in the trans position. One of these genes would be situated in the chromosomal portion of the MHS which carries the HLA-D locus. Families with a high incidence of disease would show inheritance according to the cis position of genes, when it can be shown that most of the carriers of the specific disease-associated haplotype are affected by disease, whereas in other families, complementarity between two distinct HLA haplotypes with genes acting in the trans position would result in disease.

Adolescent↗