Tritiated Imipramine Binding Sites Are Decreased in Platelets of Untreated Depressed Patients

Briley, Mike; Langer, Salomón Z.; Raisman, Rita; Sechter, D.; Zarifian, E.

doi:10.1126/science.7384806

Cited by 433 publications

(79 citation statements)

References 14 publications

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“…The presence of endogenous antidepressant-like sub stances has been suggested ever since the possible pharma cological relationship between changes in presynaptic sites in imipramine binding and manic depressive disor ders was first reported (1). Recently, it has been reported that [3H]imipramine binding sites and [3H]paroxetine binding sites that regulate 5-hydroxytryptamine (5HT) up take are modulated by unidentified endogenous sub stance(s) in human plasma (2)(3)(4)(5) and in rat brain and plas ma (6 9 (13,14).…”

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confidence: 99%

Further Studies on the Endogenous Serotonin-Uptake-Inhibitor-Like Substances in the Human Cerebrospinal Fluid

Goto

Egashira

Yamanaka

1993

Japanese Journal of Pharmacology

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ABSTRACT-Theproperties of endogenous substances that inhibit 5HT uptake in human cerebrospinal fluid (CSF) were investigated. Human CSF was loaded onto a Sephadex G-25 column, and each fraction was tested for its ability to inhibit [3H]paroxetine binding in monkey brain preparations. We found four different inhibitory peaks with respective molecular weights (M.W.) of > 12400, 2000 and two of < 1350. The third and fourth peaks (F-3, F-4: < 1350 M.W.) of inhibitory activity were determined to consist of some monoamines (5HT, etc.) or their metabolites (5HIAA, etc.) and other unidentified compounds by us ing an HPLC-electrochemical detector. (13, 14). In this study we report more detailed investiga tions of the properties of the selective 5HT uptake inhibi tor-like substances in human CSF. MATERIALS AND METHODSMonkeys were anesthetized with ketaral (30 mg/kg, s.c.), and their brains were quickly removed after withdrawing blood. Fifty milliliters of human CSF sam ples were obtained from 25 patients in the course of rou tine diagnostic lumbar puncture and were collected in the Central Laboratory of Medicine. The monkey brains and the pooled human CSF were stored at -80°C until used. Gel filtrationFive milliliters of evaporated human CSF sample was chromatographed in a Sephadex G-25 column (1.9 x 87 cm) with 1 mM phosphate buffer, pH 7.4, at a flow rate of 103 ml/hr, and effluent fractions of 5.15 ml/tube were col lected. Column effluents were monitored by measuring ab sorbances at 280 nm. Aliquots (100µl) of each fraction were assayed for the ability to displace [3H]paroxetine binding. The molecular weights (M.W.s) of endogenous 5HT-uptake-inhibitor-like substances were estimated by chromatography in the same column calibrated with mark ers of known M.W. Paroxetine binding assay (15)Monkey frontal cortices were homogenized in 25 vol. of ice-cold 50 mM Tris-HC1 buffer (containing 100 mM NaCI and 5 mM KCI, pH 7.4). The P2 fractions obtained by centrifugation of this homogenate were used as the crude membrane preparations (final concentration of ap proximately 0.1 mg protein/tube) for the assay. Aliquots of crude membrane suspension were incubated with[3H]paroxetine at 221C at a final volume of 250,u1 for 180 min. Fluoxetine at 10,uM final concentration was used to determine non-specific binding. The incubation was termi nated by rapid filtration of the membrane suspension un der reduced pressure through Whatman GF/B glass fiber filters. Each filter was rapidly washed three times with 5 ml of ice-cold 50 mM Tris-HC1 buffer, pH 7.4. The filters were then dried and the radioactivities were determined in Triton X-100-toluene scintillation fluid in a liquid scintilla tion spectrometer. Monoamine uptake assay The study of [3H]5HT, [3H]norepinephrine (NE) or[3H]dopamine (DA) uptake into synaptosomes was con ducted according to the method of Snyder and Coyle (16), but with minor modifications. The monkey brains (bilateral frontal cortex) were homogenized in 0.32M sucrose, and the crude synaptosomes were obtained by different...

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mentioning

confidence: 99%

Further Studies on the Endogenous Serotonin-Uptake-Inhibitor-Like Substances in the Human Cerebrospinal Fluid

Goto

Egashira

Yamanaka

1993

Japanese Journal of Pharmacology

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“…3H-Imipramine binding sites are reduced following electrolytic lesions of the dorsal raphe and 5,7-dihydroxytrypta mine lesions (22,23), and the decrease in binding parallels the reduction in 5-HT uptake capacity (21). Moreover, several authors have suggested that these sites are clinically impor tant, since a decrease in 3H-imipramine bind ing sites (8,24,25) as well as a decrease in 5 HT uptake (9) was reported in the platelets of depressed patients. These findings suggest that these binding sites are regulated by unidenti fied endogenous ligands.…”

Section: Discussionmentioning

confidence: 99%

“…This recognition sites labeled with 3H -imipramine have been shown to be distinct but allosterically coupled with the serotonin (5-hydroxytryptamine, 5-HT) transport system (5-7). Several lines of evidence suggest that these sites are clinically important since a de crease in 3H-imipramine binding sites (8) as well as a decrease in 5-HT uptake (9) were re ported in platelets of depressed patients.…”

mentioning

confidence: 99%

Evidence for the Existence of Serotonin Uptake Inhibitor-Like Substances in Human Cerebrospinal Fluid.

Goto¹,

Egashira²,

Yamanaka³

1991

Jpn.J.Pharmacol

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ABSTRACT-Addition of human cerebrospinal fluid (CSF) induced a marked inhibi tion of 3H-paroxetine binding to the monkey cortical membranes, while the specific binding of 3H-imipramine was slightly inhibited. Moreover, 3H-serotonin (5-hydroxy tryptamine, 5-HT) uptake inhibition in the monkey cortical synaptosomes was also in creased as the volume of added CSF was increased. Scatchard analysis of specific 3H paroxetine binding with human CSF showed non-competitive kinetics, although CSF was competitive with 3H-imipramine binding. The inhibitory effect of human CSF on 5-HT uptake was non-competitive in nature. The endogenous substances in human CSF most probably act at the recognition site labeled with 3H-paroxetine. Moreover, occupation of this site by the endogenous substances is likely to inhibit the 5-HT uptake process.High affinity binding sites for 3H-imipra mine have been demonstrated and character ized in membrane preparations from rat brain (1), the human platelets (2, 3) and human brain (4). This recognition sites labeled with 3H -imipramine have been shown to be distinct but allosterically coupled with the serotonin (5-hydroxytryptamine, 5-HT) transport system (5-7). Several lines of evidence suggest that these sites are clinically important since a de crease in 3H-imipramine binding sites (8) as well as a decrease in 5-HT uptake (9) were re ported in platelets of depressed patients.Recently, the existence of 3H-imipramine binding sites which regulate 5-HT uptake and the changes in presynaptic sites in imipramine binding and 5-HT uptake observed in depress ed patients suggest the possibility that these binding sites are regulated by unidentified en dogenous substance(s) in human plasma (10 12) or in rat brain and plasma (13,14). In addition, 5-methoxytryptoline has been dem onstrated as a potential endogenous modulator of 3H-imipramine binding and 5-HT uptake (15). However, there is doubt about 5 methoxytryptoline's action as an endogenous ligand for the 3H-imipramine binding sites (16). Other endogenous substances such as al acid glycoprotein (17) which are present in the low molecular weight fraction of human plas ma, inhibited 3H-imipramine binding, while enhancing 5-HT uptake.Here we report the presence of and pre liminary characterization of a substance(s) in human cerebrospinal fluid (CSF) that inhibits 3H -5-HT uptake in monkey cortical synapto somal preparations and also inhibits 3H-imip ramine binding and 3H-paroxetine binding to monkey cortical membranes.

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“…PLATELET PREPARATION Platelets fo r the binding studies were obta ined using a mod ification of the methods of Briley et al ("1979Briley et al (" , 1980 and As. 1rch et .11.…”

Section: Methodsmentioning

confidence: 99%

Is there a relationship between baseline and treatment-associated changes in [H]-IMI platelet binding and clinical response in major depression?

Tollefson

Heiligenstein

Tollefson

et al. 1996

Neuropsychopharmacology

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Tritiated Imipramine Binding Sites Are Decreased in Platelets of Untreated Depressed Patients

Cited by 433 publications

References 14 publications

Further Studies on the Endogenous Serotonin-Uptake-Inhibitor-Like Substances in the Human Cerebrospinal Fluid

Further Studies on the Endogenous Serotonin-Uptake-Inhibitor-Like Substances in the Human Cerebrospinal Fluid

Evidence for the Existence of Serotonin Uptake Inhibitor-Like Substances in Human Cerebrospinal Fluid.

Is there a relationship between baseline and treatment-associated changes in [H]-IMI platelet binding and clinical response in major depression?

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