A simple apparatus for studying the release of neurotransmitters from synaptosomes

Raiteri, Maurizio; Angelini, Francesco; Levi, Giulio

doi:10.1016/0014-2999(74)90272-6

Cited by 446 publications

(172 citation statements)

References 9 publications

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“…Aliquots of 1 ml of the suspension were filtered through Millipore filters, washed and placed on the bottom of a superfusion chamber (Raiteri, Angelini & Levi, 1974 preparations (Belin, Kouyoumdjian, Bardakdjian & Gonnard, 1975 Table 2, chlorimipramine, a compound reported to act primarily by inhibiting 5-HT reuptake (Carlsson, Jonason & Lindqvist, 1969b) cotics also had significant effects, -with an order of potency as '5-HT releasers' corresponding closely to their ability to inhibit the uptake. Similar results were found when spinal synaptosomes were investigated.…”

Section: Superfusion Study Resultsmentioning

confidence: 99%

Effects of Narcotic Analgesics on the Uptake and Release of 5‐hydroxytryptamine in Rat Synaptosomal Preparations

Mennini

Samanin

1978

British J Pharmacology

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1 The effects of various narcotic analgesics on the uptake and release of labelled 5-hydroxytryptamine (5-HT) in brain and spinal cord synaptosomes were investigated.2 Methadone was most active in inhibiting 5-HT uptake (IC50 2.5 x 10-M). Levorphanol also inhibited 5-HT uptake to a large extent (IC5o 8.8 x 10-7 M) while dextrorphan, pethidine and pentazocine showed much less activity. Etorphine and morphine had virtually no such activity, with IC50s higher than 10-' and 1O-M respectively.3 The same order of potency as '5-HT releasers' was found when radioactivity was measured in [3H]-5-HT preloaded synaptosomal pellets incubated for 20min with the various narcotics. Methadone, like chlorimipramine, showed a significant effect at a concentration of 10-7M while morphine, at a concentration of 10-4 M, had no effect.4 When 5-HT release was studied by a perfusion technique, which largely prevents reuptake of the released amine, only fenfluramine, an anorectic agent proposed as a 5-HT releaser, significantly increased spontaneous 5-HT release. These data suggest that the apparent 5-HT release induced by various narcotics in traditional incubation techniques may largely depend on their ability to interfere with neurotransmitter reuptake mechanisms. 5 The effects of the various narcotics on 5-HT uptake have no relationship to their relative potency as analgesics in the rat. In the light of their poor effectiveness as 5-HT releasers, it can be concluded that mechanisms other than 5-HT uptake inhibition and release are probably involved in the analgesic effects of these compounds in intact animals.

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Section: Superfusion Study Resultsmentioning

confidence: 99%

Effects of Narcotic Analgesics on the Uptake and Release of 5‐hydroxytryptamine in Rat Synaptosomal Preparations

Mennini

Samanin

1978

British J Pharmacology

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“…The experimental set up employed in this study (a thin layer of synaptosomes up-down superfused; Raiteri et al, 1974) prevents or minimized indirect effects. Thus it can be assumed that the site of action of 5-HT is on the CCK-releasing nerve terminals suggesting that the 5-HT and the CCK systems are directly interconnected in the rat brain.…”

Section: Discussionmentioning

confidence: 99%

“…Identical aliquots of the synaptosomal suspension (ranging between 0.8-1 mg protein in the different experiments) were layered at the bottom of a set of parallel superfusion chambers maintained at 37°C (Raiteri et al, 1974 Ltd, 1991 medium. 5-HT or 1-phenylbiguanide was added to the superfusion medium concomitantly with the depolarizing stimulus.…”

Section: Release Experimentsmentioning

confidence: 99%

Cholecystokinin release mediated by 5‐HT₃ receptors in rat cerebral cortex and nucleus accumbens

Paudice

Raiteri

1991

British J Pharmacology

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1 The effects of 5-hydroxytryptamine (5-HT) on the release of cholecystokinin-like immunoreactivity (CCK-LI) were examined in synaptosomes prepared from rat cerebral cortex and nucleus accumbens and depolarized by superfusion with 15 mM KCl. 2 In both areas 5-HT, tested between 0.1 and 100 nm, increased the calcium-dependent, depolarizationevoked CCK-LI release in a concentration-related manner. The concentration-response curves did not differ significantly between the two brain areas (EC50: 0.4 + 0.045 nm and 0.48 + 0.053 nm, respectively, in cortical and n. accumbens synaptosomes; maximal effect: about 60% at 10 nm 5-HT).3 The 5-HT,/5-HT2 receptor antagonist methiothepin (300 nM) did not affect the CCK-LI release elicited by 10nm 5-HT. However, the effects of 10nm 5-HT were antagonized in a concentration-dependent manner by the 5-HT3 receptor antagonists (3a-tropanyl)-lH-indole-3-carboxylic acid ester 0.1-100 nM; IC50: 3.56 + 0.42 nm in the cortex and 3.90 + 0.50 nm in the n. accumbens) and ondasetron (IC50: 8.15 + 0.73nm in the cerebral cortex). 5-HT (10nM) was also strongly antagonized by l00nM laH, 3a5aH-tropan-3-yl-3,5-dichlorobenzoate (MDL 72222) another blocker of the 5-HT3 receptor. Moreover, the 5-HT3 receptor agonist 1-phenylbiguanide (tested in the cerebral cortex between 0.1 and 100nM) enhanced CCK-LI release in a manner almost identical to that of 5-HT (EC5o = 0.64 + 0.071 nM).4 It is concluded that 5-HT can act as a potent releaser of CCK-LI in rat cerebrocortex and nucleus accumbens through the activation of receptors of the 5-HT3 type situated on the CCK-releasing terminals. This interaction may provide a rationale for the clinical development of both 5-HT3 and CCK receptor antagonists as novel anxiolytic drugs.

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“…Identical aliquots of the different synaptosomal suspensions were layered onto microporous filters at the bottom of a set of 20 parallel superfusion chambers maintained at 37°C (Raiteri et al, 1974). Superfusion was then started (time = 0 mm) at a rate of 0.5 ml/min, the standard medium being supplemented with 0.1% Polypep and aerated with 95% 02 and 5% CO2.…”

Section: Preparation Of Synaptosomes and Release Experimentsmentioning

confidence: 99%

Time‐ and Region‐Specific Variations in Somatostatin Release Following Amygdala Kindling in the Rat

Simonato

Bregola

Beani

et al. 1998

Journal of Neurochemistry

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Somatostatin biosynthesis is activated during and following kindling epileptogenesis. The aim of this study was to investigate whether this phenomenon translates into enhanced release of the peptide and whether it is involved in kindling maintenance. A marked increase in somatostatin-like immunoreactivity (somatostatin-LI) was observed in hilar interneurons of the hippocampus and in their presumed projections to the outer molecular layer 1 week, but not 1 month, after the last kindled seizure. No overt changes were observed in the striatum or in the cortex. Compared with sham-stimulated controls, (a) in the hippocampus, high-K~-evokedsomatostatin-LI release was unchanged in synaptosomes taken from rats killed 7 days after the last kindled seizure but was bilaterally reduced after 30 days; (b) in the striatum, it was increased (mainly ipsilaterally to stimulation) 7, but not 30, days after the last seizure; and (c) in the cortex, somatostatin-LI release was bilaterally increased in synaptosomes taken from kindled rats 30, but not 7, days after the last seizure. This study shows that distinct changes occur in synaptosomal somatostatin-LI release after kindling acquisition, depending on the brain area analyzed and on the time elapsed from the last generalized seizure.

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A simple apparatus for studying the release of neurotransmitters from synaptosomes

Cited by 446 publications

References 9 publications

Effects of Narcotic Analgesics on the Uptake and Release of 5‐hydroxytryptamine in Rat Synaptosomal Preparations

Effects of Narcotic Analgesics on the Uptake and Release of 5‐hydroxytryptamine in Rat Synaptosomal Preparations

Cholecystokinin release mediated by 5‐HT₃ receptors in rat cerebral cortex and nucleus accumbens

Time‐ and Region‐Specific Variations in Somatostatin Release Following Amygdala Kindling in the Rat

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A simple apparatus for studying the release of neurotransmitters from synaptosomes

Cited by 446 publications

References 9 publications

Effects of Narcotic Analgesics on the Uptake and Release of 5‐hydroxytryptamine in Rat Synaptosomal Preparations

Effects of Narcotic Analgesics on the Uptake and Release of 5‐hydroxytryptamine in Rat Synaptosomal Preparations

Cholecystokinin release mediated by 5‐HT3 receptors in rat cerebral cortex and nucleus accumbens

Time‐ and Region‐Specific Variations in Somatostatin Release Following Amygdala Kindling in the Rat

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Cholecystokinin release mediated by 5‐HT₃ receptors in rat cerebral cortex and nucleus accumbens