MDMA ("ecstasy") has been widely reported as a drug of abuse and as a neurotoxin. This report describes the mechanism of MDMA action at serotonin transporters from plasma membranes and secretory vesicles. MDMA stimulates serotonin efflux from both types of membrane vesicle. In plasma membrane vesicles isolated from human platelets, MDMA inhibits serotonin transport and [3H]imipramine binding by...

Serotonin is perhaps best known as a neurotransmitter that modulates neural activity and a wide range of neuropsychological processes, and drugs that target serotonin receptors are used widely in psychiatry and neurology. However, most serotonin is found outside the central nervous system, and virtually all of the 15 serotonin receptors are expressed outside as well as within the brain. Seroton...

The rat Na(+)- and Cl(-)-dependent serotonin transporter was expressed in Sf9 insect cells using the baculovirus system. Expression of the serotonin transporter caused the Sf9 cells to accumulate [3H]serotonin (Km 78 nM) and to bind the specific transport inhibitor [125I]RT155 (2 beta-carbomethoxy-3 beta-(4-[125I]iodophenyl)tropane) (Kd 0.22 nM). Ligand binding assays on isolated membranes show...

BACKGROUND The serotonin system has repeatedly been associated with the pathogenesis of pulmonary hypertension (PH). OBJECTIVE To comparatively analyze plasmatic and intrathrombocytic serotonin levels in arterial and mixed venous blood of patients with PH and unaffected controls to elucidate pulmonary serotonin metabolisms. PATIENTS AND METHODS Catheters were placed in the radial and pulmon...

The hormone serotonin (5-hydroxytryptamine) has been implicated as the cause of the diarrhea seen in many patients with the carcinoid syndrome. To determine whether serotonin is an intestinal secretagogue, the effect of serotonin on intestinal water and electrolyte transport was evaluated in the rabbit. Two weeks of daily subcutaneous injection of serotonin suspended in oil resulted in a blood ...

Reduced activity of CNS serotonin is reported in unipolar depression and serotonin is the major target of recent antidepressant drugs. However, an acute depletion of serotonin in healthy individuals does not induce depressive symptoms suggesting that depression does not correlate with the serotonin system only. Neuronal plasticity (structural adaptation of neurons to functional requirements) in...

It has been hypothesized that a deficit in serotonin may be a crucial determinant in the pathophysiology of major depression. Serotonin-1A receptors are located on serotonin cell bodies in the midbrain dorsal raphe (DR) nucleus, and the activation of these receptors inhibits the firing of serotonin neurons and diminishes the release of this neurotransmitter in the prefrontal cortex. Repeated tr...

To the Editor: Rosen’s Perspective article (March 5 issue)1 highlights recent findings that gut-derived serotonin inhibits bone formation by stimulating serotonin receptors on the preosteoblast.2 A critical question is whether serotonin is delivered to bone in some blood element or as free plasma serotonin. The serum serotonin measurements used by Yadav and colleagues2 reflect an undefined prop...

Highlights Daily injection of serotonin before a training session accelerated defensive reflex conditioning in snails.Daily injection of 5-hydroxytryptophan before a training session in snails with a deficiency of serotonin induced by the "neurotoxic" analog of serotonin 5,7-dihydroxytryptamine, restored the ability of snails to learn.After injection of the "neurotoxic" analogs of serotonin 5,6...

The effects of dexfenfluramine on the release of brain dopamine and serotonin into striatal dialysates were measured in freely moving rats. Samples collected every 20 min were assayed for dopamine and serotonin by high-performance liquid chromatography in a single run. The administration of a lower anorectic dose of dexfenfluramine (0.5 or 1.0 mg/kg intraperitoneally) significantly increased di...