The effect of hypericin on the expression of morphine-induced conditioned place preference (CPP) was investigated and compared with the effect of the synthetic antidepressants. The CPP paradigms took place over six days using an unbiased procedure. The results demonstrate that intra-peritoneal (IP) injection of morphine sulfate (2.5, 5 and 10 mg/Kg) significantly induce the CPP in rat. Intra-pe...

Transglutaminase (TGase)-induced activation of small G proteins via 5-hydroxytryptamine (HT)(2A) receptor signaling leads to platelet aggregation (Cell 115:851-862, 2003). We hypothesize that stimulation of 5-HT(2A) receptors in neurons activates TGase, resulting in transamidation of serotonin to a small G protein, Rac1, thereby constitutively activating Rac1. Using immunoprecipitation and immu...

Serotonin (5-hydroxytryptamine; 5-HT) is known to increase proliferation and collagen synthesis by fibroblasts. Two receptor subtypes, 5-HT2A and 5-HT2B, have been shown to play the most important roles in the lung. In the present study, the role of serotonin in lung fibrosis was investigated using the bleomycin mouse model. Serotonin concentrations in lung homogenates increased significantly o...

EditorÐWe congratulate the authors on an excellent review of aspects of the pathophysiology of malignant hyperthermia (MH). They have explained the postulated role of serotonin in MH, in particular the role of peripheral 5-HT2 receptors, based on in vitro and in vivo animal work. There are important parallels between serotonin toxicity and MH, and this review adds to our understanding of the ro...

According to the dopamine hypothesis of schizophrenia, symptoms of psychosis arise, in part, from dysregulation of central dopaminergic pathways. The activity of dopaminergic neurons is in turn modulated by several neurotransmitters, including, most prominently, serotonin and glutamate. The first generation of antipsychotic drugs (ie, typical antipsychotics) are characterized by potent D2 dopam...

Serotonin [5-hydroxytryptamine (5-HT)] plays an important role in many organs as a peripheral hormone. Most of the body's serotonin is circulating in the bloodstream, transported by blood platelets and is released upon activation. The functions of serotonin are mediated by members of the 7 known mammalian serotonin receptor subtype classes (15 known subtypes), the serotonin transporter (SERT), ...

Recent studies indicated that hyperactivity of the hypothalamo-pituitary-adrenal system is a considerable risk factor for the precipitation of affective disorders, most notably of major depression. The mechanism by which this hyperactivity eventually leads to clinical symptoms of depression is unknown. In the present animal study, we tested one possible mechanism, i.e., that long-term exposure ...

INTRODUCTION Selective serotonin reuptake inhibitors (SSRIs) differ in the severity of induced ejaculation delay. Various studies indicate that oxytocin is involved in sexual behavior. AIM To review and evaluate the involvement of oxytocin in SSRI-induced ejaculation delay. MAIN OUTCOME MEASURES Oxytocine release, 5-hydroxytryptamine (5-HT) neurotransmission, and desensitization of 5-HT(1A)...

PURPOSE The authors investigate the possible presence of 5-hydroxytryptamine (5-HT1) type serotonin receptors negatively coupled to adenylate cyclase activity in cultured human retinal pigment epithelial (RPE) cells. METHODS Adenylate cyclase activity was assessed by the determination of cellular adenosine 3':5' cyclic monophosphate (cAMP) levels and the effects of serotonin on both basal and...

Serotonin is a vasoactive substance that in different blood vessels mostly induces vasoconstriction. Considering the important role of common carotid artery in brain blood supply, the aims of this study were to investigate the effect of serotonin on isolated rat common carotid artery and also to examine participation of intact endothelium, cyclooxygenase products, Ca(++) channels and 5-HT(2) re...