Peripheral serotonin levels as a predictor of antidepressant treatment response: A systematic review.

There are currently no reliable biomarkers to predict clinical response to pharmacological treatments of depressive disorders. Peripheral blood 5-hydroxytryptamine (5-HT; serotonin) has been suggested as a biomarker of antidepressant treatment response, but there has not been an attempt to systematically summarize and evaluate the scientific evidence of this hypothesis. In this systematic review we searched MEDLINE, Embase, PsycINFO, and the Cochrane Central Register of Controlled Trials. Twenty-six relevant studies investigating peripheral 5-HT as an antidepressant biomarker were identified. In all, we did not find robust support for an association between baseline 5-HT and treatment response. Several larger studies with lower risk of bias, however, showed that higher baseline 5-HT was associated with a greater antidepressant response to SSRIs, prompting future studies to investigate this hypothesis. Our results also confirm previous reports that SSRI treatment is associated with a decrease in peripheral 5-HT levels; however, we were not able to confirm that larger decreases of 5-HT are associated with better treatment outcome as results were inconclusive.

Associations between off-label low-dose olanzapine or quetiapine and cardiometabolic mortality.

Olanzapine and quetiapine are routinely used off-label at lower doses, though it remains unclear whether treatment is associated with mortality. Here, we examined the associations between low-dose olanzapine/quetiapine, defined as 5 mg/day of olanzapine equivalents (OE) with cardiometabolic mortality in a population-based, longitudinal cohort of individuals who sought specialized psychiatric services. Through cross-linked Swedish registries, 428,525 individuals without psychotic, bipolar, or cardiometabolic disorders, or previous treatment with antipsychotics or cardiometabolic-related drugs were followed for up to 10.5 years. Extended stratified Cox proportional hazards regressions were employed to estimate the hazard ratios (HR) of cardiometabolic mortality as a function of cumulative OE exposures, adjusted for age, sex, inpatient care, and time-dependent psychiatric diagnoses and treatments. Individuals were followed for a total of 2.1 million person-years. Treatment with olanzapine/quetiapine occurred in 18,317 of the cohort. In total, 2606 cardiometabolic-related deaths occurred. Treatment status (treated vs. untreated) was not significantly associated with cardiometabolic mortality (adjusted HR 0.86, 95% CI 0.64-1.15, P = 0.307). However, compared to no treatment, treatment for <6 months was significantly associated with a reduced risk (adjusted HR 0.56, 95% CI 0.37-0.87, P = 0.010) whereas treatment for 6-12 months was significantly associated with an increased risk (adjusted HR 1.89, 95% CI 1.22-2.92, P = 0.004), but not significantly beyond 12 months. Among those treated, each year exposed to an average 5 mg/day was significantly associated with increased cardiometabolic mortality (adjusted HR 1.45, 95% CI 1.06-1.99, P = 0.019). Overall, low-dose olanzapine/quetiapine treatment was weakly associated with cardiometabolic mortality. Clinicians should consider potential cardiometabolic sequelae at lower doses.

Acute Mania and Catatonia in a Teenager Successfully Treated with Electroconvulsive Therapy and Diagnosed with Turner Syndrome and Bipolar Disorder.

BACKGROUND: Turner syndrome (TS) is an X-linked chromosomal abnormality with a global prevalence of 1/2000 live-born girls. The physiological symptoms of TS have been thoroughly characterized, but only a few studies have described associated psychiatric symptoms. We report a case of an adolescent girl who presented with acute mania with psychotic features and was successfully treated with electroconvulsive therapy (ECT). She was subsequently diagnosed with bipolar syndrome and TS. Case Presentation. A 17-year-old girl presented to us with manic symptoms, including disorganized speech, auditory hallucinations, and affect lability. Initially, she was treated with antipsychotics and benzodiazepines, whereby the positive affective symptoms declined. However, the psychotic symptoms progressed, and she developed a catatonic state. ECT was started 6 days after admission, with improvement after two treatments. When ECT was tapered after seven sessions, she relapsed, and the treatment was extended to twelve sessions, with successful outcome. Following discharge, she was diagnosed with TS with partial loss on one of the X-chromosomes (46X, del (X)(p21)), which might have contributed to the development of her sudden acute manic episode. CONCLUSIONS: This case demonstrates for the first time that ECT may be a safe and efficient treatment strategy for acute mania in adolescents with concomitant TS and that severely affected adolescents may require a prolonged series with gradual tapering of ECT. The present case also demonstrates a possible association between TS and bipolar syndrome and that the clinical presentation of a manic episode in a patient with this comorbidity could be more complex and the treatment response slower.

Monoacylglycerols activate TRPV1--a link between phospholipase C and TRPV1.

Phospholipase C-mediated hydrolysis of phosphatidylinositol 4,5-bisphosphate generates diacylglycerol, inositol 1,4,5-trisphosphate and protons, all of which can regulate TRPV1 activity via different mechanisms. Here we explored the possibility that the diacylglycerol metabolites 2-arachidonoylglycerol and 1-arachidonoylglycerol, and not metabolites of these monoacylglycerols, activate TRPV1 and contribute to this signaling cascade. 2-Arachidonoylglycerol and 1-arachidonoylglycerol activated native TRPV1 on vascular sensory nerve fibers and heterologously expressed TRPV1 in whole cells and inside-out membrane patches. The monoacylglycerol lipase inhibitors methylarachidonoyl-fluorophosphonate and JZL184 prevented the metabolism of deuterium-labeled 2-arachidonoylglycerol and deuterium-labeled 1-arachidonoylglycerol in arterial homogenates, and enhanced TRPV1-mediated vasodilator responses to both monoacylglycerols. In mesenteric arteries from TRPV1 knock-out mice, vasodilator responses to 2-arachidonoylglycerol were minor. Bradykinin and adenosine triphosphate, ligands of phospholipase C-coupled membrane receptors, increased the content of 2-arachidonoylglycerol in dorsal root ganglia. In HEK293 cells expressing the phospholipase C-coupled histamine H1 receptor, exposure to histamine stimulated the formation of 2-AG, and this effect was augmented in the presence of JZL184. These effects were prevented by the diacylglycerol lipase inhibitor tetrahydrolipstatin. Histamine induced large whole cell currents in HEK293 cells co-expressing TRPV1 and the histamine H1 receptor, and the TRPV1 antagonist capsazepine abolished these currents. JZL184 increased the histamine-induced currents and tetrahydrolipstatin prevented this effect. The calcineurin inhibitor ciclosporin and the endogenous "entourage" compound palmitoylethanolamide potentiated the vasodilator response to 2-arachidonoylglycerol, disclosing TRPV1 activation of this monoacylglycerol at nanomolar concentrations. Furthermore, intracerebroventricular injection of JZL184 produced TRPV1-dependent antinociception in the mouse formalin test. Our results show that intact 2-arachidonoylglycerol and 1-arachidonoylglycerol are endogenous TRPV1 activators, contributing to phospholipase C-dependent TRPV1 channel activation and TRPV1-mediated antinociceptive signaling in the brain.

Pungent products from garlic activate the sensory ion channel TRPA1.

Garlic belongs to the Allium family of plants that produce organosulfur compounds, such as allicin and diallyl disulfide (DADS), which account for their pungency and spicy aroma. Many health benefits have been ascribed to Allium extracts, including hypotensive and vasorelaxant activities. However, the molecular mechanisms underlying these effects remain unknown. Intriguingly, allicin and DADS share structural similarities with allyl isothiocyanate, the pungent ingredient in wasabi and other mustard plants that induces pain and inflammation by activating TRPA1, an excitatory ion channel on primary sensory neurons of the pain pathway. Here we show that allicin and DADS excite an allyl isothiocyanate-sensitive subpopulation of sensory neurons and induce vasodilation by activating capsaicin-sensitive perivascular sensory nerve endings. Moreover, allicin and DADS activate the cloned TRPA1 channel when expressed in heterologous systems. These and other results suggest that garlic excites sensory neurons primarily through activation of TRPA1. Thus different plant genera, including Allium and Brassica, have developed evolutionary convergent strategies that target TRPA1 channels on sensory nerve endings to achieve chemical deterrence.

Endogenous unsaturated C18 N-acylethanolamines are vanilloid receptor (TRPV1) agonists.

The endogenous C18 N-acylethanolamines (NAEs) N-linolenoylethanolamine (18:3 NAE), N-linoleoylethanolamine (18:2 NAE), N-oleoylethanolamine (18:1 NAE), and N-stearoylethanolamine (18:0 NAE) are structurally related to the endocannabinoid anandamide (20:4 NAE), but these lipids are poor ligands at cannabinoid CB(1) receptors. Anandamide is also an activator of the transient receptor potential (TRP) vanilloid 1 (TRPV(1)) on primary sensory neurons. Here we show that C18 NAEs are present in rat sensory ganglia and vascular tissue. With the exception of 18:3 NAE in rat sensory ganglia, the levels of C18 NAEs are equal to or substantially exceed those of anandamide. At submicromolar concentrations, 18:3 NAE, 18:2 NAE, and 18:1 NAE, but not 18:0 NAE and oleic acid, activate native rTRPV(1) on perivascular sensory nerves. 18:1 NAE does not activate these nerves in TRPV(1) gene knock-out mice. Only the unsaturated C18 NAEs elicit whole cell currents and fluorometric calcium responses in HEK293 cells expressing hTRPV(1). Molecular modeling revealed a low energy cluster of U-shaped unsaturated NAE conformers, sharing several pharmacophoric elements with capsaicin. Furthermore, one of the two major low energy conformational families of anandamide also overlaps with the cannabinoid CB(1) receptor ligand HU210, which is in line with anandamide being a dual activator of TRPV(1) and the cannabinoid CB(1) receptor. This study shows that several endogenous non-cannabinoid NAEs, many of which are more abundant than anandamide in rat tissues, activate TRPV(1) and thus may play a role as endogenous TRPV(1) modulators.

Vascular effects of anandamide and N-acylvanillylamines in the human forearm and skin microcirculation.

The endocannabinoid anandamide is an emerging potential signalling molecule in the cardiovascular system. Anandamide causes vasodilatation, bradycardia and hypotension in animals and has been implicated in the pathophysiology of endotoxic, haemorrhagic and cardiogenic shock, but its vascular effects have not been studied in man. Human forearm blood flow and skin microcirculatory flow were recorded using venous occlusion plethysmography and laser-Doppler perfusion imaging (LDPI), respectively. Each test drug was infused into the brachial artery or applied topically on the skin followed by a standardized pin-prick to disrupt the epidermal barrier. Anandamide failed to affect forearm blood flow when administered intra-arterially at infusion rates of 0.3-300 nmol min(-1). The highest infusion rate led to an anandamide concentration of approximately 1 microM in venous blood as measured by mass spectrometry. Dermal application of anandamide significantly increased skin microcirculatory flow and coapplication of the transient receptor potential vanilloid 1 (TRPV1) antagonist capsazepine inhibited this effect. The TRPV1 agonists capsaicin, olvanil and arvanil all induced concentration-dependent increases in skin blood flow and burning pain when administered dermally. Coapplication of capsazepine inhibited blood flow and pain responses to all three TRPV1 agonists. This study shows that locally applied anandamide is a vasodilator in the human skin microcirculation. The results are consistent with this lipid being an activator of TRPV1 on primary sensory nerves, but do not support a role for anandamide as a circulating vasoactive hormone in the human forearm vascular bed.

Effect of hypoxia on vasodilator responses to S-nitroso-N-acetylpenicillamine and levcromakalim in guinea pig basilar artery.

Ischaemic stroke is characterised by reduction of blood flow, tissue hypoxia, energy depletion and neuronal death. Drugs causing vasodilatation of cerebral arteries may potentially enhance blood supply to the ischaemic area and improve clinical outcome. However, vasodilators could also reduce cerebral blood flow in the ischaemic region by acting on blood vessels in non-ischaemic tissue, a phenomenon known as blood flow steal. To explore whether these drugs could act selectively on cerebral blood vessels in a hypoxic environment, we examined the effect of hypoxia on vasodilator responses to the nitric oxide (NO) donor S-nitroso-N-acetylpenicillamine (SNAP) and the ATP-dependent potassium channel (K(ATP)) opener levcromakalim in guinea-pig basilar arteries contracted by endothelin-1. Hypoxia considerably enhanced the vasodilator responses to SNAP, while those to levcromakalim were unaffected. In the presence of the NO synthase inhibitor N(G)-nitro-L-arginine, hypoxia no longer enhanced the vasodilator response to SNAP and suppressed responses to levcromakalim. The results show that the NO donor SNAP, but not the K(ATP) opener levcromakalim, is a more effective vasodilator of cerebral arteries contracted by endothelin-1 during hypoxia than under control conditions. Hypoxia-induced inhibition of basal NO synthesis could explain this enhancement of the vasodilator response to SNAP. Thus, NO donors may have a selective effect on blood vessels in ischaemic brain areas and therefore warrant further evaluation as therapeutic agents in cerebral ischaemia.