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The development of new antidepressants has had mixed results over the past decade, with several notable failures. This paper reviews a number of major initiatives in the development of new antidepressant agents. Traditional strategies to build on agents that have monoaminergic effects at the synapse (e.g., vilazodone and ketamine) have been complemented with efforts that have emphasized devices and brain circuits (e.g., deep brain stimulation and transcranial magnetic stimulation) or chemical agents that modulate neuroendocrine systems (e.g., glucocorticoid antagonists, mixed melatonin agonists/serotonin type-2 receptor antagonists). Interestingly, chemical agents, such as onabotulinumtoxin A, may affect brain circuits as well. We present data from recent studies in drug and device development--reviewing progress made, stumbling blocks encountered, and issues that need to be addressed in future studies. [ABSTRACT FROM AUTHOR]

Major depressive disorder (MDD) is one of the most disabling diseases worldwide and is becoming a significant public health threat. Current treatments forMDDprimarily consist of monoamine-targeting agents and have limited efficacy. However, the glutamate neurotransmitter system has recently come into focus as a promising alternative for novel antidepressant treatments. We review the current data on the glutamate NMDA receptor antagonist ketamine, which has been shown in clinical trials to act as a rapid antidepressant inMDD.We also examine ketamine efficacy on dimensions of psychopathology, including anhedonia, cognition, and suicidality, consistent with theNIMH Research Domain Criteria initiative. Other aspects of ketamine reviewed in this paper include safety and efficacy, different administration methods, and the risks of misuse of ketamine outside of medical settings. Finally, we conclude with a discussion of glutamatergic agents other than ketamine currently being tested as novel antidepressants. [ABSTRACT FROM AUTHOR]

This paper presents commentaries on how endoluminal antireflux procedures compare to laparoscopic fundoplication; new endoscopic procedures being studied to treat refractory gastroesophageal reflux disease (GERD); the new Stretta; the relationship between obesity and proton pump inhibitor (PPI) resistance; data concerning acid hypersensitivity and sensory receptors (vallinoid, TRPV1) causing refractory GERD; whether microscopic esophagitis is relevant in determining symptoms of non-erosive reflux disease (NERD); how concomitant functional gastrointestinal disorders affect the PPI response in NERD; the evidence that a functional esophagus is associated with inflammatory bowel syndrome (IBS); the role of GABA agonists in the treatment of refractory GERD; the role of biofeedback and antidepressants in refractory GERD; and endoluminal fundoplication using the EsophyX device. [ABSTRACT FROM AUTHOR]

Recent studies suggest that bioactive dietary polyphenol preparation (BDPP) and individual polyphenolic compounds ameliorate stress‐induced depression‐like behaviors, but the underlying molecular mechanisms are incompletely understood. VGF (non‐acronymic) in the dorsal hippocampus (dHc) has been shown to play a role in depression‐like behaviors and antidepressant efficacy, and the VGF‐derived peptide TLQP‐62 (named by the N‐terminal 4 amino acids and length) infused into dHc has been shown to have antidepressant efficacy that is BDNF–TrkB dependent. Here, we investigated whether BDPP influences VGF expression in the dHc, and whether dHc VGF is required for BDPP antidepressant efficacy. We found that BDPP produced antidepressant‐like effects in naive mice and reversed the depression‐like behaviors induced by chronic variable stress. In addition, we found that BDPP had no detectable antidepressant efficacy in floxed mice with prior knockdown in the dHc of either VGF or BDNF, achieved by adeno‐associated virus‐Cre infusion. Our data indicate that dHc VGF and BDNF expression are required for the antidepressant actions of BDPP, and therefore suggest that a VGF(TLQP‐62)–BDNF–TrkB autoregulatory feedback loop could play a role in the regulation of BDPP antidepressant efficacy, much as it has been suggested to function in the antidepressant efficacies of ketamine and TLQP‐62. [ABSTRACT FROM AUTHOR]

Cognitive impairment in late-life depression is prevalent, disabling, and heterogeneous. Although mild cognitive impairment in depression does not usually progress to dementia, accurate assessment of cognition is vital to prognosis and treatment planning. For example, executive dysfunction often accompanies late-life depression, influences performance across cognitive domains, and is associated with poor antidepressant treatment outcomes. Here, we review howassessment can capture dysfunction across cognitive domains and discuss cognitive trajectories frequently observed in late-life depression in the context of the neurobiology of this disorder. We also review the efficacy of a sample of interventions tailored to specific cognitive profiles. [ABSTRACT FROM AUTHOR]

In spite of the high prevalence and negative impact of depression, little is known about its pathophysiology. Basic research on depression needs new animal models in order to increase knowledge of the disease and search for new therapies. The work presented here aims to provide a neurobiologically validated model for investigating the relationships among sickness behavior, antidepressants treatment, and social dominance behavior. For this purpose, dominant individuals from dyads of male Swiss mice were treated with the bacterial endotoxin lipopolysaccharide (LPS) to induce social hierarchy destabilization. Two groups were treated with the antidepressants imipramine and fluoxetine prior to LPS administration. In these groups, antidepressant treatment prevented the occurrence of social destabilization. These results indicate that this model could be useful in providing new insights into the understanding of the brain systems involved in depression. [ABSTRACT FROM AUTHOR]

Increased levels of glucocorticoid hormones—the main product of the hypothalamic-pituitary-adrenal (HPA) axis—have been considered to be “depressogenic,” but this notion has largely derived from studies in patients with endocrine conditions, such as Cushing's syndrome or exogenous treatment with synthetic glucocorticoids. In these conditions, it is likely that the full impact of the high glucocorticoid levels is felt on the brain, through over-stimulation of the glucocorticoid receptors (GRs); indeed, normalizing these high levels leads to an improvement of mood in these patients. However, a completely different mechanism may be operating in major depression, where the increased levels of glucocorticoid hormones are conceptualized as driven by an impairment in GR function (glucocorticoid resistance), and therefore as a “compensatory” mechanism. Moreover, clinical and experimental studies have shown that antidepressants increase GR function, thus leading to resolution of glucocorticoid resistance. Interestingly, a number of studies have also demonstrated that manipulating GR function with both agonists and antagonists has an antidepressant effect, and indeed that other drugs targeting the HPA axis and cortisol secretion—even drugs with opposite effects on the HPA axis—have antidepressant effects. These studies do not support the notion that “high levels of glucocorticoids” always have a depressogenic effect, nor that decreasing the effects of these hormones always has an antidepressant effects. [ABSTRACT FROM AUTHOR]

Dual dopamine (DA)/serotonin (5-HT)–releasing agents are promising candidate medications for stimulant addiction and other disorders. However, certain 5-HT transporter (SERT) substrates are associated with development of idiopathic pulmonary arterial hypertension (IPAH) and valvular heart disease (VHD). According to the “5-HT hypothesis,” SERT substrates increase the risk for developing IPAH and VHD by increasing plasma 5-HT. To test this hypothesis directly, we determined the effects of acute and chronic fenfluramine, and other SERT ligands, on plasma 5-HT in male rats. For acute treatments, rats received i.v. vehicle or test drug (0.3 and 1.0 mg/kg), and serial blood samples were withdrawn. For chronic treatments, vehicle or test drug was infused via osmotic minipump (3 and 10 mg/kg/d) for 2 weeks. On the last day of infusion, rats received i.v. fenfluramine challenge (1 mg/kg), and serial blood samples were withdrawn. Plasma 5-HT was measured using ex vivo microdialysis in whole-blood samples. Baseline plasma 5-HT was <1.0 nM. Acute injection of fenfluramine or other SERT substrates caused large (up to 24-fold) dose-dependent increases in plasma 5-HT. Chronic fenfluramine at 3 and 10 mg/kg/d produced 1.7- and 3.5-fold increases in baseline plasma 5-HT, while chronic fluoxetine had no effect. Chronic infusions of fenfluramine or fluoxetine diminished the ability of acute fenfluramine to elevate dialysate 5-HT, and both drugs markedly reduced whole-blood 5-HT. Acute fenfluramine increases plasma 5-HT to concentrations that are below the micromolar levels necessary to produce adverse cardiovascular effects. Chronic fenfluramine and fluoxetine have minimal effects on plasma 5-HT, suggesting that the increased risk for IPAH associated with fenfluramine does not depend upon elevations in plasma 5-HT. [ABSTRACT FROM AUTHOR]

Previously we have examined the effects of phencyclidine and clozapine upon the gene expression in the mouse brain. Recently, fluoxetine (Prozac) has been introduced for the therapeutic purpose as an antidepressant drug. Miledi et al. reported blockage of mouse muscle and neuronal nicotinic acetylcholine receptor by various concentrations of fluoxetine. Furthermore, Kobayashi et al. discovered that fluoxetine inhibits G protein activated inwardly rectifying G protein activated K+ (GIRK) channels using Xenopus oocyte expression assay. From these experiments, we considered that it might be interesting to study the effects of fluoxetine on the gene expression in the mouse brain. After we have injected fluoxetine once a day into mouse for 20 days, we sacrificed mouse by decapitation and extracted RNA from mouse cerebral cortex. We used DNA microarray method for examining the gene expression in the brain. We found the downregulation of many spot signals in the fluoxetine-treated mouse, for example cholecystockinin and prostaglandin D2 synthase. [ABSTRACT FROM AUTHOR]