Current Neuropharmacology (v.14, #2)

Meet Our Editorial Board Member: by Massimo Avoli (117-117).

Excessive intake of food, especially palatable and energy-dense carbohydrates and fats, is largely responsible for the growing incidence of obesity worldwide. Although there are a number of candidate antiobesity drugs, only a few of them have been proven able to inhibit appetite for palatable foods without the concurrent reduction in regular food consumption. In this review, we discuss the interrelationships between homeostatic and hedonic food intake control mechanisms in promoting overeating with palatable foods and assess the potential usefulness of systemically administered pharmaceuticals that impinge on the endogenous cannabinoid, opioid, aminergic, cholinergic, and peptidergic systems in the modification of food preference behavior. Also, certain dietary supplements with the potency to reduce specifically palatable food intake are presented. Based on human and animal studies, we indicate the most promising therapies and agents that influence the effectiveness of appetite-modifying drugs. It should be stressed, however, that most of the data included in our review come from preclinical studies; therefore, further investigations aimed at confirming the effectiveness and safety of the aforementioned medications in the treatment of obese humans are necessary.

Mitochondrial Biology and Neurological Diseases by Siddharth Arun, Lei Liu, Gizem Donmez (143-154).
Mitochondria are extremely active organelles that perform a variety of roles in the cell including energy production, regulation of calcium homeostasis, apoptosis, and population maintenance through fission and fusion. Mitochondrial dysfunction in the form of oxidative stress and mutations can contribute to the pathogenesis of various neurodegenerative diseases such as Parkinson's (PD), Alzheimer's (AD), and Huntington's diseases (HD). Abnormalities of Complex I function in the electron transport chain have been implicated in some neurodegenerative diseases, inhibiting ATP production and generating reactive oxygen species that can cause major damage to mitochondria.
Mutations in both nuclear and mitochondrial DNA can contribute to neurodegenerative disease, although the pathogenesis of these conditions tends to focus on nuclear mutations. In PD, nuclear genome mutations in the PINK1 and parkin genes have been implicated in neurodegeneration [1], while mutations in APP, PSEN1 and PSEN2 have been implicated in a variety of clinical symptoms of AD [5]. Mutant htt protein is known to cause HD [2]. Much progress has been made to determine some causes of these neurodegenerative diseases, though permanent treatments have yet to be developed. In this review, we discuss the roles of mitochondrial dysfunction in the pathogenesis of these diseases.

Neuroinflammation is an important feature in the pathogenesis and progression of neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), frontotemporal dementia and amyotrophic lateral sclerosis. Based on current knowledge in the field, suggesting that targeting peripheral inflammation could be a promising additional treatment/prevention approach for neurodegenerative diseases, drugs and natural products with anti-inflammatory properties have been evaluated in animal models of neuroinflammation and neurodegeneration. In this review, we provide an extensive analysis of one of the most important and widely-used animal models of peripherally induced neuroinflammation and neurodegeneration - lipopolysaccharide (LPS)-treated mice, and address the data reproducibility in published research. We also summarize briefly basic features of various natural products, nutraceuticals, with known anti-inflammatory effects and present an overview of data on their therapeutic potential for reducing neuroinflammation in LPS-treated mice.

Kappa Opioids, Salvinorin A and Major Depressive Disorder by George T. Taylor, Francesca Manzella (165-176).
Opioids are traditionally associated with pain, analgesia and drug abuse. It is now clear, however, that the opioids are central players in mood. The implications for mood disorders, particularly clinical depression, suggest a paradigm shift from the monoamine neurotransmitters to the opioids either alone or in interaction with monoamine neurons. We have a special interest in dynorphin, the last of the major endogenous opioids to be isolated and identified. Dynorphin is derived from the Greek word for power, dynamis, which hints at the expectation that the neuropeptide held for its discoverers. Yet, dynorphin and its opioid receptor subtype, kappa, has always taken a backseat to the endogenous b-endorphin and the exogenous morphine that both bind the mu opioid receptor subtype. That may be changing as the dynorphin/ kappa system has been shown to have different, often opposite, neurophysiological and behavioral influences. This includes major depressive disorder (MDD). Here, we have undertaken a review of dynorphin/ kappa neurobiology as related to behaviors, especially MDD. Highlights include the unique features of dynorphin and kappa receptors and the special relation of a plant-based agonist of the kappa receptor salvinorin A. In addition to acting as a kappa opioid agonist, we conclude that salvinorin A has a complex pharmacologic profile, with potential additional mechanisms of action. Its unique neurophysiological effects make Salvinorina A an ideal candidate for MDD treatment research.

Alzheimer's Disease Risk and Progression: The Role of Nutritional Supplements and their Effect on Drug Therapy Outcome by A. Giulietti, A. Vignini, L. Nanetti, L. Mazzanti, R. Di Primio, E. Salvolini (177-190).
Alzheimer's disease (AD) is the most common neurodegenerative disease in the elderly population. Despite significant advancements in understanding the genetic and molecular basis of AD, the pathology still lacks treatments that can slow down or reverse the progression of cognitive deterioration. Recently, the relationship between nutrient deficiency and dementia onset has been highlighted. AD is in fact a multifactorial pathology, so that a multi-target approach using combinations of micronutrients and drugs could have beneficial effects on cognitive function in neurodegenerative brain disorders leading to synaptic degeneration. Primarily, this review examines the most recent literature regarding the effects of nutrition on the risk/progression of the disease, focusing attention mostly on antioxidants agents, polyunsaturated fatty acids and metals. Secondly, it aims to figure out if nutritional supplements might have beneficial effects on drug therapy outcome. Even if nutritional supplements showed contrasting evidence of a likely effect of decreasing the risk of AD onset that could be studied more deeply in other clinical trials, no convincing data are present about their usefulness in combination with drug therapies and their effectiveness in slowing down the disease progression.

The Role of Levomilnacipran in the Management of Major Depressive Disorder: A Comprehensive Review by Antonio Bruno, Paolo Morabito, Edoardo Spina, Maria Rosaria Muscatello (191-199).
Levomilnacipran, the more active enantiomer of the serotonin and norepinephrine reuptake inhibitor (SNRI) milnacipran, was recently approved in the US for the treatment of major depressive disorder (MDD). The drug was developed as an extended release (ER) capsule formulation to allow for once-daily administration, thereby improving patient adherence. This agent differs from other available SNRIs in having a greater potency for inhibition of norepinephrine relative to serotonin reuptake. The efficacy of levomilnacipran ER has been evaluated in seven randomised, double-blind clinical trials (one Phase II and four Phase III trials, and two long-term efficacy studies). These studies documented that levomilnacipran is generally more effective than placebo for the treatment of MDD in the short-term, whereas no firm evidence exists on long-term efficacy for relapse prevention. Preliminary evidence suggests that levomilnacipran ER may be effective in improving not only depressive symptoms but also symptoms related to functioning (social life, work, and family life). Short-and longer-term studies found that the rate of withdrawal from levomilnacipran therapy due to adverse events was rather low. Moreover the drug appeared to be generally well tolerated. The most common adverse effects included nausea, hyperhidrosis, constipation, tachycardia, palpitations, erectile dysfunction and ejaculation disorder. As hypertension or orthostatic hypotension may occur in a few patients, the cardiovascular safety of levomilnacipran needs to be more extensively investigated especially on long-term treatment. Additional active comparator trials evaluating efficacy, tolerability and cost-effectiveness are required to better define the role of levomilnacipran ER in the treatment of MDD in relation to currently available antidepressants including other SNRIs.

Memantine and Kynurenic Acid: Current Neuropharmacological Aspects by Zsófia Majláth, Nóra Török, József Toldi, László Vécsei (200-209).
Glutamatergic neurotransmission, of special importance in the human brain, is implicated in key brain functions such as synaptic plasticity and memory. The excessive activation of N-methyl- D-aspartate (NMDA) receptors may result in excitotoxic neuronal damage; this process has been implicated in the pathomechanism of different neurodegenerative disorders, such as Alzheimer's disease (AD). Memantine is an uncompetitive antagonist of NMDA receptors with a favorable pharmacokinetic profile, and is therefore clinically well tolerated. Memantine is approved for the treatment of AD, but may additionally be beneficial for other dementia forms and pain conditions. Kynurenic acid (KYNA) is an endogenous antagonist of NMDA receptors which has been demonstrated under experimental conditions to be neuroprotective. The development of a well-tolerated NMDA antagonist may offer a novel therapeutic option for the treatment of neurodegenerative disease and pain syndromes. KYNA may be a valuable candidate for future drug development.