Current Drug Targets - Volume 19, Issue 8, 2018

Premature ejaculation (PE) is one of the commonest male sexual dysfunctions. It is characterized by ejaculation which occurs before or soon after vaginal penetration, which causes significant psychological distress to the individual, and his partner. The exact cause of PE is still unknown but several mechanisms are proposed, and these involve complex interactions of neurophysiological, psychosocial, and cognitive factors. We discuss the role of serotonin, nitric oxide, phosphodiesterase enzymes and other neurotransmitters. Treatment of PE tends to co-occur with other sexual difficulties, especially erectile dysfunction (ED). Treatment with selective serotonin reuptake inhibitors (SSRIs) and Dapoxitene are also discussed in detail. The treatment strategy requires a comprehensive holistic approach incorporating both combination of psychopharmacological agent and cognitive-behavioral therapy (CBT). The present review highlights the integration of the hypothalamic-neural and reverberating emotional circuit and discusses the etiology and treatment for patients with PE.

Psychotic disorders are recognized as severe mental disorders that rigorously affect patient's personality, critical thinking, and perceptional ability. High prevalence, global dissemination and limitations of conventional pharmacological approaches compel a significant burden to the patient, medical professionals and the healthcare system. To date, numerous orally administered therapies are available for the management of depressive disorders, schizophrenia, anxiety, bipolar disorders and autism spectrum problems. However, poor water solubility, erratic oral absorption, extensive first-pass metabolism, low oral bioavailability and short half-lives are the major factors which limit the pharmaceutical significance and therapeutic feasibility of these agents. In recent decades, nanotechnology-based delivery systems have gained remarkable attention of the researchers to mitigate the pharmaceutical issues related to the antipsychotic therapies and to optimize their oral drug delivery, therapeutic outcomes, and patient compliance. Therefore, the present review was aimed to summarize the available in vitro and in vivo evidences signifying the pharmaceutical importance of the advanced delivery systems in improving the aqueous solubility, transmembrane permeability, oral bioavailability and therapeutic outcome of the antipsychotic agents.

Background: One of the goals of cancer treatment is symptoms management especially at the end stage. The common symptoms in cancer include pain, fatigue, depression and cognitive dysfunction. The available treatment options for symptom management are limited. Methylphenidate, a psychostimulant, may be of benefit for these patients. In this report, we review the use of methylphenidate for symptoms control in cancer patients. Method: Electronic literature search on PubMed was conducted using the following keywords: methylphenidate, cancer, carcinoma, oncology, oncological and tumour. We identified forty two relevant studies and publications on the use of methylphenidate in cancer patients to be included in this review. Results: Methylphenidate was found to have some evidence in reducing opioid-induced sedation, improving cognitive symptoms and reduction of fatigue in cancer patients. Nevertheless, the results were inconsistent due to variations in the study populations, study design and outcome measures, among others. There was minimal evidence on its use in treating depression. Otherwise, methylphenidate was generally well-tolerated by patients. Conclusion: This review potentially supports the use of methylphenidate for opioid-induced sedation, cognitive decline and fatigue in cancer patients. Further placebo-controlled trials would help in strengthening the evidence for this treatment.

Depression is a common psychiatric disorder that decreases the quality of life and increases the mortality of patients. It incurs significant healthcare costs if left untreated. Even though intervention with antidepressants can reduce depressive symptoms, side effects are often an issue and relapse is very common. Vitamin D, commonly known as the sunshine vitamin, is an essential fat-soluble vitamin for the absorption of calcium to prevent rickets (children) and osteomalacia (adults). Evidence on a possible relationship between vitamin D deficiency and depression is growing. In this review, the authors summarized the evidence on the association between vitamin D status and depression in human observational studies, followed by clinical trials to evaluate the effects of vitamin D supplementation in treating depression. In conclusion, vitamin D deficiency may be associated with an increased risk or severity of depression. Supplementation of vitamin D may confer protection for depressed patients.

Cognitive function and testosterone level of men decline concurrently with age. Low testosterone levels are associated with higher risk of Alzheimer's disease and mild cognitive impairment in men. There are continuous debates on whether this relationship is casual. This paper aims to summarize the current evidence on the association between testosterone level and cognitive function in elderly men. The presence of testosterone, androgen receptor and its responsive genes indicates that testosterone has biological functions in the central nervous system. The ability of the body to convert testosterone into estrogen suggests that part of the actions of testosterone could be mediated by estrogen. Observational studies generally showed that low endogenous testosterone levels were associated with poor cognitive performance in healthy elderly men. Testosterone substitution exerted positive effects on certain cognitive domains in normal and hypogonadal elderly men. In conclusion, testosterone may influence cognitive function in elderly men and its substitution may be considered in men with cognitive impairment and testosterone deficiency.

In the past decade, many studies have highlighted the role of metabotropic glutamate receptor subtype 5 (mGlu5) modulators in attenuating alcohol-related biological effects such as alcohol consumption, alcohol-seeking and relapse-like behaviors. Taken together, these findings suggest that pharmacological agents acting at mGlu5 could be promising tools in curbing inebriation. mGlu5s are present abundantly in brain regions known to be involved in emotion regulation, motivation and drug administration. On a cellular level, they are primarily located at the postsynaptic part of the neuron where the receptor is functionally linked to various downstream proteins that are involved in cell signaling and gene transcription that mediate the alcohol-induced neuroplasticity. As well, the discovery of a functional link between mGlu5 and a specific isozyme, Protein Kinase C epsilon (PKC) in mediating the attenuating effects of selective negative allosteric modulators of mGlu5 such as methyl- 6(phenylethynyl)pyridine (MPEP) and 3-((2-methyl-4-thiazolyl)ethynyl)pyridine (MTEP) has sparked interesting speculations. In this article, we shall review the following: the effects of acute and chronic alcohol intake on mGlu5 signaling; the effects of mGlu5 ligands on alcohol-related neurobehavioral changes that are currently being studied both at pre-clinical and clinical stages; and the mechanisms underlying the pharmacological effects of these drugs.

Vaginismus is an involuntary muscle contraction of the outer third of vaginal barrel causing sexual penetration almost impossible. It is generally classified under sexual pain disorder (SPD). In Diagnostic and Statistical Manual, 5th edition (DSM-5), it is classified under the new rubric of Genito-Pelvic Pain/Sexual Penetration Disorder. This fear-avoidance condition poses an ongoing significant challenge to the medical and health professionals due to the very demanding needs in health care despite its unpredictable prognosis. The etiology of vaginismus is complex: through multiple biopsycho- social processes, involving bidirectional connections between pelvic-genital (local) and higher mental function (central regulation). It has robust neural and psychological-cognitive loop feedback involvement. The internal neural circuit involves an inter-play of at least two-pathway systems, i.e. both “quick threat assessment” of occipital-limbic-occipital-prefrontal-pelvic-genital; and the chronic pain pathways through the genito-spinothalamic-parietal-pre-frontal system, respectively. In this review, a neurobiology root of vaginismus is deliberated with the central role of an emotional-regulating amygdala, and other neural loop, i.e. hippocampus and neo-cortex in the core psychopathology of fear, disgust, and sexual avoidance. Many therapists view vaginismus as a neglected art-and-science which demands a better and deeper understanding on the clinico-pathological correlation to enhance an effective model for the bio-psycho-social treatment. As vaginismus has a strong presentation in psychopathology, i.e. fear of penetration, phobic avoidance, disgust, and anticipatory anxiety, we highlighted a practical psychiatric approach to the clinical management of vaginismus, based on the current core knowledge in the perspective of neuroscience.

Neurodegenerative disease is an incurable disease which involves the degeneration or death of the nerve cells. Alzheimer's Disease (AD) is a neurodegenerative disease discovered in 1906 by Alois Alzheimer, a German clinical psychiatrist and neuroanatomist. The main pathological hallmarks of this disease are the formation of extracellular amyloid β (Aβ) plaques and intracellular neurofibrillary tangle (NFT). The accumulation of the amyloid protein aggregates in the brain of AD patients leads to oxidative stress and inflammation. Other postulated reasons for the development of this disease are cholinergic depletion and excessive glutamatergic neurotransmission. The current drugs approved and marketed for the treatment of AD are cholinesterase inhibitors (ChEIs) and N-methyl-Daspartate (NMDA) receptor antagonists. The function of ChEIs is to avoid cholinergic depletion; whereas the function of NMDA receptor antagonist is to block excessive glutamatergic neurotransmission. Unfortunately, the current drugs prescribed for AD show only modest improvement in terms of symptomatic relief and delay the progression of the disease. This review will discuss about several polyphenolic compounds as potential natural treatment options for AD. Three compounds are highlighted in this review — Curcumin (Cur), Resveratrol (Rsv) and Epigallocatechin-3- gallate (EGCG). These compounds have huge potential for AD treatment, especially due to their low frequency of adverse events. However, the current conventional pharmaceutical drugs remain as the mainstay of treatment for AD.

Over the past few decades, evidence accumulated to indicate that parasympathetic innervation regulates liver injury and regeneration. Liver derives its parasympathetic input via vagus nerve. In animal models, vagus nerve stimulation and transection are frequently used to determine the impact of parasympathetic input on liver injury responses. Such strategies provide limited understanding of postneuronal mechanisms involved in the regulation of liver injury. The hepatic branch of vagus nerve releases acetylcholine (ACh), which activates muscarinic and nicotinic receptors in hepatocytes as well as non-parenchymal cells to modulate cellular functions. Moreover, vagus nerve releases other neurotransmitters such as vasoactive intestinal peptide (VIP), which also modulates liver injury responses and hemodynamics. Therefore, our understanding of the post-neuronal modulation of liver injury in models utilizing vagus nerve activity remains limited. Gene-silencing technologies and pharmacological manipulation of receptor activity have not only improved our understanding of the role of specific cholinergic receptors but also elucidated the role of various liver cell sub-populations in modulating liver injury response. With advent of organ- and cell-specific transgenic mice, our understanding of neural regulation of liver injury is likely to improve further. This review comprehensively provides current understanding of cholinergic regulation of liver injury, and points to potential therapeutic targets to treat liver injury.

Background: Metformin, a widely prescribed blood glucose normalizing antidiabetic drug, is now beginning to receive increasing attention due to its anti-inflammatory properties. Objective:To provide a critical and comprehensive review of the available literature describing the effects of metformin on the immune system and on auto-inflammatory diseases. Results:Based on the available scientific literature, metformin suppresses immune responses mainly through its direct effect on the cellular functions of various immune cell types by induction of AMPK and subsequent inhibition of mTORC1, and by inhibition of mitochondrial ROS production. Among key immune events, this results in inhibited monocyte to macrophage differentiation and restrained inflammatory capacity of activated macrophages. In addition, metformin treatment increases differentiation of T cells into both regulatory and memory T cells, as well as decreasing the capacity of neutrophils to commence in NETosis. Due to its inhibitory effect on the proinflammatory phenotype of immune cells, metformin seems to reduce auto-immune disease burden not only in several animal models, but has also shown beneficial results in some human trials. Conclusions: Based on its immunomodulatory properties and high tolerability as a drug, metformin is an interesting add-on drug for future trials in treatment of immune mediated inflammatory diseases.

Background: Individuals with chronic diseases have persistent pain as the main symptom, which can often reduce their life quality and functional capacity. The suffering of patients results from the interaction of aversive perception of pain with physical disability, social and family isolation, financial worries and fear of mutilation and death. As an individual and subjective phenomenon that involves many complex aspects, chronic pain should be evaluated and treated in its various components. Several drugs are currently used, but besides the high cost, they have side effects that are harmful to patients. Therefore, there is the need to search for new options for pain relief. Natural products as monoterpenes have been the target of many researchers. Objective: This systematic review aimed to briefly summarize the knowledge of the analgesic potential of monoterpenes facing chronic pain. Results: After a search in PubMed, Lilacs, Scopus and Cochrane, 27 articles were selected, which described the analgesic potential of 16 monoterpenes for relief of chronic pain. Conclusion: After analyzing the data, it can be suggested that these compounds are strong candidates for the treatment of painful states.

Background: Mitochondrial aconitase (Aco2), a member of the family of iron-sulfur [4Fe- 4S]-containing dehydratases, is involved in cellular metabolism through the tricarboxylic acid cycle. Aco2 is highly susceptible to oxidative damage in a way that exposure to the reactive species and free radicals leads to release of iron from the central [4Fe-4S] cluster resulting in the production of the inactive form of Aco2. Objective: There is increasing evidence supporting a direct association between impaired energy metabolism and the incidence and progression of neurodegenerative disorders in neuronal cells. Results: It has been shown that alteration in bioenergetic parameters is a common pathological feature of the neurodegenerative diseases leading to neuronal dysfunction. Numerous studies have demonstrated that dysfunctional Aco2, among the other bioenergetic parameters, is a key factor that could promote neurodegeneration. Conclusion: Increasing our knowledge about energy metabolism-related molecules including Aco2 affected by neurodegenerative disorders might be useful to find an efficient therapeutic strategy for those central nervous system-related diseases. Accordingly, in this review, we have focused on the events and processes that occur in neurodegeneration, leading to the inactivation of Aco2 in the brain.