Current Pharmaceutical Design - Volume 22, Issue 10, 2016

It is well accepted that cortical and hippocampal synaptic densities are reduced in Alzheimer’s disease (AD). These alterations in neuronal networking occur at the very onset of AD and may lead to the neuronal loss displayed in later stages of the disease, which is characterized by severe cognitive and behavioral impairments. Many studies suggest that amyloid-β (Aβ) oligomers are responsible for synaptic disconnections and neuronal death. The effects of Aβ in different brain regions are pleotropic, thus suggesting a common mechanism for toxicity. One potential site for this mechanism of toxicity is the neuronal membrane. It is recognized that Aβ can associate to the plasma membrane and induce the formation of pores after the interaction with lipids like GM1 and cholesterol, and proteins such as APP and NMDA receptors. After this early event, the membrane increases its permeability allowing the influx of small ions and larger molecules. Thus, one of the main toxic consequences of Aβ oligomer interaction with neurons is an increase in intracellular Ca2+ concentration that causes alterations in ionic homeostasis. It has been proposed that Aβ perforates the membrane similarly to pore-forming toxins producing a series of effects that include synaptic failure and cell death. These actions of Aβ appear to be potentiated by neuroinflammation, which results in a series of effects that, when prolonged, will affect membrane integrity, pore formation and cellular homeostasis. Here, we will review the most recent data on Aβ actions at the membrane level and how its relationship with neuroinflammation could further potentiate brain impairment in AD. The notion of having drugs acting with dual inhibitory actions, inhibition of membrane damage and inflammation, could serve as a starting conceptual point for the development of new therapies for the disease.

Parkinson’s disease (PD) is a relatively common disorder of the Central Nervous System (CNS), whose etiology is characterized by a selective and progressive degeneration of dopaminergic neurons, and the presence of Lewy bodies in the pars compacta of the substantia nigra, and gaping dopamine depletion in the striatum. Patients with this disease suffer from tremors, slowness of movements, gait instability, and rigidity. These patients may also present functional disability, reduced quality of life, and rapid cognitive decline. It has been shown that nicotine exerts beneficial effects in patients with PD and in in-vitro and in-vivo models of this disease. Astrocytes are an important component in the immune response associated with PD, and that nicotine might be able to inhibit the inflammation-related apoptosis of these cells, being this a potential strategy for PD treatment. This action of nicotine could be due mainly to activation of α7 nicotinic acetylcholine receptors (α7-nAChRs) expressed in glial cells. However, nicotine administration can protect dopaminergic neurons against degeneration by inhibiting astrocytes activation in the substantia nigra pars compacta (SNpc) and therefore reduce inflammation. Owing to the toxicity and capacity of nicotine to induce addiction, analogues of this substance have been designed and tested in various experimental paradigms, and targeting α7-nAChRs expressed in glial cells may be a novel therapeutic strategy for PD treatment.

Neurodegenerative disorders are one of the most critical public health concerns of our times. Regrettably, therapeutic interventions currently available have shown only partial benefits to patients affected by one of these disorders. Although the important advances made during the last decades, several questions regarding physiopathological aspects of these diseases are still open. On this regard, the role of neuroinflammation is recognized as critical during the establishment and progression of the neurodegenerative process, and several authors have suggested that neuroinflammatory modulation should be at the basis of therapeutic treatment. In the present review we summarize the general aspects of the neuroinflammatory process and the cellular component of such response whose have been commonly related with the main neurodegenerative disorders, particularly Alzheimer’s and Parkinson’s disease, as well as, the main molecular events that might trigger the inflammatory process and affect neuronal support structures, such as the blood brain barrier, leading to neurodegeneration. Additionally, we discuss recent advances regarding Nuclear Receptors research, such as peroxisome proliferators-activated receptors and liver X receptor, and the molecular basis of its potential role against neuroinflammation and neurodegeneration.

Neuroinflammation is a common characteristic of several mental health conditions such as major depression, bipolar disorder, post-traumatic stress disorder (PTSD) and schizophrenia (SCHZ). Inflammatory processes trigger and/or further deteriorate mental functions and are regarded as targets for therapeutic drug development. Cotinine is an alkaloid present in tobacco leaves and the main metabolite of nicotine. Cotinine is safe, non-addictive and has pharmacokinetic properties adequate for therapeutic use. Research has shown that cotinine has antipsychotic, anxiolytic, and antidepressant properties and modulates the serotonergic, cholinergic and dopaminergic systems. Consistent with the modulation of these neurotransmitter systems, cotinine behaves as a positive allosteric modulator of the nicotinic acetylcholine receptors (nAChRs) and has anti-inflammatory effects. The decrease in neuroinflammation induced by the stimulation of the cholinergic system seems to be a key element explaining the beneficial effects of cotinine in a diverse range of neurological and psychiatric conditions. This review discusses new evidence of the role of neuroinflammation as a key aspect in bipolar disorder, PTSD and major depression, as well as the potential use of cotinine to reduce neuroinflammation in those conditions.

Inflammatory response in the nervous system, called neuroinflammation, is a common process of several neurodegenerative diseases and brain disorders. To understand the underlying mechanism of this brain response to damage would be interesting to identify new common therapy targets to neurodegenerative processes. Ischemic stroke has an important socioeconomic impact being the second cause of mortality and the first cause of long-term disability in the world. Until now, there is not any pharmacological treatment to reduce the brain damage induced. In this review, we will expose recent evidences about neuroinflammation after stroke in animal models and in human. We summarize the most relevant information about the inflammatory-cellular component: microglia/ astrocytes response and peripheral blood cells infiltration to the brain describing the key adhesion molecules implicated in this process. Also, we review the inflammatory-molecular response including the beneficial/detrimental role of chemokines and cytokines after ischemia. Currently, female sexual hormones (estradiol and progesterone) are considered as neuroprotective agents. We and others laboratories demonstrated anti-inflammatory actions of these hormones after stroke, modulating not only the cellular response (reducing the reactive gliosis), but also the immune response. Here, we will present the current data about the neuroprotective role of estradiol and progesterone after ischemic injury focused in their anti-inflammatory action. Additionally, we will review the recent information about the mechanism of action of both hormones, including different receptors and signaling pathways. Finally, we will discuss the synergistic or antagonic therapeutic effects when they are administered together.

Multiple lines of evidence suggest that disease-related neurodegeneration seems to be a multifactorial process that involves different cytotoxic pathways converging in cell death. Neuropathological evidence indicates that neuroinflammation, excitotoxicity, redox-active metals, increased reactive oxygen and nitrogen species, abnormalities in the activity of the ubiquitin-proteasome system, impairments in endogenous antioxidant defense mechanisms, mitochondrial dysfunction, as well as a reduction in the expression of trophic factors in neuronal tissues might play a role in the pathobiology of disease. In addition, increased expression of proapoptotic proteins, which leads to neuronal cell death, plays an important role in the onset and progression of neurodegeneration. With respect to the inefficacy of single-target drugs for the treatment of numerous neurodegenerative disorders, much attention has been paid to natural products with pluripharmacological properties as well as negligible adverse effects. Ellagic acid is known as an important natural phenolic antioxidant, that is widely found in different fruits and vegetables. Recent studies have shown that ellagic acid may invoke a spectrum of cell signaling pathways to attenuate or slow down the development of neurodegenerative disorders. Ellagic acid possesses potent neuroprotective effects through its free radical scavenging properties, iron chelation, activation of different cell signaling pathways, and mitigation of mitochondrial dysfunction. The aim of this review is to critically summarize and analyze the available literature regarding the neuroprotective effects of ellagic acid with emphasis on its molecular mechanisms of action. In addition, we also discuss the biosynthesis, sources, bioavailability, and metabolism, of ellagic acid to provide as accurately as possible the much needed information for assessment of the overall protective effects of this compound in the central nervous system.

Energy intake and expenditure are regulated by a complex network of neurochemical systems. The results of numerous studies have provided information about receptors involved, the sites of action within the brain and interactions between various systems, including opioid and cannabinoid, in regulation of energy balance. This review summarizes our present knowledge on the opioid and cannabinoid system appetite and satiety pathways. The involvement of the three main types of opioid receptors (MOR, DOR and KOR) and CB1 cannabinoid receptor, as well as the endogenous ligands of these receptors in food intake is documented. Finally, the use of opioid-cannabinoid system interactions as a new approach in the search for the next generation therapeutics controlling food intake disorders is discussed.

Nanomedicine, the application of nanotechnology to medicine, is being increasingly used to improve and exploit the advantages of efficient drug delivery. Different nanodevices have been developed in recent years, among them protein-based nanoparticles which have gained considerable interest. Albumin is a versatile protein carrier with several characteristics that make it an ideal candidate for drug delivery, such as its availability, its biocompatibility, its biodegradability, and its lack of toxicity and immunogenicity. This review embodies an overview of different methods available for production of albumin-based nanoparticles, with focus on high-energy emulsification methods. A comparison between production by using sonication, which involves acoustic cavitation, and the high pressure homogenization method, where occurs hydrodynamic cavitation, is presented. Taking into account important properties of nanoparticles required for intravenous administration, the use of poloxamers, tri-block copolymer surfactants is discussed as it improves blood circulation time and bioavailability of nanoparticles. Thus, nanoparticles can be engineered to provide adequate features to therapeutic applications, in which can be included surface functionalization with targeting agents. Different albumin-based formulations and their therapeutic applications are presented in this review, with emphasis on applications in cancer therapy, where albumin-based strategies are promising for targeted drug delivery in innovative clinical strategies.

Nature uses combination of lipid bilayers and cross-linked macromolecular networks to achieve workability, multifunctionality, and dynamism in living cells of different types. Despite the concept of liposome-nanogel structures (lipobeads) is known for about 30 years, lipobead-based drug delivery systems are still largely experimental. The data available on nano- and giant lipobeads are reviewed to demonstrate technological achievability of lipobeads and to support the expectations that additional expenses on their production will be reimbursed by the potential advantages of their use. Indeed, lipobeads exhibit the properties attractive for the next generation of drug delivery systems: (i) retaining all the important benefits of polymeric and liposomal drug carriers, the hydrogel core brings mechanical stability and environmental responsiveness to the formulation in one construct, (ii) lipobeaddelivered combination therapy shows no toxicity on intravenously administered mice, accumulation of drug-loaded lipobeads both in the area surrounding tumor and within the tumor itself outside the vasculature, high therapeutic activity at the targeted site, and drastically increased survival, (iii) bipartite structure of lipobeads can provide a number of novel and unique options (e.g., consecutive multistep triggering and combined drug delivery systems). In addition, some ideas on the conceptually new drug delivery systems, new mechanisms of lipobead internalization into the cell and new schemes of drug release regulated by specific signaling are discussed.