GLP-1 and nicotine combination therapy engages hypothalamic and mesolimbic pathways to reverse obesity.

Glucagon-like peptide-1 receptor (GLP-1R) agonists promote nicotine avoidance. Here, we show that the crosstalk between GLP-1 and nicotine extends beyond effects on nicotine self-administration and can be exploited pharmacologically to amplify the anti-obesity effects of both signals. Accordingly, combined treatment with nicotine and the GLP-1R agonist, liraglutide, inhibits food intake and increases energy expenditure to lower body weight in obese mice. Co-treatment with nicotine and liraglutide gives rise to neuronal activity in multiple brain regions, and we demonstrate that GLP-1R agonism increases excitability of hypothalamic proopiomelanocortin (POMC) neurons and dopaminergic neurons in the ventral tegmental area (VTA). Further, using a genetically encoded dopamine sensor, we reveal that liraglutide suppresses nicotine-induced dopamine release in the nucleus accumbens in freely behaving mice. These data support the pursuit of GLP-1R-based therapies for nicotine dependence and encourage further evaluation of combined treatment with GLP-1R agonists and nicotinic receptor agonists for weight loss.

Sleep-controlling neurons are sensitive and vulnerable to multiple forms of α-synuclein: implications for the early appearance of sleeping disorders in α-synucleinopathies.

Parkinson's disease, Multiple System Atrophy, and Lewy Body Dementia are incurable diseases called α-synucleinopathies as they are mechanistically linked to the protein, α-synuclein (α-syn). α-syn exists in different structural forms which have been linked to clinical disease distinctions. However, sleeping disorders (SDs) are common in the prodromal phase of all three α-synucleinopathies, which suggests that sleep-controlling neurons are affected by multiple forms of α-syn. To determine whether a structure-independent neuronal impact of α-syn exists, we compared and contrasted the cellular effect of three different α-syn forms on neurotransmitter-defined cells of two sleep-controlling nuclei located in the brainstem: the laterodorsal tegmental nucleus and the pedunculopontine tegmental nucleus. We utilized size exclusion chromatography, fluorescence spectroscopy, circular dichroism spectroscopy and transmission electron microscopy to precisely characterize ​​timepoints in the α-syn aggregation process with three different dominating forms of this protein (monomeric, oligomeric and fibril) and we conducted an in-depth investigation of the underlying neuronal mechanism behind cellular effects of the different forms of the protein using electrophysiology, multiple-cell calcium imaging, single-cell calcium imaging and live-location tracking with fluorescently-tagged α-syn. Interestingly, α-syn altered membrane currents, enhanced firing, increased intracellular calcium and facilitated cell death in a structure-independent manner in sleep-controlling nuclei, and postsynaptic actions involved a G-protein-mediated mechanism. These data are novel as the sleep-controlling nuclei are the first brain regions reported to be affected by α-syn in this structure-independent manner. These regions may represent highly important targets for future neuroprotective therapy to modify or delay disease progression in α-synucleinopathies.

α-Synuclein Responses in the Laterodorsal Tegmentum, the Pedunculopontine Tegmentum, and the Substantia Nigra: Implications for Early Appearance of Sleep Disorders in Parkinson's Disease.

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disorder associated with insoluble pathological aggregates of the protein α-synuclein. While PD is diagnosed by motor symptoms putatively due to aggregated α-synuclein-mediated damage to substantia nigra (SN) neurons, up to a decade before motor symptom appearance, patients exhibit sleep disorders (SDs). Therefore, we hypothesized that α-synuclein, which can be present in monomeric, fibril, and other forms, has deleterious cellular actions on sleep-control nuclei. OBJECTIVE: We investigated whether native monomer and fibril forms of α-synuclein have effects on neuronal function, calcium dynamics, and cell-death-induction in two sleep-controlling nuclei: the laterodorsal tegmentum (LDT), and the pedunculopontine tegmentum (PPT), as well as the motor-controlling SN. METHODS: Size exclusion chromatography, Thioflavin T fluorescence assays, and circular dichroism spectroscopy were used to isolate structurally defined forms of recombinant, human α-synuclein. Neuronal and viability effects of characterized monomeric and fibril forms of α-synuclein were determined on LDT, PPT, and SN neurons using electrophysiology, calcium imaging, and neurotoxicity assays. RESULTS: In LDT and PPT neurons, both forms of α-synuclein induced excitation and increased calcium, and the monomeric form heightened putatively excitotoxic neuronal death, whereas, in the SN, we saw inhibition, decreased intracellular calcium, and monomeric α-synuclein was not associated with heightened cell death. CONCLUSION: Nucleus-specific differential effects suggest mechanistic underpinnings of SDs' prodromal appearance in PD. While speculative, we hypothesize that the monomeric form of α-synuclein compromises functionality of sleep-control neurons, leading to the presence of SDs decades prior to motor dysfunction.

Stress-related endogenous neuropeptides induce neuronal excitation in the Laterodorsal Tegmentum.

Stress is a physiological response that promotes maintenance of balance against harmful stimuli. Unfortunately, chronic activation of stress systems facilitates the development of psychiatric disorders. A stress-mediated hypercholinergic state could underlie this facilitation, as cholinergic mechanisms have been suggested to play a role in anxiety, depression, and substance use disorder (SUD). Stimulation by stress hormones, urocortin (Ucn1) or corticotropin-releasing factor (CRF), of the CRF receptor type 1 (CRFR1) of acetylcholine-containing neurons of the laterodorsal tegmental nucleus (LDT) could be involved in modulation of cholinergic transmission during periods of stress hormone activation, which could play a role in psychiatric disorders as cholinergic LDT neurons project to, and control activity in, mood-, arousal- and SUD-controlling regions. The present study investigated for the first time the membrane effects and intracellular outcomes of CRFR1 activation by endogenous stress hormones on LDT neurons. Patch clamp recordings of immunohistochemically-identified cholinergic and non-cholinergic LDT neurons with concurrent calcium imaging were used to monitor cellular responses to CRFR1 stimulation with Ucn1 and CRF. Postsynaptically-mediated excitatory currents were elicited in LDT cholinergic neurons, accompanied by an enhancement in synaptic events. In addition, CRFR1 activation resulted in rises in intracellular calcium levels. CRFR1 stimulation recruited MAPK/ERK and SERCA-ATPase involved pathways. The data presented here provide the first evidence that Ucn1 and CRF exert pre and postsynaptic excitatory membrane actions on LDT cholinergic neurons that could underlie the hypercholinergic state associated with stress which could play a role in the heightened risk of psychiatric disorders associated with a chronic stress state.

Increasing cellular lifespan with a flow system in organotypic culture of the Laterodorsal Tegmentum (LDT).

Organotypic brain culture is an experimental tool widely used in neuroscience studies. One major drawback of this technique is reduced neuronal survival across time, which is likely exacerbated by the loss of blood flow. We have designed a novel, tube flow system, which is easily incorporated into the commonly-used, standard semi-permeable membrane culture methodology which has significantly enhanced neuronal survival in a brain stem nucleus involved in control of motivated and arousal states: the laterodorsal tegmental nucleus (LDT). Our automated system provides nutrients and removes waste in a comparatively aseptic environment, while preserving temperature, and oxygen levels. Using immunohistochemistry and electrophysiology, our system was found superior to standard techniques in preserving tissue quality and survival of LDT cells for up to 2 weeks. In summary, we provide evidence for the first time that the LDT can be preserved in organotypic slice culture, and further, our technical improvements of adding a flow system, which likely enhanced perfusion to the slice, were associated with enhanced neuronal survival. Our perfusion system is expected to facilitate organotypic experiments focused on chronic stimulations and multielectrode recordings in the LDT, as well as enhance neuronal survival in slice cultures originating from other brain regions.

Morphine in Plasma and Cerebrospinal Fluid of Patients Addicted to Opiates Undergoing Surgery: High-performance Liquid Chromatography Method.

BACKGROUND: The prevalence of opium addiction among Iranians is considerable. Since endogenous opioid systems may be altered as a consequence of addiction, it is very important to determine the plasma and cerebrospinal fluid (CSF) levels of morphine in Iranian patients addicted to opiates who will undergo surgery. METHODS: We obtained CSF and plasma samples from 50 volunteers with an established opioid addiction pattern. Samples were analyzed using high-performance liquid chromatography (HPLC). Additionally, frequency of nausea and vomiting, baseline heart rate (BHR), and systolic blood pressure (SBP) were recorded within the surgery and postoperatively during a 10-min interval. FINDINGS: 84% of participants were men with a median age of 39.08 years. Mean score of body mass index (BMI) was 23.30 and most of the participants (46%) used opium in its traditional inhaled form. A higher concentration of morphine in blood was found in comparison with CSF (P < 0.001) in relation to the way of use. However, no statistically significant differences were found in relation to the type of addictive substance. No other association was found between the levels of morphine and the clinical characteristics of the patients. Moreover, results revealed no difference between hemodynamic-related data with blood and CSF level in opium-dependent patients. CONCLUSION: Quantification of plasma and CSF morphine, both immediately before initiation of surgery and subsequently on recovery room, showed that although clinical efficacy of systemic morphine was poor in addicted patients, it had no effect on patients' hemodynamic variable and following complications after surgery.

Vías de señalización mTOR y AKT en epilepsia / Signaling pathways mTOR and AKT in epilepsy

Introducción. La vía de señalización AKT/mTOR es un eje central en la regulación celular, especialmente en las enfermedades neurológicas. En la epilepsia, se ha evidenciado su alteración dentro de su proceso fisiopatológico. Sin embargo, aún no se han descrito todos los mecanismos de estas rutas de señalización, las cuales podrían abrir la puerta hacia nuevas investigaciones y estrategias terapéuticas, que finalmente permitan desarrollar tratamientos efectivos en enfermedades neurológicas como la epilepsia. Objetivo. Revisar las asociaciones existentes entre las rutas de señalización intracelular de mTOR y AKT en la fisiopatología de la epilepsia. Desarrollo. La epilepsia es una enfermedad neurológica con un alto impacto epidemiológico en el mundo, por lo cual es de sumo interés la investigación de los componentes fisiopatológicos que puedan generar nuevos tratamientos farmacológicos. En esta búsqueda se han involucrado diferentes rutas de señalización intracelular en neuronas, como determinantes epileptógenos. Los avances en esta materia han permitido incluso la implementación de nuevas estrategias terapéuticas exitosas y que abren el camino hacia nuevas investigaciones. Conclusiones. Mejorar los conocimientos respecto al papel fisiopatológico de la vía de señalización mTOR/AKT en la epilepsia permite plantear nuevas investigaciones que ofrezcan nuevas alternativas terapéuticas para el tratamiento de la enfermedad. El uso de inhibidores de mTOR ha surgido en los últimos años como una alternativa eficaz en el tratamiento de algunos tipos de epilepsias, pero es evidente la necesidad de seguir en la búsqueda de nuevas terapias farmacológicas involucradas en estas vías de señalización (AU)

Introduction. The signaling pathway AKT/mTOR is a central axis in regulating cellular processes, particularly in neurological diseases. In the case of epilepsy, it has been observed alteration in the pathophysiological process of the same. However, they have not described all the mechanisms of these signaling pathways that could open the opportunity to new research and therapeutic strategies. Aim. To review existing partnerships between intracellular signaling pathways AKT and mTOR in the pathophysiology of epilepsy. Development. Epilepsy is a disease with a high epidemiological impact globally, so it is widely investigated regarding the pathophysiological components thereof. In that search they have been involved different intracellular signaling pathways in neurons, as determinants epileptogenic. Advances in this field have even allowed the successful implementation of new therapeutic strategies and to open the way to new research in the field. Conclusions. Improving knowledge about the pathophysiological role of the signaling pathway mTOR/AKT in epilepsy can raise new investigations regarding therapeutic alternatives. The use of mTOR inhibitors, has emerged in recent years as effective in treating this disease entity alternative however is clear the necessity of continue the research for new drug therapies (AU)

Mecanismos de transporte de calcio en neuroprotección y neurotoxicidad / Calcium transport mechanisms in neuroprotection and neurotoxicity

Introducción. El calcio (Ca2+) se ha encontrado involucrado en procesos de neuroprotección, iniciando cascadas enzimáticas indispensables para la síntesis y funcionamiento de los elementos efectores de este proceso. Sin embargo, resulta paradójico que este ión sea uno de los principales iniciadores de cascadas apoptóticas. Esta diferencia en sus efectos está condicionada por diferencias en las concentraciones citoplásmicas. Desarrollo. El Ca2+ tiene un papel en la activación de señales antiapoptóticas en la neurona cuando sus concentraciones se elevan de forma moderada, pero también inicia procesos apoptóticos desencadenados principalmente por su acumulación en las mitocondrias. Este Ca2+ proviene del exterior o de los depósitos intracelulares a través de transportadores de diverso tipo. Para evaluar el papel del Ca2+ de estos procesos, es necesario considerar todas las vías de transporte en forma integrada, pues su manipulación farmacológica genera procesos protectores o tóxicos, al alterar las concentraciones intracelulares del ión. Conclusiones. Es notable el avance que se ha dado en la comprensión de los efectos del Ca2+ en el sistema nervioso central y en los mecanismos para su control y transporte. Es importante destacar cómo el conocimiento de dichos procesos fisiológicos ha llevado al desarrollo de fármacos con efectos protectores y, aunque la mayoría está en fase de estudio o posee efectos adversos importantes, éste es un campo prometedor que ayudará al desarrollo de estrategias terapéuticas útiles en neuroprotección (AU)

Introduction. Calcium (Ca2+) has been found to be involved in neuroprotective processes, by triggering enzymatic cascades that are essential for the synthesis and functioning of the elements that carry out this process. However, it is paradoxical that this ion is one of the main initiators of apoptotic cascades. This difference in its effects is conditioned by differences in the cytoplasmic concentrations. Development. Ca2+ plays a role in the activation of antiapoptotic signals in the neuron when its levels rise moderately, but it also starts apoptotic processes that are triggered mainly by its accumulation in mitochondria. This Ca2+ comes from the outside or from intracellular deposits by means of different types of transporters. In order to assess the role of Ca2+ in these processes, it is necessary to consider all the means of transport in an integral manner, since manipulating it pharmacologically gives rise to either protective or toxic processes, due to alterations in the intracellular concentrations of the ion. Conclusions. Notable progress has been made in the understanding of the effects of Ca2+ on the central nervous system and on the mechanisms for controlling and transporting it. It is important to stress that understanding these physiological processes has led to the development of drugs with protective effects and, although most of them are still in the study phase or display important side effects, it remains a promising field that will help in the development of useful therapeutic strategies in neuroprotection (AU)