Adenosine A2A and dopamine D2 receptor interaction controls fatigue resistance.

Introduction: Caffeine and the selective A2A receptor antagonist SCH58261 both have ergogenic properties, effectively reducing fatigue and enhancing exercise capacity. This study investigates in male Swiss mice the interaction between adenosine A2A receptors and dopamine D2 receptors controlling central fatigue, with a focus on the striatum where these receptors are most abundant. Methods: We employed DPCPX and SCH58261 to antagonize A1 and A2A receptors, caffeine as a non-competitive antagonist for both receptors, and haloperidol as a D2 receptor antagonist; all compounds were tested upon systemic application and caffeine and SCH58261 were also directly applied in the striatum. Behavioral assessments using the open field, grip strength, and treadmill tests allowed estimating the effect of treatments on fatigue. Results and discussion: The results suggested a complex interplay between the dopamine and adenosine systems. While systemic DPCPX had little effect on motor performance or fatigue, the application of either caffeine or SCH58261 was ergogenic, and these effects were attenuated by haloperidol. The intra-striatal administration of caffeine or SCH58261 was also ergogenic, but these effects were unaffected by haloperidol. These findings confirm a role of striatal A2A receptors in the control of central fatigue but suggest that the D2 receptor-mediated control of the ergogenic effects of caffeine and of A2A receptor antagonists might occur outside the striatum. This prompts the need of additional efforts to unveil the role of different brain regions in the control of fatigue.

The dopaminergic D1 receptor modulates the hyperactivity of Bapa mutant mice.

The mutant bate-palmas ("claps"; symbol - bapa) mice induced by the mutagenic chemical ENU present motor incoordination and postural alterations. A previous study showed that bapa mice present increased motor/exploratory behaviors during the prepubertal period due to increased striatal tyrosine hydroxylase expression, suggesting striatal dopaminergic system hyperactivity. This study aimed to evaluate the involvement of striatal dopaminergic receptors in the hyperactivity of bapa mice. Male bapa mice and their wild strain (WT) were used. Spontaneous motor behavior was observed in the open-field test, and stereotypy was evaluated after apomorphine administration. The effects of DR1 and DR2 dopaminergic antagonists (SCH-23,390; sulpiride) and the striatal DR1 and D2 receptor gene expression were evaluated. Relative to WT, bapa mice showed: 1) increased general activity for four days; 2) increased rearing and sniffing behavior and decreased immobility after apomorphine; 3) blockage of rearing behavior after the DR2 antagonist but no effect after DR1 antagonist; 4) blockage of sniffing behavior after the DR1 antagonist in bapa and WT mice but no effect after the DR2 antagonist; 5) increased immobility after the DR1 antagonist but no effect after the DR2 antagonist; 6) increased expression of striatal DR1 receptor gene and reduced the DR2 expression gene after apomorphine administration. Bapa mice showed increased activity in open field behavior. The increased rearing behavior induced by apomorphine of bapa mice resulted from the increased gene expression of the DR1 receptor.

Endophytic Fungus of Achyrocline satureioides: Molecular Identification, Chemical Characterization, and Cytotoxic Evaluation of its Metabolites in Human Melanoma cell line.

Endophytic fungi are important sources of anticancer compounds. An endophytic fungus was isolated from the medicinal plant Achyrocline satureioides, and molecularly identified as Biscogniauxia sp. (family Xylariaceae) based on partial nucleotide sequences of the internal transcribed spacer genomic region (GenBank Accession No. ON257911). The chemical characterization and cytotoxic properties of secondary metabolites produced by Biscogniauxia sp. were evaluated in a human melanoma cell line (A375). The fungus was grown in potato-dextrose liquid medium for 25 days, and the extracted compounds were subjected to solid-phase fractionation to obtain the purified FDCM fraction, for which the metabolites were elucidated via ultra-performance chromatography coupled to a mass spectrometer. In the present study, 17 secondary metabolites of Biscogniauxia sp., including nine polyketide derivatives, five terpenoids, and three isocoumarins, were putatively identified. This is the first study to report of the ability of Biscogniauxia sp. in the production of isocoumarin orthosporin; the terpenoids nigriterpene A and 10-xylariterpenoid; the polyketide derivatives daldinin C, 7'dechloro-5'-hydroxygriseofulvin, daldinone D, Sch-642305, curtachalasin A, cytochalasin E, epoxycytochalasins Z8, Z8 isomer, and Z17. Furthermore, this study has reported the biosynthesis of Sch-642305 by a Xylariaceae fungus for the first time. FDCM significantly reduced the viability and proliferation of human melanoma cells at half-maximal inhibitory concentrations ​​of 10.34 and 6.89 µg/mL, respectively, and induced late apoptosis/necrosis and cell cycle arrest in G2/M phase after 72 h of treatment. Given its ability to produce unique metabolites with promising cytotoxic effects, Biscogniauxia sp. of A. satureioides may be a reservoir of compounds with important therapeutic applications.

Dopamine D1/D5 Receptors in the Retrosplenial Cortex Are Necessary to Consolidate Object Recognition Memory.

The retrosplenial cortex (RSC) has been widely related to spatial and contextual memory. However, we recently demonstrated that the anterior part of the RSC (aRSC) is required for object recognition (OR) memory consolidation. In this study, we aimed to analyze the requirement of dopaminergic inputs into the aRSC for OR memory consolidation in male rats. We observed amnesia at 24-h long-term memory when we infused SCH23390, a D1/D5 dopamine receptors antagonist, into aRSC immediately after OR training session. However, the same infusion had no effect on OR short-term memory. Then, we analyzed whether the ventral tegmental area (VTA) is necessary for OR consolidation. VTA inactivation by intra-VTA administration of muscimol, a GABAA agonist, immediately after an OR training session induced amnesia when animals were tested at 24 h. Moreover, we observed that this VTA inactivation-induced amnesia was reversed by the simultaneous intra-aRSC delivery of SKF38393, a D1/D5 receptor agonist. Altogether, our results suggest that VTA dopaminergic inputs to aRSC play an important modulatory role in OR memory consolidation.

Adenosine A2A Receptor: A New Neuroprotective Target in Light-Induced Retinal Degeneration.

Continuous illumination induces the degeneration of photoreceptors. This animal model of light-induced retinal degeneration resembles many characteristics of human degenerative diseases of the outer retina, such as age-related macular degeneration. This work aimed to evaluate the potential neuroprotective effect of the modulation of adenosine A2A receptor in the model of light-induced retinal degeneration. Sprague-Dawley rats were intravitreally injected in the right eye with either CGS 21680, an adenosine A2A receptor agonist, or SCH 58261, an adenosine A2A receptor antagonist. Contralateral eyes were injected with respective vehicles as control. Then, rats were subjected to continuous illumination (12,000 lux) for 24 h. Retinas were processed by glial fibrillary acidic protein (GFAP) immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) technique, Western blotting (WB), and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Another group of rats was subjected to functional studies by electroretinography. Animals treated with CGS21680 showed a significant increase of apoptotic nuclei in the outer nuclear layer and a significant increase of GFAP immunoreactive area of the retinas but did not alter WB nor electroretinography results. qRT-PCR showed that CGS 21680 significantly increased the expression of interleukin-1ß. On the opposite, SCH 58261 significantly decreased apoptotic nuclei in the outer nuclear layer and GFAP immunoreactive area of the retinas. It also significantly decreased GFAP and activated caspase-3 levels as measured by WB and preserved retinal function, as treated eyes showed significantly greater amplitudes of a- and b-waves and oscillatory potentials. qRT-PCR revealed that SCH 58261 significantly decreased the expression of tumor necrosis factor-α. These results show that the blockade of the A2A receptor before the start of the pathogenic process is neuroprotective, as it prevents light-induced retinal damage. The use of A2A receptor antagonists deserves to be evaluated in retinal degenerative diseases.

Stability of hydroalcoholic extracts of two species of guaco; Mikania glomerata SPRENG. and Mikania laevigata SCHULTZ. (Asteraceae), by UHPLC-MS

It is important to study the stability of plant extracts used as active ingredients in phytotherapic medicine, as degradation of the active principles directly affects the efficacy and safety of these products. Therefore, a stability study of the hydroalcoholic extract of the species: Mikania glomerata and Mikania laevigata was conducted in order to determine the speed of degradation and shelf life of these extracts, which are incorporated in cough syrup in Brazil. Leaves of both species were dried in an oven or by lyophilization (freeze-dried). Hydroalcoholic extracts underwent both accelerated stability study of six months and long-term stability study for 12 months. Samples were stored at different temperatures and every three months were analysed by ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) to monitor their chemical profile, quantifying coumarin and chlorogenic acid. For all conditions of the study, a reduction of the content of the chemical marker of this species, coumarin, greater than 5% was observed, so a shelf life of two years cannot be assigned to the hydroalcoholic extracts of these species as observed in commercial extracts.

Participation of Dopamine D1 and D2 Receptors in the Rapid-Onset Behavioral Sensitization to Modafinil.

Studies on the abuse potential of modafinil, a psychostimulant-like drug used to treat narcolepsy, are still controversial. While some studies claim no potential for abuse, increasing evidence suggests that modafinil induces abuse-related effects, including rapid-onset behavioral sensitization (i.e., a type of sensitization that develops within hours from the drug priming administration). The rapid-onset sensitization paradigm is a valuable tool to study the neuroplastic changes that occur quickly after drug administration, and shares neuroadaptations with drug abuse in humans. However, the mechanisms involved in the rapid-onset behavioral sensitization induced by modafinil are uncertain. Our aim was to investigate the possible involvement of dopamine D1 and D2 receptors on acute modafinil-induced hyperlocomotion and on the induction and expression of rapid-onset behavioral sensitization induced by modafinil in male Swiss mice. Treatment with the D1 receptor antagonist SCH 23390 or the D2 receptor antagonist sulpiride attenuated the acute modafinil-induced hyperlocomotion in a dose-dependent manner. Pretreatment with either antagonist before the priming injection of modafinil prevented the development of sensitization in response to a modafinil challenge 4 h later. However, only SCH 23390 decreased the expression of modafinil-induced rapid-onset behavioral sensitization. Taken together, the present findings provide evidence of the participation of D1 and D2 receptors on the development of rapid-onset behavioral sensitization to modafinil, and point to a prominent role of D1 receptors on the expression of this phenomenon.

Selective A2A receptor antagonist SCH 58261 modulates striatal oxidative stress and alleviates toxicity induced by 3-Nitropropionic acid in male Wistar rats.

The aim of the present study was to investigate the effects of SCH58261, a selective adenosine A2A receptor antagonist, on striatal toxicity induced by 3-nitropropionic acid (3-NP) in rats. The experimental protocol consisted of 10 administrations (once a day) of SCH58261 (0.01 or 0.05 mg/kg/day, intraperitoneal, i.p.). From 7th to 10th day, 3-NP (20 mg/kg/day, i.p.) was injected 1 h after SCH58261 administration. Twenty-four hours after the last 3-NP injection, the body weight gain, locomotor activity (open-field test), motor coordination (rotarod test), striatal succinate dehydrogenase (SDH) activity and parameters linked to striatal oxidative status were evaluated in rats. The marked body weight loss resulting from 3-NP injections in rats was partially protected by SCH 58261 at both doses. SCH 58261 at the highest dose was effective against impairments on motor coordination and locomotor activity induced by 3-NP. SCH 58261 was unable to restore the inhibition of SDH activity caused by 3-NP. In addition, the increase in striatal reactive species (RS) levels, depletion of reduced glutathione (GSH) content and stimulation of glutathione reductase (GR) activity provoked by 3-NP injections were alleviated by both doses of SCH 58261. The highest dose of SCH 58261 was also effective in attenuating the increase of protein carbonyl levels as well as the inhibition of glutathione peroxidase (GPx) activity in rats exposed to 3-NP. Our results revealed that reduction of oxidative stress in rat striatum by adenosine A2A receptor antagonism contributes for alleviating 3-NP-induced toxicity.

Dorsal striatum D1-expressing neurons are involved with sensorimotor gating on prepulse inhibition test.

Prepulse inhibition (PPI) is a behavioral test in which the startle reflex response to a high-intensity stimulus (pulse) is inhibited by the prior presentation of a weak stimulus (prepulse). The classic neural circuitry that mediates startle response is localized in the brainstem; however, recent studies point to the contribution of structures involved in higher cognitive functions in regulating the sensorimotor gating, particularly forebrain regions innervated by dopaminergic nuclei. The aim of the present study was to verify the role of dorsal striatum (DS) and dopaminergic transmitting mediated by D1 and D2 receptors on PPI test in rats. DS inactivation induced by muscimol injection did not affect PPI (%PPI and startle response), although it impaired the locomotor activity and caused catalepsy. Infusion of D1-like antagonist SCH23390 impaired %PPI but did not disturb the startle response and locomotor activity evaluated immediately after PPI test. D2 antagonist microinjection (sulpiride) did not affect %PPI and startle response, but impaired motor activity. These results point to an important role of DS, probably mediated by direct basal ganglia pathway, on modulation of sensorimotor gating, in accordance with clinical studies showing PPI deficits in schizophrenia, Tourette syndrome, and compulsive disorders - pathologies related to basal ganglia dysfunctions.

Protection against cisplatin in calorie-restricted Saccharomyces cerevisiae is mediated by the nutrient-sensor proteins Ras2, Tor1, or Sch9 through its target glutathione.

There is substantial interest in developing alternative strategies for cancer chemotherapy aiming to increase drug specificity and prevent tumor resistance. Calorie restriction (CR) has been shown to render human cancer cells more susceptible to drugs than normal cells. Indeed, deficiency of nutrient signaling proteins mimics CR, which is sufficient to improve oxidative stress response and life expectancy only in healthy cells. Thus, although CR and reduction of nutrient signaling may play an important role in cellular response to chemotherapy, the full underlying mechanisms are still not completely understood. Here, we investigate the relationship between the nutrient sensor proteins Ras2, Sch9, or Tor1 and the response of calorie-restricted Saccharomyces cerevisiae cells to cisplatin. Using wild-type and nutrient-sensing mutant strains, we show that deletion of any of these proteins mimics CR and is sufficient to increase cell protection. Moreover, we show that glutathione (GSH) is essential for proper CR protection of yeast cells under cisplatin chemotherapy. By measuring the survival rates and GSH levels, we found that cisplatin cytotoxicity leads to a decrease in GSH content reflecting in an increase of oxidative damage. Finally, investigating DNA fragmentation and apoptosis, we conclude that GSH contributes to CR-mediated cell survival.

Actividad antioxidante y antiinflamatoria del extracto hidroalcohólico de las flores de Tanacetum parthenium L. Sch. Bip. "Santa María". Ayacucho, 2014 / Antioxidant and anti-inflammatory activity of the hydroalcoholic extract of the flowers of Tanacetum parthenium L. Sch. Beep. "Santa Maria". Ayacucho, 2014

Los procesos inflamatorios no controlados producen daño celular donde los radicales libres están presentes y representan un peligro para la vida del paciente, en este contexto la búsqueda de moléculas de origen vegetal son incesantes por su aceptación cultural, una mejor compatibilidad con el cuerpo humano y menos efectos secundarios. El objetivo fue determinar la actividad antioxidante y antiinflamatoria del extracto hidroalcohólico de las flores de Tanacetum parthenium L. Sch. Bip. "santa maria", empleando la técnica in vitro del DPPH y el modelo in vivo de edema plantar inducida por carragenina en ratas Wistar. Se llevó a cabo en los laboratorios de la Escuela de Farmacia y Bioquímica de la Universidad Nacional de San Cristóbal de Huamanga, Ayacucho, Perú. La muestra fue recolectada en la ciudad de Huancayo, región Junin. Se ensayó concentraciones de 1, 2 y 3% en ungüentos base como vehículo semisólido usando el estándar de referencia diclofenaco gel 1%. El extracto hidroalcohólico contiene fenoles y taninos, flavonoides, faetonas y/o cumarinas, triterpenos y/o esteroides y aminoácidos. La concentración de extracto hidroalcohólico de las flores de Tanacetum parthenium L. Sch. Bip. "santa maria" con mayor actividad antiinflamatoria fue al 3%, con un porcentaje de desinflamación del84.6% {porcentaje de inflamación de 15.4%) y con un ABC de 6,214 mllt2. La concentración de extracto hidroalcohólico de las flores de Tanacetum parthenium L. Sch. Bip. "santa maria" con mayor actividad antioxidante fue a 100 ¡Jg/ml, con un porcentaje de 63,9%. Se concluye que el extracto hidroalcohólico de las flores de Tanacetum parthenium L. Sch. Bip. "santa maría" tiene poca actividad antioxidante in vitro pero buena actividad antiinflamatoria in vivo estadísticamente similar al diclofenaco por lo que constituyen una fuente potencial para el tratamiento antiinflamatorio tópico.

Analysis of brain nuclei accessible to ghrelin present in the cerebrospinal fluid.

Ghrelin is a stomach-derived peptide hormone that acts in the brain to regulate many important physiological functions. Ghrelin receptor, named the growth hormone secretagogue receptor (GHSR), is present in many brain areas with or without obvious direct access to ghrelin circulating in the bloodstream. Ghrelin is also present in the cerebrospinal fluid (CSF) but the brain targets of CSF ghrelin are unclear. Here, we studied which brain areas are accessible to ghrelin present in the CSF. For this purpose, we centrally injected mice with fluorescein-labeled ghrelin (F-ghrelin) peptide tracer and then systematically mapped the distribution of F-ghrelin signal through the brain. Our results indicated that centrally injected F-ghrelin labels neurons in most of the brain areas where GHSR is present. Also, we detected F-ghrelin uptake in the ependymal cells of both wild-type and GHSR-null mice. We conclude that CSF ghrelin is able to reach most of brain areas expressing GHSR. Also, we propose that the accessibility of CSF ghrelin to the brain parenchyma occurs through the ependymal cells in a GHSR-independent manner.

Proline-induced changes in acetylcholinesterase activity and gene expression in zebrafish brain: reversal by antipsychotic drugs.

Hyperprolinemia is an inherited disorder of proline metabolism and hyperprolinemic patients can present neurological manifestations, such as seizures, cognitive dysfunctions, and schizoaffective disorders. However, the mechanisms related to these symptoms are still unclear. In the present study, we evaluated the in vivo and in vitro effects of proline on acetylcholinesterase (AChE) activity and gene expression in the zebrafish brain. For the in vivo studies, animals were exposed at two proline concentrations (1.5 and 3.0mM) during 1h or 7 days (short- or long-term treatments, respectively). For the in vitro assays, different proline concentrations (ranging from 3.0 to 1000 µM) were tested. Long-term proline exposures significantly increased AChE activity for both treated groups when compared to the control (34% and 39%). Moreover, the proline-induced increase on AChE activity was completely reverted by acute administration of antipsychotic drugs (haloperidol and sulpiride), as well as the changes induced in ache expression. When assessed in vitro, proline did not promote significant changes in AChE activity. Altogether, these data indicate that the enzyme responsible for the control of acetylcholine levels might be altered after proline exposure in the adult zebrafish. These findings contribute for better understanding of the pathophysiology of hyperprolinemia and might reinforce the use of the zebrafish as a complementary vertebrate model for studying inborn errors of amino acid metabolism.

Púrpura de Sch§nlein- Henoch en adultos / Henoch-Sch§nlein purpura in adults

La púrpura de Sch§nlein-Henoch es una vasculitis sistémica mediada por inmunoglobulina A, caracterizada clínicamente por púrpura palpable, dolor abdominal, artralgias y hematuria o proteinuria en el laboratorio. La inmunofluorescencia directa de las lesiones cutáneas, así como la del riñón, revelan la presencia de depósitos perivasculares de este anticuerpo, dato de valor para confirmar el diagnóstico. Se presentan cinco pacientes adultos con PSH, insuficiencia renal aguda y neoplasias malignas en tres de ellos. (AU)

Henoch-Sch÷nlein Purpura is a systemic vasculitis mediated by Ig A, clinically characterizedby non-thrombocytopenic palpable purpura, abdominal pain, arthritis and proteinuria orhematuria. Histologically, it is characterized by deposition of immunoglobulin A in the skinand kidneys, being these features essential for the diagnosis. We report five adult patientswith Henoch-Sch÷nlein purpura with acute kidney failure, and malignant neoplasms onthree of them.(AU)