Modulation of the endocannabinoids N-Arachidonoylethanolamine (AEA) and 2-Arachidonoylglycerol (2-AG) on Executive Functions in Humans

Animal studies point to an implication of the endocannabinoid system on executive functions. In humans, several studies have suggested an association between acute or chronic use of exogenous cannabinoids (Δ9-tetrahydrocannabinol) and executive impairments. However, to date, no published reports establish the relationship between endocannabinoids, as biomarkers of the cannabinoid neurotransmission system, and executive functioning in humans. The aim of the present study was to explore the association between circulating levels of plasma endocannabinoids N-arachidonoylethanolamine (AEA) and 2-Arachidonoylglycerol (2-AG) and executive functions (decision making, response inhibition and cognitive flexibility) in healthy subjects. One hundred and fifty seven subjects were included and assessed with the Wisconsin Card Sorting Test; Stroop Color and Word Test; and Iowa Gambling Task. All participants were female, aged between 18 and 60 years and spoke Spanish as their first language. Results showed a negative correlation between 2-AG and cognitive flexibility performance (r = −.37; p<.05). A positive correlation was found between AEA concentrations and both cognitive flexibility (r = .59; p<.05) and decision making performance (r = .23; P<.05). There was no significant correlation between either 2-AG (r = −.17) or AEA (r = −.08) concentrations and inhibition response. These results show, in humans, a relevant modulation of the endocannabinoid system on prefrontal-dependent cognitive functioning. The present study might have significant implications for the underlying executive alterations described in some psychiatric disorders currently associated with endocannabinoids deregulation (namely drug abuse/dependence, depression, obesity and eating disorders). Understanding the neurobiology of their dysexecutive profile might certainly contribute to the development of new treatments and pharmacological approaches

INVESTIGACIÓN - ESTIMACIÓN DE LA FIJACIÓN BIOLÓGICA DE NITRÓGENO EN LEGUMINOSAS FORRAJERAS MEDIANTE LA METODOLOGÍA DEL 15N (Estimation of biological nitrogen fixation in forage legumes using a 15N labeling methodology)

Se estudió la contribución de la fijación biológica de N2 (FBN) en cuatro leguminosas forrajeras, trébol blanco (Trifolium repens L.), trébol rosado (Trifolium pratense L.), trébol subterráneo (Trifolium subterraneum L.) y alfalfa (Medicago sativa L.), con y sin inoculación específica de rhizobio, mediante la metodología isotópica del Valor A, empleando tres gramíneas, avena (Avena sativa L.), ballica perenne (Lolium perenne L.) y festuca (Festuca arundinacea Schreb.) como cultivos de referencia. El estudio se llevó a cabo en un andisol (Typic fulvudand), en el Centro Regional de Investigación Carillanca, del Instituto de Investigaciones Agropecuarias, IX Región, Chile, durante tres temporadas. Las dosis aplicadas de N correspondieron a 10 kg ha-1 como sulfato de amonio (10% átomos exceso 15N) para las especies leguminosas y de 30 kg ha-1 como sulfato de amonio (5% átomos exceso 15N) para las gramíneas de referencia. En las muestras de material vegetal se analizó N total (Kjeldahl) y 15N (espectrometría de emisión óptica). Los tres cultivos de referencia mostraron estimaciones similares de la FBN en las leguminosas. La capacidad de FBN alcanzó el 90% en todas las temporadas y para todas las leguminosas. No se encontró efecto significativo respecto a la inoculación con rhizobium, excepto en alfalfa y sólo en la primera temporada. La cantidad de N fijado en todas las temporadas fue alta y con todas las leguminosas, variando entre 60 y 770 kg ha-1 a?o-1, para trébol subterráneo y alfalfa, respectivamente, ratificando la gran eficiencia del mecanismo de FBN en las leguminosas forrajeras en estudio. Estimation of biological nitrogen fixation in forage legumes using a 15N labeling methodology. The contribution of biological nitrogen N2 fixation (FBN) in four forage legumes: white clover (Trifolium repens L.), red clover (Trifolium pratense L.), subterranean clover (Trifolium subterraneum L.) and alfalfa (Medicago sativa L.), with and without specific rhizobium inoculation, was evaluated by the A value isotope technique, using three grasses: oats (Avena sativa L.), perennial ryegrass (Lolium perenne L.) and fescue (Festuca arundinacea Schreb.) as reference crops. The study was carried out for three years on an andisol (Typic fulvudand), at the Carillanca Regional Research Center of de National Agricultural Research Institute, IX Region, Chile. The dose of N applied was 10 kg N ha-1 using ammonium sulfate (10 atom % 15N excess) for legume species, and 30 kg ha-1 as ammonium sulfate (5 atom % 15N excess) for grass species. Plant samples were analyzed for total N (Kjeldahl) and atom % 15N excess (optical emission spectrometry). All the three reference crops showed similar values of FBN to the legumes. The FBN capacity reached 90% in all seasons and by all the legumes. No significant influence of inoculation with rhizobium was found, except for alfalfa and only in the first season. The quantity of N fixed in all seasons was high and for all the legumes, ranging from 60 to 770 kg ha-1 year-1, for subterranean clover and alfalfa, respectively, confirming the great efficiency of the FBN mechanism on the forage legumes under study