Rivastigmine but not vardenafil reverses cannabis-induced impairment of verbal memory in healthy humans

RATIONALE: One of the most often reported cognitive deficits of acute cannabis administration is an impaired recall of previously learned information. OBJECTIVE: The aim of the present study was to determine whether cannabis-induced memory impairment in humans is mediated via glutamatergic or cholinergic pathways. METHODS: Fifteen occasional cannabis users participated in a double-blind, placebo-controlled, six-way cross-over study. On separate test days, subjects received combinations of pretreatment (placebo, vardenafil 20 mg or rivastigmine 3 mg) and treatment (placebo or 1,376 mg cannabis/kg body weight). Cognitive tests were administered immediately after inhalation of treatment was finished and included measures of memory (visual verbal learning task, prospective memory test, Sternberg memory test), perceptual-motor control (critical tracking task), attention (divided attention task) and motor impulsivity (stop signal task). RESULTS: The results of this study demonstrate that subjects under the influence of cannabis were impaired in all memory tasks, in critical tracking, divided attention and the stop signal task. Pretreatment with rivastigmine attenuated the effect of cannabis on delayed recall and showed a trend towards significance on immediate recall. When cannabis was given in combination with vardenafil, there were no significant interaction effects in any of the tasks. CONCLUSIONS: The present data therefore suggest that acetylcholine plays an important role in cannabis-induced memory impairment, whereas similar results for glutamate have not been demonstrated in this study

Eliminación catalítica de compuestos orgánicos volátiles presentes en pequeñas y medianas empresas mediante la adaptación de extractores comerciales de aire

El trabajo se enmarca en la modificación de un extractor de aire comercial, al cual se le colocó en la chimenea de venteo un sistema catalítico, evaluándose la eliminación de Compuestos Orgánicos Volátiles (COVs) tales como metiletilcetona, cloroformo, tolueno, m-xileno, o-xileno y p-xileno. Se estudió la actividad catalítica de sistemas en base a platino, óxido de manganeso, y óxido de manganeso dopado con Pt, todos ellos soportados sobre monolitos de bentonita. La elección de los COVs a eliminar se realizo en base a una caracterización del aire intramuros en varias Pequeñas y Medianas Empresas (PyMEs), hogares y escuelas de la ciudad de La Plata y alrededores, mediante la utilización de monitoreadores de difusión pasiva 3M 3500 y posterior análisis por cromatografía gaseosa. Dentro de los rubros PyMEs, se analizaron laboratorios químicos, talleres textiles, electromecánica y pintura, casa de comida y un local de fotocopias; encontrándose los mayores niveles COVs en el taller de electromecánica y pintura seguido por los laboratorios de análisis químicos junto con el taller textil. En cuanto a los hogares y escuelas los niveles detectados de COVs fueron similares entre si. Los resultados de la actividad catalítica indican un mejor funcionamiento del catalizador mixto de platino/manganeso por sobre los catalizadores de platino y manganeso. La actividad del catalizador de Pt fue mayor que el de MnOx aunque los tres sistemas fueron capaces de reducir la emisión de cloroformo, detectándose la formación de ácido clorhídrico en el efluente gaseoso. Los resultados muestran que estos sistemas catalíticos pueden ser acoplados satisfactoriamente en los venteos de los equipos de extracción de aire aún trabajando a caudales elevados

Pharmacokinetics of acute tryptophan depletion using a gelatin-based protein in male and female Wistar rats

The essential amino acid tryptophan is the precursor of the neurotransmitter serotonin. By depleting the body of tryptophan, brain tryptophan and serotonin levels are temporarily reduced. In this paper, several experiments are described in which dose and treatment effects of acute tryptophan depletion (ATD) using a gelatin-based protein–carbohydrate mixture were studied in male and female Wistar rats. Two or three doses of tryptophan depleting mixture resulted in 65–70% depletion after 2–4 h in males. ATD effects were similar in females, although females may return to baseline levels faster. Treatment effects after four consecutive days of ATD were similar to the effects of 1 day of treatment. Object recognition memory was impaired 2, 4, and 6 h after the first of two doses of ATD, suggesting that the central effects occurred rapidly and continued at least 6 h, in spite of decreasing treatment effects on plasma tryptophan levels at that time point. The method of acute tryptophan depletion described here can be used to study the relationship between serotonin and behaviour in both male and female rats

Methylphenidate produces selective enhancement of declarative memory consolidation in healthy volunteers

RATIONALE: Methylphenidate inhibits the reuptake of dopamine and noradrenaline and is used to treat children with attention deficit hyperactivity disorder (ADHD). Besides reducing behavioral symptoms, it improves their cognitive function. There are also observations of methylphenidate-induced cognition enhancement in healthy adults, although studies in this area are relatively sparse. We assessed the possible memory-enhancing properties of methylphenidate. OBJECTIVE: In the current study, the possible enhancing effects of three doses of methylphenidate on declarative and working memory, attention, response inhibition and planning were investigated in healthy volunteers. METHODS: In a double blind placebo-controlled crossover study, 19 healthy young male volunteers were tested after a single dose of placebo or 10, 20 or 40 mg of methylphenidate. Cognitive performance testing included a word learning test as a measure of declarative memory, a spatial working memory test, a set-shifting test, a stop signal test and a computerized version of the Tower of London planning test. RESULTS: Declarative memory consolidation was significantly improved relative to placebo after 20 and 40 mg of methylphenidate. Methylphenidate also improved set shifting and stopped signal task performance but did not affect spatial working memory or planning. CONCLUSIONS: To the best of our knowledge, this is the first study reporting enhanced declarative memory consolidation after methylphenidate in a dose-related fashion over a dose range that is presumed to reflect a wide range of dopamine reuptake inhibition

Effects of tryptophan depletion and tryptophan loading on the affective response to high-dose CO2 challenge in healthy volunteers

It has been reported that in panic disorder (PD), tryptophan depletion enhances the vulnerability to experimentally induced panic, while the administration of serotonin precursors blunts the response to challenges. Using a high-dose carbon dioxide (CO2) challenge, we aimed to investigate the effects of acute tryptophan depletion (ATD) and acute tryptophan loading (ATL) on CO2-induced panic response in healthy volunteers. Eighteen healthy volunteers participated in a randomized, double-blind placebo-controlled study. Each subject received ATD, ATL, and a balanced condition (BAL) in separate days, and a double-breath 35% CO2 inhalation 4.5 h after treatment. Tryptophan (Trp) manipulations were obtained adding 0 g (ATD), 1.21 g (BAL), and 5.15 g (ATL) of l-tryptophan to a protein mixture lacking Trp. Assessments consisted of a visual analogue scale for affect (VAAS) and panic symptom list. A separate analysis on a sample of 55 subjects with a separate-group design has also been performed to study the relationship between plasma amino acid levels and subjective response to CO2. CO2-induced subjective distress and breathlessness were significantly lower after ATD compared to BAL and ATL (p <0.05). In the separate-group analysis, Delta VAAS scores were positively correlated to the ratio Trp:I LNAA pound after treatment (r = 0.39; p <0.05). The present results are in line with preclinical data indicating a role for the serotonergic system in promoting the aversive respiratory sensations to hypercapnic stimuli (Richerson, Nat Rev Neurosci 5(6):449-461, 2004). The differences observed in our study, compared to previous findings in PD patients, might depend on an altered serotonergic modulatory function in patients compared to healthy subjects