A single high dose of chlorpyrifos reduces long-term basal c-fos expression in the rat arcuate hypothalamic nucleus / La administración de una dosis aguda de clorpirifós reduce a largo plazo la expresión basal de c-fos en el núcleo arqueado del hipotálamo

Chlorpyrifos (CPF) is an organophosphate compound used worldwide as a pesticide in agriculture that, after subcutaneous injection, keeps acetylcholinesterase (AChE) activity inhibited within an organism for months. Ample clinical and experimental evidence shows that CPF exposure induces relevant and persistent neurobehavioral deficits in humans and animals, even after one single episode/injection. Additionally, clinical and epidemiological studies evidence that a significant percentage (60%) of Gulf War veterans as well as agricultural workers suffering from acute OP intoxication may have developed intolerance to nicotine and ethanol-containing beverages. Consistent with it, administration of a single high dose of CPF to adult Wistar rats elicited long-lasting reduced voluntary ethanol drinking and increased sedation to ethanol without evidence of altered ethanol metabolism, which indicates that CPF-ethanol neurobiological interactions may exist. In this study, we explore whether CPF exposure induces significant disturbances in basal and/or ethanol-evoked neural activity in a set of cholinoceptive brain regions critically involved with neurobiological responses to ethanol. For this aim, brain regional c-fos expression in response to acute ethanol (1.5 or 3.0 g/kg, i.p.) or saline was assessed in adult male Wistar rats previously injected with either a single high dose of CPF (250 mg/kg, sc) or vehicle. We found that CPF administration reduces long-term basal, but not ethanol-evoked, c-fos expression in the arcuate hypothalamic nucleus. Because independent brain pathways may modulate acute responses to ethanol and voluntary ethanol consumption, we do not rule out the contribution of basal neural disturbances observed in the Arc to CPF-elicited ethanol avoidance.

El clorpirifós (CPF) es un compuesto organofosforado utilizado como plaguicida en todo el mundo. Después de ser inyectado de manera subcutánea, mantiene la actividad de la enzima acetilcolinesterasa (AChE) inhibida durante meses. Estudios clínicos y experimentales muestran que la exposición al CPF induce déficits neuroconductuales persistentes en seres humanos y animales, incluso después de un solo episodio/inyección. Además, estudios epidemiológicos evidencian que un porcentaje significativo (60%) de los veteranos de la Guerra del Golfo, así como los agricultores que sufren una intoxicación aguda por organofosforados, desarrollan intolerancia a la nicotina y las bebidas que contienen etanol. Datos experimentales mostraron que la administración de una sola dosis alta de CPF en ratas Wistar adultas provoca una reducción a largo plazo del consumo voluntario de etanol y un incremento en la sedación provocada por etanol sin evidencias de alteración del metabolismo de esta sustancia, lo que indica que pueden existir interacciones neurobiológicas entre CPF-etanol. En este estudio, se explora si la exposición a CPF induce alteraciones significativas en la actividad neuronal basal o evocada por el etanol en un conjunto de regiones colinoceptivas del cerebro involucradas en las respuestas neurobiológicas al etanol. Para ello, se evaluó la expresión de c-fos en respuesta a una dosis de etanol aguda (1.5 o 3.0 g/kg, ip) o solución salina en ratas Wistar macho adultas previamente inyectados con dosis aguda de CPF (250 mg/kg, sc) o un vehículo. Encontramos que la administración de CPF redujo la expresión basal de c-fos a largo plazo, pero no la evocada por el etanol en el núcleo arqueado del hipotalámo. Debido a que vías cerebrales independientes podrían modular las respuestas agudas al etanol y el consumo voluntario del mismo, no se descarta la contribución de las alteraciones neuronales basales observadas en el Arc en la evitación del consumo de etanol provocado por CPF.

Deletion of agouti-related protein blunts ethanol self-administration and binge-like drinking in mice.

The melanocortin (MC) system is composed of peptides that are cleaved from the polypeptide precursor proopiomelanocortin (POMC). Recent pharmacological and genetic evidence suggests that melanocortin receptor (MCR) signaling modulates neurobiological responses to ethanol and ethanol intake. Agouti-related protein (AgRP) is synthesized by neurons in the arcuate nucleus of the hypothalamus and is a natural antagonist of MCRs. Because central administration of the functionally active AgRP fragment AgRP-(83-132) increases ethanol intake by C57BL/6 J mice, we determined if mutant mice lacking normal production of AgRP (AgRP(-/-)) and maintained on a C57BL/6 J genetic background would show reduced self-administration of ethanol relative to littermate wild-type (AgRP(+/+)) mice. AgRP(-/-) mice showed reduced 8% (v/v) ethanol-reinforced lever-pressing behavior relative to AgRP(+/+) mice in daily 2-h sessions, but normal sucrose-, saccharin- and water-reinforced lever-pressing. Similarly, AgRP(-/-) mice showed reduced consumption of 8% ethanol in a two-bottle limited access test (2 h/day), although this effect was largely sex-dependent. Using drinking-in-the-dark (DID) procedures, AgRP(-/-) mice showed blunted binge-like drinking of 20% (v/v) ethanol which was associated with lower blood ethanol levels (85 mg/dl) relative to AgRP(+/+) mice (133 mg/dl) after 4 h of intake. AgRP(-/-) mice showed normal ethanol metabolism and did not show altered sensitivity to the sedative effects of ethanol. These observations with genetically altered mice are consistent with previous pharmacological data and suggest that endogenous AgRP signaling modulates the reinforcing properties of ethanol and binge-like ethanol drinking.

Neuroanatomical targets of the organophosphate chlorpyrifos by c-fos immunolabeling.

Chlorpyrifos (CPF) is an organophosphate widely used as an insecticide in agriculture which elicits short- and long-term neurobehavioral deficits after acute administration. Because little is known about the specific brain areas targeted by CPF, investigating for the location of its neuroanatomical targets could help to describe the brain systems involved in the neurobehavioral toxicity developed in CPF-exposed organisms. To meet this objective, in the present study we evaluated CPF-induced c-fos expression. In addition, locomotor behavior and cerebral cholinesterase level were evaluated. We found two main sets of results. First, no significant c-fos expression was found in cholinoceptive regions in CPF-treated rats 2 h or 24 h post-administration, despite the fact that 41% and 62% acetylcholinesterase inhibition, respectively, were present in brain homogenates. These results are consistent with previous reports showing CPF-induced activation of adaptive neural mechanisms re-establishing cholinergic tone. Second, 24 h post-intoxication CPF elicited c-fos expression in cytokine-related areas. Cytokines have been involved in anxiety-like responses and psychiatric stress syndromes. Taking into account that CPF triggers the synthesis of peripheral cytokines, the present data stress the need to further clarify functional relations between organophosphate-triggered peripheral cytokines and emotional disturbances reported in intoxicated organisms.

Aversiones gustativo-nutritivas desarrolladas en situaciones experimentales y clínicas: características y mecanismos biológicos implicado / Food aversions in clinical arad experimental context: characteristic and biological mechanisms involved

El rechazo de los alimentos que se produce tras experiencias que implican malestar gastrointestinal (náuseas, vómitos, etc.) es un fenómeno biológicamente predispuesto que se observa frecuentemente tanto en la investigación animal como en nuestra propia vida diaria. Pero la adquisición de estas aversiones suele producirse y puede adoptar tintes dramáticos en el caso de pacientes oncológicos que sufren frecuentes vómitos y náuseas como consecuencia del tratamiento con quimioterapia o radioterapia. La calidad de vida de estas personas, ya de por sí comprometida por la propia enfermedad, puede verse seriamente mermada. En los últimos años se han realizado grandes esfuerzos por minimizar los efectos colaterales de esos tratamientos pero sus resultados no siempre han sido suficientemente eficaces. Parece necesario desarrollar nuevas líneas de investigación que proporcionen alternativas profilácticas factibles de ser llevadas a la práctica por su sencillez y por su inocuidad. La aplicación de los conocimientos y de los principios que rigen la formación de las aversiones gustativas aprendidas podía ser una de ellas. En este trabajo se analizan las características de estas aversiones gustativas/nutritivas entre las que destacan su rápida adquisición, su especificidad estimular y una amplia demora interestimular. Se examinan igualmente alguno de los sistemas neuroquímicos y anatómicos implicados en este proceso adquisitivo. Finalmente, se revisan algunas de las estrategias farmacológicas y conductuales derivadas de la investigación básica y encaminadas a la prevención del desarrollo de estas perturbadoras aversiones nutritivas El rechazo de los alimentos que se produce tras experiencias que implican malestar gastrointestinal (náuseas, vómitos, etc.) es un fenómeno biológicamente predispuesto que se observa frecuentemente tanto en la investigación animal como en nuestra propia vida diaria. Pero la adquisición de estas aversiones suele producirse y puede adoptar tintes dramáticos en el caso de pacientes oncológicos que sufren frecuentes vómitos y náuseas como consecuencia del tratamiento con quimioterapia o radioterapia. La calidad de vida de estas personas, ya de por sí comprometida por la propia enfermedad, puede verse seriamente mermada. En los últimos años se han realizado grandes esfuerzos por minimizar los efectos colaterales de esos tratamientos pero sus resultados no siempre han sido suficientemente eficaces. Parece necesario desarrollar nuevas líneas de investigación que proporcionen alternativas profilácticas factibles de ser llevadas a la práctica por su sencillez y por su inocuidad. La aplicación de los conocimientos y de los principios que rigen la formación de las aversiones gustativas aprendidas podía ser una de ellas. En este trabajo se analizan las características de estas aversiones gustativas/nutritivas entre las que destacan su rápida adquisición, su especificidad estimular y una amplia demora interestimular. Se examinan igualmente alguno de los sistemas neuroquímicos y anatómicos implicados en este proceso adquisitivo. Finalmente, se revisan algunas de las estrategias farmacológicas y conductuales derivadas de la investigación básica y encaminadas a la prevención del desarrollo de estas perturbadoras aversiones nutritivas (AU)

Lateral parabrachial lesions impair taste aversion learning induced by blood-borne visceral stimuli.

The lateral parabrachial area (LPB), main relay from the area postrema (AP), plays a role in processing visceral information and is thus of potential importance in taste aversion learning (TAL). This study used a lesion approach to address whether LPB functional relevance depends upon the features of toxins that serves as visceral stimuli in TAL. In addition, we explored whether LPB involvement in TAL is restricted to those toxic events detected by the AP or whether it has a more general role. Results showed that LPB-lesioned animals were disrupted in acquiring a TAL induced by blood-borne AP-dependent aversive stimuli (intraperitoneal methylscopolamine) and by AP-independent stimulus (intraperitoneal ethanol), but still, clearly developed strong aversions when intragastric hypertonic sodium chloride, a vagally processed aversive stimulus, served as the aversive stimulus. These findings suggest that the LPB plays a critical role in TAL induced by blood-borne toxins, such as methylscopolamine or ethanol, but is not necessary for vagally mediated stimulus, such as sodium chloride. The present results are discussed in the context of the hypothesis holding separable and independent neural systems underlying TAL.

A practical route to partially protected pyrrolidines as precursors for the stereoselective synthesis of alexines.

Either 3-O-benzoyl- (2a) or 3-O-benzyl-1,2-O-isopropylidene-beta-D-fructopyranose (2b) were regioselectively O-benzylated at C-4 to give 4a and 4b, respectively, which were transformed into 5-azido-3-O-benzoyl-4-O-benzyl- (6a) and 5-azido-3,4-di-O-benzyl-5-deoxy-1,2-O-isopropylidene-alpha-L-sorbopyranose (6b) by nucleophilic displacement of the corresponding 5-O-mesyl derivatives 5a and 5b by sodium azide in DMF, respectively. Compound 6b was also prepared from 4b in one step by the Mitsunobu methodology. Deacetonation of 6a and 6b gave the partially protected free azidouloses 8a and 8b, respectively, that were protected as their 1-O-TBDPS derivatives 9a and 9b. Hydrogenation of 9b over Raney nickel gave stereoselectively (2R,3R,4R,5S)-3,4-dibenzyloxy-2'-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine (12) which was identified by transformation into the well known (2R,3R,4R,5S)-3,4-dihydroxy-2,5-bis(hydroxymethyl)pyrrolidine (1, DGDP).

Electrical stimulation of the insular cortex induces flavor-preferences in rats.

The present study examined the role of the Insular cortex (IC) in flavor-guided behavior. For that purpose, a flavored stimulus was paired with delayed electrical stimulation of this region. In addition, a standard operant task explored the involvement of the IC in a prefrontal self-stimulation reward-circuit. The results showed strong preferences for the flavored stimulus previously paired to the Insular stimulation, in a discriminative free choice test. However, the operant task revealed a failure to induce IC self-stimulation, suggesting that flavor preferences elicited by electrical stimulation of the IC are not due to activation of the prefrontal-stimulation reward circuit. These results are discussed in terms of the Insular Cortex as critical in processing visceral stimulus, hedonic valence and/or food-reward incentive learning.

Ethanol-induced c-fos expression in catecholamine- and neuropeptide Y-producing neurons in rat brainstem.

BACKGROUND: Previous studies have used c-Fos-like immunoreactivity (cFLI) to examine the neuroanatomical location of cells that are activated in response to ethanol administration. However, the use of cFLI alone fails to reveal the phenotypical identity of cells. In the present study we used double-labeling procedures to identify the neurochemical phenotype of neurons that showed ethanol-induced cFLI in the rat brainstem. METHODS: Individual groups of rats received intraperitoneal injection of ethanol (1.5 g/kg or 3.5 g/kg) or isotonic saline (23 ml/kg). To assess the specificity of cFLI induced by ethanol, we injected other rats with the drug lithium chloride (LiCl; 76 mg/kg). Two hours after injection, rats were killed and their brains were processed for immunohistochemistry. RESULTS: Both doses of ethanol promoted cFLI in several brainstem regions, including the nucleus of the solitary tract (NTS), the locus coeruleus (LC), and the ventrolateral medulla (VLM). Although LiCl caused significant cFLI in the NTS, this drug promoted only minimal cFLI in the VLM and no significant activation in the LC. We found that a significant proportion of tyrosine hydroxylase (TH)-positive neurons coexpressed ethanol-induced cFLI in the VLM (approximately 75-85%), the NTS (approximately 65-75%), and the LC (approximately 30-65%). Additionally, a significant proportion of neuropeptide Y (NPY)-producing neurons in the VLM coexpressed ethanol-induced cFLI (approximately 60-75%). On the other hand, LiCl promoted activation of TH-positive neurons in the VLM and the NTS but failed to stimulate cFLI in TH-producing neurons in the LC or in NPY-producing neurons of the VLM. CONCLUSIONS: Neurons in the rat brainstem that show ethanol-induced c-Fos expression produce catecholamines and NPY. This research demonstrates the usefulness of double-labeling immunohistochemistry procedures for identifying the neurochemical identity of neurons that are activated after ethanol administration.

Lateral parabrachial lesions impair intraperitoneal but not intraventricular methylscopolamine-induced taste aversion learning.

The role of the lateral parabrachial area (lPB) in the acquisition of a delayed taste aversion learning task (TAL) was examined by delivering the peripherally acting aversive compound, methylscopolamine (MSP), through two different routes, intraperitoneal and intraventricular. Consistent with previous anatomical, behavioral and molecular work, electrolytic lesions centered at the lPB did impair TAL when the MSP was injected intraperitoneally. However, lPB-lesioned animals exhibited intact learning capacities when MSP was administered intraventricularly. These results are interpreted in terms of the lPB as a critical anatomical relay involved in bottom-up visceral processing of aversive stimuli and also in relation to the relevance of forebrain structures in TAL.

cFos induction during conditioned taste aversion expression varies with aversion strength.

Fos-like immunoreactivity (FLI) can indicate the location of neurons activated following expression of conditioned taste aversion (CTA). After one conditioning trial FLI has been identified in the intermediate nucleus of the solitary tract (iNTS) with little expression in other brain regions. The present study assessed the effect of increasing aversion strength on the magnitude and anatomical distribution of FLI during CTA expression. When animals received three rather than one conditioning trial, significant FLI was seen not only in the iNTS but also in the parabrachial nucleus (PBN), and the central nucleus of the amygdala (CNA), regions thought to be important in taste aversion learning.

Insular cortex lesions and taste aversion learning: effects of conditioning method and timing of lesion.

The specific role of insular cortex in acquisition and expression of a conditioned taste aversion was assessed using two different conditioning methods, which vary mode of taste delivery. Involvement of insular cortex in the induction of c-Fos-immunoreactivity in the nucleus of the solitary tract, a cellular correlate of the behavioral expression of a conditioned taste aversion, was also assessed. Electrolytic lesions of insular cortex blocked behavioral expression of a conditioned taste aversion and this was evident not only when lesions were placed prior to conditioning, but also when they were made after conditioning but before testing. In contrast to the effects on behavior, lesions did not completely block the c-Fos-immunoreactivity which accompanies re-exposure to the aversive taste. In addition, the blocking of behavioral evidence of aversion conditioning by cortical lesions was seen both in animals trained under an intraoral acquisition procedure and those trained with bottle-conditioning. This contrasts with previous work with amygdala lesions which showed that amygdala was absolutely necessary for taste aversions conditioned with the intraoral method but not for those conditioned using bottle presentation of the taste. Overall, these findings imply that the details of the neural circuitry involved in taste aversion learning, including its anatomical distribution, complexity and degree of redundancy, vary with the type of conditioning method employed.

Enantiospecific synthesis fromD-fructose of (2S,5R)- and (2R,5R)-2-methyl-1,6-dioxaspiro[4.5]decane [the odor bouquet minor components ofParavespula vulgaris (L.)].

The synthesis of (2S,5R)-(1) and (2R,5R)-2-methyl-1,6-dioxaspiro [4.5]decane (2) from (2RS,5R,8R,9R,10S)-8,9,10-trihydroxy-2-methyl-1, 6-dioxaspiro[4.5]decane (8), obtained in five steps fromD-fructose using Wittig's methodology, reduction, and spiroketalation, has been accomplished by a Corey dideoxygenation at C-8,9, followed by a Barton deoxygenation at C-10, of the appropriately protected derivatives.

Enantiospecific synthesis of (3S,6R)-3-hydroxy-1,7-dioxaspiro[5.5]undecane and its (4R)-4-hydroxy isomer [minor components of olive fruit fly (Dacus oleae) sex pheromone].

The synthesis of (3S,6R)-3-hydroxy-1,7-dioxaspiro[5.5]undecane (8) and its (4R)-4-hydroxy isomer (11) from (3R,4S,6R)-3,4-dihydroxy-1,7-dioxaspiro[5.5]undecane (1), obtained from D-fructose, has been accomplished by regioselective deoxygenation at C-4 and C-3, respectively, of the appropriately protected derivatives.

Enantiospecific synthesis of (R)-1,7-dioxaspiro [5.5]undecane [major component of olive fruit fly (Dacus Oleae) sex pheromone] from d-Fructose.

The synthesis of the title compound13 has been carried out through the preparation of its precursor, (3R,4R,5S,6R)-3,4,5-trihydroxy-1,7-dioxaspiro[5.5]undecane (6), obtained fromD-fructose using Wittig's methodology, reduction, and spiroketalation. Compound6 was transformed into13 by a Barton deoxygenation at C-5 followed by a Corey dideoxygenation at C-3,4 of the appropriately protected derivatives.

Mammillary polydipsia and diabetes insipidus: a study of the rhythmicity of water intake.

Rats with polydipsia induced by electrolytic mammillary lesions show a normal daily rhythmicity of water intake compared with sham lesioned animals, when kept in a 12:12 hours light-dark cycle of illumination. Water is mainly consumed during the dark phase (approximately 80-90% of the total amount). On the other hand, rats with centrally induced diabetes insipidus by means of electrolytic lesions in the median eminence show a clear-cut alteration in this rhythmicity, drinking only 67% of the total amount during the dark phase. This effect could be due to the continuous necessity of these animals to drink water in order to maintain fluid homeostasis, and is not related to food rhythmicity alterations. Taken together, and on the basis of the daily rhythmicity of water intake, these results suggest that mammillary polydipsia may be different from that observed when diabetes insipidus is present.

Sensitivity of macrophages from different species to African swine fever (ASF) virus.

The swine white blood cells sensitive to African swine fever (ASF) virus are monocytes differentiated in vitro to macrophages. These cells have been characterized by their morphology, phagocytic capacity and the presence of receptors for swine immunoglobulin G in their membranes. ASF virus does not produce any detectable effect on macrophages from humans, rabbits, guinea pigs, hamsters or rats, whereas ASF virus-infected chicken macrophages show an enhancement of cellular DNA synthesis and an intense cytopathic effect. ASF virus, adapted to grow in VERO cells, produces a strong cytopathic effect in human macrophages leading to cell destruction. This effect is not associated with the synthesis of infectious virus, cellular or virus DNA nor with the formation of detectable virus-related structures.