Explorant teràpies biotecnològiques contra les malalties neurodegeneratives

Les malalties neurodegeneratives es troben entre les causes més importants de mort i discapacitat als països occidentals. Les teràpies clàssiques, com ara les farmacològiques, són purament simptomàtiques, és a dir, tracten els símptomes de la malaltia (com pot ser la pèrdua progressiva de memòria en l’Alzheimer o els efectes motors de la malaltia de Parkinson), però no són capaces d’aturar la seua progressió ni curar-les. Això és així perquè no s’ataca la causa de la malaltia. Les noves teràpies basades en la biotecnologia podrien ajudar-nos en el futur a vèncer algunes d’aquestes terribles malalties atacant directament les seues causes i promocionant la regeneració neuronal.Las enfermedades neurodegenerativas se encuentran entre las causas más importantes de muerte y discapacidad en la sociedad occidental. Las terapias clásicas, como las farmacológicas, son puramente sintomáticas, es decir, solo son capaces de aliviar los síntomas (como la pérdida de memoria progresiva en el Alzheimer o los efectos motores de la enfermedad de Parkinson), pero no pueden detener su progresión ni curarlas, ya que no atacan la causa de las mismas. Las nuevas terapias basadas en la biotecnología podrían ayudarnos en el futuro a vencer algunas de estas terribles enfermedades atacando directamente sus causas y promocionando la regeneración neuronal.Les maladies neurodégénératives se trouvent parmi les causes les plus importantes de mort et de handicap dans la société actuelle. Les thérapies classiques, comme les pharmacologiques, sont purament symptomatiques, c’est-à-dire qu’elles ne peuvent soulager que les symptomes (comme la perte de mémoire progressive chez l’Alzheimer ou les effets moteurs de la maladie de Parkinson), mais elles ne peuvent ni arrêter leur progression ni les soigner, puisqu’elles n’attaquent pas leurs causes. Les nouvelles thérapies fondées sur la biotechnologie pourraient nous aider dans l’avenir à vaincre quelques-unes de ces terribles maladies, attaquant directement leurs causes et favorisant la régénération neuronale.Neurodegenerative diseases are among the leading causes of death and disability in the Western World. Traditional pharmacological therapies are purely symptomatic, as they merely alleviate symptoms such as gradual memory loss in Alzheimer’s and motor dysfunction in Parkinson’s disease. However, these therapies are unable to cure or stop the progression of these neurodegenerative diseases, as they do not target the causes. New therapies based on recent advances in biotechnology could help to tackle some of these diseases by directly targeting their causes and enhancing neuronal regeneration

The autistic brain: Exploring the strength of a different kind of mind

Temple Grandin is one of the most well known persons with autism. Most people met her first when the neurologist Oliver Sacks portrayed her in his famous book “An anthropologist on Mars”. But Dr Grandin –BA in Psychology, PhD in Animal Science, professor at Colorado State University, and an accomplished engineer in the livestock industry- had written by that time a considerable number of scientific papers and books

Neuroquímica del refuerzo inducido por feromonas.

RESUMEN Las feromonas sexuales masculinas atraen a de manera innata a las hembras de ratón. Estos estímulos no sólo son explorados intensa y preferentemente por las hembras sino que inducen preferencia condicionada de lugar (PCL), lo cual constituye una prueba de que la detección de las feromonas de macho es una recompensa para las hembras. Así pues, la utilización de feromonas sexuales proporciona un modelo novedoso para para el estudio de los mecanismos y las bases neurales de los procesos de refuerzo. En la tesis doctoral Neuroquímica del refuerzo inducido por feromonas se pretendió explorar cuales son los neurotransmisores que regulan el comportamiento de atracción innata por feromonas de macho y la adquisición de PCL, así como investigar sobre qué estructuras cerebrales estan actuando estos neurotransmisores. Para ello, se utilizó una aproximación farmacológica sobre protocolos comportamentales, y se complementó la información derivada de estos experimentos con lesiones de ciertos núcleos cerebrales. Adicionalmente, se compararon los resultados obtenidos con estos experimentos con el papel de algunos de los neurotransmisores estudiados en el refuerzo inducido por otras recompensas naturales, como el sabor dulce. En primer lugar, el estudio de los sistemas catecolaminérgicos (dopamina y noradrenalina) reveló que los fármacos agonistas dopaminérgicos, principalmente a través del receptor D1 de la dopamina, inhiben la atracción innata por feromonas de macho, mientras que ni los antagonistas dopaminérgicos ni los agonistas noradrenérgicos afectan al refuerzo de feromonas. A continuación se estudiaron diversos fármacos opioidérgicos, lo cual mostró que un antagonista genérico de opioides no afecta ni a la atracción innata ni a la adquisición de PLC, mientras que un agonista de los receptores µ de opioides elimina la preferencia innata por feromonas de macho. Los mismos fármacos produjeron un efecto opuesto sobre el consumo preferente de una solución azucarada, sugiriendo que estímulos químicos naturales recompensantes (sacarosa y feromonas sexuales), que son detectados por distintos sistemas sensoriales, utilizan diferentes mecanismos neurobiológicos para ejercer su efecto reforzante. Se estudiaron asimismo los efectos de fármacos serotonérgicos, pero los resultados obtenidos no arrojaron conclusiones sólidas acerca del papel de la serotonina en el refuerzo de feromonas. Por el contrario, al investigar el papel del óxido nítrico se demostró que la inhibición farmacológica de la síntesis de este neurotransmisor gaseoso bloquea la atracción innata por feromonas de macho. En el contexto de los datos anatómicos y neuroquímicos disponibles, se procedió por último a investigar el efecto de lesiones electrolíticas de la zona de proyección de la corteza vomeronasal (el sistema que detecta las feromonas atractivas en ratones) sobre el estriado ventral, que se supone el centro del sistema del refuerzo. Estas lesiones, comprendiendo la zona de los islotes de Calleja mediales, eliminaron la respuesta de atracción innata por feromonas de macho. En resumen, los resultados de esta tesis revelan que el comportamiento de atracción innata que muestran las hembras de ratón por feromonas sexuales de macho depende de las proyecciones de la corteza vomeronasal sobre el estriado ventral, que se inhiben por la activación farmacológica de los sistemas dopaminérgicos y opiáceos, y se facilitan por la acción del óxido nítrico. Este estudio tiene implicaciones para la comprensión profunda de los procesos del refuerzo, cuyo mal funcionamiento deriva en estados patológicos como las adicciones a drogas o a comportamientos compulsivos, así como para la comprensión de los mecanismos de la comunicación social en roedores. __________________________________________________________________________________________________Female mice display an innate attraction towards male sexual pheromones, which in addition are reinforcing to them, as demonstrated by the induction of conditioned place preference rewarded by male-soiled bedding. Thus, male sexual pheromones provide an original and advantageous model to study reward mechanisms and neural basis. The thesis Neurochemistry of pheromone-induced reward aimed to explore what neurotransmitters control innate attraction and place preference acquisition conditioned by male pheromones, as well as the brain nuclei where they are acting. To do so, it was used a pharmachological approach and lesions of brain nuclei upon behavioural protocols involving pheromone-elicited behaviours. Additionally, the results from these experiments were compared with the role of studied neurotransmitters in sweet reward. First, studies involving catecholaminergic systems revealed that dopaminergic agonists, through D1 receptor, inhibit innate attraction towards male pheromones, whereas dopaminergic or noradrenergic antagonists do not affect pheromone reward. Similarly, opioidergic agonists abolish innate attraction towards male pheromones, but this behavoiour and place preference acquisition are not affected by opioidergic antagonists. Quite the opposite, opioidergic antagonists reduce, and agonists do not affect, preference for a sucrose solution in front of plain water. On the other hand, nitric oxide synthesis inhibition blocked innate attraction towards male pheromones, whereas serotonergic drugs use gave rise to inconclusive results. Finally, electrolytic lesions of the zone of the ventral striatum which receives direct projections from the vomeronasal cortex (centred at the medial islands of Calleja) abolished innate attraction as well. Taken together, the results of the thesis reveal that innate attraction behaviour that show female mice for male sexual pheromones depends on vomeronasal projections upon ventral striatum, which are inhibited by dopamine and opioids and facilitated by nitric oxide

Focal Lesions within the ventral striato-pallidum abolish attraction for male chemosignals in female mice

In rodents, socio-sexual behaviour is largely mediated by chemosensory cues, some of which are rewarding stimuli. Female mice display an innate attraction towards male chemosignals, dependent on the vomeronasal system. This behaviour likely reflects the hedonic value of sexual chemosignals. The anteromedial aspect of the olfactory tubercle, along with its associated islands of Calleja, receives vomeronasal inputs and sexually-dimorphic vasopressinergic innervation. Thus, we hypothesised that this portion of the ventral striato-pallidum, known to be involved in reward processing, might be important for sexual odorant-guided behaviours. In this study, we demonstrate that lesions of this region, but not of regions in the posterolateral striato-pallidum, abolish the attraction of female mice for male chemosignals, without affecting significantly their preference for a different natural reward (a sucrose solution). These results show that, at least in female mice, the integrity of the anterior aspect of the medioventral striato-pallidum, comprising a portion of the olfactory tubercle and associated islands of Calleja, is necessary for the attraction for male chemosignals. We suggest that this region contributes to the processing of the hedonic properties of biologically significant odorants

Inhibition of the medial amygdala disrupts escalated aggression in lactating female mice after repeated exposure to male intruders

Virgin female laboratory mice readily express pup care when co-housed with dams and pups. However, pup-sensitized virgins fail to express intruder-directed aggression on a single session of testing. To study whether repeated testing would affect the onset and dynamics of maternal or intruder-directed aggression, we tested dams and their accompanying virgins from postpartum day 4 to 6. Repeated testing led to escalated aggression towards male intruders in dams, but virgins never developed aggression. In dams, inhibition of the medial amygdala using DREADD (designer receptors exclusively activated by designer drugs) vectors carrying the hM4Di receptor blocked the expected increase in maternal aggression on the second testing day. Our data support that the onset of maternal aggression is linked to physiological changes occurring during motherhood, and that medial amygdala, a key centre integrating vomeronasal, olfactory and hormonal information, enables the expression of escalated aggression induced by repeated testing. Future studies selectively targeting specific neuronal populations of the medial amygdala are needed to allow a deeper understanding of the control of experience-dependent aggression increase, a phenomenon leading to the high aggression levels found in violent behaviours

MeCP2 haplodeficiency and early-life stress interaction on anxiety-like behavior in adolescent female mice

Background: Early-life stress can leave persistent epigenetic marks that may modulate vulnerability to psychiatric conditions later in life, including anxiety, depression and stress-related disorders. These are complex disorders with both environmental and genetic influences contributing to their etiology. Methyl-CpG Binding Protein 2 (MeCP2) has been attributed a key role in the control of neuronal activity-dependent gene expression and is a master regulator of experience-dependent epigenetic programming. Moreover, mutations in the MECP2 gene are the primary cause of Rett syndrome and, to a lesser extent, of a range of other major neurodevelopmental disorders. Here, we aim to study the interaction of MeCP2 with early-life stress in variables known to be affected by this environmental manipulation, namely anxiety-like behavior and activity of the underlying neural circuits. Methods: Using Mecp2 heterozygous and wild-type female mice we investigated the effects of the interaction of Mecp2 haplodeficiency with maternal separation later in life, by assessing anxiety-related behaviors and measuring concomitant c-FOS expression in stress- and anxiety-related brain regions of adolescent females. Moreover, arginine vasopressin and corticotropin-releasing hormone neurons of the paraventricular hypothalamic nucleus were analyzed for neuronal activation. Results: In wild-type mice, maternal separation caused a reduction in anxiety-like behavior and in the activation of the hypothalamic paraventricular nucleus, specifically in corticotropin-releasing hormone-positive cells, after the elevated plus maze. This effect of maternal separation was not observed in Mecp2 heterozygous females that per se show decreased anxiety-like behavior and concomitant decreased paraventricular nuclei activation

Avoidance and contextual learning induced by a kairomone, a pheromone and a common odorant in female CD1 mice

Chemosignals mediate both intra- and inter-specific communication in most mammals. Pheromones elicit stereotyped reactions in conspecifics, whereas kairomones provoke a reaction in an allospecific animal. For instance, predator kairomones elicit anticipated defensive responses in preys. The aim of this work was to test the behavioral responses of female mice to two chemosignals: 2-heptanone (2-HP), a putative alarm pheromone, and 2,4,5-trimethylthiazoline (TMT), a fox-derived putative kairomone, widely used to investigate fear and anxiety in rodents. The banana-like odorant isoamyl acetate (IA), unlikely to act as a chemosignal, served as a control odorant. We first presented increasing amounts of these odorants in consecutive days, in a test box in which mice could explore or avoid them. Female mice avoided the highest amounts of all three compounds, with TMT and IA eliciting avoidance at lower amounts (3.8 pmol and 0.35 μmol, respectively) than 2-HP (35 μmol). All three compounds induced minimal effects in global locomotion and immobility in this set up. Further, mice detected 3.5 pmol of TMT and IA in a habituation–dishabituation test, so avoidance of IA started well beyond the detection threshold. Finally, both TMT and IA, but not 2-HP, induced conditioned place avoidance and increased immobility in the neutral compartment during a contextual memory test. These data suggest that intense odors can induce contextual learning irrespective of their putative biological significance. Our results support that synthetic predator-related compounds (like TMT) or other intense odorants are useful to investigate the neurobiological basis of emotional behaviors in rodents. Since intense odorants unlikely to act as chemosignals can elicit similar behavioral reactions than chemosignals, we stress the importance of using behavioral measures in combination with other physiological (e.g., hormonal levels) or neural measures (e.g., immediate early gene expression) to establish the ethological significance of odorants

Tuning the brain for motherhood: prolactin-like central signalling in virgin, pregnant, and lactating female mice

Prolactin is fundamental for the expression of maternal behaviour. In virgin female rats, prolactin administered upon steroid hormone priming accelerates the onset of maternal care. By contrast, the role of prolactin in mice maternal behaviour remains unclear. This study aims at characterizing central prolactin activity patterns in female mice and their variation through pregnancy and lactation. This was revealed by immunoreactivity of phosphorylated (active) signal transducer and activator of transcription 5 (pSTAT5-ir), a key molecule in the signalling cascade of prolactin receptors. We also evaluated non-hypophyseal lactogenic activity during pregnancy by administering bromocriptine, which suppresses hypophyseal prolactin release. Late-pregnant and lactating females showed significantly increased pSTAT5-ir resulting in a widespread pattern of immunostaining with minor variations between pregnant and lactating animals, which comprises nuclei of the sociosexual and maternal brain, including telencephalic (septum, nucleus of the stria terminalis, and amygdala), hypothalamic (preoptic, paraventricular, supraoptic, and ventromedial), and midbrain (periaqueductal grey) regions. During late pregnancy, this pattern was not affected by the administration of bromocriptine, suggesting it to be elicited mostly by non-hypophyseal lactogenic agents, likely placental lactogens. Virgin females displayed, instead, a variable pattern of pSTAT5-ir restricted to a subset of the brain nuclei labelled in pregnant and lactating mice. A hormonal substitution experiment confirmed that estradiol and progesterone contribute to the variability found in virgin females. Our results reflect how the shaping of the maternal brain takes place prior to parturition and suggest that lactogenic agents are important candidates in the development of maternal behaviours already during pregnancy.This work has been funded by the Spanish MINECO-FEDER (BFU2013-47688-P), the Junta de Comunidades de Castilla-La Mancha/FEDER (PEIC11-0045-4490), and the Universitat Jaume I. This work is part of the Doctoral Thesis of Hugo Salais-López, granted by the FPU (Formación de Profesorado Universitario) programme of the Spanish Ministry of Education and Science

Motherhood-induced gene expression in the mouse medial amygdala: Changes induced by pregnancy and lactation but not by pup stimuli

During lactation, adult female mice display aggressive responses toward male intrud-ers, triggered by male- derived chemosensory signals. This aggressive behavior is not shown by pup- sensitized virgin females sharing pup care with dams. The genetic mechanisms underlying the switch from attraction to aggression are unknown. In this work, we investigate the differential gene expression in lactating females ex-pressing maternal aggression compared to pup- sensitized virgin females in the me-dial amygdala (Me), a key neural structure integrating chemosensory and hormonal information. The results showed 197 genes upregulated in dams, including genes encoding hormones such as prolactin, growth hormone, or follicle- stimulating hor-mone, neuropeptides such as galanin, oxytocin, and pro- opiomelanocortin, and genes related to catecholaminergic and cholinergic neurotransmission. In contrast, 99 genes were downregulated in dams, among which we find those encoding for inhibins and transcription factors of the Fos and early growth response families. The gene set analysis revealed numerous Gene Ontology functional groups with higher expres-sion in dams than in pup- sensitized virgin females, including those related with the regulation of the Jak/Stat cascade. Of note, a number of olfactory and vomeronasal receptor genes was expressed in the Me, although without differences between dams and virgins. For prolactin and growth hormone, a qPCR experiment comparing dams, pup- sensitized, and pup- naïve virgin females showed that dams expressed higher lev-els of both hormones than pup- naïve virgins, with pup- sensitized virgins showing intermediate levels. Altogether, the results show important gene expression changes in the Me, which may underlie some of the behavioral responses characterizing ma-ternal behavior