Autonomous University of Tlaxcala
Tlaxcala, Mexico

The Autonomous University of Tlaxcala is a Mexican public university based in the state of Tlaxcala. Wikipedia.

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Flores G.,Autonomous University of Puebla | Morales-Medina J.C.,Autonomous University of Tlaxcala | Diaz A.,Autonomous University of Puebla
Behavioural Brain Research | Year: 2016

Schizophrenia, a severe and debilitating disorder with a high social burden, affects 1% of the adult world population. Available therapies are unable to treat all the symptoms, and result in strong side effects. For this reason, numerous animal models have been generated to elucidate the pathophysiology of this disorder. All these models present neuronal remodeling and abnormalities in spine stability. It is well known that the complexity in dendritic arborization determines the number of receptive synaptic contacts. Also the loss of dendritic spines and arbor stability are strongly associated with schizophrenia. This review evaluates changes in spine density and dendritic arborization in animal models of schizophrenia. By understanding these changes, pharmacological treatments can be designed to target specific neural systems to attenuate neuronal remodeling and associated behavioral deficits. © 2015 Elsevier B.V.

Hoffman K.L.,Autonomous University of Tlaxcala | Basurto E.,Autonomous University of Tlaxcala
Behavioural Brain Research | Year: 2013

The spontaneous response to novelty is the basis of one-trial object recognition tests for the study of object recognition memory (ORM) in rodents. We describe an object recognition task for the rabbit, based on its natural tendency to scent-mark ("chin") novel objects. The object recognition task comprised a 15. min sample phase in which the rabbit was placed into an open field arena containing two similar objects, then removed for a 5-360. min delay, and then returned to the same arena that contained one object similar to the original ones ("Familiar") and one that differed from the original ones ("Novel"), for a 15. min test phase. Chin-marks directed at each of the objects were registered. Some animals received injections (sc) of saline, ketamine (1. mg/kg), or MK-801 (37. μg/kg), 5 or 20. min before the sample phase. We found that chinning decreased across the sample phase, and that this response showed stimulus specificity, a defining characteristic of habituation: in the test phase, chinning directed at the Novel, but not Familiar, object was increased. Chinning directed preferentially at the novel object, which we interpret as novelty-induced sensitization and the behavioral correlate of ORM, was promoted by tactile/visual and spatial novelty. ORM deficits were induced by pre-treatment with MK-801 and, to a lesser extent, ketamine. Novel object discrimination was not observed after delays longer than 5. min. These results suggest that short-term habituation and sensitization, not long-term memory, underlie novel object discrimination in this test paradigm. © 2013 Elsevier B.V.

Hoffman K.L.,Autonomous University of Tlaxcala | Rueda Morales R.I.,Autonomous University of Tlaxcala
Behavioural Brain Research | Year: 2012

Nest building behavior in the pregnant female rabbit (Oryctolagus cuniculus) is a model for compulsive behavior in Obsessive Compulsive Disorder (OCD). This behavior comprises a cycle of repeated, stereotyped components (collecting straw, entering nest box and depositing the straw there, returning to collect more straw), which itself is repeated 80+ times in a single bout that lasts approximately 50. min. The bout, in turn, is repeated if necessary, according to the rabbit's perception of whether or not the nest is finished. We administered SCH23390 (5-100μg/kg; D1/D5 antagonist) or raclopride (0.05-1.0. mg/kg; D2/D3 antagonist), subcutaneously to day 28 pregnant female rabbits, 30 or 60. min before placing straw inside their home cage. At doses that minimally affected ambulatory behavior in open field (5-12.5μg/kg SCH23390, 0.5-1.0. mg/kg raclopride), both antagonists dramatically reduced bout duration while not significantly affecting the initiation of straw carrying behavior, the sequential performance of the individual cycle components, maximum cycle frequency, or the total number of bouts performed. These results point to an important role for dopamine neurotransmission for the prolonged expression of a normal, repetitive and compulsive-like behavior. Moreover, the finding that dopamine receptor antagonists decrease the time spent engaged in repetitive behavior (without significantly altering the form of the repetitive behavior itself) suggests a possible explanation for why neuroleptics can be clinically effective for treating OCD. © 2012 Elsevier B.V.

Hoffman K.L.,Autonomous University of Tlaxcala
Expert Opinion on Drug Discovery | Year: 2011

Introduction: Obsessive compulsive disorder (OCD) is a debilitating condition with limited treatment options. OCD is heterogeneous with respect to the content of obsessions and compulsions and their underlying motivation, among other characteristics. Animal models have provided important insights into the pathophysiology of OCD. Areas covered: The phenomenology of OCD is discussed, with emphasis on clinically-relevant subgroups. The paper also discusses the advantages and limitations of animals as models of OCD, along with considerations on assessing their validity. A PubMed database search using the terms'animal model' and'obsessive compulsive disorder' revealed ongoing studies in several models, including stereotypy in the deer mouse, quinpirole-induced checking, spontaneous alternation, compulsive lever pressing, genetic models, pathogenic models and models involving normal compulsive-like behavioral patterns. These models are presented with respect to their similarity to specific features of OCD and the information gained from them. Studies in many of these models point to the participation of corticostriatal thalamocortical circuitry and corticostriatal glutamate neurotransmission in the pathophysiology of compulsive-like behavior. Expert opinion: The use of animal models takes us beyond simple serotonin- or dopamine-based models of OCD that are founded on the often limited, and still unexplained, response of OCD symptoms to serotonin reuptake inhibitors or antipsychotic therapy. Pharmacological challenges that selectively target neurochemical systems that modulate either corticostriatal glutamate or striatal dopamine neurotransmission, or indeed both, should be investigated in animal models of compulsive-like behavior. Such systems include metabotropic glutamate, adenosine and endocannabinoid receptors, among others. © 2011 Informa UK, Ltd.

Estrada-Reyes R.,Instituto Nacional Of Psiquiatria Ramon Of La Fuente Muniz | Carro-Juarez M.,Autonomous University of Tlaxcala | Martinez-Mota L.,Instituto Nacional Of Psiquiatria Ramon Of La Fuente Muniz
Journal of Ethnopharmacology | Year: 2013

Ethnopharmacological relevance: Turnera diffusa Wild has been used in folk medicine by its aphrodisiac and tranquilizing properties. Previously we experimentally showed the aphrodisiac effect of a chemically characterized aqueous extract of Turnera diffusa in male rats. However, the mechanism of action underlying such effects has not been studied. Study aims: As part of our systematic studies of pharmacological properties of Turnera diffusa, we aimed to analyze whether the increased sexual motivation and the augmented sexual performance of sexually sluggish (SL) male rats treated with Turnera diffusa involves the NO pathway. Additionally we analyzed whether such effects were exerted at the level of the brain or the spinal cord. Finally, anxiety levels and ambulatory activity were also evaluated. Material and methods: Turnera diffusa (10-40 mg/kg) and sildenafil citrate (10 mg/kg) with or without a nonspecific inhibitor of NO synthase, Nω-nitro-l-arginine methyl esther (l-NAME, 12.5 mg/kg) were evaluated in SL rats, in a standard sexual behavior test and in the fictive ejaculation model in spinal cord transected and urethane-anaesthetized SL rats. Anxiety levels or ambulation were assessed in the burying behavior and open-field tests. Results: Turnera diffusa and sildenafil (both at 10 mg/kg) facilitated expression of male sexual behavior by shortening mainly ejaculation latency. Treatments also facilitated the number of discharges in the ejaculatory motor pattern as well as the number of ejaculatory motor patterns and its associated penile erections. l-NAME prevented the pro-sexual effects of treatments on both experimental models. Besides, the extract of Turnera diffusa (10 mg/kg) produced an anxiolytic-like effect in male rats without affecting ambulation. Conclusions: Findings from the present work support the notion that pro-sexual effect of the aqueous extract of Turnera diffusa in rats involves the participation of NO pathway, mainly at central level. The anxiolytic-like effect of Turnera diffusa is an advantage to its use for improving sexual performance. © 2012 Elsevier Ireland Ltd. All rights reserved.

Hoffman K.L.,Autonomous University of Tlaxcala
Expert Opinion on Drug Discovery | Year: 2013

Introduction: The extensive comorbidity among psychiatric disorders underscores the need for a fundamental change in the way psychopathology is classified. An alternative 'dimensional' system classifies disorders based on relationships with respect to heritability patterns and comorbidity. It is from this 'dimensional view' that mouse modeling of neuropsychiatric disorders is presently discussed. Areas covered: This review describes three proposed dimensions of psychopathology: internalizing (disorders of negative emotions), externalizing (disorders of impulsivity) and schizophrenic. The article, furthermore, presents and explains the concept of endophenotype and discusses the possible endophenotypes relevant to each of these dimensions. Finally, the article also describes mouse behavioral tests that are used for quantifying these endophenotypes and presents examples of recent studies that have used these tests. Expert opinion: Considering animal models within the context of endophenotypes associated with psychopathological 'dimensions', rather than focusing on modeling specific disorders, might facilitate the discovery of new pharmacotherapies. Mouse models will be powerful tools for exploring how environmental factors interact with genetic vulnerability to cause psychopathology, possibly leading to novel preventative treatment strategies. Future pharmacotherapies for neuropsychiatric disorders such as depression might comprise drugs or drug combinations that target key components of multiple systems, including neurotransmitter systems, cytokine production, oxidative stress and the HPA axis. © 2013 Informa UK, Ltd.

Hoffman K.L.,Autonomous University of Tlaxcala
Expert Opinion on Drug Discovery | Year: 2016

Introduction: Dimensional models of psychopathology describe mental illness in terms of natural variance along certain phenotypic dimensions that are continuous with normal. Vulnerability to psychopathology might arise when certain adaptive psychophysiological processes, conserved between humans and non-human animals, function outside of their "normal" range. Therefore, an in-depth understanding of the neurobiology and neurochemistry underlying these processes could identify possible novel drug targets.Areas covered: Psychophysiological processes that might be related to anxiety disorders and depression are proposed and discussed. Those processes relevant to depressive disorders include: hedonic responsiveness, biases in the processing of stimuli, and sleep architecture. Those relevant to anxiety disorders include: startle reactivity, CO2 sensitivity, and fear generalization. Rodent behavioral tests for assessing the function of these processes and investigating their neurobiology are described. A psychophysiological process strategy for translational research is proposed, which focusses on understanding the neurobiology and neurochemistry underlying key psychophysiological processes that, when their activity deviates from normal, are associated with neuropsychiatric symptoms. This strategy emphasizes the use of analogous tests and measures in both preclinical and clinical studies, while de-emphasizing the use of preclinical animal models that attempt to replicate features of the neuropsychiatric disorder through experimental manipulations.Expert opinion: Investigating the neurobiology of key psychophysiological processes in rodents should enhance our understanding of the pathophysiology of neuropsychiatric disorders. New drug development could be directed toward developing pharmacological strategies that would normalize the function of these psychophysiological processes. © 2016 Informa UK Limited, trading as Taylor & Francis Group.

Lomanowska A.M.,Laval University | Melo A.I.,Autonomous University of Tlaxcala
Hormones and Behavior | Year: 2016

This article is part of a Special Issue on "Parental Care". Maternal behavior has an important function in stimulating adequate growth and development of the young. Several approaches have been used in primates and rodents to deconstruct and examine the influence of specific components of maternal stimulation on offspring development. These approaches include observational studies of typical mother-infant interactions and studies of the effects of intermittent or complete deprivation of maternal contact. In this review, we focus on one unique approach using rats that enables the complete control of maternal variables by means of rearing rat pups artificially without contact with the mother or litter, while maintaining stable nutrition, temperature and exposure to stressful stimuli. This artificial rearing model permits the removal and controlled replacement of relevant maternal and litter stimuli and has contributed valuable insights regarding the influence of these stimuli on various developmental outcomes. It also enables the analysis of factors implicated in social isolation itself and their long-term influence. We provide an overview of the effects of artificial rearing on behavior, physiology, and neurobiology, including the influence of replacing maternal tactile stimulation and littermate contact on these outcomes. We then discuss the relevance of these effects in terms of the maternal role in regulating different aspects of offspring development and implications for human research. We emphasize that artificial rearing of rats does not lead to a global insult of nervous system development, making this paradigm useful in investigating specific developmental effects associated with maternal stimulation. © 2015 Elsevier Inc.

Hoffman K.L.,Autonomous University of Tlaxcala | Basurto E.,Autonomous University of Tlaxcala
Behavioural Brain Research | Year: 2014

Studies in humans indicate that acute administration of sub-anesthetic doses of ketamine, an NMDA receptor antagonist, provokes schizophrenic-like symptoms in healthy volunteers, and exacerbates existing symptoms in individuals with schizophrenia. These and other findings suggest that NMDA receptor hypofunction might participate in the pathophysiology of schizophrenia, and have prompted the development of rodent pharmacological models for this disorder based on acute or subchronic treatment with NMDA receptor antagonists, as well as the development of novel pharmacotherapies based on increasing extrasynaptic glycine concentrations. In the present study, we tested whether acute hyperlocomotory behavior and/or deficits in the novel object recognition (NOR) task, induced in male rabbits by the acute subcutaneous (s.c.) administration of MK-801 (0.025 and 0.037. mg/kg s.c., respectively), were prevented by prior administration of the atypcial antipsychotic, clozapine (0.2. mg/kg, s.c.), or the glycine pro-drug glycinamide (56. mg/kg, s.c.). We found that clozapine fully prevented the MK-801-induced hyperlocomotion, and both clozapine and glycinamide prevented MK-801-induced deficits in the NOR task. The present results show that MK-801-induced hyperlocomotion and deficits in the NOR task in the domestic rabbit demonstrate predictive validity as an alternative animal model for symptoms of schizophrenia. Moreover, these results indicate that glycinamide should be investigated in pre-clinical models of neuropsychiatric disorders such as schizophrenia, obsessive compulsive disorder and anxiety disorders, where augmentation of extrasynaptic glycine concentrations may have therapeutic utility. © 2014.

Sanchez Lopez C.,Autonomous University of Tlaxcala
Revista Mexicana de Fisica | Year: 2012

In this paper, a high-frequency Chua's chaotic oscillator based on unity gain cells (UGCs) is introduced. Leveraging the internal buffers of the integrated circuit AD844, a voltage mirror (VM) and a positive current follower (CF+) are designed, taking into account the parasitic elements associated to each UGC. Afterwards, the behavior of the nonlinear resistor and of the grounded inductor are designed by using several VMs, CF+s, discrete capacitors and resistors. In this way, Chua's circuit is built by coupling a nonlinear resistor and an active LC tank circuit by using an RC passive filter. Hspice simulations performed at the state space and in the time and frequency domains show that the proposed topology generates chaos at 1.7 MHz. Experimental results are given, verifying that the chaotic spectrum is extended to high-frequency and showing close agreement with theoretical analysis. The proposed topology is compared with other topologies reported in the literature, showing that a number reduced of active devices and passive elements along with smaller supply voltages can be used to generate chaotic oscillations at high-frequency. Sensitivity and Monte Carlo analysis are also done in order to research the robustness of the proposed chaotic circuit.

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