Potential drugs for the treatment of Alzheimer's disease.

It is well known that amyloid precursor protein (APP), the enzyme ß-secretase 1 (BACE1), cyclooxygenase 2 (COX-2), nicastrin (NCT), and hyperphosphorylated tau protein (p-tau) are closely related to the development of Alzheimer's disease (AD). In addition, recent evidence shows that neuroinflammation also contributes to the pathogenesis of AD. Although the mechanism is not clearly known, such inflammation could alter the activity of the aforementioned molecules. Therefore, the use of anti-inflammatory agents could slow the progression of the disease. Nimesulide, resveratrol, and citalopram are three anti-inflammatory agents that could contribute to a decrease in neuroinflammation and consequently to a decrease in the overexpression of APP, BACE1, COX-2, NCT, and p-Tau, as they possess anti-inflammatory effects that could regulate the expression of APP, BACE1, COX-2, NCT, and p-Tau of potent pro-inflammatory markers indirectly involved in the expression of APP, BACE1, NCT, COX-2, and p-Tau; therefore, their use could be beneficial as preventive treatment as well as in the early stages of AD.

Perspectiva bioética para México, España y Estados Unidos en los modelos in vivo de inducción de daño al ADN

En la actualidad, la investigación biomédica se ha centrado en el estudio de enfermedades como el cáncer, que causan un elevado índice de mortalidad. Existen diferentes modelos animales, empleados para generar diversos tipos de carcinogénesis; el daño directo al ADN es uno de los mecanismos más utilizados. Sin embargo, en la normatividad nacional e internacional vigente, no se señalan los aspectos bioéticos que se deben seguir para desarrollar un modelo experimental de daño al ADN. Además, no se realiza una correcta semejanza de la enfermedad. Debido a lo anterior, esta revisión analiza los avances en cuanto a normatividad que se han generado en diferentes países, comparando los estudios encontrados en Estados Unidos, México y España. La perspectiva a futuro es poder contar con guías de experimentación actualizadas, que permitan pautar las normas necesarias para el adecuado desarrollo de los modelos de investigación animal de daño al ADN y que cumplan con la regla de las 3R en la experimentación animal. Esta iniciativa se debe de realizar en conjunto entre la Organización Mundial de la Salud y los organismos especializados en manejo y cuidado de animales de laboratorio en los ámbitos nacional e internacional.

Currently, biomedical research has focused on the study of diseases such as cancer that causes a high mortality rate. Different animal models are used to generate different types of carcinogenesis; direct DNA damage is one of the most used mechanisms. However, current national and international regulations do not indicate the bioethical aspects that must be followed to develop an experimental model of DNA damage. In addition, they do not perform a correct resemblance of the disease. Due to the above, this review analyzes the advances in regulations generated in different countries, comparing the studies found in the United States, Mexico, and Spain. The future perspective is to be able to count on updated experimentation guidelines, which allow the establishment of the necessary norms for the adequate development of animal research models of DNA damage that comply with the 3R rule in animal experimentation. This initiative should be carried out jointly by the World Health Organization and organizations specialized in managing and caring laboratory animals at the national and international levels.

Na atualidade, a pesquisa biomédica vem se focando no estudo de doenças que causam um elevado índice de mortalidade, como o câncer. Existem diferentes modelos animais utilizados para gerar diversos tipos de carcinogêneses; o dano direto ao DNA é um dos mecanismos mais utilizados. Contudo, na legislação nacional e internacional vigente, não são sinalizados os aspectos bioéticos que devem ser seguidos para desenvolver um modelo experimental de dano ao DNA, além de não ser realizada uma correta semelhança da doença. Devido a isso, esta revisão analisa o avanço quanto à legislação que vem sendo gerada em diferentes países, comparando os estudos encontrados nos Estados Unidos, no México e na Espanha. A perspectiva para o futuro é poder contar com atualizadas, que permitam estabelecer as normas necessárias para desenvolver os modelos de pesquisa animal de dano ao DNA e que cumpram com a regra das 3R na experimentação animal. Essa iniciativa se deve realizar em conjunto entre a Organização Mundial da Saúde e as organizações especializadas na gestão e cuidado de animais de laboratório nos contextos nacional e internacional.

Lower ΔFosB expression in the dopaminergic system after stevia consumption in rats housed under environmental enrichment conditions.

Environmental enrichment (EE) has been proven to reduce drug seeking and the development of addiction-related behaviors in rodent models, but the effects of EE on natural reward acquisition in the form of sweet beverages are poorly understood. Accumulating evidence shows that the intake of sugar, the main ingredient of sweet beverages, alters the dopaminergic system, leading to addiction-related physiological and molecular changes. Sugar in sweet beverages has been replaced with natural sweeteners, such as stevia extract, which has greater sweetener potential but no energy content. Our research group found that sucralose consumption increased the expression of ΔFosB in reward-related nuclei, suggesting activation of the dopaminergic system. The present study assessed the effects of EE on stevia consumption and the expression of ΔFosB in the nucleus accumbens, caudate putamen, and prefrontal cortex. Sixteen male Wistar rats, 21 days old, were randomly assigned to an EE group (n = 8) or standard environment (SE) group (n = 8) and reared for 30 days. On postnatal day 52 (PND52), the brains of four animals in each housing condition were extracted to determine basal ΔFosB levels. Stevia consumption with intermittent access and ΔFosB immunoreactivity were measured for 21 days in the remainder of the rats. Compared with SE animals, EE animals exhibited a reduction of stevia consumption and alterations of ΔFosB immunoreactivity in the reward system. These results indicate that EE reduces stevia consumption and the stevia-induced ΔFosB expression, suggesting addiction-related changes in dopaminergic nuclei, which may be interpreted as a neuroprotective effect.

c-Fos immunoreactivity in the hypothalamus and reward system of young rats after social novelty exposure.

Socialization is an adaptive behavior during the early stages of life because it helps young animals become independent and determines healthy adult social behavior. Therefore, it is probable that the brain areas involved in the processing of social stimuli are more sensitive to social novelty during early life stages. To test this hypothesis, four groups of young male rats were exposed to different socioenvironmental stimuli; nonsocial physical novelty, social familiarity, social novelty, and a control group which received no stimulation. After stimuli exposure, brains were fixed and cut in coronal sections for c-Fos immunohistochemistry. The number of c-Fos-immunoreactive (c-Fos-ir) neurons in the paraventricular nucleus and supraoptic nucleus, the main producers of oxytocin and vasopressin, was compared, as well as in the nucleus accumbens and ventral pallidum, the main areas involved in reinforced behavior. A significantly higher number of c-Fos-ir neurons were found in animals exposed to social novelty in all areas, except in the supraoptic nucleus. In particular, the increase in c-Fos-ir in the paraventricular nucleus seems to be selective in response to social novelty, while the increase of c-Fos-ir in the nucleus accumbens and ventral pallidum suggests that social novelty during youth is a highly rewarding stimulus compared with social familiarity and nonsocial physical novelty.

Effect of hyperprolactinemia on PRL-receptor expression and activation of Stat and Mapk cell signaling in the prostate of long-term sexually-active rats.

The abnormal elevation of serum PRL, referred to as hyperprolactinemia (HyperPRL), produces alterations in several reproductive parameters of male rats such as penile erection or decreased tendency to reach ejaculation. Additionally, this situation produces a significant modification of prostate histology, as observed in the epithelial structure and alveolar area, which could reach a level of hyperplasia in the long-term. In this tissue, HyperPRL produces an increase in expression of PRL receptors and activation of the Stat3 signaling pathway that is correlated with the evolution of prostate pathologies. However, the impact of HyperPRL in long-term sexually active male rats is unknown. In this work, using constantly copulating Wistar male rats with induced HyperPRL, we analyzed the level of serum PRL, the effect on prostate PRL receptors, and activation of pStat3, pStat5 and Mapk signaling pathways. Two procedures to induce HyperPRL were employed, comprising daily IP administration or adenohypophysis transplant, and although neither affected the execution of sexual behavior, the serum PRL profile following successive ejaculations was affected. Messenger RNA expression of the short and long isoforms of the PRL receptor at the ventral prostate was affected in different ways depending on the procedure to induce HyperPRL. The ventral prostate did not show any modification in terms of activation of the pStat5 signaling pathway in subjects with daily administration of PRL, although this was significantly increased in ADH transplanted subjects in the second and fourth consecutive ejaculation. A similar profile was found for the pStat3 pathway which additionally showed a significant increase in the third and fourth ejaculation of daily-injected subjects. The Mapk signaling pathway did not show any modifications in subjects with daily administration of PRL, but showed a significant increase in the second and third ejaculations of subjects with ADH transplants. Thus, although sexual behavior was not modified, HyperPRL modified the expression of PRL receptors and the activation of signal pathways in the prostate tissue. Hence, it is probable that prostatic alterations precede the sexual behavioral deficits observed in subjects with HyperPRL.

Correlation of prolactin levels and PRL-receptor expression with Stat and Mapk cell signaling in the prostate of long-term sexually active rats.

Prolactin (PRL) is a key hormone for prostate function, with a basal level in serum and associated with two characteristic circadian peaks. In the male rat, the execution of one bout of sexual behavior with consecutive ejaculations produces a significant transient increase in PRL. However, the impact of a constant sexual life on both PRL levels and prostate function is unknown. Thus, by using constantly copulating males we analyzed the levels of serum PRL, the effect on prostate PRL receptors, and activation of pStat3, pStat5 and Mapk signaling pathways. Sexually experienced Wistar male rats were used, which underwent periodic sessions of sexual behavior tests. Males were subjected to a session of sexual behavior to achieve at least one and up to four ejaculations. Of these, a blood sample was collected from randomly selected males and the ventral prostate was removed for analysis. Serum PRL was quantified, the mRNA for PRL receptors was determined, and signaling pathways were analyzed. Data show that a constant sexual life produced a constant elevation of PRL in serum during four consecutive ejaculations. The ventral prostate showed a different mRNA expression profile for the long and short isoform of the PRL receptor, and both mRNA levels increased. Although the gland did not show modification of the activation of the pStat5 signaling pathway, the levels of pStat3 increased, and the Mapk pathway showed one significant elevation after the third ejaculation. Thus, we showed that an active and constant sexual life produces a sustained increase in serum PRL, its receptors, and the pStat3 signaling pathway. These responses seem to underlie the required physiological need to produce the quantity and quality of prostatic semen to ensure the appropriate environment for sperm to reach and fertilize the ovum.

Prolactin-induced prostate tumorigenesis links sustained Stat5 signaling with the amplification of basal/stem cells and emergence of putative luminal progenitors.

Current androgen ablation therapies for prostate cancer are initially successful, but the frequent development of castration resistance urges the generation of alternative therapies and represents an important health concern. Prolactin/signal transducer and activator of transcription 5 (STAT5) signaling is emerging as a putative target for alternative treatment for prostate cancer. However, mechanistic data for its role in development or progression of prostate tumors are scarce. In vivo mouse studies found that local prolactin induced the amplification of prostate epithelial basal/stem cells. Because these cells are proposed cells of origin for prostate cancer and disease recurrence, we looked further into this amplification. Our results indicated that sustained Stat5 activation was associated with the occurrence of abnormal basal/stem cell clusters in prostate epithelium of prostate-specific prolactin-transgenic mice. Analysis of epithelial areas containing these clusters found high proliferation, Stat5 activation, and expression of stem cell antigen 1. Furthermore, enhanced prolactin signaling also led to amplification of a luminal cell population that was positive for stem cell antigen 1. These cells may originate from amplified basal/stem cells and might represent important progenitors for tumor development in prostate epithelium. These data provide a deeper understanding of the initial stages of prostate tumorigenesis induced by prolactin to help determine whether this hormone or its downstream messengers could be useful targets for prostate cancer treatment in the future.