A study of the prostate, androgens and sexual activity of male rats

BACKGROUND: The prostate is a sexual gland that produces important substances for the potency of sperm to fertilize eggs within the female reproductive tract, and is under complex endocrine control. Taking advantage of the peculiar behavioral pattern of copulating male rats, we developed experimental paradigms to determine the influence of sexual behavior on the level of serum testosterone, prostate androgen receptors, and mRNA for androgen receptors in male rats displaying up to four consecutive ejaculations. METHODS: The effect of four consecutive ejaculations was investigated by determining levels of (i) testosterone in serum by solid phase RIA, (ii) androgen receptors at the ventral prostate with Western Blots, and (iii) androgen receptors-mRNA with RT-PCR. Data were analyzed with a one-way ANOVA followed by a post hoc application of Dunnett's test if required. RESULTS: The constant execution of sexual behavior did not produce any change in the weight of the ventral prostate. Serum testosterone increased after the second ejaculation, and remained elevated even after four ejaculations. The androgen receptor at the ventral prostate was higher after the first to third ejaculations, but returned suddenly to baseline levels after the fourth ejaculation. The level of mRNA increased after the first ejaculation, continued to increase after the second, and reached the highest peak after the third ejaculation; however, it returned suddenly to baseline levels after the fourth ejaculation. CONCLUSION: Four consecutive ejaculations by sexually experienced male rats had important effects on the physiological responses of the ventral prostate. Fast responses were induced as a result of sexual behavior that involved an increase and decrease in androgen receptors after one and four ejaculations, respectively. However, a progressive response was observed in the elevation of mRNA for androgen receptors, which also showed a fast decrease after four ejaculations. All of these changes with the prostate gland occurred in the presence of a sustained elevation of testosterone in the serum that started after two ejaculations. A consideration of these fast-induced changes suggests that the nerve supply plays a key role in prostate physiology during the sexual behavior of male rats

Factores, causas y perspectivas de la obesidad infantil en México

This work is a review of the information about childhood obesity in Mexico from 2000 to 2012. Obesity is a public health problem, which has recently reached epidemic proportions in some countries. This pathology is the main problem of adult malnutrition and has dramatically increased in children, since it is estimated that over 40 million children have overweight or obesity. It involves several factors such as genetic, metabolic, psychosocial and environmental ones. As a result, it is difficult to distinguish their influence in different cases. However, a well-recognized factor in the development of childhood obesity is the media, which promotes a sedentary lifestyle. Childhood obesity is a risk factor associated with cardiovascular disease in adults, hypertension, hypercholesterolemia and diabetes Type II. (MÉD.UIS. 2013;26(1)59:68).  Este escrito comprende una revisión bibliográfica sobre la obesidad infantil en México desde el año 2000 a 2012. La obesidad constituye un problema de salud pública la cual recientemente ha alcanzado proporciones de epidemia en algunos países. Esta patología constituye el principal problema de malnutrición en el adulto y es una enfermedad que ha aumentado notoriamente en la población infantil, ya que se calcula que más de 40 millones de niños padecen sobrepeso u obesidad. Es un trastorno multifactorial en cuya etiopatogenia están implicados factores genéticos, metabólicos, psicosociales y ambientales, por lo que es difícil distinguir en cada caso en particular la importancia relativa de estos factores. La obesidad infantil es uno de los factores de riesgo vinculados al aumento de enfermedad cardiovascular en el adulto, junto con la hipertensión, hipercolesterolemia y diabetes tipo II; se ha identificado que un factor importante en el desarrollo de la obesidad infantil es la influencia de los medios electrónicos que promueven un estilo de vida básicamente sedentario. (MÉD.UIS. 2013;26(1)59:68). &nbsp

Prostate response to prolactin in sexually active male rats

BACKGROUND: The prostate is a key gland in the sexual physiology of male mammals. Its sensitivity to steroid hormones is widely known, but its response to prolactin is still poorly known. Previous studies have shown a correlation between sexual behaviour, prolactin release and prostate physiology. Thus, here we used the sexual behaviour of male rats as a model for studying this correlation. Hence, we developed experimental paradigms to determine the influence of prolactin on sexual behaviour and prostate organization of male rats. METHODS: In addition to sexual behaviour recordings, we developed the ELISA procedure to quantify the serum level of prolactin, and the hematoxilin-eosin technique for analysis of the histological organization of the prostate. Also, different experimental manipulations were carried out; they included pituitary grafts, and haloperidol and ovine prolactin treatments. Data were analyzed with a One way ANOVA followed by post hoc Dunnet test if required. RESULTS: Data showed that male prolactin has a basal level with two peaks at the light-dark-light transitions. Consecutive ejaculations increased serum prolactin after the first ejaculation, which reached the highest level after the second, and started to decrease after the third ejaculation. These normal levels of prolactin did not induce any change at the prostate tissue. However, treatments for constant elevations of serum prolactin decreased sexual potency and increased the weight of the gland, the alveoli area and the epithelial cell height. Treatments for transient elevation of serum prolactin did not affect the sexual behaviour of males, but triggered these significant effects mainly at the ventral prostate. CONCLUSION: The prostate is a sexual gland that responds to prolactin. Mating-induced prolactin release is required during sexual encounters to activate the epithelial cells in the gland. Here we saw a precise mechanism controlling the release of prolactin during ejaculations that avoid the detrimental effects produced by constant levels. However, we showed that minor elevations of prolactin which do not affect the sexual behaviour of males, produced significant changes at the prostate epithelium that could account for triggering the development of hyperplasia or cancer. Thus, it is suggested that minute elevations of serum prolactin in healthy subjects are at the etiology of prostate abnormal growth

Factores, causas y perspectivas de la obesidad infantil en México

This work is a review of the information about childhood obesity in Mexico from 2000 to 2012. Obesity is a public health problem, which has recently reached epidemic proportions in some countries. This pathology is the main problem of adult malnutrition and has dramatically increased in children, since it is estimated that over 40 million children have overweight or obesity. It involves several factors such as genetic, metabolic, psychosocial and environmental ones. As a result, it is difficult to distinguish their influence in different cases. However, a well-recognized factor in the development of childhood obesity is the media, which promotes a sedentary lifestyle. Childhood obesity is a risk factor associated with cardiovascular disease in adults, hypertension, hypercholesterolemia and diabetes Type II. (MÉD.UIS. 2013;26(1)59:68).Este escrito comprende una revisión bibliográfica sobre la obesidad infantil en México desde el año 2000 a 2012. La obesidad constituye un problema de salud pública la cual recientemente ha alcanzado proporciones de epidemia en algunos países. Esta patología constituye el principal problema de malnutrición en el adulto y es una enfermedad que ha aumentado notoriamente en la población infantil, ya que se calcula que más de 40 millones de niños padecen sobrepeso u obesidad. Es un trastorno multifactorial en cuya etiopatogenia están implicados factores genéticos, metabólicos, psicosociales y ambientales, por lo que es difícil distinguir en cada caso en particular la importancia relativa de estos factores. La obesidad infantil es uno de los factores de riesgo vinculados al aumento de enfermedad cardiovascular en el adulto, junto con la hipertensión, hipercolesterolemia y diabetes tipo II; se ha identificado que un factor importante en el desarrollo de la obesidad infantil es la influencia de los medios electrónicos que promueven un estilo de vida básicamente sedentario. (MÉD.UIS. 2013;26(1)59:68)

El papel de los estrógenos y sus receptores en la prevención y promoción de enfermedades proliferativas de la glándula prostática

Estrogens are steroid hormones acting through their receptors (ER) α and β, act as transcription factors. Despite being primarly involved in female physiology, estrogens are important regulators of some males physiological processes, existing organs such as the prostate, which is influenced by these hormones. In prostate, through its α and β RE estrogens promote or limit the cell proliferation in normal conditions, and are implicated in the pathophysiology of benign prostatic hyperplasia (BPH) and prostate cancer (PCa). There is evidence that REα promotes proliferation, while REβ activation induces protection against the mentioned diseases. However, in advanced stages of prostate cancer, the presence of REβ in prostate cells is associated with increased cell proliferation and increased patient mortality. It is likely that in this case REβ activate signaling pathways that promote androgen-independent proliferation, which would be important in the lack of response to androgen deprivation therapy frequently observed in PCa. REβ another important aspect is the regulation of the ERβ expression. This process is known to involve steroid hormones, but on the other hand, prolactin, a protein pituitary hormone, is also involved in both physiological and pathophysiological contexts. The knowledge of the normal and pathological mechanisms through the estrogens and its β receptors and prolactin regulate the prostate will contribute to the development of strategies for the treatment and prevention of BPH and PCaLos estrógenos son hormonas esteroides que actúan a través de sus receptores (RE) α y β, los cuales actúan como factores de transcripción. A pesar de estar implicados principalmente en la fisiología femenina, los estrógenos son importantes en procesos fisiológicos de los machos, existiendo órganos tales como la próstata cuya homeostasis está influenciada por estas hormonas. En próstata, los estrógenos promueven o limitan la proliferación celular dependiendo del receptor activado, lo cual tiene implicaciones en la fisiopatología de la hiperplasia prostática benigna (HPB) y el cáncer prostático (CaP). Existe evidencia de que RE α promueve proliferación mientras que REβ la regula, comportándose como un factor protector de las patologías mencionadas. No obstante, en etapas avanzadas del CaP, la presencia de REβ en células prostáticas se relaciona con mayor proliferación de éstas y aumento en la mortalidad de los pacientes. Es probable que en este caso REβ active vías de señalización andrógeno-independientes que favorecen la proliferación, lo que resultaría importante en la falta de respuesta al tratamiento de supresión androgénica observado frecuentemente en el CaP. Otro aspecto importante sobre REβ es la regulación de su expresión. En este proceso se conoce la participación de las hormonas esteroides, pero existen indicios de que prolactina, una hormona proteica, participa también en contextos fisiológicos y patológicos. El conocimiento de estos y otros aspectos de la acción estrogénica en próstata contribuirá al desarrollo de estrategias para el tratamiento y prevención de HPB y CaP

El receptor a andrógenos en la fisiopatología prostática

The biological effects of testosterone and dihydrotestosterone (DHT), the main androgens in mammals, are mediated through the androgen receptor (AR), a transcription factor belonging to the nuclear receptor superfamily. When androgens bind to AR, it is activated, translocated to the nucleus and bound to specific DNA sequences. In the prostate, AR perform the growth, differentiation and survival of epithelial cells, however, also participates in the development and progression of pathologies, such as benign prostatic hyperplasia (BPH) and prostate cancer (PCa). The PCa is of great interest because it is the most commonly diagnosed and one of the leading causes of death in Mexico. At the beginning of its development, the PCa is dependence on androgens, which explains the classical approach towards the blockade of androgens, resulting in decreased neoplastic growth. Nevertheless, sooner or later, PCa becomes independent to the androgens, resuming growth in a more aggressive form. Thus, the progression of a cancer from androgen-dependent to androgen-independent is a critical step in the progression of the disease. It is unknown the mechanism by which this transition occurs, however, is thought AR plays a critical role. Thus, this review describes the central role played by the AR in the prostate physiology and development of PCa.Los efectos biológicos de la testosterona y la dihidrotestosterona (DHT), los principales andrógenos en los mamíferos, son mediados a través del receptor a andrógenos (RA), un factor de transcripción perteneciente a la superfamilia de receptores nucleares. Cuando los andrógenos se unen al RA, éste se activa, se transloca al núcleo y se une a secuencias específicas del DNA. En la próstata, el RA dirige el crecimiento, diferenciación y supervivencia de las células epiteliales, sin embargo, también participa en el desarrollo y progresión de patologías como la hiperplasia prostática benigna (HPB) y el cáncer de próstata (CaP). El CaP es de gran interés debido a que es uno de los cánceres más diagnosticados y una de las principales causas de muerte en México. Al inicio de su desarrollo, el CaP depende de los andrógenos, de ahí que el tratamiento clásico consista en bloquear la acción de éstos, resultando en una disminución del crecimiento neoplásico. A pesar de ello, tarde o temprano, el CaP se vuelve independiente de los andrógenos, reanudando su crecimiento en una forma más agresiva. Así, la progresión de un CaP dependiente de andrógenos a uno independiente es un paso crítico en el avance de esta enfermedad. Hasta ahora se desconoce el mecanismo por el cual ocurre esta transición, sin embargo, se piensa que el RA juega un papel relevante. De esta manera, la presente revisión describe el papel central que juega el RA en la fisiología de la próstata y en el desarrollo del CaP