Rol de los fitoestrógenos en la calcificación vascular e interacciones óseo-vasculares / Role of phytoestrogens in vascular calcification and bonevascular interactions

La osteoporosis y las enfermedades cardiovasculares son patologías prevalentes en mujeres posmenopáusicas. La calcificación vascular es un proceso en el que se produce una distorsión de la arquitectura natural del tejido arterial con una transformación símil osteogénica. La fisiología vascular y la osteogénesis (formación y remodelación ósea) comparten una complejidad metabólica y funcional crítica, que ha sido poco explorada en forma conjunta, lo que ha impulsado la concepción del Eje Óseo-Vascular como nueva área de investigación, con una visión de estudio integradora con la finalidad de identificar vínculos entre ambos sistemas. En virtud de la controversia planteada sobre los riesgos/beneficios de la terapia de reemplazo hormonal para prevenir enfermedades asociadas a la menopausia, se ha incentivado la búsqueda de nuevas opciones de tratamiento. Los fitoestrógenos, como compuestos nutracéuticos, surgen como una potencial alternativa terapéutica. En particular, las isoflavonas presentan gran analogía estructural con el estrógeno humano 17ß-estradiol, lo que les permite unirse al receptor de estrógenos e inducir acciones estrogénicas tanto en células animales como humanas. Basado en la experiencia propia como en lo reportado en la bibliografía, este artículo analiza la información disponible sobre las acciones vasculares y óseas de los fitoestrógenos (específicamente la isoflavona genisteína), con una visión de ciencia traslacional. Es de esperar que los avances en el conocimiento derivado de la ciencia básica, en un futuro cercano, pueda contribuir a decisiones clínicas a favor de promover terapias naturales de potencial acción dual, para la prevención de enfermedades de alta prevalencia y significativo costo social y económico para la población. (AU)

Osteoporosis and cardiovascular diseases are prevalent diseases in postmenopausal women. Vascular calcification is a cellmediated process that leads to the loss of the natural architecture of the arterial vessels due to osteogenic transdifferentiation of smooth muscle cells, and matrix mineralization. Vascular physiology and osteogenesis (bone formation and remodeling) share a critical metabolic and functional complexity. Given the emerging integrative nature of the bonevascular axis, links between both systems are a matter of ongoing interest. In view of the controversy stated about the risks/benefits of hormone replacement therapy to prevent diseases associated with menopause, phytoestrogens arise as a potential natural therapeutic alternative. In particular, isoflavones have a strong structural analogy with the human estrogen 17ß-estradiol, that allows them to bind to the estrogen receptor and induce estrogenic actions in animal and human cells. Based in on our own experience and the information available in the literature, in this paper we provide an overview of the role of phytoestrogens on vascular and bone tissues, with focus on Genistein actions. We wish that the basic knowledge acquired may contribute to guide clinical decisions for the promotion of natural therapies for the treatment of diseases that conspire against human health. (AU)

El splicing alternativo del exón 5 de la citocromo p450 aromatasa podría ser un mecanismo de regulación de la producción de estrógenos en humanos / Exon 5 alternative splicing of the cytochrome P450 aromatase could be a regulatory mechanism for estrogen production in humans

La enzima P450 aromatasa (P450Aro) participa en la síntesis de estrógenos a partir de andrógenos. La mutación c655G>A, descripta en forma heterocigota en una niña y en forma homocigota en un hombre adulto, ambos con déficit de aromatasa, genera la disrupción del sitio dador de splicing exón5-intrón5. Se ha postulado que la retención del intrón5 y la generación de una proteína truncada inactiva serían las consecuencias de esta mutación. Sorpresivamente, la paciente presentó desarrollo espontáneo de mamas y niveles puberales de estradiol, sugiriendo una actividad aromatasa (AA) residual. En principio postulamos que la mutación c655G>A generaría la pérdida del exón5 con conservación del marco de lectura, generándose una proteína con menor actividad que podría explicar el déficit parcial. La expresión del ARNm sin exón5 (ARNm- E5) en linfocitos de la paciente sugiere una asociación entre la pérdida del exón y la presencia de la mutación; posteriormente confirmada realizando ensayos de splicing en células Y1. Sin embargo, la expresión del cDNAE5 en células Y1 presentó una AA nula que no explicaría un déficit parcial. La expresión del ARNm-E5 fue detectada en placenta, testículo y adrenal humanos como una variante de splicing normal. Estos resultados indicarían la ocurrencia de splicing alternativo (SA) en la zona codificante de P450Aro como un posible mecanismo regulador de la producción de estrógenos en tejidos esteroidogénicos humanos. La mutación c655G>A podría alterar los mecanismos fisiológicos reguladores del SA del exón5 favoreciendo su exclusión. De esta forma, bajos niveles de ARNm+E5 podrían expresarse aun en presencia de la mutación explicando el fenotipo de déficit parcial observado en la paciente.

P450 aromatase (P450Aro), involved in androgen to estrogen conversion, is encoded by the CYP19 gene. P450Aro c655G>A mutation described in heterozygous form in a girl and in homozygous form in an adult male with P450Aro deficiency results in an aberrant splicing due to disruption of a donor splice site. A truncated inactive protein would be expected if intron5 is retained. Surprisingly, the girl described with this mutation showed spontaneous breast development and pubertal estradiol (E2) levels suggesting residual P450Aro activity (AA). Formerly, we postulate the in frame E5 skipping as a consequence of this mutation generating a protein with some degree of activity. When P450Aro mRNA expression was analysed from patient's lymphocytes, an aberrant spliced mRNA lacking E5 (-E5mRNA) was detected, suggesting an association between E5 skipping and the presence of the mutation. Splicing assays in Y1 cells confirmed this association. -Ex5 cDNA expression in Y1 cells resulted in an inactive protein that could not explain patient's phenotype. Exon 5 might be predicted as a poorly defined exon suggesting a susceptibility to splicing mutations and physiological alternative splicing (AS) events. Therefore, -Ex5mRNA was assessed as a natural occurring alternative transcript in normal human steroidogenic tissues. As P450Aro -E5mRNA expression was detected in human term placenta, prepubertal testis and prepubertal adrenal, we might speculate that AS of P450Aro coding region would occur in humans and would be involved in the complex AA regulation. Furthermore, tissue specific regulation of AS might suggest low expression of +E5mRNA from the c655G>A allele explaining residual AA evidenced in the affected girl.

Estrogens and male reproduction: a new concept

The mammalian testis serves two main functions: production of spermatozoa and synthesis of steroids; among them estrogens are the end products obtained from the irreversible transformation of androgens by a microsomal enzymatic complex named aromatase. The aromatase is encoded by a single gene (cyp19) in humans which contains 18 exons, 9 of them being translated. In rats, the aromatase activity is mainly located in Sertoli cells of immature rats and then in Leydig cells of adult rats. We have demonstrated that germ cells represent an important source of estrogens: the amount of P450arom transcript is 3-fold higher in pachytene spermatocytes compared to gonocytes or round spermatids; conversely, aromatase activity is more intense in haploid cells. Male germ cells of mice, bank voles, bears, and monkeys express aromatase. In humans, we have shown the presence of a biologically active aromatase and of estrogen receptors (alpha and ß) in ejaculated spermatozoa and in immature germ cells in addition to Leydig cells. Moreover, we have demonstrated that the amount of P450arom transcripts is 30 percent lower in immotile than in motile spermatozoa. Alterations of spermatogenesis in terms of number and motility of spermatozoa have been described in men genetically deficient in aromatase. These last observations, together with our data showing a significant decrease of aromatase in immotile spermatozoa, suggest that aromatase could be involved in the acquisition of sperm motility. Thus, taking into account the widespread localization of aromatase and estrogen receptors in testicular cells, it is obvious that, besides gonadotrophins and androgens, estrogens produced locally should be considered to be physiologically relevant hormones involved in the regulation of spermatogenesis and spermiogenesis.

Influência do gênero e da variação dos hormônios femininos (estrógeno e progesterona) na farmacocinética do etanol / Influence of sex female hormone (estrogen and progesterone) on the pharmacokinetics of ethanol

O uso do álcool entre mulheres é uma questão atual e preocupante, face a maior vulnerabilidade destas aos danos hepáticos, cerebrais, entre outros, quando comparadas aos homens com padrões semelhantes de consumo.Sendo assim, investigaram-se as possíveis variações na farmacocinética do etanol em mulheres, considerando duas fases do ciclo menstrual (pré-folicular e lútea), bem como o uso de anticoncepcionais orais (AO). Participaram voluntários dos sexos feminino (n=22) e masculino (n=14), administrando-lhes 0,3 g/kg de etanol, na forma de uísque. Os resultados indicaram: a) os parâmetros farmacocinéticos do etanol não variam em função do ciclo menstrual (fase pré-folicular e lútea); b) as mulheres que tomavam (AO)...

Bone mineral density in primary and secondary amenorrhea.

Amenorrhea in young women is one of the best clinical indicators for estrogen deficiency, except in the presence of gynecological structural pathology. This study aimed at investigating bone mineral density (BMD) in patients with primary and secondary amenorrhea. Thirty-six patients were enrolled in the study, seven with primary amenorrhea (mean age 24.3 +/- 4.5 yrs.) and twenty-nine with secondary amenorrhea (mean age 31.1 +/- 6.9 yrs.). Eighteen regularly menstruating women (mean age 31.8 +/- 3.7 yrs.) served as controls. BMD was measured at lumbar spine, femoral neck, Ward's triangle and trochanter. RESULTS: BMD was significantly decreased in both primary and secondary hypoestrogen amenorrheic patients. Primary amenorrheic patients were more severely affected with a BMD mean Z score below 80 per cent (osteopenia) at all sites measured. The age of primary amenorrheic women also strongly correlated with degree of demineralization. This should emphasize the importance of early diagnosis and treatment of young amenorrheic patients.

Anti-steroidogenic activity of floral extract of Thespesia populnea Corr. in mouse ovary.

Anti-steroidogenic activity of various extracts of T. populnea was screened in female albino mice. The weight of the uterus and ovaries were reduced significantly and the cholesterol and ascorbic acid content in ovaries were significantly elevated due to the treatment with extract of T. populnea. The significant inhibition of delta 5, 3 beta hydroxy steroid dehydrogenase and glucose-6-phosphate dehydrogenase, the two key enzymes involved in ovarian steroidogenesis were also observed in mouse ovaries after 15 days of treatment.

Effect of insulin-like growth factor-1 on steroidogenesis in cultured carp ovarian follicles: interactions with estradiol.

The biological action of insulin like growth factor-1 (IGF-1) on follicular steroidogenesis during follicular development in common carp was examined. Studies were carried out by culturing small (1-2 mm diam.) and large (> 2 mm diam.) follicles. IGF-1 (0.3-100 ng/ml) had no effect on progesterone accumulation or aromatase activity during 48 hr culture of small follicles. Progesterone accumulation by large follicles was also unaffected by IGF-1 over the same period, although aromatase activity was stimulated in a dose dependent manner (8-fold increase over basal levels with a maximum stimulatory dose of 30 ng IGF-1/ml). In contrast, small and large follicles responded to IGF-1 in terms of both progesterone accumulation and aromatase activity after longer periods of culture (4 days for progesterone and 6 days for aromatase). Concurrent treatment of small follicles with estradiol (10(-7) M) enhanced the action of IGF-1 on both indices of steroidogenesis and advanced the time at which IGF-1 stimulated activity was first detectable. The effect of estradiol on follicular IGF-1 responsiveness were independent of cell number. In summary, these results demonstrate varied actions of IGF-1 carp ovarian follicular steroidogenesis in vitro. The results indicate that carp follicles acquire responsiveness to IGF-1 in terms of aromatase activity during follicular development in vivo and that estradiol can induce the response in vitro. The results also suggest that estrogen and progesterone biosynthesis by cultured carp ovarian follicles is differentially regulated by IGF-1. Together, these results provide new insights into the biological actions of IGF-1 in fish ovary.

Effect of graded doses of nicotine on ovarian and uterine activities in albino rats.

Nicotine (2 and 4 mg/kg body weight, i.p.) administered to albino rats for 20 days decreased the number of healthy follicles and increased the number of regressing follicles in the ovary. Uterine weight, its diameter, thickness of myometrium and endometrium and height of epithelium were reduced. Increase in the ovarian cholesterol level and decrease in glycogen content in nicotine treated rats indicate the inhibition brought in the steroidogenesis which is dependent on pituitary gonadotrophins. Decreased protein content of the ovary and uterus may be due to their retarded growth. Reduced number of estrous cycle with prolonged metaestrus and diestrus also supports the decreased estrogen synthesis responsible for cornification of vaginal smear in nicotine treated rats.

El sistema lisosomal en los mecanismos hormonales: revisión / Lysosomal system in hormonal mechanisms: review

Los lisosomas no deben considerarse sólo orgánulos que participan en la lisis de diferentes moléculas en proceso de digestión o defensa celular, ya que participan en diversos procesos de metabolismo celular, incluyendo los regulados hormonales. La actividad lisosomal se ve alterada minutos después de la administración de hormonas tanto esteroides como peptídicas incluyendo efectos como: labilización de membranas, cambio en la estructura química de las hidrolasas (latencia estructural) y migración perinuclear de lisosomas. Estas alteraciones demuestran que la actividad lisosomal es hormino-dependiente, y que hidrolasas como fosfatasa ácida pueden esta actuando de alguna manera a nivel de des-represión génica. Por otro lado, los lisosomas pueden propagar efectos hormonales desde la superficie de las células blanco hasta el núcleo. Es muy probable que ésta propagación se efectúe por medio de poblaciones especializadas de lisosomas que bajo el efecto hormonal migran a la región perinuclear. Se ha demostrado que ciertas substancias naturales y sintéticas que estabilizan membranas pueden bloquear esos eventos de distinto grado, de tal manera, que estos restablecen la labilización lisosomal y por consiguiente impiden la liberación enzimática. De una u otra forma, por lo anteriormente descrito, el sistema lisosomal participa en los mecanismos de comunicación autocrina, paracrina y endocrina

Oestrogen-secreting adrenocortical adenoma causing gynecomastia in a prepubertal boy

An 8-year-old boy with isolated gynaecomastia is described. In addition to elevated serum oestradiol, levels of dehydroepiandrosterone sulphate, androstenedione and testosterone were low with normal cortisol, suggesting pure-oestrogen secreting tumour. An adrenocortical adenoma was surgically removed. The oestradiol level returned to normal with gradual regression of the breast size and normal growth velocity. A brief review of the literature on feminizing adrenocortical tumours in boys is presented

Las hormonas esteroides y la etiopatogénesis de padecimientos hepáticos de naturaleza fibrótica / Fibrotic liver disease and steroid hormones

Existen hipótesis en el sentido de que el estatus hormonal está involucrado en la distinta susceptibilidad entre el hombre y la mujer en el desarrollo de enfermedad hepatobiliar, ya que el hígado es órgano blanco para hormonas esteroides. En el desarrollo del fenómeno fibrogénico durante la cirrosis hepática de diversa etiología están involucradas las células de Ito, los miofibroblastos y diversas citocinas como factor transformador de crecimiento-ß, interleucina-6 y factor de necrosis tumoral-alfa. Se sabe que en el organismo existen asas de regulación mutua entre citocinas, glucocorticoides y esteroides sexuales; en el hígado, esta interacción pudiera afectar el proceso fibrogénico a través de diferenciación de células de Ito. El conocimiento del papel preciso de los glucocorticoides y las hormonas esteroides sexuales sobre los mecanismos fibrogénicos, permitiría sustentar racionalmente la viabilidad de la manipulación hormonal en el tratamiento de padecimiento hepático de natulareza fibrótica

Capacidad endócrina del blastocito de mamífero: II biosíntesis y metabolismo estrogénico / Endocrine capacity of blastocyst (mammal) II Biosynthesis and estrogenic, metabolism

De los estudios realizados en embriones preimplantados de mamíferos, llama la atención su capacidad endócrina para sintetizar hormonas esteroides: progesterona, progestinas y diversos estrógenos, los cuales efectuan localmente las propiedades del oviducto y del endometrio para crear un entorno apropiado para su nutrición, migración y desarrollo que permita su implantación en el útero materno. Entre los esteroides secretados por el embrión, los estrógenos son de un interés especial debido a su importancia potencial en los eventos bioquímicos asociados con el proceso de implantación. El propósito de este artículo es contribuir el conocimiento de la biosíntesis y metabolismo estrogénico por el embrión preimplantado.

In vitro effect of human placental lactogen on steroidogenesis in human placental tissue from early pregnancy.

Studies were carried out with human placental lactogen (hPL) to elucidate its role in regulation of steroidogenesis (progesterone and estrogens) during early pregnancy in humans. Our in vitro studies with early pregnancy placenta under different doses of hPL demonstrated that this hormone could stimulate the synthesis of progesterone as well as estrogens (estrone and estradiol) from their respective precursors.