Aplicación práctica de métodos estereológicos renales en modelos animales experimentales / Practical application of stereological methods in experimental kidney animal models

Los riñones son órganos vitales que realizan funciones de excreción, equilibrio hidroelectrolítico y producción de hormonas. La nefrona es su unidad estructural y funcional. El número, tamaño y distribución de los componentes de la nefrona contienen información relevante sobre la función renal. La estereología es una rama de la morfometría que permite, aplicando reglas matemáticas, obtener información tridimensional de estructuras biológicas a partir de cortes microscópicos bidimensionales, seriados, paralelos y equidistantes. Ante la complejidad de los estudios estereológicos y la carencia de una bibliografía clara sobre el desarrollo de los mismos, el objetivo de este trabajo es explicar de forma sencilla y con ejemplos, utilizando un modelo animal, los conceptos básicos de estereología, así como el cálculo de los principales parámetros estereológicos renales y que estos puedan ser aplicados en futuros estudios experimentales (AU)

The kidneys are vital organs responsible for excretion, fluid and electrolyte balance and hormone production. The nephrons are the kidney's functional and structural units. The number, size and distribution of the nephron components contain relevant information on renal function. Stereology is a branch of morphometry that applies mathematical principles to obtain three-dimensional information from serial, parallel and equidistant two-dimensional microscopic sections. Because of the complexity of stereological studies and the lack of scientific literature on the subject, the aim of this paper is to clearly explain, through animal models, the basic concepts of stereology and how to calculate the main kidney stereological parameters that can be applied in future experimental studies (AU)

Practical application of stereological methods in experimental kidney animal models. / Aplicación práctica de métodos estereológicos renales en modelos animales experimentales.

The kidneys are vital organs responsible for excretion, fluid and electrolyte balance and hormone production. The nephrons are the kidney's functional and structural units. The number, size and distribution of the nephron components contain relevant information on renal function. Stereology is a branch of morphometry that applies mathematical principles to obtain three-dimensional information from serial, parallel and equidistant two-dimensional microscopic sections. Because of the complexity of stereological studies and the lack of scientific literature on the subject, the aim of this paper is to clearly explain, through animal models, the basic concepts of stereology and how to calculate the main kidney stereological parameters that can be applied in future experimental studies.

Stevia preferences in Wistar rats / Preferencia gustativa de las ratas Wistar por la estevia

BACKGROUND: The Stevia rebaudiana plant is likely to become a major source of high-potency sweetener for the growing natural-food market. S. rebaudiana is the source of a number of sweet diterpenoid glycosides, but the major sweet constituents are rebaudioside A and stevioside. These two constituents have similar pharmacokinetic and metabolic profiles in rats and humans, and thus, studies carried out with either steviol glycoside are relevant to both. Other studies illustrate the diversity of voluntary sweet intake in mammals. METHOD: This study was done using a series of two-bottle tests that compared a wide range of sweetener concentrations versus saccharin concentrations and versus water. RESULTS: Wistar rats displayed preferences for stevia extract and pure rebaudioside A solutions over water at a range of concentrations (0.001% to 0.3%), and their intake peak occurred at 0.1% concentration. They also preferred solutions prepared with a commercial rebaudioside A plus erythritol mixture to water, and their peak was at 2% concentration. CONCLUSIONS: The present study provides new information about the responses of Wistar rats to stevia compounds and commercial stevia products such as Truvia. These results could help with the appropriate dosage selection for focused behavioral and physiological studies on stevia

ANTECEDENTES: la planta Stevia rebaudiana se convertirá en una de las principales fuentes de edulcorantes debido al crecimiento del consumo de productos naturales en el mercado. S. rebaudiana contiene distintos glucósidos diterpenoides, pero los que proporcionan dulzor son el rebaudiosido A y el esteviosido. Estos dos compuestos tienen perfiles farmacocinéticos y metabólicos similares en ratas y humanos. Por otro lado, hay estudios que muestran la existencia de distintos patrones de ingesta voluntaria de edulcorantes en los mamíferos. MÉTODO: se realizaron series de la prueba de libre elección entre dos botellas. Comparamos la ingesta de un rango de concentraciones de edulcorantes frente al agua y frente a sacarina. RESULTADOS: las ratas Wistar prefieren el extracto de estevia y el rebaudiosido A (concentraciones desde 0,001% hasta 0,3%) frente al agua, la ingesta máxima fue a la concentración de 0,1%. También prefieren las soluciones preparadas con el producto comercial Truvia (rebaudiósido A y eritritol) frente al agua, la ingesta máxima fue a la concentración de 2%. CONCLUSIONES: nuestro trabajo proporciona nueva información sobre la preferencia gustativa de las ratas Wistar por distintos compuestos de estevia. Estos resultados ayudarán al diseño de estudios centrados en los efectos comportamentales y fisiológicos del consumo de estevia

Stevia preferences in Wistar rats.

BACKGROUND: The Stevia rebaudiana plant is likely to become a major source of high-potency sweetener for the growing natural-food market. S. rebaudiana is the source of a number of sweet diterpenoid glycosides, but the major sweet constituents are rebaudioside A and stevioside. These two constituents have similar pharmacokinetic and metabolic profiles in rats and humans, and thus, studies carried out with either steviol glycoside are relevant to both. Other studies illustrate the diversity of voluntary sweet intake in mammals. METHOD: This study was done using a series of two-bottle tests that compared a wide range of sweetener concentrations versus saccharin concentrations and versus water. RESULTS: Wistar rats displayed preferences for stevia extract and pure rebaudioside A solutions over water at a range of concentrations (0.001% to 0.3%), and their intake peak occurred at 0.1% concentration. They also preferred solutions prepared with a commercial rebaudioside A plus erythritol mixture to water, and their peak was at 2% concentration. CONCLUSIONS: The present study provides new information about the responses of Wistar rats to stevia compounds and commercial stevia products such as Truvia. These results could help with the appropriate dosage selection for focused behavioral and physiological studies on stevia.