Herrera GH, Vergara OM Rosado-García A , Rosales TAM

Idioma: Español/Inglés
Referencias bibliográficas: 136
Paginas: 339-360
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RESUMEN

La expresión reproductiva en la mayoría de los vertebrados depende de que cada individuo asuma la conducta estereotípica propia de su sexo, para ello se requiere de una serie de eventos fisiológicos que integran coordinadamente la información sensorial y hormonal. En el cerebro de machos y hembras existen importantes diferencias anatómico-funcionales; por ejemplo, en la rata macho, el núcleo dimórfico sexual del área preóptica (NDS-APO) es seis veces más grande que en la hembra, mientras que en el núcleo ventromedial y arqueado de la hembra son más abundantes las conexiones sinápticas que en los machos. Desde los estudios iniciales precursores del concepto actual de la diferenciación sexual cerebral, se sugiere que en este proceso, además del sexo genético, el ambiente hormonal que rodea al tejido neuronal es fundamental. En este sentido, las gónadas juegan un papel crucial, ya que la secreción de hormonas esteroides en una fase específica del desarrollo del sistema nervioso central (SNC), llamado “periodo crítico” es capaz de ejercer cambios morfoanatómicos, bioquímicos y fisiológicos que dan lugar a modificaciones permanentes y a establecer estructuras sexualmente dimórficas. En mamíferos domésticos y de laboratorio, así como en otras especies, el estradiol es la hormona que dirige o provoca la diferenciación sexual del SNC, a través de mecanismos como la neurogénesis, apoptosis y diferenciación o funcionalidad de las células involucradas. No obstante que las técnicas moleculares que se aplican actualmente para el desarrollo de las ciencias biológicas han hecho grandes aportaciones al conocimiento científico sobre este proceso de la esfera reproductiva, aún quedan importantes incógnitas por dilucidar. En este trabajo se presenta un panorama actual del estado del conocimiento sobre la diferenciación sexual del SNC y con ello motivar o promover el interés para el estudio sobre este tema y su posible aplicación en la producción animal. En este trabajo se describen las áreas o zonas cerebrales que son consideradas dimórficas y se presenta una revisión profunda aunque sintética de los efectos que tiene el estradiol en la modificación de patrones de expresión de los genes que controlan los proceso de neurogénesis, sinaptogénesis o de la apoptosis del SNC y como esto determina el número de neuronas que componen los núcleos dimórficos sexuales. Además se presentan en forma cronológica los conocimientos que se tuvieron sobre este tema, de acuerdo con las herramientas metodológicas disponibles.

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