Accumulation of Estradiol in Brain, Uterus and Pituitary: Strain, Species, Suborder and Order Comparisons

Abstract

Tritiated estradiol-17β was administered toovariectomized rats, C57B1/6 mice, Swiss-Webster mice, guinea pigs, chinchillas, ground squirrels and squirrel monkeys. Uterus, pituitary and brain tissues were taken for analysis of retention patterns 1, 2 and 4 h after estradiol administration. The squirrel monkey retained less target tissue radioactivity and more plasma radioactivity than other species. A suborder analysis of ratios of target tissue to plasma radioactivity revealed the following progression: Myomorpha (rat, mouse) > Hystrichomorpha (guinea pig, chinchilla) > Sciuromorpha (ground squirrel). Ratios of anterior hypothalamic to cerebral cortical radioactivity were higher in the C57B1/6 mouse than the Swiss-Webster mouse. Seasonal breeders (chinchilla, ground squirrel and squirrel monkey) retained less target tissue radioactivity and more plasma radioactivity than nonseasonal species.