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  • Title: 3H-Estradiol uptake and retention by target tissues of light-sterilized female rats.
    Author: Heffner LJ.
    Journal: Neuroendocrinology; 1976; 20(4):319-27. PubMed ID: 987553.
    Abstract:
    Tissue distribution of radioactivity was studied at 2, 4 and 6 h after intravenous injection of 3H-estradiol-17beta (41.7 ng/100 g b.w.) in 12 light-sterilized and 11 control female rats ovariectomized 72 h prior to injection. Female rats were light-sterilized by exposure to continuous illumination for 82 days and, based on the duration of continuous vaginal cornification and the absence of corpora lutea at post-mortem histological examination of the ovaries, were anovulatory for at least 30 days prior to injection. Control rats were housed under conditions similar to the experimentals except that they were exposed to alternating lighting (14 h light:10 h dark). They remained ovulatory throughout the experiment. Uterine 3H-estradiol uptake and retention were significantly depressed in the light-sterilized group. There were no significant differences in 3H-estradiol uptake or retention as a result of light-sterilization in any of the other tissues studied, including anterior, middle, and posterior hypothalamus, hippocampus, amygdala, cerebrum, anterior pituitary and plasma. The failure to detecta reduction in neural 3H-estradiol uptake demonstrates that the anovulatory state can exist without a concomitant reduction in the hypothalamic estrogen binding capacity. The possibility is discussed that the decreased target tissue binding noted in various types of anovulatory animals is the result, not the cause, of altered ovarian function. Tritiated-estradiol uptake and retention by target tissues of light-sterilized female rats is discussed. Tissue distribution of radioactivity was studied at 2, 4, and 6 hours after iv injection of 41.7 ng tritiated-estradiol-17 beta/100 gm body weight in 12 light-sterilized and 11 control female rats ovariectomized 72 hours prior to injection. The rats were light-sterilized by exposure to continuous illumination for 82 days and, based on the duration of continuous vaginal cornification and the absence of corpora lutea at post-mortem histological examination of the ovaries, were anovulatory for at least 30 days prior to injection. The control rats were housed under similar conditions as the experimentals except that they were exposed to alternating lighting of 14 hours light and 10 hours dark. They remained ovulatory. Uterine uptake and retention were significantly depressed (p less than or equal to .005) in the light-sterilized group. There were no marked differences in uptake or retention as a result of light-sterilization in the anterior, middle, and posterior hypothalamus, hippocampus, amygdala, cerebrum, anterior pituitary, or plasma. Failure to detect a reduction in neural tritiated-estradiol uptake demonstrates that the anovulatory state can exist without a concomitant reduction in the hypothalamic estrogen binding capacity. It is suggested that the decreased target tissue binding noted in various types of anovulatory animals is the result, not the cause, of altered ovarian function.
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