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      Induction of Precocious Puberty in Newborn Female Guinea Pigs by a Positive Feedback Action of Estrogens


      Hormone Research in Paediatrics

      S. Karger AG

      Estrogen, Positive feedback, Gonadotrophins, Guinea pig, HCG, Newborn, Neural maturation

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          The existence of a positive feedback of estrogen on the gonadotrophin-releasing mechanism at birth, was tested in the female guinea pig. Estradiol benzoate (100 ng during the first 5 days of life) or HCG (100 RU during the first 5 days of life) induced a true precocious puberty, with similar characteristics to the control animals (60% of the animals ovulated at puberty age: corpora lutea present at the ovaries). The uterus was larger in ovulating than in nonovulating animals. Reserpine (2.5 mg/kg) on 15, 17 and 19 days of age did not modify the precocious puberty induced by estradiol at birth. It is concluded that exogenous or endogenous estrogen (induced by exogenous gonadotrophin administration) have a positive feedback action on the newborn female guinea pig to release gonadotrophin and develop puberty. These results are very different than those observed in the rat and differences can be related to the stage of somatic and nervous maturation attained by the animals at birth.

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          Author and article information

          Horm Res Paediatr
          Hormone Research in Paediatrics
          S. Karger AG
          25 November 2008
          : 8
          : 4
          : 224-230
          Department of Histology and Embryology, School of Medicine, Montevideo
          178804 Horm Res 1977;8:224–230
          © 1977 S. Karger AG, Basel

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          Page count
          Pages: 7


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