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      Endocrine and Behavioral Modifications in Aging Male Rats

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          Endocrine and behavioral effects of age and aging have been studied in 4 groups of Sprague-Dawley male rats (2, 6, 12, 24 months old). Plasma testosterone decreases after 6 months of age, plasma estradiol decreases from 2 to 6 months, then it increases with age and decreases again with aging (from 12 to 24 months). Aromatization of testosterone in brain tissue is similar in 2-, 12- and 24-month-old rats, but at 6 months a significant increase is observed. Testosterone biosynthesized in the gonad from dehydroepiandrosterone increases from 2 to 6 months, then it decreases, while the other metabolites of dehydroepiandrosterone show an increment with age. Corticosterone and 17α-hydroxyprogesterone biosynthesized in the adrenal decrease with aging. Explorative and loco-motor activity decreases with age and aging, while emotionality decreases from 2 to 12 months, but it increases with aging. These results indicate that endocrine equilibrium is remarkably altered by aging process showing a decrease of plasma sexual hormones and of gonadal activity. The decrement of aromatization of testosterone in the brain, which occurs between 6 and 12 months, is correlated with the decrement of plasma testosterone. It could be hypothesized that the hormones of the brain-pituitary-gonad axis are involved in the control of explorative behavior or that both hormonal and behavioral parameters are controlled by a common factor.

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          Author and article information

          Horm Res Paediatr
          Hormone Research in Paediatrics
          S. Karger AG
          25 November 2008
          : 12
          : 3
          : 149-160
          Istituto di Fisiologia umana, Università di Siena, Siena, and Istituto di Zoologia, Università di Firenze, Firenze
          179116 Horm Res 1980;12:149–160
          © 1980 S. Karger AG, Basel

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          Pages: 12
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