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    • Plasma gonadotropin, prolactin levels and hypothalamic tyrosine hydroxylase activity in rats during estrous cycle, after overiectomy and after blockade of catecholamine biosynthesis

      G Nagesh Babu E Vijayan

      Volume 5 Issue 2 June 1983 pp 139-145

    • Fulltext

       

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      Permanent link:
      https://www.ias.ac.in/article/fulltext/jbsc/005/02/0139-0145

    • Keywords

       

      Estrous cycle; ovariectomy; reserpine, α-methyl p-tyrosine; gonadotropins; prolactin; tyrosine hydroxylase

    • Abstract

       

      Plasma gonadotropin, prolactin levels and hypothalamic tyrosine hydroxylase activity were evaluated at 0900, 1200 and 1700 h during diestrus, proestrus and estrus, ovariectomized and after systemic administration of reserpine or α-methyl p-tyrosine, which interfere with catecholamine biosynthesis, in rats. Gonadotropin and prolactin levels showed peak values during the afternoon of proestrus, while hypothalamic tyrosine hydroxylase activity was markedly lowered at 1200 on proestrus. Gonadotropin levels were slightly lowered whereas prolactin concentrations and hypothalamic tyrosine hydroxylase activity were significantly increased by reserpine. Depletion of hypothalamic dopamine by reserpine apparently resulted in significant elevation of prolactin levels which inturn induce tyrosine hydroxylase. Gonadotropin levels and hypothalamic tyrosine hydroxylase activity were significantly suppressed after the administration of α-methyl p-tyrosine. Prolactin levels, however, were elevated significantly. These results indicate that catecholamines are involved in the control of gonadotropin and prolactin release during estrous cycle and inhibition of catecholamines biosynthesis by α-methyl p-tyrosine could result in suppression of gonadotropin levels, whereas removal of tonic inhibition of hypothalamic dopamine by α-methyl-p-tyrosine elevate prolactin levels.

    • Author Affiliations

       

      G Nagesh Babu1 E Vijayan1

      1. School of Life Sciences, University of Hyderabad, Hyderabad - 500 134

    • Dates

       
      Published
      June 1983
      Manuscript received
      25 February 1983
      Manuscript revised
      7 May 1983

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