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      Thyrotropin Response to Thyrotropin-Releasing Hormone in Rats with Hypothalamic Knife Cuts

      , , ,

      Neuroendocrinology

      S. Karger AG

      TSH, TRH, Hypothalamus, T4 , Knife cut

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          Abstract

          Regulation of the pituitary-thyroid axis in rats with hypothalamic knife cuts has been studied. Complete hypothalamic deafferentation, either limited to the median eminence and the arcuate nucleus, or including parts of the dorsomedial nucleus and the whole ventromedial nucleus caused an increase in thyrotopin (TSH)-releasing hormone (TRH)-induced TSH secretion. Using an immunocytochemical procedure, a few TRH-positive fibers were observed within the median eminence of the larger island, while almost no fibers were identified in the smaller island. The exaggerated TSH response to TRH appeared within 3 days after the surgery and lasted for at least 1 week, when blood thyroxine (T4) level was significantly lowered. Exogenously injected T4 could inhibit such responses of TSH in the deafferented rats in a dose-related manner. These results support the hypothesis that the increase in the TSH response to TRH following hypothalamic deafferentation is due, at least in part, to the lowered thyroid hormone level in the blood.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1987
          1987
          02 April 2008
          : 46
          : 4
          : 312-317
          Affiliations
          Departments of Physiology and Morphology, Institute of Endocrinology, Gunma University, Maebashi, Japan
          Article
          124838 Neuroendocrinology 1987;46:312–317
          10.1159/000124838
          3118229
          © 1987 S. Karger AG, Basel

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          Page count
          Pages: 6
          Categories
          Original Paper

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