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Horm Metab Res 2003; 35(5): 279-281
DOI: 10.1055/s-2003-41302
Original Basic
© Georg Thieme Verlag Stuttgart · New York

Angiotensinase Activity in Hypothalamus and Pituitary of Hypothyroid, Euthyroid and Hyperthyroid Adult Male Rats

I.  Prieto 1 , A.  B.  Segarra1 , F.  Vargas 2 , F.  Alba 3 , M.  de Gasparo 4 , M.  Ramírez 1
  • 1 Unit of Physiology, University of Jaén, Bldg B-3, Jaén, Spain
  • 2 Department of Physiology, University of Granada, Granada, Spain
  • 3 Instituto de Neurociencias Federico Oloriz, Granada, Spain
  • 4 Novartis Pharma, Basle, Switzerland
This work was supported by Junta de Andalucía through PAI CVI-221 (Peptides and Peptidases) (Acciones coordinadas).
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Publikationsverlauf

Received 13 August 2002

Accepted after Revision 5 November 2002

Publikationsdatum:
13. August 2003 (online)

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Abstract

A local renin-angiotensin system (RAS) that may be involved in their regulatory functions has been identified in hypothalamus and pituitary. Altered thyroid status induces modifications in the secretory function of hypothalamus and pituitary. However, few studies have analyzed the role of the RAS in hypothalamus and, to our knowledge, there is no data on the pituitary RAS during thyroid dysfunction. In the present study, angiotensinase activities (glutamyl, aspartyl and alanyl aminopeptidase: GluAP, AspAP and AlaAP, respectively) were studied in hypothalamus and in the anterior and posterior lobes of pituitary of euthyroid, hypothyroid and hyperthyroid adult male rats. In the anterior pituitary, compared with euthyroid and hyperthyroid rats, hypothyroid animals showed a highly significant increase of GluAP and AspAP activities; the percentage increase in GluAP was markedly higher than the percentage increase in AspAP. This suggests an increased metabolism of angiotensin (Ang) I and Ang II to des-Asp1-Ang I and Ang III, respectively. We also observed an increase of Ang III-degrading activity (AlaAP) in the hypothalamus of hyperthyroid rats in soluble fraction. Increased Ang I and Ang II metabolism in the anterior pituitary of hypothyroid rats and increased metabolism of Ang III in the hypothalamus of hyperthyroid animals may be related to alterations in the secretory function of hypothalamus and pituitary in these thyroid dysfunctions.

Key words

Aminopeptidases - Angiotensin - Thyroid Dysfunction - Pituitary - Hypothalamus

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M. Ramírez

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