RSS-Feed abonnieren
DOI: 10.1055/s-2003-41302
Angiotensinase Activity in Hypothalamus and Pituitary of Hypothyroid, Euthyroid and Hyperthyroid Adult Male Rats
This work was supported by Junta de Andalucía through PAI CVI-221 (Peptides and Peptidases) (Acciones coordinadas).Publikationsverlauf
Received 13 August 2002
Accepted after Revision 5 November 2002
Publikationsdatum:
13. August 2003 (online)
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
References
- 1 Vila-Porcile E, Corvol P. Angiotensinogen, prorenin, and renin are co-localized in the secretory granules of all granular cells of the rat anterior pituitary: an immunoultrastructural study. J Hystochem Cytochem. 1998; 46 301-311
- 2 Ganong W F. Blood, pituitary, and brain renin-angiotensin systems and regulation of secretion of anterior pituitary gland. Front Neuroendocrinol. 1993; 14 233-249
- 3 Prieto I, Martinez J M, Ramirez M J, Arechaga G, Alba F, De Gasparo M, Vargas F, Segarra A B, Ramirez M. Aminopeptidase activities after water deprivation in male and female rats. Regul Pept. 2001; 101 189-194
- 4 Marchant C, Brown L, Sernia C. Renin-angiotensin system in thyroid dysfunction in rats. J Cardiovasc Plarmacol. 1993; 22 449-455
- 5 Kirby J D, Jetton A E, Cooke P S, Hess R A, Bunick D, Ackland J F, Turek F W, Schwartz N B. Developmental hormonal profiles accompanying the neonatal hypothyroidism-induced increase in adult testicular size and sperm production in the rat. Endocrinology. 1992; 131 559-565
- 6 Rondeel J M, Klootwijk W, Linkels E, van Haasteren G A, de Greef W J, Visser T J. Regulation of thyrotropin-releasing hormone in the posterior pituitary. Neuroendocrinology. 1995; 61 421-429
- 7 Samuels M H, Wierman M E, Wang C, Ridgway E C. The effect of altered thyroid status on pituitary hormone messenger ribonucleic acid concentrations in the rat. Endocrinology. 1989; 124 2277-2282
- 8 Tohei A, Akai M, Tomabechi T, Mamada M, Taya K. Adrenal and gonadal function in hypothyroid adult male rats. J Endocrinol. 1997; 152 147-154
- 9 Hong-Brown L Q, Deschepper C F. Effects of thyroid hormones on angiotensinogen gene expression in rat liver, brain, and cultured cells. Endocrinology. 1992; 130 1231-1237
- 10 Wright J W, Harding J W. Important roles for angiotensin III and IV in the brain renin-angiotensin system. Brain Res Rev. 1997; 25 96-124
- 11 Barret A J, Rawlings N D, Woessner J F. Handbook of Proteolytic Enzymes. London; Academic Press 1998
- 12 Ramirez-Exposito M J, Martinez J M, Prieto I, Alba F, Ramirez M. Comparative distribution of glutamyl and aspartyl aminopeptidase activities in mouse organs. Horm Metab Res. 2000; 32 161-163
- 13 Wilk S, Wilk E, Magnusson R P. Purification, characterization, and cloning of a cytosolic aspartyl aminopeptidase. J Biol Chem. 1998; 273 15 961-15 970
- 14 Vargas F, Atucha N M, Sabio J M, Quesada T, Garcia-Estan J. Pressure-diuresis-natriuresis response in hyperthyroid and hypothyroid rats. Clin Sci (Lond). 1994; 87 323-328
- 15 Paxinos G, Watson C. The rat brain in stereotaxic coordinates. New York; Academic press 1998
- 16 Prieto I, Martinez J M, Hermoso F, Ramirez M J, de Gasparo M, Vargas F, Alba F, Ramirez M. Effect of valsartan on angiotensin II- and vasopressin-degrading activities in the kidney of normotensive and hypertensive rats. Horm Metab Res. 2001; 33 559-563
- 17 Sim M K. Degradation of angiotensin I in the endothelium and smooth muscle of the rat aorta. Biochem Pharmacol. 1993; 45 1524-1527
- 18 Sim M K, Qiu X S. Formation of des-Asp-angiotensin I in the hypothalamic extract of normo- and hypertensive rats. Blood Pressure. 1994; 3 260-264
- 19 Sim M K, Radhakrishnan R. Novel central action of des-Asp-angiotensin I. Eur J Pharmacol. 1994; 257 R1-R3
- 20 Reaux A, Fournie-Zaluski M C, Llorens-Cortes C. Angiotensin III: a central regulator of vasopressin release and blood pressure. Trends Endocrinol Metab. 2001; 12 157-162
- 21 Reaux A, deMota N, Zini S, Cadel S, Fournie-Zaluski M C, Roques B P, Corvol P, Llorens-Cortes C. PC18, a specific aminopeptidase N inhibitor, induces vasopressin release by increasing the half-life of brain angiotensin III. Neuroendocrinology. 1999; 69 370-376
-
22 Moses A M, Scheinman S J.
The kidneys and electrolyte metabolism in hypothyroidism. In: Braveerman LE, Utinger RD (eds) The Thyroid. Philadelphia; Lippincott-Raven Publishers 1996: 812-820 - 23 Park C W, Shin Y S, Ahn S J, Kim S Y, Choi E J, Chang Y S, Bang B K. Thyroxine treatment induces upregulation of renin-angiotensin-aldosterone system due to decreasing effective plasma volume in patients with primary myxoedema. Nephrol Dial Transplant. 2001; 16 1799-1806
M. Ramírez
Unit of Physiology · University of Jaén
Bldg B-3 · Room 213 · 23071 Jaén · Spain ·
Telefon: + 34-953-012302
Fax: + 34-953-012141
eMail: msanchez@ujaen.es