Artikel
Differential Expression of beta1- and beta2-Adrenergic Receptors in HPA Axis of SHR
Unterschiedliche Expression der Beta1- und Beta2-Adrenergen Rezeptoren in der HPA-Achse in SHR
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Veröffentlicht: | 11. November 2004 |
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Gliederung
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Various specific neuroendocrine factors such as pituitary ACTH and adrenal corticosterone are crucial in the development of high blood pressure in spontaneously hypertensive rats (SHR). Increasing evidence shows the involvement of central beta -adrenergic receptors (beta -ADR) in the regulation of ACTH, corticosterone and aldosterone release. To further evaluate the role of beta -ADR in the development of hypertension we investigated the expression of beta 1- and beta 2-ADR in the hypothalamo-pituitary-adrenal (HPA) axis of prehypertensive and hypertensive male SHR at mRNA and protein levels using RT-PCR and Western blot technique, respectively and compared with age-matched normotensive Wistar-Kyoto (WKY) rats.
Basal plasma levels of ACTH, corticosterone and aldosterone were significantly higher in prehypertensive SHR and only corticosterone in hypertensive SHR. Hypothalamic beta 1-ADR mRNA and protein levels were significantly higher in both pre- and hypertensive SHR, whereas beta 2-ADR mRNA level was higher in hypertensive SHR. In contrast, both adrenal beta 1+2- and pituitary beta 2-ADR mRNA levels were significantly attenuated and protein levels were elevated in pre- and hypertensive SHR.
Enhanced expression of hypothalamic beta 1-ADR together with an increased adrenal and pituitary beta 2-ADR receptor expression may influence the release of neurohormones from the HPA axis which may play a key role in the early development and later in the maintenance of hypertension in SHR.