PubMed:2854272 JSONTXT 6 Projects

Binding of 3H-(3-MeHis2) thyrotropin-releasing hormone to spinal cord membranes of spontaneously hypertensive and Wistar-Kyoto normotensive rats. Previous studies from this laboratory had indicated that in spontaneously hypertensive (SHR) rats the development of hypertension paralleled increases in brain receptors for thyrotropin-releasing hormone (TRH). The increase appeared to be confined to hypothalamus and striatum. The present studies were undertaken to determine the binding characteristics of TRH receptors in the peripheral tissues of SHR and normotensive Wistar-Kyoto (WKY) rats. TRH receptors were labeled with 3H-MeTRH. The binding of 3H-MeTRH to membranes prepared from spinal cord, heart, lung, kidney and adrenal gland of SHR and WKY rats was determined. In WKY rats, the binding of 3H-MeTRH to various tissue membranes was in the following order: spinal cord greater than kidney greater than lung greater than heart = adrenals. The binding of 3H-MeTRH to spinal cord membranes of SHR rats was significantly higher in comparison to WKY rat tissues, whereas the binding of 3H-MeTRH in kidney, heart, lung and adrenals of the two strains of rats did not differ. The increase in the binding of 3H-MeTRH to spinal cord of SHR rats was due to increases in the Bmax values and not in the Kd values. The results suggest that in addition to the brain, TRH receptors in the spinal cord of SHR rats are also up-regulated and may also play an important role in the regulation of blood pressure.