Expression and transport of Angiotensin II AT sub(1) receptors in spinal cord, dorsal root ganglia and sciatic nerve of the rat

• Published in: Brain research 2008-12, Vol.1246, p.111-122
• Main Authors: Pavel, J, Tang, H, Brimijoin, S, Moughamian, A, Nishioku, T, Benicky, J, Saavedra, J M
• Format: Article
• Language: English
• ISSN: 0006-8993
• DOI: 10.1016/j.brainres.2008.09.099

To clarify the role of Angiotensin II in the regulation of peripheral sensory and motor systems, we initiated a study of the expression, localization and transport of Angiotensin II receptor types in the rat sciatic nerve pathway, including L sub(4)-L sub(5) spinal cord segments, the corresponding dorsal root ganglia (DRGs) and the sciatic nerve. We used quantitative autoradiography for AT sub(1) and AT sub(2) receptors, and in situ hybridization to detect AT sub(1) sub(A), AT sub(1) sub(B) and AT sub(2) mRNAs. We found substantial expression and discrete localization of Angiotensin II AT sub(1) receptors, with much higher numbers in the grey than in the white matter. A very high AT sub(1) receptor expression was detected in the superficial dorsal horns and in neuronal clusters of the DRGs. Expression of AT sub(1) sub(A) mRNA was significantly higher than that of AT sub(1) sub(B). AT sub(1) receptor binding and AT sub(1) sub(A) and AT sub(1) sub(B) mRNAs were especially prominent in ventral horn motor neurons, and in the DRG neuronal cells. Unilateral dorsal rhizotomy significantly reduced AT sub(1) receptor binding in the ipsilateral side of the superficial dorsal horn, indicating that a substantial number of dorsal horn AT sub(1) receptors have their origin in the DRGs. After ligation of the sciatic nerve, there was a high accumulation of AT sub(1) receptors proximal to the ligature, a demonstration of anterograde receptor transport. We found inconsistent levels of AT sub(2) receptor binding and mRNA. Our results suggest multiple roles of Angiotensin II AT sub(1) receptors in the regulation of sensory and motor functions.