This Article Full Text Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Khan, I. M. Articles by Taylor, P. Search for Related Content PubMed PubMed Citation Articles by Khan, I. M. Articles by Taylor, P.

(Hypertension. 1996;28:1093-1099.)
© 1996 American Heart Association, Inc.

Articles

Spinal Nicotinic Receptor Expression in Spontaneously Hypertensive Rats

Imran M. Khan; Kenna L. Youngblood; Morton P. Printz; Tony L. Yaksh; Palmer Taylor

the Departments of Pharmacology (I.M.K., K.L.Y., M.P.P., T.L.Y., P.T.) and Anesthesiology (T.L.Y.), University of California, San Diego.

Correspondence to Dr Palmer Taylor, Department of Pharmacology 0636, University of California, San Diego, La Jolla, CA 92093.

Intrathecal administration of nicotinic agonists previously has been shown to result in exaggerated pressor and heart rate responses as well as greater nociceptive behavior in adult (12-week-old) spontaneously hypertensive rats (SHR) than in age-matched normotensive Wistar-Kyoto rats (WKY). Paradoxical to these augmented responses to nicotinic agonists in SHR, nicotinic receptor number in the spinal cord as measured by cytisine binding sites is lower in adult SHR than normotensive WKY and Sprague-Dawley rats. Using the high-affinity agonist epibatidine, we found similar differences in receptor number between strains in both in vitro ligand binding experiments with spinal cord membranes and in situ autoradiographic analyses. Spinal nicotinic receptor number did not differ in 5-week-old prehypertensive SHR and age-matched WKY; however, receptor numbers were higher in young rats of both strains than in their adult counterparts. Antihypertensive treatment (25 mg/kg per day hydralazine PO) in 6-week-old SHR from 6 to 12 weeks of age markedly reduced the progressive rise in blood pressure yet did not alter nicotinic receptor number compared with untreated rats. Similar treatment of WKY with hydralazine produced a slight fall in blood pressure but no change in receptor number. Thus, normalization of blood pressure by hydralazine in SHR does not result in a return of receptor expression to levels seen in normotensive rats. Higher centrally mediated pressor activity or augmented postcoupling events after neuronal nicotinic receptor stimulation may slowly downregulate expression of spinal nicotinic receptors in this genetically hypertensive rat strain.

Key Words: rats, inbred SHR • receptors, nicotinic • nicotinic agonists • spinal nerves • neurotransmitters

This article has been cited by other articles:

				I. M. Khan, E. Singletary, A. Alemayehu, S. Stanislaus, M. P. Printz, T. L. Yaksh, and P. Taylor Nicotinic receptor gene cluster on rat chromosome 8 in nociceptive and blood pressure hyperresponsiveness Physiol Genomics, October 29, 2002; 11(2): 65 - 72. [Abstract] [Full Text] [PDF]

				I. M. Khan, S. Stanislaus, L. Zhang, P. Taylor, and T. L. Yaksh A-85380 and Epibatidine Each Interact with Disparate Spinal Nicotinic Receptor Subtypes to Achieve Analgesia and Nociception J. Pharmacol. Exp. Ther., April 1, 2001; 297(1): 230 - 239. [Abstract] [Full Text]