Concomitant hypotensive and antinociceptive effects of guanabenz in conscious rats: Involvement of nucleus reticularis gigantocellularis

Subcutaneous administration of guanabenz (1, 2, 5, or 8 mg/kg) in conscious Sprague-Dawley rats exerted concomitant suppressive actions on systolic pressure (tail-cuff sphygmomanometric measurement) and pain responses (hot-plate algesiometric assay) that varied both in degree (antinociception ⋙ hypotension) and response pattern. Furthermore, both depressive effects were appreciably attenuated by bilateral lesions of the nucleus reticularis gigantocellularis in the medulla oblongata. It is speculated that separate subpopulations of neurons within this reticular nucleus may be involved in the expression of hypotension and antinociception by this amino-guanidine derivative.