Clonidine diminishes c-jun gene expression in the cardiovascular sensitiveareas of the rat brainstem

The present study investigated the effect of clonidine on the basal and ind ucible c-jun and c-fos mRNA expression in the nucleus tract-us solitarius ( middle, mNTS, and rostral, rNTS) and the rostral ventrolateral medulla (cau dal, cRVLM, and rostral, rRVLM). Conscious rats received saline, clonidine (30 mu g/kg, i.v.), saline plus sodium nitroprusside (NP), or clonidine plu s NP. Under basal conditions (saline-infused rats), c-jun mRNA was expresse d in the mNTS and rRVLM but not in the rNTS or cRVLM whereas c-Sos mRNA was not detectable. Clonidine attenuated the increases in c-fos in the mNTS an d cRVLM and c-jun gene expression in the mNTS and rRVLM caused by NP-evoked hypotension and also reduced the basal expression of c-jun mRNA in the mNT S and rRVLM. These findings establish a causal link between clonidine inhib ition of c-Sos expression in brainstem and its hypotensive action, and prov ide the first evidence that clonidine attenuates the expression of the clos ely linked c-jun gene in neurons implicated in centrally mediated hypotensi on. (C) 2000 Elsevier Science B.V. All rights reserved.