Seizure-induced c-fos expression in rat medulla oblongata is not dependent on associated elevation of blood pressure.
This study was performed to determine whether c-fos immunoreactivity (IR) induced in medulla oblongata by pentylenetetrazole seizures is a consequence of seizure-associated blood pressure elevation and activation of baroreceptor afferent pathways, or occurs independently of hypertension. Immunohistochemical study of sections of medulla oblongata revealed that seizures are followed by induction of c-fos IR in nucleus tractus solitarius (NTS), dorsal motor nucleus of the vagus (DMN 10), and ventrolateral medulla (VLM), while there is negligible c-fos IR after saline sham injections. Seizures were associated with blood pressure elevation peaking at 31 +/- 17% (+/- SD) above baseline. Experimental hypertension at a similar level induced by i.p. phenylephrine also resulted in induction of c-fos IR in NTS. When seizures were preceded by antihypertensive treatment with the alpha-adrenergic antagonist, phentolamine, peak blood pressure tended to remain near the baseline level and lower than sham-injected controls. Normotensive seizures were associated with c-fos IR in NTS, DMN 10, and VLM similar to the pattern following hypertensive seizures. Seizure-induced activation of c-fos IR occurred despite normal blood pressure, and thus can be attributed to a direct effect of the seizure, and not to an indirect effect mediated by hypertension.
D000344:Afferent Pathways; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D015870:Gene Expression; D007150:Immunohistochemistry; D008526:Medulla Oblongata / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D011311:Pressoreceptors; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis* / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000139:chemically induced*
D016760:Proto-Oncogene Proteins c-fos; D010656:Phenylephrine