Rk. Kanter et al., SEIZURE-INDUCED C-FOS EXPRESSION IN RAT MEDULLA-OBLONGATA IS NOT DEPENDENT ON ASSOCIATED ELEVATION OF BLOOD-PRESSURE, Neuroscience letters, 194(3), 1995, pp. 201-204
This study was performed to determine whether c-fos immunoreactivity (
IR) induced in medulla oblongata by pentylenetetrazole seizures is a c
onsequence of seizure-associated blood pressure elevation and activati
on of baroreceptor afferent pathways, or occurs independently of hyper
tension. Immunohistochemical study of sections of medulla oblongata re
vealed 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 af
ter saline sham injections. Seizures were associated with blood pressu
re elevation peaking at 31+/-17% (+/-SD) above baseline. Experimental
hypertension at a similar level induced by i.p. phenylephrine also res
ulted in induction of c-fos IR in NTS. When seizures were preceded by
antihypertensive treatment with the alpha-adrenergic antagonist, phent
olamine, peak blood pressure tended to remain near the baseline level
and lower than sham-injected controls. Normotensive seizures were asso
ciated with c-fos IR in NTS, DMN 10, and VLM similar to the pattern fo
llowing 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.