Haemorrhage-induced production of Fos in neurons of the lamina terminalis: role of endogenous angiotensin II.

Abstract

Hypotensive haemorrhage increased the production of Fos, a marker of cell activation, in cells of the subfornical organ (SFO) and the organum vasculosum of the lamina terminalis (OVLT) as well as in the supraoptic (SON) and paraventricular (PVN) nuclei in conscious rats. Pretreatment with captopril (100 mg/kg i.p.) inhibited the production of Fos in cells of the SFO and OVLT but did not reduce the concentration of Fos-positive cell nuclei in the PVN and SON. The results suggest that the production of Fos in the SFO and OVLT induced by the haemorrhage is probably due to elevated levels of circulating angiotensin II.