Involvement of adrenoceptors in the angiotensin II-induced expression of inducible transcription factors in the rat forebrain and hypothalamus

Angiotensin 11 (Ang II) acts as a neuromodulator/neurotransmitter in specific brain nuclei involved in the regulation of blood pressure and volume homeostasis. It also induces a highly differentiated transcription factor expression in these nuclei. We investigated whether adrenoceptors, which modulate other central actions of angiotensin 11 like the vasopressin release, also play a role in the AT1 receptor-mediated expression of the transcription factors (TF) c-Fos, c-Jun and Krox-24 in the rat brain. Ana 11, injected intracerebroventricularly, induced the expression of c-Fos, c-Jun and Krox-24 in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Pretreatment with the alpha1-adrenoceptor antagonist, prazosin, significantly inhibited the Ang II-induced transcription factor expression in the SON and PVN. The alpha2-adrenoceptor antagonist, yohimbine, also reduced Ana II-stimulated transcription factors significantly in both nuclei. This inhibition was mainly localized in vasopressinergic magnocellular neurons in both nuclei. The beta-adrenoceptor antagonist, propranolol, did not influence the Ang II-induced expression of TF. Our results show that both, Ana II-induced vasopressin release and transcription factor expression, involve the same neuronal connections in the brain, implicating that the signal transduction pathways leading to the two different effects are at least to a certain degree convergent. (C) 2002 Elsevier Science Ltd. All rights reserved.