Glial angiotensinogen regulates brain angiotensin II receptors in transgenic rats TGR(ASrAOGEN)


  • J. Monti
  • M. Schinke
  • M. Boehm
  • D. Ganten
  • M. Bader
  • G. Bricca


  • American Journal of Physiology Regulatory Integrative and Comparative Physiology


  • Am J Physiol Regul Integr Comp Physiol 280 (1): R233-R240


  • TGR(ASrAOGEN)680, a newly developed transgenic rat line with specific downregulation of astroglial synthesis of angiotensinogen, exhibits decreased brain angiotensinogen content associated with a mild diabetes insipidus and lower blood pressure. Autoradiographic experiments were performed on TGR(ASrAOGEN) (TG) and Sprague-Dawley (SD) control rats to quantify AT 1and AT 2 receptor-binding sites in different brain nuclei and circumventricular organs. Dose-response curves for drinking response to intracerebroventricular injections of ANG II were compared between SD and TG rats. In most of the regions inside the blood-brain barrier [paraventricular nucleus (PVN), piriform cortex, lateral olfactory tract (LOT), and lateral preoptic area (LPO)], AT 1 receptor binding (sensitive to CV-11974) was significantly higher in TG compared with SD. In contrast, in the circumventricular organs investigated [subfornical organ (SFO) and area postremal, AT 1 receptor binding was significantly lower in TG. AT 2 receptors (binding sensitive to PD-123319) were detected at similar levels in the inferior olive (IO) of both strains. Angiotensin-binding sites sensitive to both CV-11974 and PD-123319 were detected in the LPO of SD rats and specifically upregulated in LOT, IO, and most notably PVN and SFO of TG. The dose-response curve for water intake after intracerebroventricular injections showed a higher sensitivity to ANG II of TG (EC 50 = 3.1 ng) compared with SD (EC 50 = 11.2 ng), strongly suggesting that the upregulation of AT 1 receptors inside the blood-brain barrier of TG rats is functional. Finally, we showed that downregulation of angiotensinogen synthesized by astroglial cells differentially regulates angiotensin receptor subtypes inside the brain and in circumventricular organs.