title: Angiotensin III stimulates ERK1/2 mitogen-activated protein kinases and astrocyte growth in cultured rat astrocytes.
abstract: Angiotensin (Ang) III is a biologically active metabolite of Ang II with similar effects and receptor binding properties as Ang II. Most Ang III studies delineate physiological effects of the peptide but, the intracellular pathways leading to the actions are unknown and are a focus of these studies. We investigated in cultured brainstem and cerebellum rat astrocytes whether Ang III stimulates ERK1/2 mitogen activated protein (MAP) kinases and astrocyte growth. Ang III significantly stimulated ERK1/2 MAP kinases in a dose- and time-dependent manner. The maximal stimulation occurred with 100 nM Ang III (2.8±0.3 and 2.3±0.1-fold over basal, in brainstem and cerebellum astrocytes, respectively). This stimulation occurred as early as 1 min, and was sustained for at least 15 min. Moreover, inhibition of the ERK1/2 MAP kinase pathway by 10 μM PD98059 attenuated Ang III-induced ERK1/2 phosphorylation. Ang III induction of ERK1/2 occurred via stimulation of the Ang AT(1) receptor since pretreatment with 10 μM Losartan, a selective AT(1) receptor blocker, prevented Ang III-induced ERK1/2 phosphorylation. The selective AT(2) Ang receptor blocker PD123319 was ineffective. Comparable to Ang II, Ang III also stimulated astrocyte growth in a concentration-dependent manner, an effect that occurred via activation of the AT(1) receptor as well. These findings suggest that Ang III has similar effects as Ang II in astrocytes since it rapidly stimulates the phosphorylation of the ERK1/2 MAP kinases and induces astrocyte proliferation through activation of the AT(1) receptor. These studies are important in establishing signaling pathways for Ang III and provide validation of the central role of Ang III.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33328, United States. miclark@nova.edu
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Clark
authors.forename: Hsieu
authors.initials: H
authors.lastname: Tran
authors.forename: Chinh
authors.initials: C
authors.lastname: Nguyen
mesh_terms: D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D057912:Angiotensin II Type 2 Receptor Blockers / Q000494:pharmacology; D000805:Angiotensin III / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000201:enzymology*; D001933:Brain Stem / Q000187:drug effects* / Q000201:enzymology; D002478:Cells, Cultured; D002531:Cerebellum / Q000187:drug effects* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D019808:Losartan / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D057912:Angiotensin II Type 2 Receptor Blockers; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D011725:Pyridines; D000804:Angiotensin II; D000805:Angiotensin III; C073402:PD 123319; D020928:Mitogen-Activated Protein Kinases; D019808:Losartan; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one