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(Hypertension. 2009;54:845.)
© 2009 American Heart Association, Inc.

Original Articles

Phosphate-Activated Glutaminase-Containing Neurons in the Rat Paraventricular Nucleus Express Angiotensin Type 1 Receptors

Nan Jiang; Peng Shi; Hongwei Li; Shun Lu; Leah Braseth; Adolfo E. Cuadra; Mohan K. Raizada; Colin Sumners

From the Departments of Physiology and Functional Genomics (N.J., P.S., H.L., L.B., A.E.C., M.K.R., C.S.) and Medicine (S.L.), University of Florida, Gainesville, Fla.

Correspondence to Colin Sumners, Department of Physiology and Functional Genomics, College of Medicine, University of Florida, 1600 SW Archer Rd, Gainesville, FL 32610-0274. E-mail csumners{at}ufl.edu

The centrally mediated cardiovascular regulatory actions of angiotensin II in normal and hypertensive rats include angiotensin II type 1 receptor (AT1R)–mediated actions at the paraventricular nucleus (PVN) of the hypothalamus. Because the PVN consists of multiple neuronal populations, it is important to understand which neuronal types in the PVN are influenced by angiotensin II. Here we have developed a viral vector (Adeno-associated vector 2 [AAV2]-PAG-eGFP [PAG; phosphate-activated glutaminase promoter]) to drive expression of green fluorescent protein (GFP) primarily within glutamate neurons. At 10 to 14 days after bilateral microinjection (200 nL per side; 1.2x10¹² genome copies) of AAV2-PAG-eGFP into adult Sprague-Dawley rat PVN, animals were euthanized and brains removed and used for isolation and culture of PVN neurons. Fluorescence microscopy and immunostaining using neuron and PAG-specific antibodies revealed the presence of GFP-containing glutamatergic neurons in these PVN cultures. Whole-cell patch-clamp recordings demonstrated that angiotensin II (100 nmol/L) produced a 16% decrease in delayed rectifier potassium current in 50% of the GFP-containing neurons, an effect that was abolished by the AT1R antagonist losartan (1 µmol/L). Consistently, 9 of 28 GFP/PAG-expressing neurons contained AT1R mRNA, as indicated by single-cell RT-PCR. Furthermore, specific GFP/PAG-positive neurons in the PVN that project to the rostral ventrolateral medulla of the brain stem express immunoreactive AT1R. In conclusion, we have demonstrated the presence of functional AT1R on PAG-positive (largely glutamate) neurons within rat PVN, certain of which project to the rostral ventrolateral medulla.

Key Words: angiotensin II • paraventricular nucleus • phosphate-activated glutaminase • potassium current • AT1 receptor