Analysis of angiotensin type 2 receptors in vasopressinergic neurons and pituitary in the rat.
Previous functional studies indicated that an angiotensin type 2 (AT2) receptor subtype may participate in the regulation of vasopressin release by angiotensin II (AngII). In the present study, AT2 receptor-directed antiserum immunohistochemically detected AT2 receptors within the hypothalamic paraventricular (PVN) and the supraoptic nuclei (SON) of the rat brain, more specifically, in identified vasopressinergic neurons. Considering the lack of AT2 binding in the PVN and the SON using receptor autoradiography, we tested the hypothesis that these AT2 receptors are transported to the posterior pituitary. Western blot analysis detected AT2 immunoreactivity in the posterior pituitary. However, no AT2 binding was detected in posterior pituitary membranes, and no AT2 binding was detected with quantitative receptor autoradiography in the neurohypophysis. Thus, if AT2 receptors are transported from the magnocellular vasopressin neurons to the posterior pituitary, their role in AngII regulation of vasopressin release at the neurohypophyseal terminals remains to be clarified.
Shelat
S G
SG
Institute of Neurological Sciences, Department of Animal Biology, University of Pennsylvania, Philadelphia 19104, USA.
Reagan
L P
LP
King
J L
JL
Fluharty
S J
SJ
Flanagan-Cato
L M
LM
D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D001345:Autoradiography; D015153:Blotting, Western; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011945:Receptors, Angiotensin / Q000378:metabolism*; D013495:Supraoptic Nucleus / Q000378:metabolism; D014667:Vasopressins / Q000378:metabolism*
D011945:Receptors, Angiotensin; D014667:Vasopressins; D000804:Angiotensin II