Angiotensin II Receptors in the Ventral Portion of the Bed Nucleus of the Stria terminalis

Abstract

In vitro receptor autoradiography, using the radiolabeled angiotensin II (Ang II) antagonist ¹²⁵I-sar¹, ile⁸ Ang II (^∣25I-SI Ang II; 250 pM) in the absence or presence of 1 µM Ang II, was used to identify Ang II receptor binding sites in the preoptic-anterior hypothalamic (POAH) brain region of cycling female rats. A nucleus within this region, lateral to the organum vasculosum of the lamina terminalis and ventral to the anterior commissure, displayed a discrete locus of ¹²⁵I-SI Ang II binding sites (385 fmol/g tissue). This nucleus, which corresponds to the area of the POAH from which Ang II is most effective at eliciting luteinizing hormone release, has been identified as the ventral portion of the bed nucleus of the stria terminalis (BSTV) by the rat brain atlas of Paxinos and Watson. The selective nonpeptidic Ang II_α receptor antagonist Dup 753 completely inhibited the binding of ¹²⁵I-SI Ang II to the BSTV and other hypothalamic nuclei, suggesting that these receptors are of the Ang II_α subtype.

Projections from bed nuclei of the stria terminalis, dorsomedial nucleus: Implications for cerebral hemisphere integration of neuroendocrine, autonomic, and drinking responses

“…Anteroventral territories of the BST including the BSTdm contain abundant angiotensin II-immunoreactive fibers (Lind et al, 1985) and very high levels of angiotensin II receptors (Grove et al, 1991;Denton et al, 1996) that could be activated by relatively low blood levels of angiotensin II (McKinley et al, 1998). The BSTdm also projects to the region of the vascular organ of the lamina terminalis/median preoptic nucleus, which projects back massively to the BSTdm (Thompson and Swanson, 2003).…”

Angiotensin II Receptor Development in the Bed Nucleus of the Stria terminalis and Other Perihypothalamic Brain Regions of the Female and Male Rat

“…Comparisons of l25l-SI All binding in the selected regions of the anterior hypo thalamus of the PPF rats with adult (12-week-old) proestrous (PE) female rats, reported previously [9], re- vealed a significantly lower concentration of binding in the BSTV of the PPF rat (p<0.05) (table 1). The three other perihypothalamic brain regions surveyed displayed no significant difference between the two age groups (table 1).…”

“…The fact that sub-and supra-Kd concentrations of l25I-SI All give a similar age-related increase in All re ceptor binding in the BSTV and SCh, which have been shown to have the ATi All receptor subtype [9,15], sug gests that the affinity of the binding sites for 1231-Sl All are similar in 2-, 4-and 10-week-old rats.…”

“…These two groups of brains were processed using identical conditions; therefore, the most appropriate comparison data for the 2-week-old rats in this experiment is from this group of adult female rats. As previously described [9], the adult female rats in this experiment were housed on a 14:10 h light-dark cycle (lights on at 06.00 h). Vaginal smears were obtained daily at approximately 09.00 h to de termine cyclicity.…”

“…More recently, a specific All receptor subtype (ATi) was localized to this same subregion of the POAH, identified as the ventral portion of the bed nu cleus of the stria terminalis (BSTV) [9]. This area also con tains a high concentration of estrogen binding neurons [10], which could account for the steroid-dependent ac tions of All on LH release [3].…”