Distribution of angiotensin type 1a receptor-containing cells in the brains of bacterial artificial chromosome transgenic mice

Abstract

In the central nervous system, angiotensin II (AngII) binds to angiotensin type 1 receptors (AT1R) to affect autonomic and endocrine functions as well as learning and memory. However, understanding the function of cells containing AT1Rs has been restricted by limited availability of specific antisera, difficulties discriminating AT1 receptor-immunoreactive cells in many brain regions and, the identification of AT1R-containing neurons for physiological and molecular studies. Here, we demonstrate that an Agtr1a bacterial artificial chromosome (BAC) transgenic mouse line that expresses type A AT1Rs (AT1aRs) identified by enhanced green fluorescent protein (EGFP) overcomes these shortcomings. Throughout the brain, AT1aR-EGFP was detected in the nuclei and cytoplasm of cells, most of which were neurons. EGFP often extended into dendritic processes and could be identified either natively or with immunolabeling of EGFP. The distribution of AT1aR-EGFP cells in brain closely corresponded to that reported for AngII binding and AT1aR protein and mRNA. In particular, AT1aR-EGFP cells were in autonomic regions (e.g., hypothalamic paraventricular nucleus, central nucleus of the amygdala, parabrachial nucleus, nuclei of the solitary tract and rostral ventrolateral medulla) and in regions involved in electrolyte and fluid balance (i.e., subfornical organ) and learning and memory (i.e., cerebral cortex and hippocampus). Additionally, dual label electron microscopic studies in select brain areas demonstrate that cells containing AT1aR-EGFP colocalize with AT1R-immunoreactivity. Assessment of AngII-induced free radical production in isolated EGFP cells demonstrated feasibility of studies investigating AT1aR signaling ex vivo. These findings support the utility of Agtr1a BAC transgenic reporter mice for future studies understanding the role of AT1 receptor containing cells in brain function.

Angiotensin AT1A receptors on leptin receptor–expressing cells control resting metabolism

“…We examined expression patterns of both LEPR and AT 1A by using the NZ44-transgenic mouse, which expresses GFP inserted into the AT1a locus in a recombineered BAC transgene (11), and mice that conditionally Leptin contributes to the control of resting metabolic rate (RMR) and blood pressure (BP) through its actions in the arcuate nucleus (ARC). The renin-angiotensin system (RAS) and angiotensin AT 1 receptors within the brain are also involved in the control of RMR and BP, but whether this regulation overlaps with leptin's actions is unclear.…”

Angiotensin Type-2 Receptors Influence the Activity of Vasopressin Neurons in the Paraventricular Nucleus of the Hypothalamus in Male Mice

“…Further, several recent studies have indicated that AVP may play an important role in RAS-dependent hypertension (36). Based on data from BAC transgenic reporter mice, it is unlikely that magnocellular neurons of the PVN (or supraoptic nucleus) contain AT1R or AT2R (12,37), and the impact of Ang-II on AVP secretion may therefore be mediated by Ang-II receptor positive neural connections arising from upstream brain nuclei, such as the organum vasculosum of the lamina terminalis and subfornical organ (38,39). While the stimulatory effects of Ang-II on AVP secretion are likely mediated by the AT1R (34,35,40), several lines of evidence support the notion that activation of AT2R acts in opposition to this neurosecretory effect.…”

Sex differences in NMDA GluN1 plasticity in rostral ventrolateral medulla neurons containing corticotropin-releasing factor type 1 receptor following slow-pressor angiotensin II hypertension

“…This antibody has been used to label EGFP expression in several different transgenic mouse lines (Gonzalez et al, 2012; Marques-Lopes et al, 2015; Marques-Lopes et al, 2014; Milner et al, 2010). In addition, this antibody does not label cells in brain tissue from mice lacking EGFP (Gonzalez et al, 2012). …”