Using high resolution imaging to determine trafficking of corticotropin-releasing factor receptors in noradrenergic neurons of the rat locus coeruleus

Abstract

Trafficking of G protein-coupled receptors (GPCRs) is a critical determinant of cellular sensitivity of neurons. To understand how endogenous or exogenous ligands impact cell surface expression of GPCRs, it is essential to employ approaches that achieve superior anatomical resolution at the synaptic level. In situations in which light and fluorescence microscopy techniques may provide only limited resolution, electron microscopy provides enhanced subcellular precision. Dual labeling immunohistochemistry employing visually distinct immunoperoxidase and immunogold markers has been an effective approach for elucidating complex receptor profiles at the synapse and to definitively establish the localization of individual receptors and neuromodulators to common cellular profiles. The immuno-electron microscopy approach offers the potential for determining membrane versus intracellular protein localization, as well as the association with various identifiable cellular organelles. Corticotropin-releasing factor (CRF) is an important regulator of endocrine, autonomic, immunological, behavioral and cognitive limbs of the stress response. Dysfunction of this neuropeptide system has been associated with several psychiatric disorders. This review summarizes findings from neuroanatomical studies, with superior spatial resolution, that indicate that the distribution of CRF receptors is a highly dynamic process that, in addition to being sexually dimorphic, involves complex regulation of receptor trafficking within extrasynaptic sites that have significant consequences for adaptations to stress, particularly within the locus coeruleus (LC), the major brain norepinephrine-containing nucleus.

Extended Amygdala to Ventral Tegmental Area Corticotropin-Releasing Factor Circuit Controls Binge Ethanol Intake

“…Additionally, while we found no changes in CRF receptor mRNA in the VTA, binge-induced reductions of CRF-1R protein was significance. It has been reported that increases in CRF signaling promote the internalization and recycling of the CRF-1R (34-37), and thus the reduction in protein expression seen here likely reflects a compensatory response to counter increased CRF signaling…”

Neural Substrates of Depression and Resilience

“…Adapted from Krishnan et al, [14] NE Mechanisms of Resilience Emerging evidence implicates the LC-NE system in stress resilience [67][68][69]. It is well known that the LC-NE nucleus responds to stress by Bpriming^neurons throughout the brain [68,[70][71][72][73][74][75][76]. For instance, in response to acute stress, the LC-NE system shifts the brain into a rapid defense-mechanism state [77].…”

A Genetic Animal Model of Alcoholism for Screening Medications to Treat Addiction

“…Neuroanatomical evidence indicates that noradrenergic system in the brain arise from the cell bodies in the locus coeruleus and project to different cerebral regions and to the spinal cord (Cooper et al, 2002). Moreover, there is a complex interaction between norepinephrine (NE) and corticotrophin releasing factor (CRF), a neuropeptide strongly associated with central autonomic and stress activity, receptors within the locus coeruleus (Reyes, Bangasser, Valentino, & Van Bockstaele, 2014). In addition to major projections to the frontal cortex, (NE) neurons project to the limbic system (Flavin & Winder, 2013), including amygdala, bed nucleus of the stria terminalis, hippocampus, and hypothalamus where it is implicated in addiction (Becker, 2012; Koob, 2013; Sofuoglu, Rosenheck, Petrakis, 2014; See also Al’ Absi, 2007), anxiety (Geiger, Neufang, Stein, & Domschke, 2014), attention (Geiger et al, 2014; Hegerl & Hensch, 2014), cognition (Chandler, Waterhouse, & Gao, 2014), memory, mood (Gold, 2015), pain (Elman, Borsook, & Volkow, 2013; Strobel, Hunt, Sullivan, Sun, & Sah, 2014), post-traumatic stress disorder (PTSD, Sofuoglu et al, 2014; Wimalawansa, 2014), sleep (Zeitzer, 2013), suicide (Elman et al, 2013), and associated physiological processes (Klimek, Rajkowska, Luker, Dilley, et al, 1999; Moret & Briley, 2011).…”