Distribution of corticotropin‐releasing factor (CRF) receptor binding in the mouse brain using a new, high‐affinity radioligand, [¹²⁵I]‐PD‐Sauvagine

Abstract

The corticotropin-releasing factor (CRF) family of peptides includes CRF and three urocortins, which signal through two distinct G-protein coupled receptors, CRF and CRF . Although the cellular distribution of CRF receptor expression has been well characterized at the mRNA level, the localization of receptor protein, and, by inference, of functional receptors, has been limited by a lack of reliable immunohistochemical evidence. Recently, a CRF-related peptide, termed PD-sauvagine, was isolated from the skin of the frog, Pachymedusa dacnicolor, and validated as a high-affinity ligand for CRF receptor studies. A radiolabeled analog, [ I]-PD-sauvagine, with high signal-to-noise ratio, was used in autoradiographic studies to map the distribution of CRF receptor binding sites in the mouse brain. Through the use of receptor-deficient mice and subtype-specific antagonists, CRF and CRF binding sites were isolated, and found to be readily reconcilable with regional patterns of mRNA expression. Binding site distributions within a given structure sometimes differed from mRNA patterns, however, particularly in laminated structures of the isocortex, hippocampus, and cerebellum, presumably reflecting the trafficking of receptors to their operational homes on neuronal (mostly dendritic) processes. Binding patterns of [ I]-PD-sauvagine provided independent assessments of controversial receptor localizations, failing to provide support for CRF expression in central autonomic components of the limbic forebrain, the locus coeruleus and cerebellar Purkinje cells, or for CRF in any aspect of the cerebellar cortex. Though lacking in ideal resolution, in vitro binding of the PD-sauvagine radioligand currently provides the most sensitive and accurate available tool for localizing CRF receptors in rodent brain.

Profiling of G protein-coupled receptors in vagal afferents reveals novel gut-to-brain sensing mechanisms

“…Using double in situ hybridization, it was further shown that Crhr2 colocalized with roughly one third of Cck1r - and half of Gpr65 -expressing neurons ( Figure S4 ). Since Crhr2 binding sites are prominent in the nucleus of solitary tract [65] , it is likely that Crhr2 may serve as a presynaptic receptor on vagal terminals. Hence, it is tempting to speculate that Crhr2 signaling in gastrointestinal vagal afferents may link stress to the regulation of satiety.…”

“…Hypothetically, neurotransmitters deriving from the enteric nervous system including acetylcholine and glutamate could act on vagal terminals [82] . The aforementioned neurotransmitters and peptides may also be released within the brainstem and modulate the activity of vagal afferents at the presynaptic level [65] . Hence, more studies are warranted to determine whether the receptors for neurotransmitters and neuropeptides may serve as presynaptic receptors in addition to or rather than peripheral receptors.…”

Sex Differences in the Subcellular Distribution of Corticotropin-Releasing Factor Receptor 1 in the Rat Hippocampus following Chronic Immobilization Stress

“…Application of CRF to the DG of male rats produces long-lasting synaptic efficacy of neurons in this region (Wang et al, 2000). Although the phenotype of CRFR1-containing neurons in the rat hilus in not known, their topographic distribution by light microscopy (Chen et al, 2000; Tan et al, 2017) indicates that they likely contain SOM and/or neuropeptide Y (NPY) (Freund and Buzsáki, 1996). Our previous studies have shown that SOM/NPY-containing interneurons and, to a lesser extent, parvalbumin-labeled interneurons colocalize CRF as well as DORs in the male and female rat hilus (Williams and Milner, 2011; Williams et al, 2011b).…”

“…In the adult rodent hippocampus, endogenous sources of CRF originate from local GABAergic interneurons, especially those containing parvalbumin and somatostatin (SOM) (Yan et al, 1998; Williams and Milner, 2011). Moreover, CRF receptor type 1 (CRFR1) is prominently located on pyramidal neurons and in GABAergic interneurons (Williams et al, 2011a; Chen et al, 2012; Tan et al, 2017). In response to short-term (minutes) stimulation, CRF released in the hippocampus excites synapses and enhances synaptic efficacy (Wang et al, 1998; Wang et al, 2000; Chen et al, 2012).…”

Prospective-controlled assessment of stress hormones and pain in patients undergoing myomectomy as performed by laparoscopy against laparotomy

“…CRF is a peptide hormone that actively participates in stress responses [22][23][24][25][26][27]. CRF receptors and CRF itself have been identified in numerous extracellular brain sites [28].…”