Distribution of corticotropin-releasing factor receptor mRNA expression in the rat brain and pituitary.

Abstract

Corticotropin-releasing factor (CRF) is a major hypophysiotropic peptide regulating pituitary-adrenal response to stress, and it Is also widely expressed in the central nervous system. (2), with some major areas of mismatch (14). One potential basis for this discrepancy derives from the recent identification of a distinct CRF-binding protein (CRF-BP), which is prominently expressed in brain, including subsets of CRF-containing pathways and/or their targets (15). The identification of this distinct high-affinity CRF-binding moiety, which is in a position to modify central and pituitary actions of CRF by autocrine or paracrine mechanisms, could limit the ability to draw inferences concerning CRF-R distributions on the basis of ligand-binding patterns alone. The present study employed hybridization histochemical methods to provide an initial overview ofthe cellular sites ofexpression ofthe CRF-R in rat brain and pituitary. Dual staining approaches were used to directly compare loci of CRF-R mRNA expression with those of ACTH in the pituitary and of CRF-BP in brain. MATERIALS AND METHODSIn Situ Hybridization. Male (n = 7) and female (n = 3) adult Sprague-Dawley albino rats (200-300 g) were perfused transcardially with 4% paraformaldehyde in 0.1 M pH 9.5 sodium borate buffer, and regularly spaced series of 20-to 30-,umthick frozen sections through brain and pituitary were taken as described (16). Radiolabeled antisense and sense (control) complementary RNA (cRNA) copies were synthesized from a full-length or N-terminal 344 bp fragment of the rat CRF cDNA subcloned in pBluescript KS vector (Stratagene). (a-33P]UTP was used for probe synthesis, and in situ hybridization was performed as previously described (16,17). cRNA probes to full-length rat CRF-R coding region were labeled to 40-60% total incorporation, and hybridization was carried out under high stringency [50%6 (vol/vol) formamide with final washes carried out in 0.2x SSC at 700C (lx SSC is 0.15 M NaCl/0.015 M sodium citrate, pH 7.0)].Combined in Situ Hybridization and Immun emis try. Concurrent localization of ACTH immunoreactivity -ir) and CRF-R mRNA in pituitaries was performed by using a modification of a procedure described by Watts and Swanson (18). This involved first applying a conventional biotinavidin-immunoperoxidase protocol, to localize primary antibodies raised in rabbit against the rat corticotropin fragment ACTH-(23-39). Rat ACTH-(23-39) was coupled to human a-globulins with bisdiazotized benzidine, and antisera were

The developmental profile of the corticotropin releasing factor receptor (CRF2) in rat brain predicts distinct age-specific functions

“…Little CRF 2 -mRNA signal was detected in the central nucleus of the amygdala. This nucleus plays a major role in the transduction of stress signals and contains a large cluster of CRF-expressing neurons, as well as modest amounts of CRF 1 -mRNA [2,10,14,31,38]. Current knowledge of the distribution of the two members of the CRF receptor family in the amygdala is insufficient to determine the relative roles of these receptors in mediating the effects of CRF on the hormonal and behavioral responses to stress.…”

“…The CRF 2 receptor exists in at least two isoforms [22]. The distribution and expression of the two CRF receptors have been documented in the adult rat brain [10,31,47]. The differential anatomical distributions of the two receptors indicate that they may serve distinct functional roles.…”

Developmental profile of messenger RNA for the corticotropin-releasing hormone receptor in the rat limbic system

“…Autoradiography and radioligand binding studies during early postnatal life in the rat have demonstrated changes in receptor number and regional distribution [5,6,11,12,15]. The two methods have yielded conflicting information regarding CRH receptor distribution in a number of brain regions [12,16,17]. A potential basis for this discrepancy derives from CRH binding protein which may interact with the CRH ligand [12,16].…”

“…A potential basis for this discrepancy derives from CRH binding protein which may interact with the CRH ligand [12,16]. Binding studies may also provide limited information on the actual site of receptor synthesis because ligands may bind to neural receptors on cell bodies and along dendrites and axons [17]. The recent cloning of cDNAs encoding the rat CRH receptor [4,14] permits mapping the distribution of cells expressing CRH receptor messenger ribonucleic acid (mRNA) [17,21].…”

Association of a corticotropin-releasing hormone receptor 1 haplotype and antidepressant treatment response in Mexican-Americans

“…[4][5][6] There is a long body of evidence indicating disruption of hypothalamicpituitary-adrenal (HPA) axis function in depression, including the following key observations: increased 24-h elevations in cortisol production, 7 lack of suppression of plasma cortisol levels by dexamethasone, 8 increased concentrations of CRH in cerebrospinal fluid, 9 dysregulation of HPA responses to exogenous CRH administration [10][11][12] and loss of the negative correlation between plasma cortisol and continuously collected CSF CRH. 13 Of particular relevance, it has been demonstrated that antidepressants of various classes suppress CRH gene expression [14][15][16] in rodents and HPA activity in depressed 17 and healthy humans.…”