Corticotropin-releasing Hormone Receptor mRNA Research Articles

Allopregnanolone reduces neuroendocrine response to acute stressful stimuli in sheep.

The verified hypothesis assumed that centrally administered neurosteroid, allopregnanolone (AL), could affect basal and/or stress-induced activity of the hypothalamic-pituitary-adrenal (HPA) axis in sheep. Four groups (n = 6 each) of luteal-phase sheep were intracerebroventricularly infused for 3 days with a vehicle without stress (control); a vehicle treated with stressful stimuli (isolation and partial movement restriction) on the third day; AL (4 × 15 µg/60 µL/30 min, at 30-min intervals) treated with stressful stimuli, and AL alone. Simultaneously, the push-pull perfusion of the infundibular nucleus/median eminence and plasma sample collection were performed. After the experiment, the sheep were killed to collect the hypothalamic and anterior pituitary (AP) tissues. Stressful stimuli evoked an increase in the expression of corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) mRNA in the hypothalamic paraventricular nucleus (PVN), and AVP receptor (V1b) and proopiomelanocortin (POMC) mRNA in the AP; the concentrations of perfusate CRH, and plasma adrenocorticotropic hormone (ACTH) and cortisol compared to controls. Conversely, the expression of the CRH receptor (CRHR1) mRNA in the AP was downregulated. AL decreased the expression of CRH and AVP mRNA in the PVN, and AVPRV1b and POMC mRNA in the AP in stressed sheep, compared to only stressed ones. There was also a reduction in perfusate CRH, and plasma ACTH and cortisol concentrations. AL alone decreased the expression of CRHR1 mRNA in the AP, and plasma cortisol concentration at the beginning of the collection period compared to controls. In conclusion, AL may function centrally as a suppressor of HPA axis activity in stressed sheep.

Thyrotropic activity of corticotropin-releasing hormone in an altricial bird species, the zebra finch (Taeniopygia guttata)

In chicken, corticotropin-releasing hormone (CRH) acts as a thyrotropin (TSH)-releasing factor, mediated by the type 2 CRH receptor (CRHR2) on the thyrotropes of the pituitary gland. It is not known whether CRH also controls TSH release in non-precocial avian species that have a different pattern of thyroidal activity during their life cycle. Therefore, we investigated the TSH-releasing capacity of CRH in an altricial species, the zebra finch (Taeniopygia guttata). Cellular localisation of type 1 CRH receptor (CRHR1) and CRHR2 mRNA in the pituitary was determined by in situ hybridisation, combined with immunohistochemical staining of pituitary thyrotropes. In addition, isolated pituitary glands were stimulated with CRH to determine the effect on TSH release. Lastly, the mRNA levels of hormones and receptors involved in the control of thyroidal and adrenal function were measured by qPCR in zebra finch chicks between hatching and fledging, and in adults. Most of the hypophyseal CRHR2 mRNA co-localised with thyrotropes, whereas CRHR1 mRNA was found inbetween thyrotropes. Pituitary glands stimulated in vitro with CRH showed increased secretion of TSH-like activity. Pituitary CRHR2 mRNA expression decreased while pituitary TSHB mRNA and brain CRH mRNA levels increased towards fledging, similar as seen in chicken hatching. These results suggest that CRHR2 expressed on thyrotropes is likely mediating CRH-induced TSH release in altricial avian species like it does in precocial species, and that the increased thyroid hormone levels towards fledging in altricial birds are the result of increased hypothalamic stimulation, in which the thyrotropic activity of CRH may initially play a role.

MiR-34b attenuates trauma-induced anxiety-like behavior by targeting CRHR1.

Exposure to trauma is a potential contributor to anxiety; however, the molecular mechanisms responsible for trauma-induced anxiety require further clarification. In this study, in an aim to explore these mechanisms, we observed the changes in the hypothalamic pituitary adrenal (HPA) axis using a radioimmunoassay and the changes in anxiety-like behavior using the open field test and elevated plus maze test in a rat model following intervention with NBI-27914, a specific corticotropin-releasing hormone receptor 1 (CRHR1) antagonist. CRHR1 was found to be involved in trauma-induced anxiety. We then applied bioinformatic analysis to screen microRNAs (miRNAs or miRs) that target CRHR1, and miR-34b was determined to negatively regulate CRHR1 mRNA in primary hypothalamic neurons. The overexpression of miR-34b in the paraventricular nucleus (PVN) by a miRNA agomir using a drug delivery system decreased the hyperactivity of the HPA axis and anxiety-like behavior. Overall, the involvement of the HPA axis in trauma-induced anxiety was demonstrated, and trauma-induced anxiety was attenuated by decreasing the hyperactivity of the HPA axis via miR-34b by targeting CRHR1.

Exaggerated phosphorylation of brain tau protein in CRH KO mice exposed to repeated immobilization stress

Neuroendocrine and behavioral stress responses are orchestrated by corticotropin-releasing hormone (CRH) and norepinephrine (NE) synthesizing neurons. Recent findings indicate that stress may promote development of neurofibrillary pathology in Alzheimer's disease. Therefore, we investigated relationships among stress, tau protein phosphorylation, and brain NE using wild-type (WT) and CRH-knockout (CRH KO) mice. We assessed expression of phosphorylated tau (p-tau) at the PHF-1 epitope and NE concentrations in the locus coeruleus (LC), A1/C1 and A2/C2 catecholaminergic cell groups, hippocampus, amygdala, nucleus basalis magnocellularis, and frontal cortex of unstressed, singly stressed or repeatedly stressed mice. Moreover, gene expression and protein levels of tyrosine hydroxylase (TH) and CRH receptor mRNA were determined in the LC. Plasma corticosterone levels were also measured. Exposure to a single stress increases tau phosphorylation throughout the brain in WT mice when compared to singly stressed CRH KO animals. In contrast, repeatedly stressed CRH KO mice showed exaggerated tau phosphorylation relative to WT controls. We also observed differences in extent of tau phosphorylation between investigated structures, e.g. the LC and hippocampus. Moreover, CRH deficiency leads to different responses to stress in gene expression of TH, NE concentrations, CRH receptor mRNA, and plasma corticosterone levels. Our data indicate that CRH effects on tau phosphorylation are dependent on whether stress is single or repeated, and differs between brain regions. Our findings indicate that CRH attenuates mechanisms responsible for development of stress-induced tau neuropathology, particularly in conditions of chronic stress. However, the involvement of central catecholaminergic neurons in these mechanisms remains unclear and is in need of further investigation.

Locus coeruleus response to single-prolonged stress and early intervention with intranasal neuropeptide Y.

Dysregulation of the central noradrenergic system is a core feature of post-traumatic stress disorder (PTSD). Here, we examined molecular changes in locus coeruleus (LC) triggered by single-prolonged stress (SPS) PTSD model at a time when behavioral symptoms are manifested, and the effect of early intervention with intranasal neuropeptide Y (NPY). Immediately following SPS stressors, male SD rats were administered intranasal NPY (SPS/NPY) or vehicle (SPS/V). Seven days later, TH protein, but not mRNA, was elevated in LC only of the SPS/V group. Although 90% of TH positive cells expressed GR, its levels were unaltered. Compared to unstressed controls, LC of SPS/V, but not SPS/NPY, expressed less Y2 receptor mRNA with more CRHR1 mRNA in subset of animals, and elevated corticotropin-releasing hormone (CRH) in central nucleus of amygdala. Following testing for anxiety on elevated plus maze (EPM), there were significantly increased TH, DBH and NPY mRNAs in LC of SPS-treated, but not previously unstressed animals. Their levels highly correlated with each other but not with behavioral features on EPM. Thus, SPS triggers long-term noradrenergic activation and higher sensitivity to mild stressors, perhaps mediated by the up-regulation influence of amygdalar CRH input and down-regulation of Y2R presynaptic inhibition in LC. Results also demonstrate the therapeutic potential of early intervention with intranasal NPY for traumatic stress-elicited noradrenergic impairments. Single-prolonged stress (SPS)-triggered long-term changes in the locus coeruleus/norepinephrine (LC/NE) system with increased tyrosine hydroxylase (TH) protein and CRH receptor 1(CRHR1) mRNA and lower neuropeptide Y receptor 2 (Y2R) mRNA levels as well as elevated corticotropin-releasing hormone (CRH) in the central nucleus of amygdala (CeA) that were prevented by early intervention with intranasal neuropeptide Y (NPY). SPS treatment led to increased sensitivity of LC to mild stress of elevated plus maze (EPM), with elevated mRNA for NE biosynthetic enzymes in subset of animals.

Developmental alterations in CNS stress-related gene expression following postnatal immune activation

Early-life adversity is associated with dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis and increased susceptibility to later-life psychopathology. Specifically, there is mounting evidence suggesting that the immune system plays an important role in central nervous system (CNS) development and in the programing of behavior. The current study investigated how early-life immune challenge affects the development of CNS stress neurocircuitry by examining the gene expression profile of corticotropin-releasing hormone (CRH), CRH receptors, and the major corticosteroid receptors within the limbic-hypothalamic circuit of the developing rodent brain. Mice were administered a 0.05mg/kg lipopolysaccharide (LPS) injection on postnatal day (P) 3 and 5 and gene expression was assessed using in situ hybridization from P14 to P28. Target genes investigated were CRH, CRH receptor-1 (CRHR1), CRH receptor-2, the mineralocorticoid receptor, and the glucocorticoid receptor (GR). Early LPS challenge resulted in a transient decrease in CRHR1 mRNA expression in the cornuammonis 1 (CA1) and CA3 regions of the hippocampus that were accompanied by increased hippocampal GR mRNA expression in the CA1 region between P14 and P21. This was followed by increased hypothalamic CRH expression in LPS-mice on P28. Our current findings suggest that early-life LPS challenge impacts the developmental trajectory of CNS stress neurocircuitry. These results lend insight into the molecular basis for the later development of stress-related behaviors as previously described in early immune challenge rodents.

Transgenerational Effects of Prenatal Synthetic Glucocorticoids on Hypothalamic-Pituitary-Adrenal Function

Approximately 10% of pregnant women are at risk of preterm delivery and receive synthetic glucocorticoids (sGC) to promote fetal lung development. Studies have indicated that prenatal sGC therapy modifies hypothalamic-pituitary-adrenal (HPA) function in first-generation (F1) offspring. The objective of this study was to determine whether differences in HPA function and behavior are evident in the subsequent (F2) generation. Pregnant guinea pigs (F0) received betamethasone (BETA; 1 mg/kg) or saline on gestational d 40/41, 50/51, and 60/61. F1 females were mated with control males to create F2 offspring. HPA function was assessed in juvenile and adult F2 offspring. Locomotor activity was assessed in juvenile offspring. Analysis of HPA-related gene expression was undertaken in adult hippocampi, hypothalami, and pituitaries. Locomotor activity was reduced in F2 BETA males (P < 0.05). F2 BETA offspring displayed blunted cortisol response to swim stress (P < 0.05). After dexamethasone challenge, F2 BETA males and females displayed increased and decreased negative feedback, respectively. F2 BETA females had reduced pituitary levels of proopiomelanocortin (and adrenocorticotropic hormone), and corticotropin-releasing hormone receptor mRNA and protein (P < 0.05). F2 BETA males displayed increased hippocampal glucocorticoid receptor (P < 0.001), whereas in BETA females, hippocampal glucocorticoid receptor and mineralocorticoid receptor mRNA were decreased (P < 0.05). In conclusion, prenatal BETA treatment affects HPA function and behavior in F2 offspring. In F2 BETA females, pituitary function appears to be primarily affected, whereas hippocampal glucocorticoid feedback systems appear altered in both F2 BETA males and females. These data have clinical implication given the widespread use of repeat course glucocorticoid therapy in the management of preterm labour.

Substance P (SP) Induces Expression of Functional Corticotropin-Releasing Hormone Receptor-1 (CRHR-1) in Human Mast Cells

Corticotropin-releasing hormone (CRH) is secreted under stress and regulates the hypothalamic-pituitary-adrenal (HPA) axis. However, CRH is also secreted outside the brain where it exerts pro-inflammatory effects through activation of mast cells, which are increasingly implicated in immunity and inflammation. Substance P (SP) is also involved in inflammatory diseases. Human LAD2 leukemic mast cells express only CRHR-1 mRNA weakly. Treatment of LAD2 cells with SP (0.5–2 µM) for 6 hr significantly increases CRHR-1 mRNA and protein expression. Addition of CRH (1 µM) to LAD2 cells “primed” with SP for 48 hr and then washed, induces synthesis and release of IL-8, tumor necrosis factor (TNF) and vascular endothelial growth factor (VEGF) 24 hr later. These effects are blocked by pretreatment with an NK-1 receptor antagonist. Treatment of LAD2 cells with CRH (1 µM) for 6 hr induces gene expression of NK-1 as compared to controls. However, repeated stimulation of mast cells with CRH (1 µM) leads to downregulation of CRHR-1 and upregulation in NK-1 gene expression. These results indicate that SP can stimulate mast cells and also increase expression of functional CRHR-1, while CRH induces NK-1 gene expression. These results may explain CRHR-1 and NK-1 expression in lesional skin of psoriatic patients.

Corticotropin-releasing hormone downregulates IL-10 production by adaptive forkhead box protein 3–negative regulatory T cells in patients with atopic dermatitis

Corticotropin-releasing hormone (CRH) is the central regulating hormone of the hypothalamic-pituitary-adrenal axis. CRH also has diverse functional effects in the periphery and is related to the aggravation of several cutaneous diseases; however, the effect of CRH on T cells in patients with atopic dermatitis (AD) has not been well evaluated. We investigated whether CRH directly affects peripheral T(H)1, T(H)2, and regulatory T (Treg) cells in patients with AD. We assessed whether T cells express the CRH receptor protein and mRNA by using flow cytometry, Western blotting, immunofluorescence, immunohistochemistry, and RT-PCR. We evaluated cytokine expression using ELISA after treating the T cells extracted from patients with AD and healthy control subjects (HCs) with CRH. Flow cytometry was then used to evaluate any direct effects of CRH on T(H)1, T(H)2, and Treg cells from patients with AD and HCs. T cells from patients with AD expressed significantly lower CRH receptor 1/2 mRNA levels than T cells from HCs. T cells from HCs reacted with different IL-4 and IFN-γ secretions to CRH treatment, whereas T cells from patients with AD did not. IL-10 production was significantly decreased in the supernatants from both the HCs and patients with AD after CRH treatment. CRH upregulated IL-4 production by T(H)2 cells and downregulated IFN-γ production by T(H)1 cells in HCs. CRH also suppressed the production of IL-10 by forkhead box protein 3-negative Treg cells in both groups, but the difference was only significant in patients with AD. CRH-mediated suppression of IL-10 secretion from Treg cells might explain stress-related exacerbations in patients with AD.

Sex differences in prenatally programmed anxiety behaviour in rats: Differential corticotropin-releasing hormone receptor mRNA expression in the amygdaloid complex

We recently reported that male, but not female, offspring born to mothers exposed to social stress during late gestation show heightened anxiety-type behaviour in adulthood. The amygdala organises anxious behaviour, which involves actions of corticotropin-releasing hormone (CRH). CRH gene expression and/or its release are increased in the amygdala in prenatally stressed (PNS) rats. CRH type 1 receptor (CRH-R1) mediates actions of CRH and urocortin I to promote anxiety-like behaviour, whereas the CRH type 2 receptor (CRH-R2) may mediate anxiolytic actions, through actions of urocortins 2 and 3. Here, using quantitative in situ hybridisation, we investigated whether altered CRH receptor mRNA expression in the amygdaloid nuclei may explain the sex differences in anxiety behaviour in adult male and female PNS rats. CRH-R1 mRNA expression was significantly greater in the central amygdala and basolateral amygdala (BLA) in male PNS rats compared with controls, with no change in the basomedial amygdala (BMA) or medial amygdala (MeA). In PNS females, CRH-R1 mRNA expression was greater than controls only in the MeA. Conversely, CRH-R2 mRNA expression was significantly lower in the BMA of male PNS rats compared with controls, but greater in female PNS rats, with no change in the BLA or MeA in either sex. The ratio of CRH-R1:CRH-R2 mRNA in the amygdaloid nuclei was generally increased in PNS males, but not in the PNS females. In conclusion, sex differences in anxiety-type behaviour in PNS rats may be explained by differential mRNA expression for CRH-R1 (pro-anxiogenic) and CRH-R2 (pro-anxiolytic) in the amygdaloid complex.

Effect of Animal Facility Construction on Basal Hypothalamic-Pituitary-Adrenal and Renin-Aldosterone Activity in the Rat

Although loud noise and intense vibration are known to alter the behavior and phenotype of laboratory animals, little is known about the effects of nearby construction. We studied the effect of a nearby construction project on the classic stress hormones ACTH, corticosterone, renin, and aldosterone in rats residing in a barrier animal facility before, for the first 3 months of a construction project, and at 1 month after all construction was completed. During some of the construction, noise and vibrations were not obvious to investigators inside the animal rooms. Body weight matched for age was not altered by nearby construction. During nearby construction, plasma ACTH, corticosterone, and aldosterone were approximately doubled compared with those of pre- and postconstruction levels. Expression of CRH mRNA in the paraventricular nucleus of the hypothalamus, CRH receptor and POMC mRNA in the anterior pituitary, and most mRNAs for steroidogenic genes in the adrenal gland were not significantly changed during construction. We conclude that nearby construction can cause a stress response without long-term effects on hypothalamic-pituitary-adrenal axis gene expression and body weight.

Changes in Placental CRH, Urocortins, and CRH-Receptor mRNA Expression Associated with Preterm Delivery and Chorioamnionitis

The pathogenesis of preterm delivery (PTD) is not clear, although inflammation/infection play a major role. Corticotropin releasing-hormone (CRH) and Urocortins (Ucns) are involved in the pathophysiology of PTD. This study evaluates trophoblast mRNA expression of CRH, Ucn, Ucn2, Ucn3, and their receptors [CRH-type 1 receptor (CRH-R1), CRH-R2] in infective conditions. To determine whether infection or glucocorticoids contribute to change their placental mRNA expression, the effects of lipopolysaccharide or dexamethasone was evaluated. Placentas were obtained from spontaneous PTD; premature rupture of membranes (pPROM) and pPROM with chorioamnionitis. Placental specimens were collected from women receiving perinatal care at our Division of Obstetrics and Gynecology. Pregnant women delivered preterm were enrolled. mRNA expression was evaluated by RT-PCR. Because CRH and Ucns are involved in immunological functions we evaluated their involvement in PTD with or without infection. CRH, Ucn2, and CRH-R1 mRNA expression were higher, while Ucn and CRHR-2 were lower in pPROM with chorioamnionitis than in PTD and pPROM. Ucn3 mRNA expression was lower in pPROM with and without chorioamnionitis than in PTD. The addition of lipopolysaccharide in trophoblast explants decreased Ucn, Ucn3, and CRH-R2 and increased CRH, Ucn2, and CRH-R1 mRNA expression in a dose-dependent manner. Dexamethasone increased CRH and decreased Ucn2 mRNA expression in a dose dependent manner. Our findings showed a significant impact of pPROM with chorioamnionitis on placental CRH peptides and receptors, suggesting that placental expression of stress-related pathways is activated in infective process.

Influence of trichloroacetic acid peeling on the skin stress response system

Although trichloroacetic acid (TCA) peeling is widely applied for cosmetic treatment of photodamaged skin, the entire biological mechanisms have yet to be determined. The skin stress response system (SSRS) involves corticotropin-releasing hormone (CRH) and proopiomelanocortin (POMC) products that are locally-generated in response to locally-provided stressors or pro-inflammatory cytokines. This system would restrict tissue damage and restore local homeostasis. To determine the influence of TCA peeling on the SSRS in vitro and in vivo, expressions of POMC, melanocortin receptor 1 (MC1R), CRH and CRH receptor 1 (CRHR1) mRNA were examined by reverse transcription polymerase chain reaction in Pam212 murine keratinocytes, murine plantar and healthy human abdominal skin specimens after TCA treatment. In addition, their protein expressions as well as those of POMC-derived peptides were examined immunohistochemically. After TCA treatment, transient upregulation of POMC and MC1R mRNA expressions was observed in both murine and human skin, as well as in Pam212. Enhanced POMC protein, recovery of once-impaired MC1R protein, and no enhancement of POMC-derived peptide productions were revealed immunohistochemically in both murine and human epidermis. In contrast, neither expression levels of CRH and CRHR1 mRNA nor epidermal protein were enhanced after TCA application in murine and human skin, except for induction of human CRH mRNA expression. These results suggest that TCA activates the SSRS by inducing POMC and MC1R productions of keratinocytes in the CRH-independent manner, and that the biological effects of POMC itself are responsible for the TCA-induced epidermal SSRS activation.

Expression of genes related to corticotropin production and glucocorticoid feedback in corticotroph adenomas of dogs with Cushing’s disease

Cushing’s disease caused by pituitary corticotroph adenoma is a common endocrine disease in dogs. A characteristic biochemical feature of corticotroph adenomas is their relative resistance to negative feedback by glucocorticoids. In this study, we examined gene expression related to adrenocorticotropic hormone (ACTH) production and secretion, and the negative feedback by glucocorticoids in canine corticotroph adenoma. We used resected corticotroph adenomas from 10 dogs with Cushing’s disease. In order to investigate the alteration of gene expression between corticotroph adenoma and normal corticotrophic cells, ACTH-positive cells in the anterior lobe were microdissected using a laser-capture microdissection system, and mRNA levels of proopiomelanocortin (POMC), corticotropin releasing hormone receptor 1 (CRHR1), glucocorticoid receptor (GR), mineralocorticoid receptor (MR), and 11 beta hydroxysteroid dehydrogenase (11HSD) type 1 and type 2 were determined using real-time RT-PCR. POMC, CRHR1, and 11HSD2 mRNA levels in corticotroph adenoma were greater than those in normal corticotrophic cells (POMC, 5.5-fold; CRHR1, 4.9-fold; 11HSD2, 4.2-fold, P < 0.01, respectively). MR and 11HSD1 mRNA levels in corticotroph adenoma were lower than those in normal corticotrophic cells (MR, 2.2-fold; 11HSD1, 2.9-fold, P < 0.01, respectively). GR mRNA levels did not differ between corticotroph adenoma and normal corticotrophic cells. Our results may help to understand the increased ACTH production and the resistance to negative feedback suppression by glucocorticoids in canine corticotroph adenomas. These changes in gene expression may have a role in the growth of canine corticotroph adenoma, and help elucidate the pathophysiology of dogs with Cushing’s disease.

Differential gene expression in ACTH -secreting and non-functioning pituitary tumors

Differential expression of several genes between ACTH-secreting pituitary tumors causing Cushing' disease (CD), silent corticotroph adenoma (SCA), and non-functioning pituitary tumors (NFT) was investigated. We used tissue specimens from 35 pituitary tumors (12 CD, 8 SCA, and 15 NFT). Steady-state mRNA levels of the genes related to proopiomelanocortin (POMC) transcription, synthesis, processing, and secretion, such as neurogenic differentiation 1 (NeuroD1), T-box 19 (Tpit), corticotropin releasing hormone receptor (CRHR), vasopressin receptor 1b (V1bR), prohormone convertase (PC) 1/3 and PC2, 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 and type 2, glucocorticoid receptor alpha (GRalpha), annexin A1, histone deacetylase 2 (HDAC2), and BRM/SWI2-related gene 1, were determined by real-time RT-PCR. POMC and Tpit mRNA levels were greater in CD and SCA than those in NFT. NeuroD1 mRNA levels were less in CD than those in NFT, but almost comparable between SCA and NFT. PC1/3 mRNA levels were greater in CD, but less in SCA than those in NFT. PC2 mRNA levels in CD and SCA were less than those in NFT. CRHR, V1bR, and 11beta-HSD2 mRNA levels in CD were greater than those in SCA and NFT. HDAC2 mRNA levels in CD and SCA were lower than those in NFT. In conclusion, our study demonstrated that the genes related to transcription, synthesis, processing, and secretion of POMC are differentially regulated in ACTH-secreting pituitary tumors causing CD and SCA compared with those in NFT. This may partly explain the development of clinically active and inactive CD.

Corticotropin-releasing hormone (CRH) regulates macromolecular permeability via mast cells in normal human colonic biopsies in vitro

Objective:Persistent stress and life events affect the course of ulcerative colitis and irritable bowel syndrome by largely unknown mechanisms. Corticotropin-releasing hormone (CRH) has been implicated as an important mediator of...

Corticotropin releasing hormone receptor alterations elicited by acute and chronic unpredictable stressor challenges in stressor-susceptible and resilient strains of mice

Stressors increase corticotropin releasing hormone (CRH) functioning in hypothalamic and frontal cortical brain regions, and thus may contribute to the provocation of anxiety and depressive disorder. As the effects of stressors on these behavioral changes are more pronounced in some strains of mice (e.g., BALB/cByJ) than in others (e.g., C57BL/6ByJ), the present investigation assessed whether acute and chronic stressors would differentially influence CRH receptor immunoreactivity (ir-CRHr) and CRH receptor mRNA expression (CRH 1 and CRH 2) in the orbital frontal cortex (OFC) of these strains. An acute noise stressor, and to a greater extent a chronic, variable stressor regimen reduced ir-CRHr in BALB/cByJ mice. In contrast, in the hardier C57BL/6ByJ mice the acute stressor increased ir-CRHr in portions of the OFC, whereas a chronic stressor tended to reduce ir-CRHr. However, whereas the acute stressor did not influence CRH 1 mRNA expression, the chronic stressor increased CRH 1 mRNA expression in both mouse strains. The CRH 2 expression appeared in low abundance in both strains and was unaltered by the stressor. In addition to the OFC variations, quantitative immunohistochemistry indicated that the chronic stressor treatment increased CRH immunoreactivity in the median eminence of C57BL/6ByJ mice, but co-expression of CRH and arginine vasopressin (AVP) immunoreactivity was not provoked by the stressors. The data support the view that stressors provoke marked variations of ir-CRHr in the OFC that might contribute to the differential anxiety/depression-like profiles ordinarily apparent in the stressor-vulnerable and -resilient mouse strains.

Corticotropin-Releasing Hormone (CRH) and Urocortin Act through Type 1 CRH Receptors to Stimulate Dehydroepiandrosterone Sulfate Production in Human Fetal Adrenal Cells

Near term, the human fetal adrenal increases the production of cortisol and dehydroepiandrosterone sulfate (DHEAS). DHEAS, which acts as substrate for placental estrogen production, induces key changes involved in parturition. The objective of this study was to determine quantitatively the effect of CRH on mRNA levels of enzymes needed for DHEAS production (steroidogenic acute regulatory protein, CYP11A, CYP17, and SULT2A1), to determine the CRH receptor (CRH-R) subtype(s) responsible for CRH action, and to determine the effect of CRH on CRH-R mRNA expression in human adrenal fetal zone (FZ) cells. Human adrenal FZ cells were treated with CRH, ACTH, urocortin (Unc), and CRH antagonists, and RNA was analyzed by microarray and real-time RT-PCR. This study was performed at an academic research laboratory. The main outcome measure was the expression of steroidogenic enzymes and CRH-R. Microarray analysis of human FZ cells treated for 24 h with CRH or ACTH showed increased mRNA expression levels of the genes needed for DHEAS production. Real-time RT-PCR analysis confirmed these data. Induction was lost in the presence of CRH-R1 antagonists, but not CRH-R2 antagonists. Stimulation was reproduced by Unc. The CRH-R1alpha mRNA splice variant was the only type 1 receptor isoform expressed in the fetal adrenal, and treatment with CRH up-regulates its mRNA levels. CRH, Unc, and ACTH stimulate all elements of the DHEAS synthetic pathway and activate CRH-R1 as well. The resulting increased DHEAS levels can be used for placental estrogen synthesis and contribute to the process leading to parturition in humans.

Plasma leptin and ghrelin in the neonatal rat: interaction of dexamethasone and hypoxia

Ghrelin, leptin, and endogenous glucocorticoids play a role in appetite regulation, energy balance, and growth. The present study assessed the effects of dexamethasone (DEX) on these hormones, and on ACTH and pituitary proopiomelanocortin (POMC) and corticotropin-releasing hormone receptor-1 (CRHR1) mRNA expression, during a common metabolic stress - neonatal hypoxia. Newborn rats were raised in room air (21% O2) or under normobaric hypoxia (12% O2) from birth to postnatal day (PD) 7. DEX was administered on PD3 (0.5 mg/kg), PD4 (0.25 mg/kg), PD5 (0.125 mg/kg), and PD6 (0.05 mg/kg). Pups were studied on PD7 (24 h after the last dose of DEX). DEX significantly increased plasma leptin and ghrelin in normoxic pups, but only increased ghrelin in hypoxic pups. Hypoxia alone resulted in a small increase in plasma leptin. Plasma corticosterone and pituitary POMC mRNA expression were decreased 24 h following the last dose of DEX, whereas plasma ACTH and pituitary CRHR1 mRNA expression had already increased (normoxia and hypoxia). Hypoxia alone increased corticosterone, but had no effect on ACTH or pituitary POMC and CRHR1 mRNA expression. Neonatal DEX treatment, hypoxia, and the combination of both affect hormones involved in energy homeostasis. Pituitary function in the neonate was quickly restored following DEX-induced suppression of the hypothalamic-pituitary-adrenal axis. The changes in ghrelin, leptin, and corticosterone may be beneficial to the hypoxic neonate through the maintenance of appetite and shifts in intermediary metabolism.

Stress-related gene expression in brain and adrenal gland of porcine fetuses and neonates

This study was conducted to examine stress-induced effects on gene expression of specific markers for HPA axis and neuronal activity in fetuses and neonatal pigs. Brain, pituitary gland, and adrenal gland were obtained to determine the mRNA levels for corticotropin-releasing hormone (CRH), CRH receptor 1 (CRHR1), pro-opiomelanocortin (POMC), ACTH receptor (MC2R), c-jun and c-fos. The suitability of these molecular markers was determined in neonatal pigs which were maternally deprived for two hours. It was found that maternal deprivation caused significantly higher transcript levels of c-fos and CRH in brain accompanied by a down-regulation of CRHR1 mRNA and an up-regulation of c-jun in the pituitary gland. To determine the effect of elevated maternal cortisol levels on gene expression of these molecular markers in fetuses, pregnant sows were treated with 100 IU ACTH (Synacthen ® Depot) s.c. every two days between Day 49 and Day 75 of gestation (normal gestation length 114 days). Animals were killed 48 hours after the last ACTH administration and fetuses of each sow were isolated. The ACTH treatment of sows significantly increased mRNA expression of c-fos but not of CRH in the fetal brain, and significantly decreased MC2R mRNA expression in the adrenal gland. However, HPA axis seems not to be fully developed in Day 77-fetuses because fetal pituitary CRHR1 and POMC mRNA expression was low in most of the fetuses. Although the expression of endocrine regulatory factors was partially incomplete in fetuses at the beginning of the third-trimester, ACTH dependent activation of c-fos mRNA in brain indicates a stress-related increase of neuronal activity. Based on these results it is assumed that prenatal stress in pigs may also have effects on the activity of the HPA axis in the offspring.