Corticotropin-releasing Factor Concentrations Research Articles

Mechanisms of Peitu Yimu acupuncture in repairing intestinal mucosal barrier by regulating CRF/CRFR1 pathway in diarrhea-predominant irritable bowel syndrome rats.

To investigate the effect of Peitu Yimu(strengthening spleen and soothing liver) acupuncture on intestinal mucosal barrier function and corticotropin-releasing factor (CRF)/CRF receptor 1 (CRFR1) pathway in rats with diarrhea-predominant irritable bowel syndrome (IBS-D), so as to explore its underlying mechanism in alleviating IBS-D. Forty female SD rats were randomly divided into blank, model, electroacupuncture (EA), and agonist groups, with 10 rats in each group. Except for the blank group, rats in the other groups were given folium sennae infusion by gavage combined with chronic unpredictable mild stress to establish IBS-D model. Rats in the EA group received acupuncture at "Tianshu"(ST25) and EA at "Zusanli"(ST36) and "Taichong"(LR3) (2 Hz/15 Hz) on one side for 20 min, with the side chosen alternately every other day, for 14 days after modeling. Rats in the agonist group received acupuncture 30 min after intravenous injection of CRFR1 agonist urocortin, with the same manipulation method and time as the EA group. Before and after intervention, visceral pain threshold and stool Bristol scores were measured. Elevated plus maze test and open field test were used to detect anxiety and depression like behavior of rats. ELISA was used to detect the contents of CRF and CRFR1 in rats serum. Immunohistochemistry was used to detect the positive expressions of CRF, CRFR1, zonula occludens protein 1(ZO-1), occlusal protein(Occludin), and closure protein 1 (Claudin-1) in colon tissue. Compared with the blank group, the visceral pain threshold, open arm time percentage (OT%), total distance of movement in the open field test, and positive expression of ZO-1, Occludin, and Claudin-1 in colon were decreased (P<0.01, P<0.05), while Bristol stool scores, serum CRF and CRFR1 contents, and positive expressions of CRF and CRFR1 in colon were increased (P<0.01) in the model group. After intervention and compared with the model group, the visceral pain threshold, OT%, total distance of movement in the open field test, and positive expressions of ZO-1, Occludin, and Claudin-1 in colon were increased (P<0.05, P<0.01), while Bristol stool scores, serum CRF and CRFR1 contents, and positive expressions of CRF and CRFR1 in colon were decreased (P<0.01) in the EA group；the Bristol stool scores, serum CRF content, and CRF positive expression in colon were significantly decreased in the agonist group (P<0.01). Peitu Yimu acupuncture can significantly improve visceral hypersensitivity and anxiety-depression state in IBS-D rats. Its mechanism may be related to the inhibition of CRF/CRFR1 pathway and restoration of intestinal tight junction protein expressions.

The Effects of Alcohol Intoxication and Withdrawal on Hypothalamic Neurohormones and Extrahypothalamic Neurotransmitters.

The aim of the present study was to determine the effects of alcohol intoxication and withdrawal on hypothalamic neurohormones such as corticotropin-releasing factor (CRF) and arginine vasopressin (AVP), and extrahypothalamic neurotransmitters such as striatal dopamine (DA), amygdalar gamma aminobutyric acid (GABA), and hippocampal glutamate (GLU). In addition, the participation of the two CRF receptors, CRF1 and CRF2, was investigated. For this purpose, male Wistar rats were exposed to repeated intraperitoneal (ip) administration of alcohol every 12 h, for 4 days and then for 1 day of alcohol abstinence. On the fifth or sixth day, intracerebroventricular (icv) administration of selective CRF1 antagonist antalarmin or selective CRF2 antagonist astressin2B was performed. After 30 min, the expression and concentration of hypothalamic CRF and AVP, the concentration of plasma adrenocorticotropic hormone (ACTH) and corticosterone (CORT), and the release of striatal DA, amygdalar GABA, and hippocampal GLU were measured. Our results indicate that the neuroendocrine changes induced by alcohol intoxication and withdrawal are mediated by CRF1, not CRF2, except for the changes in hypothalamic AVP, which are not mediated by CRF receptors.

Juvenile social isolation affects the structure of the tanycyte–vascular interface in the hypophyseal portal system of the adult mice

Accumulating evidence indicates that social stress in the juvenile period affects hypothalamic–pituitary–adrenal (HPA) axis activity in adulthood. The biological mechanisms underlying this phenomenon remain unclear. We aimed to elucidate them by comparing adult mice that had experienced social isolation from postnatal day 21–35 (juvenile social isolation (JSI) group) with those reared normally (control group). JSI group mice showed an attenuated HPA response to acute swim stress, while the control group had a normal response to this stress. Activity levels of the paraventricular nucleus in both groups were comparable, as shown by c-Fos immunoreactivities and mRNA expression of c-Fos, Corticotropin-releasing factor (CRF), Glucocorticoid receptor, and Mineralocorticoid receptor. We found greater vascular coverage by tanycytic endfeet in the median eminence of the JSI group mice than in that of the control group mice under basal condition and after acute swim stress. Moreover, CRF content after acute swim stress was greater in the median eminence of the JSI group mice than in that of the control group mice. The attenuated HPA response to acute swim stress was specific to JSI group mice, but not to control group mice. Although a direct link awaits further experiments, tanycyte morphological changes in the median eminence could be related to the HPA response.

Corticotropin-releasing factor is involved in acute stress-induced analgesia and antipruritus.

Under the condition of stress, the hypothalamic-pituitary-adrenal axis (HPA axis) is activated and causes the secretion of corticotropin-releasing factor (CRF). Previous studies have demonstrated that CRF is involved in the regulation of pain and itch. Thus, it remains worthy to explore whether the desensitization of pain and itch under high-intensity acute stress (such as high fear and tension) is related to the sharp increase of CRF. Forced swimming was used to simulate acute stress. ELISA and pharmacological methods were conducted to observe the effects of forced swimming on acute pain or itch and the relationship between blood CRF content and itch or pain behavior. Intracerebroventricular (ICV) administration of CRF was conducted to examine the effects of CRF on acute pain or itch. Intrathecal administration of CRF receptor agonist or antagonist was conducted to examine the receptor mechanisms of the regulatory role of CRF in pain and itch. ELISA experiment showed that the serum CRF in mice reached its peak within 5-10 min after acute stress (forced swimming). Behavioral data showed that the scratching behavior induced by itch agents decreased after acute swimming, while the mechanical pain threshold increased significantly. The inhibitory effect of acute stress on pain and itch is mediated by CRF receptor2 (CRFR2). Then, ICV injection of CRF was used to simulate the massive release of CRF under acute stress, and we observed that the scratching behavior induced by histamine or chloroquine was significantly inhibited after ICV injection of CRF. The above effects of CRF are mainly mediated by CRFR2. These results suggest that 5-10min after acute stress, a large amount of CRF is released into the blood from the hypothalamus, which significantly inhibits acute pain and itch by acting on CRFR2. ICV injection of CRF can replicate the antipruritus effects of acute stress. The present study investigated the mechanism of acute stress-induced analgesia and antipruritus and provided theoretical support for the treatment of pain and itch.

Superior control of inflammatory pain by corticotropin-releasing factor receptor 1 via opioid peptides in distinct pain-relevant brain areas

BackgroundUnder inflammatory conditions, the activation of corticotropin-releasing factor (CRF) receptor has been shown to inhibit pain through opioid peptide release from immune cells or neurons. CRF’s effects on human and animal pain modulation depend, however, on the distribution of its receptor subtypes 1 and 2 (CRF-R1 and CRF-R2) along the neuraxis of pain transmission. The objective of this study is to investigate the respective role of each CRF receptor subtype on centrally administered CRF-induced antinociception during inflammatory pain.MethodsThe present study investigated the role of intracerebroventricular (i.c.v.) CRF receptor agonists on nociception and the contribution of cerebral CRF-R1 and/or CRF-R2 subtypes in an animal model of Freund’s complete adjuvant (FCA)-induced hind paw inflammation. Methods used included behavioral experiments, immunofluorescence confocal analysis, and reverse transcriptase-polymerase chain reaction.ResultsIntracerebroventricular, but systemically inactive, doses of CRF elicited potent, dose-dependent antinociceptive effects in inflammatory pain which were significantly antagonized by i.c.v. CRF-R1-selective antagonist NBI 27914 (by approximately 60%) but less by CRF-R2-selective antagonist K41498 (by only 20%). In line with these findings, i.c.v. administration of CRF-R1 agonist stressin I produced superior control of inflammatory pain over CRF-R2 agonist urocortin-2. Intriguingly, i.c.v. opioid antagonist naloxone significantly reversed the CRF as well as CRF-R1 agonist-elicited pain inhibition. Consistent with existing evidence of high CRF concentrations in brain areas such as the thalamus, hypothalamus, locus coeruleus, and periaqueductal gray following its i.c.v. administration, double-immunofluorescence confocal microscopy demonstrated primarily CRF-R1-positive neurons that expressed opioid peptides in these pain-relevant brain areas. Finally, PCR analysis confirmed the predominant expression of the CRF-R1 over CRF-R2 in representative brain areas such as the hypothalamus.ConclusionTaken together, these findings suggest that CRF-R1 in opioid-peptide-containing brain areas plays an important role in the modulation of inflammatory pain and may be a useful therapeutic target for inflammatory pain control.

Locus Coeruleus Noradrenergic Modulation of Diurnal Corticosterone, Stress Reactivity, and Cardiovascular Homeostasis in Male Rats

Introduction: Activation of the locus coeruleus-noradrenergic (LC-NA) system during awakening is associated with an increase in plasma corticosterone and cardiovascular tone. These studies evaluate the role of the LC in this corticosterone and cardiovascular response. Methods: Male rats, on day 0, were treated intraperitoneally with either DSP4 (50 mg/kg body weight) (DSP), an LC-NA specific neurotoxin, or normal saline (SAL). On day 10, animals were surgically prepared with jugular vein (hypothalamic-pituitary-adrenal [HPA] axis) or carotid artery (hemodynamics) catheters and experiments performed on day 14. HPA axis activity, diurnally (circadian) and after stress (transient hemorrhage [14 mL/kg body weight] or air puff-startle), and basal and post-hemorrhage hemodynamics were evaluated. On day 16, brain regions from a subset of rats were dissected for norepinephrine and corticotropin-releasing factor (CRF) assay. Results: In DSP rats compared to SAL rats, (1) regional brain norepinephrine was decreased, but there was no change in median eminence or olfactory bulb CRF content; (2) during HPA axis acrophase, the plasma corticosterone response was blunted; (3) after hemorrhage and air puff-startle, the plasma adrenocorticotropic hormone response was attenuated, whereas the corticosterone response was dependent on stressor category; (4) under basal conditions, hemodynamic measures exhibited altered blood flow dynamics and systemic vasodilation; and (5) after hemorrhage, hemodynamics exhibited asynchronous responses. Conclusion: LC-NA modulation of diurnal and stress-induced HPA axis reactivity occurs via distinct neurocircuits. The integrity of the LC-NA system is important to maintain blood flow dynamics. The importance of increases in plasma corticosterone at acrophase to maintain short- and long-term cardiovascular homeostasis is discussed.

Overexpression of corticotropin-releasing factor in intestinal mucosal eosinophils is associated with clinical severity in Diarrhea-Predominant Irritable Bowel Syndrome

Corticotropin-releasing factor (CRF) has been identified in intestinal mucosal eosinophils and associated with psychological stress and gut dysfunction. Irritable bowel syndrome (IBS) is commonly characterized by altered intestinal motility, immune activation, and increased gut barrier permeability along with heightened susceptibility to psychosocial stress. Despite intensive research, the role of mucosal eosinophils in stress-associated gut dysfunction remains uncertain. In this study, we evaluated eosinophil activation profile and CRF content in the jejunal mucosa of diarrhea-predominant IBS (IBS-D) and healthy controls (HC) by gene/protein expression and transmission electron microscopy. We also explored the association between intestinal eosinophil CRF and chronic stress, and the potential mechanisms underlying the stress response by assessing eosinophil response to neuropeptides. We found that mucosal eosinophils displayed higher degranulation profile in IBS-D as compared to HC, with increased content of CRF in the cytoplasmic granules, which significantly correlated with IBS clinical severity, life stress background and depression. Eosinophils responded to substance P and carbachol by increasing secretory activity and CRF synthesis and release, without promoting pro-inflammatory activity, a profile similar to that found in mucosal eosinophils from IBS-D. Collectively, our results suggest that intestinal mucosal eosinophils are potential contributors to stress-mediated gut dysfunction through CRF production and release.

The effects of the urocortins on the hypothalamic-pituitary-adrenal axis - similarities and discordancies between rats and mice

The urocortins (Ucn I, Ucn II and Ucn III) are structural analogues of corticotropin-releasing factor (CRF). The aim of our present experiments was to compare the effects of the urocortins on the hypothalamic-pituitary-adrenal (HPA) axis in rats and mice, including the hypothalamic adrenocorticotropic hormone (ACTH) secretagogues, such as CRF and arginine vasopressin (AVP). Therefore, male CFLP mice and male Wistar rats were injected intracerebroventricularly (icv) with 0.5, 1, 2 and 5 μg/2 μl of Ucn I, Ucn II or Ucn III. After 30 min the animals were decapitated, and then, hypothalamic CRF and AVP concentrations and plasma ACTH and corticosterone (CORT) levels were measured. All measurements were performed by enzyme-linked immunosorbent assays (ELISA), except that of the plasma CORT level, which was determined by chemofluorescent assay. Ucn I increased significantly the hypothalamic CRF and AVP concentrations in both rats and mice. Ucn II and Ucn III influenced significantly only the hypothalamic CRF concentration in rats, without affecting the hypothalamic AVP concentration. In contrast, Ucn II and Ucn III increased significantly only the hypothalamic AVP concentration in mice, without affecting the hypothalamic CRF concentration. The hypothalamic changes were reflected more or less accurately by changes of the plasma ACTH and CORT levels. The present experiments demonstrate that the urocortins regulate the HPA axis centrally via modulation of the hypothalamic ACTH secretagogues and that there are some similarities and discordancies between rats and mice regarding this regulation.

Reciprocal Interaction between Hypothalamic Orexin‐A and Corticotropin‐releasing Factor under Stressed Condition

In response to stressful stimuli, expression of orexin‐A (OXA) is increased within central nervous system. The orexinergic cells reside in lateral hypothalamic area (LHA) have dense projections on hypothalamic paraventricular nucleus (PVN), furthermore, corticotropin‐releasing factor (CRF) receptors are expressed in orexin‐producing neurons within LHA. However, the interaction between these neuropeptides is understood incompletely. Using acute restraint stress (ARS) model in rats, the purpose of the present study was designed to investigate (i) the interaction between hypothalamic OXA and CRF, and (ii) the contribution hypothalamic OXA in CRF‐mediated glucocorticoid release. Adult male Wistar rats underwent stereotaxic cannulation for intracerebroventricular (icv) drug injection and microdialysis 7 days prior to the experiments. Under basal and stressed conditions, microdialysis samples were collected from LHA and PVN to monitor the alterations in OXA and CRF, respectively, whereas, their antagonists were administered centrally prior to the stress loading. The immunoreactivities for both neuropeptides were detected in hypothalamic sections by immunohistochemistry. The corticosterone (CORT) concentrations in plasma samples were assayed using enzyme immunoassay. Compared to their basal levels, OXA and CRF concentrations in microdialysates were increased in ARS‐loaded rats, while they were attenuated significantly by the receptor antagonists. ARS increased the immunoreactivities for OXA and CRF in hypothalamus remarkably, while increasing the plasma CORT. Central preadministration of the antagonists reduced the ARS‐induced increased hypothalamic immunoreactivites and plasma CORT. Under stressed condition, OXA and CRF seem to play in a synergistic signaling pathway through their specific receptors. The endogenous hypothalamic OXA appears to contribute to the CRF‐mediated neuroendocrine stress response. The interaction between OXA and CRF may lead to better understanding of the etiopathogenesis of stress‐related disorders.Support or Funding InformationThe present study was supported by the Research Foundation of Akdeniz University (Project number: TSA‐2017‐2418)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Early Life Stress Associated With Increased Striatal N-Acetyl-Aspartate: Cerebrospinal Fluid Corticotropin-Releasing Factor Concentrations, Hippocampal Volume, Body Mass, and Behavioral Correlates

Introduction Using proton magnetic resonance spectroscopy imaging, the effects of early life stress on nonhuman primate striatal neuronal integrity were examined as reflected by N-acetyl aspartate (NAA) concentrations. NAA measures were interrogated through examining their relationship to previously documented early life stress markers—cerebrospinal fluid corticotropin-releasing factor concentrations, hippocampal volume, body mass, and behavioral timidity. Rodent models of depression exhibit increases in neurotrophic effects in the nucleus accumbens. We hypothesized that rearing under conditions of early life stress (variable foraging demand, VFD) would produce persistent elevations of NAA concentrations (in absolute or ratio form) in ventral striatum/caudate nucleus (VS/CN) with altered correlation to early life stress markers. Methods Eleven bonnet macaque males reared under VFD conditions and seven age-matched control subjects underwent proton magnetic resonance spectroscopy imaging during young adulthood. Voxels were placed over VS/CN to capture nucleus accumbens. Cisternal cerebrospinal fluid corticotropin-releasing factor concentrations, hippocampal volume, body mass, and response to a human intruder had been previously determined. Results VFD-reared monkeys exhibited significantly increased NAA/creatine concentrations in right VS/CN in comparison to normally reared controls, controlling for multiple comparisons. In comparison to controls, VFD cerebrospinal fluid corticotropin-releasing factor concentrations were directly associated with right VS/CN absolute NAA. Left hippocampal volume was inversely associated with left VS/CN NAA/creatine in VFD reared but not in controls. Disruption of a normative inverse correlation between left VS/CN NAA and body mass was noted in VFD. Only non-VFD subjects exhibited a direct relationship between timidity response to an intruder and right VS/CN NAA. Conclusion Early life stress produced persistent increases in VS/CN NAA, which demonstrated specific patterns of association (or lack thereof) to early life stress markers in comparison to non-VFD subjects. The data are broadly consistent with a stable nonhuman primate phenotype of anxiety and mood disorder vulnerability whereby in vivo indicators of neuronal integrity, although reduced in hippocampus, are increased in striatum. The findings may provide a catalyst for further studies in humans and other species regarding a reciprocal hippocampal/nucleus accumbens relationship in affective disorders.

Maternal hypothalamic-pituitary-adrenal axis response to foraging uncertainty: A model of individual vs. social allostasis and the "Superorganism Hypothesis".

IntroductionFood insecurity is a major global contributor to developmental origins of adult disease. The allostatic load of maternal food uncertainty from variable foraging demand (VFD) activates corticotropin-releasing factor (CRF) without eliciting hypothalamic-pituitary-adrenal (HPA) activation measured on a group level. Individual homeostatic adaptations of the HPA axis may subserve second-order homeostasis, a process we provisionally term “social allostasis.” We postulate that maternal food insecurity induces a “superorganism” state through coordination of individual HPA axis response.MethodsTwenty-four socially-housed bonnet macaque maternal-infant dyads were exposed to 16 weeks of alternating two-week epochs of low or high foraging demand shown to compromise normative maternal-infant rearing. Cerebrospinal fluid (CSF) CRF concentrations and plasma cortisol were measured pre- and post-VFD. Dyadic distance was measured, and blinded observers performed pre-VFD social ranking assessments.ResultsDespite marked individual cortisol responses (mean change = 20%) there was an absence of maternal HPA axis group mean response to VFD (0%). Whereas individual CSF CRF concentrations change = 56%, group mean did increase 25% (p = 0.002). Our "dyadic vulnerability" index (low infant weight, low maternal weight, subordinate maternal social status and reduced dyadic distance) predicted maternal cortisol decreases (p < 0.0001) whereas relatively “advantaged” dyads exhibited maternal cortisol increases in response to VFD exposure.CommentIn response to a chronic stressor, relative dyadic vulnerability plays a significant role in determining the directionality and magnitude of individual maternal HPA axis responses in the service of maintaining a “superorganism” version of HPA axis homeostasis, provisionally termed “social allostasis.”

A low degree of high ambient temperature decreased food intake and activated median preoptic and arcuate nuclei

High ambient temperature (HTa) activates both behavioral and autonomic responses. Decreased food intake (FI) is a well-known behavioral response under HTa. In general, this behavioral response seems to be mediated under the activation of the stress axis. The present study, however, revealed that decreased FI after a low degree of HTa appeared to be activated earlier than stress axis activation. By comparing low and high levels of HTa exposure in rats, the present experiment demonstrated that the HTa-induced decrease in FI was clear in both conditions. However, only the high degree HTa rats showed prominent physiological responses to HTa. The results indicated that low degree HTa exposure decreased FI earlier than activated physiological responses. Using the low degree HTa condition, the next experiment revealed that only the median preoptic nucleus (MnPO) and arcuate nucleus (Arc) were activated. These results suggested that the MnPO and Arc (MnPO-Arc) are apparently involved in the low degree HTa effect on FI and that the paraventricular hypothalamic nucleus, which is the upper part of the stress axis, was not associated with this effect. A separate experiment also showed no differences in the corticotropin-releasing factor (CRF) concentrations from many selected nuclei. This result suggested that the effect of HTa to decrease FI via the MnPO-Arc was not associated with CRF. The current findings introduce a new behavioral aspect of the HTa effect on FI, representing important information to explain the mechanism of obesity relative to environmental conditions.

Sound-stress-induced altered nociceptive behaviors are associated with increased spinal CRFR2 gene expression in a rat model of burn injury.

Sound stress (SS) elicits behavioral changes, including pain behaviors. However, the neuronal mechanisms underlying SS-induced pain behaviors remain to be explored. The current study examined the effects of SS on nociceptive behaviors and changes in expression of the spinal corticotropin-releasing factor (CRF) system in male Sprague Dawley rats with and without thermal pain. We also studied the effects of SS on plasma corticosterone and fecal output. Rats were exposed to 3 days of SS protocol (n = 12/group). Changes in nociceptive behaviors were assessed using thermal and mechanical pain tests. Following the induction of SS, a subgroup of rats (n = 6/group) was inflicted with thermal injury and on day 14 postburn nociceptive behaviors were reassessed. Spinal CRF receptor mRNA expression was analyzed by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). In addition, plasma corticosterone and spinal CRF concentrations were quantified using enzyme-linked immunosorbent assay (ELISA). Increased defecation was observed in SS rats. SS produced transient mechanical allodynia in naive rats, whereas it exacerbated thermal pain in thermally injured rats. Spinal CRFR2 mRNA expression was unaffected by stress or thermal injury alone, but their combined effect significantly increased its expression. SS had no effect on plasma corticosterone and spinal CRF protein in postburn rats. To conclude, SS is capable of exacerbating postburn thermal pain, which is linked to increased CRFR2 gene expression in the spinal cord. Future studies have to delineate whether attenuation of CRFR2 signaling at the spinal level prevents stress-induced exacerbation of burn pain.

Tectal corticotropin-releasing factor (CRF) neurons respond to fasting and a reactive stressor in the African Clawed Frog, Xenopus laevis

It is well established that hypothalamic neurons producing the peptide corticotropin-releasing factor (CRF) play a key role in stress adaptation, including reduction of food intake when a threat or stressor is present. We have previously reported on the presence of an intrinsic CRF signaling system within the optic tectum (OT), a brain area that plays a key role in visually guided prey capture/predator avoidance decisions. To better understand the potential role of tectal CRF neurons in regulating adaptive behavior and energy balance during stress we examined evidence for modulation of tectal CRF neuronal activity after stressor exposure and food deprivation in the African clawed frog Xenopus laevis. We tested two predictions, 1) that exposure to categorically distinct stressors (ether vapors and shaking) will reduce food intake and modulate the activity of tectal CRF cells, and 2) that food deprivation will modulate the activity of tectal CRF cells. Exposure to ether increased tectal content of CRF and CRF transcript, but lowed CRFR1 transcript abundance. Two weeks of food deprivation reduced total fat stores in frogs and decreased tectal content of CRF content while having no effect on CRF and CRFR1 transcript abundance. Our data are consistent with a role for tectal CRF neurons in modulating food intake in response to certain stressors.

The Role of Central Orexin‐A in Restraint Stress‐induced Gastric Dysmotility in Rats

Stress exposure stimulates the production of corticotropin‐releasing factor (CRF) in hypothalamic paraventricular nucleus (PVN) which in turn influences gastrointestinal (GI) motor functions by altering autonomic outflow in brain. In rodents, acute restraint stress (ARS) has been shown to delay gastric emptying (GE) by impairing the postprandial coordination of of antro‐pyloric contractions through a CRF‐dependent pathway. Besides its well‐defined orexigenic function, the hypothalamic neuropeptide orexin‐A (OXA) is also known to alter GI motor functions through central autonomic pathways. OXA‐producing cells reside mainly in lateral hypothalamic area (LHA), while its receptor OX1R is found in PVN. Accumulating evidence indicate that OXA‐containing neurons send intra‐hypothalamic projections to the CRF‐producing cells in PVN. Furthermore, central administration of OXA has been shown to enhance CRF‐induced neuroendocrine functions suggesting that central OXA may contribute to the CRF‐mediated impairment of GI motor functions under stressed conditions. The aim of the present study was to investigate the involvement of orexin‐A in CRF‐induced gastric motor dysfunction under stressed conditions. Central (icv) drug administrations were performed through an injection cannula stereotaxically placed into the lateral ventricle. Solid GE was measured following an overnight fasting in non‐stressed (NS) and ARS‐loaded rats following central pretreatment of CRF and OXA antagonists α‐helical‐CRF9,41 (10 nmol, 5 μl) and SB‐334867 (100 nmol, 5 μl), respectively. For recording of gastric motility, two miniature strain gages were implanted onto the serosal surface of antrum and pylorus. Postprandial antro‐pyloric contractions were monitored in conscious and freely‐moving rats simultaneously with microdialysis. To perform microdialysis, a probe with high molecular cut‐off membrane was placed into the PVN. The intra‐PVN microinjection of vehicle or selective SB‐334867 (10 nmol, 100 nL) was performed prior to the perfusion of the probe with artificial cerebro‐spinal fluid (aCSF) containing high KCl (100 mmol/L). CRF concentrations in microdialysis samples were quantified by enzyme immunoassay. Compared with NS rats, ARS significantly (p&lt;0.01) delayed GE. The ARS‐induced delayed GE was partially attenuated both by pretreatment of SB‐334867 (p&lt;0.05) and α‐helical‐CRF9,41 (p&lt;0.05), whereas it was completely restored (p&lt;0.01) when both antagonists were administered together. Perfusion with high KCl‐containing aCSF significantly increased the CRF level in microdialysates which was significantly attenuated by intra‐PVN microinjection of SB‐334867. Perfusion of KCl impaired the coordination of postprandial antro‐pyloric contractions. Compared with vehicle‐injected rats, KCL‐induced alterations were remarkably abolished by SB‐334867. These results suggest that central OXA plays a role in stress‐induced alterations in gastric motor functions through OX1R. Therefore, OX1R antagonism appears to be a candidate for the treatment of the stress‐related gastric motor dysfunctions.

Beyond the Classic VTA: Extended Amygdala Projections to DA-Striatal Paths in the Primate

The central extended amygdala (CEA) has been conceptualized as a ‘macrosystem’ that regulates various stress-induced behaviors. Consistent with this, the CEA highly expresses corticotropin-releasing factor (CRF), an important modulator of stress responses. Stress alters goal-directed responses associated with striatal paths, including maladaptive responses such as drug seeking, social withdrawal, and compulsive behavior. CEA inputs to the midbrain dopamine (DA) system are positioned to influence striatal functions through mesolimbic DA-striatal pathways. However, the structure of this amygdala-CEA-DA neuron path to the striatum has been poorly characterized in primates. In primates, we combined neuronal tracer injections into various arms of the circuit through specific DA subpopulations to assess: (1) whether the circuit connecting amygdala, CEA, and DA cells follows CEA intrinsic organization, or a more direct topography involving bed nucleus vs central nucleus divisions; (2) CRF content of the CEA-DA path; and (3) striatal subregions specifically involved in CEA-DA-striatal loops. We found that the amygdala-CEA-DA path follows macrostructural subdivisions, with the majority of input/outputs converging in the medial central nucleus, the sublenticular extended amygdala, and the posterior lateral bed nucleus of the stria terminalis. The proportion of CRF+ outputs is >50%, and mainly targets the A10 parabrachial pigmented nucleus (PBP) and A8 (retrorubal field, RRF) neuronal subpopulations, with additional inputs to the dorsal A9 neurons. CRF-enriched CEA-DA projections are positioned to influence outputs to the ‘limbic-associative’ striatum, which is distinct from striatal regions targeted by DA cells lacking CEA input. We conclude that the concept of the CEA is supported on connectional grounds, and that CEA termination over the PBP and RRF neuronal populations can influence striatal circuits involved in associative learning.

Corticotropin-releasing factor stimulates colonic motility via muscarinic receptors in the rat.

AIMTo measure exogenous corticotropin-releasing factor (CRF)-induced motility of the isolated rat colon and to demonstrate the effect of pharmacologic inhibition on CRF-induced motility.METHODSThe isolated vascularly-perfused rat colon was used. Luminal pressure was monitored via microtip catheter pressure transducers in the proximal and distal colon. At first, exogenous CRF was administered in a stepwise manner and the concentration of CRF yielding maximal colonic motility was selected. After recording basal colonic motility, hexamethonium, phentolamine, propranolol, atropine and tetrodotoxin were infused into the isolated colon. Initially, only the test drug was infused; then, CRF was added. The motility index was expressed as percentage change over basal level.RESULTSAdministration of 1.4, 14.4, 144 and 288 pmol/L CRF progressively increased colonic motility in the proximal and distal colon. Infusion of atropine or tetrodotoxin reduced CRF-induced motility of both the proximal and distal colon, whereas hexamethonium, phentolamine and propranolol had no effect.CONCLUSIONCRF-induced colonic motility appears to be mediated by local cholinergic signaling via muscarinic receptors. Muscarinic receptors are potential targets for counteracting CRF-induced colonic hypermotility.

A comparison between the equine and bovine hypothalamus-pituitary-adrenocortical axis

In this review, we address the function of the hypothalamus-pituitary-adrenocortical (HPA) axis with special emphasis on the comparison between the bovine and equine species. The pars intermedia of the pituitary gland is particularly well developed in horses and cattle. However, its function is not well appreciated in cattle yet. The Wulzen's cone of the adenohypophysis is a special feature of ruminants. Total basal cortisol concentration is much higher in horses than that in cows with similar free cortisol fractions. Corticotropin-releasing factor (CRF) concentrations in equine pituitary venous blood are lower compared with other species, whereas plasma ACTH concentrations in cows are higher than those in horses. A CRF challenge test induced a more pronounced cortisol response in horses compared with cattle, whereas regarding ACTH challenge testing, the opposite seems true. Based on data from literature, the bovine species is characterized by relatively high basal blood CRF and ACTH and low cortisol and glucose concentrations. Obviously, further lowering of blood cortisol in cattle is easily prevented by the high sensitivity to ACTH, and as a consequence, subsequent increased gluconeogenesis prevents imminent hypoglycemia. Hypoglycemia is less likely in horses given their high muscle glycogen content and their relatively high cortisol concentration. When assessing HPA axis reactivity, response patterns to exogenous ACTH or CRH might be used as a reliable indicator of animal welfare status in cows and horses, respectively, although it is emphasized that considerable caution should be exercised in using measures of HPA activity solely to assess animal welfare.

Reduced response to chronic mild stress in PACAP mutant mice is associated with blunted FosB expression in limbic forebrain and brainstem centers

Pituitary adenylate cyclase-activating polypeptide (PACAP) has been implicated in stress adaptation with potential relevance in mood disorder management. PACAP deficient (KO) mice on CD1 background were shown to have depression-like phenotype. Here we aimed at investigating effects of chronic variable mild stress (CVMS) in non-injected, vehicle and imipramine-treated KO mice vs. wildtype (WT) counterparts. We hypothesized reduced FosB neuronal activity in stress-related centers, altered activity and peptide/neurotransmitter content of corticotropin-releasing factor (CRF) cells of the oval (ovBST) bed nucleus of stria terminalis (BST), urocortin 1 (Ucn1) neurons of centrally projecting Edinger-Westphal nucleus (cpEW) and serotonin (5HT) cells of dorsal raphe (DR) in PACAP deficiency.CVMS caused decreased body weight and increased adrenal size, corticosterone (CORT) titers and depression-like behavior in WT mice, in contrast to KO animals. CVMS increased FosB in the central (CeA) and medial amygdala, dorsomedial (dmBST), ventral (vBST), ovBST, CA1 area, dentate gyrus (DG), ventral lateral septum, parvo- (pPVN) and magnocellular paraventricular nucleus, lateral periaqueductal gray, cpEW and DR. Lack of PACAP blunted the CVMS-induced FosB rise in the CeA, ovBST, dmBST, vBST, CA1 area, pPVN and DR.The CVMS-induced FosB expression in ovBST-CRF and cpEW-Ucn1 neurons was abolished in KO mice. Although CVMS did not induce FosB in 5HT-DR neurons, PACAP KO mice had increased 5HT cell counts and 5HT content.We conclude that PACAP deficiency affects neuronal reactivity in a brain area-specific manner in stress centers, as well as in ovBST-CRF, cpEW-Ucn1 and 5HT-DR neurons leading to reduced CVMS response and altered depression level.

Corticotropin releasing factor up-regulates the expression and function of norepinephrine transporter in SK-N-BE (2) M17 cells.

Corticotropin releasing factor (CRF) has been implicated to act as a neurotransmitter or modulator in central nervous activation during stress. In this study, we examined the regulatory effect of CRF on the expression and function of the norepinephrine transporter (NET) invitro. SK-N-BE (2) M17 cells were exposed to different concentrations of CRF for different periods. Results showed that exposure of cells to CRF significantly increased mRNA and protein levels of NET in a concentration- and time-dependent manner. The CRF-induced increase in NET expression was mimicked by agonists of either CRF receptor 1 or 2. Furthermore, similar CRF treatments induced a parallel increase in the uptake of [(3) H] norepinephrine. Both increased expression and function of NET caused by CRF were abolished by simultaneous administration of CRF receptor antagonists, indicating a mediation by CRF receptors. However, there was no additive effect for the combination of both receptor antagonists. Chromatin immunoprecipitation assays confirm an increased acetylation of histone H3 on the NET promoter following treatment with CRF. Taken together, this study demonstrates that CRF up-regulates the expression and function of NET invitro. This regulation is mediated through CRF receptors and an epigenetic mechanism related to histone acetylation may be involved. This CRF-induced regulation on NET expression and function may play a role in development of stress-related depression and anxiety. This study demonstrated that corticotropin release factor (CRF) up-regulated the expression and function of norepinephrine transporter (NET) in a concentration- and time-dependent manner, through activation of CRF receptors and possible histone acetylation in NET promoter. The results indicate that their interaction may play an important role in stress-related physiological and pathological status.