Increased Plasma Adrenocorticotropic Hormone Research Articles

The effect of month and breed on plasma adrenocorticotropic hormone concentrations in equids

Use of plasma adrenocorticotropic hormone (ACTH) concentrations for the diagnosis of PPID in equids requires awareness of other factors that might influence ACTH concentrations, including breed and time of year. This study was designed to investigate effects of breed on plasma ACTH concentrations and potential interactions between breed and time of year. Ten breeds were selected from a laboratory database containing data on plasma ACTH concentrations. Breeds represented were Arabians, Cobs, Connemara ponies, donkeys, Irish Sports horses, New Forest ponies, Shetland ponies, Thoroughbreds, Warmbloods and Welsh breeds. Multivariable analysis was used to determine the effects of month and breed on plasma ACTH concentrations.A circannual pattern of ACTH concentration was documented, with a nadir in April and a peak in September. Arabian horses and donkeys had significantly higher ACTH concentrations than some other breeds, primarily from May to November, whereas in Shetland ponies and Welsh breeds, relatively higher ACTH concentrations only occurred from July to November. The annual increase in plasma ACTH appeared to commence in late April/early May in response to increasing daylight and decreased again promptly after the late September equinox as daylength fell below 12 h per day. Inter-breed differences in plasma ACTH were substantial and indicated that breed and time of year should be considered when interpreting plasma ACTH concentrations in equids suspected for PPID.

Suspected hyperadrenocorticism in an Atlantic bottlenose dolphin (Tursiops truncatus): Diagnostic approach and treatment with ketoconazole

AbstractA 35‐year‐old female Atlantic bottlenose dolphin (Tursiops truncatus) presented with lethargy, dysorexia, obesity and locomotor difficulties. An abnormal deposition of fat and superficial skin lesions was observed. Laboratory findings showed lymphopenia and eosinopenia associated with hypercholesterolemia. Endocrinological assessment revealed chronically increased serum cortisol values associated with increased plasma adrenocorticotrophic hormone (ACTH) concentration. ACTH‐dependent hyperadrenocorticism, also known as Cushing's syndrome, was strongly suspected. The bottlenose dolphin was treated with ketoconazole (2.3 mg/kg every 12 hours) and prednisone (0.03 mg/kg every 48 hours), which resulted in an improvement in clinical signs, except for obesity. Long‐term treatment with ketoconazole and prednisolone did not cause any adverse effects. However, the authors recommend avoiding concurrent hormonal treatment with altrenogest as it might cause a relapse of hyperadrenocorticism or drug–drug interaction with ketoconazole. Endocrinopathies are rare in cetaceans but this case highlights the importance of considering hyperadrenocorticism as a differential diagnosis in dolphins with obesity and skin lesions.

Adrenal insufficiency in immunochemotherapy for small-cell lung cancer with ectopic ACTH syndrome.

SummaryEctopic ACTH (adrenocorticotrophic hormone) syndrome (EAS) is rarely associated with small-cell lung cancer (SCLC). Although chemotherapy is initially effective for SCLC, complicated EAS scarcely improves. Recently, immune checkpoint inhibitors have been used to treat SCLC. Atezolizumab plus chemotherapy for SCLC improved progression-free survival compared to conventional chemotherapy. However, little has been reported on the efficacy of the combination therapy for SCLC with EAS. We report a 72-year-old male who presented with 4-week history of leg oedema, proximal myopathy, weight loss, and worsened symptoms of diabetes and hypertension. Laboratory findings revealed hypokalaemia, increased plasma ACTH, and serum cortisol levels. Cortisol levels were not suppressed by the high-dose dexamethasone test. Chest and abdominal CT revealed a right lower lobe tumour with multiple metastases on the hilar lymph nodes, liver, lumbar spine, and bilateral enlarged adrenal glands. The patient was diagnosed with stage 4B SCLC with EAS. Hypercortisolaemia was then treated with metyrapone and atezolizumab plus chemotherapy, which was started for SCLC. After 10 days, the tumour shrank noticeably, and the ACTH level drastically decreased concomitantly with low cortisol levels with symptoms of fever, appetite loss, and general fatigue. Hydrocortisone treatment was initiated, and the symptoms resolved immediately. We describe a case of SCLC with EAS treated with atezolizumab plus chemotherapy, presenting with adrenal insufficiency. Close observation is required for patients with adrenal insufficiency receiving atezolizumab plus chemotherapy because of its stronger effect. Furthermore, advances in cancer therapy and care for endocrine paraneoplastic syndrome needs to be adapted.Learning pointsThe immune checkpoint inhibitor atezolizumab has recently been approved for the treatment of small-cell lung cancer (SCLC).Approximately 1–6% of tumour ectopically produce ACTH and cause ectopic ACTH syndrome (EAS) as an endocrine paraneoplastic syndrome.The use of combined chemotherapy and atezolizumab in the ectopic ACTH syndrome secondary to small-cell lung cancer may cause a precipitous fall in circulating ACTH/cortisol, resulting in symptomatic adrenal insufficiencyThe advances in cancer therapy and treatment for endocrine paraneoplastic syndrome need to be adapted.

Effects of CRN04894, a Nonpeptide Orally Bioavailable ACTH Antagonist, on Corticosterone in Rodent Models of ACTH Excess

CRN04894 is an orally administered nonpeptide that is a potent and selective antagonist for adrenocorticotropic hormone (ACTH) acting at the melanocortin 2 receptor (MC2R) and is currently under development for the treatment of diseases of ACTH excess such as Cushing’s disease, congenital adrenal hyperplasia, and ectopic ACTH-secreting tumors. Cushing’s disease results from an adenoma derived from pituitary corticotropic cells that secrete excess ACTH, whereas ectopic ACTH syndrome arises from nonpituitary ACTH secreting tumors. Congenital adrenal hyperplasia is a genetic disease that results in cortisol deficiency leading to high levels of ACTH and adrenal androgens. Each of these indications is characterized by high ACTH levels that act on MC2R expressed in the adrenal cortex to drive pathological elevations of adrenally derived steroid hormones. CRN04894 blocks the action of ACTH at MC2R, providing a potential novel treatment for these diseases. Preclinical models of chronic hypercortisolemia include implantation of ACTH-secreting pituitary tumor cells in mice and continuous administration of ACTH via subcutaneously implanted osmotic pumps in rats. These models induce features consistent with human diseases of ACTH excess including hypercortisolemia and hypertrophy of the adrenal glands. We employed both rodent models to examine the pharmacodynamic effects of CRN04894 on corticosterone levels and adrenal gland morphology. In the mouse pituitary tumor model, subcutaneous inoculation of the ACTH-secreting mouse pituitary tumor cell line, AtT-20, into immunodeficient mice resulted in formation of tumors and increased plasma ACTH and corticosterone levels. Repeated daily oral administration of CRN04894 for 14 days dose-dependently and robustly suppressed plasma corticosterone levels in mice with AtT-20 tumors. In the rat model, subcutaneous implantation of osmotic pumps delivering ACTH resulted in increased corticosterone levels, reduction in body weight, and hypertrophy of the adrenal glands after 7 days. Daily oral administration of CRN04894 over 7 days dose-dependently suppressed corticosterone levels, mitigated the effect of ACTH excess on body weight, and rescued the adrenal gland hypertrophy. These findings provide evidence that CRN04894 functions as an effective ACTH antagonist at MC2R to suppress adrenal corticosterone secretion in both mouse and rat models of ACTH excess and hypercortisolemia, thus providing a strong rationale for its potential therapeutic utility in diseases of ACTH excess. This work was supported in part by an SBIR grant from the NIH awarded to Dr. Struthers (R43- DK115245)

Simultaneous quantification of nine components in the plasma of depressed rats after oral administration of Chaihu-Shugan-San by ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry and its application to pharmacokinetic studies

Chaihu-Shugan-San (CSS), a classic Chinese formula, has long been used to treat depression. For a better and rational use of this formula, here, we investigated the comprehensive pharmacokinetic features of multiple ingredients from CSS using ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS) in depressed rats. Force swimming experiments were conducted to establish a rat model of depression. Prolonged immobility time, increased plasma adrenocorticotropic hormone, and decreased plasma 5-hydroxytryptamine (5-HT) and dopamine (DA) were confirmed in this model. Nine compounds from CSS, including ferulic acid, naringin, hesperidin, meranzin hydrate, glycyrrhizic acid, saikosaponin A, nobiletin, and hesperetin, were simultaneously determined in plasma samples. Sulfamethoxazole and schisandrin were used as internal standards. The separation was performed on a C18 column with gradient elution over 10 min, and detection was executed using multiple reaction monitoring (MRM) in the positive ionization mode. The optimized MRM transitions showed no interference in rat plasma. Validation parameters were all in accordance with the current criterion. The established method was successfully applied to the pharmacokinetic study of these nine components after the oral administration of CSS to depressed rats. This study provides a chemical basis for the clinical application of this formula.

Chronic alcohol disrupts hypothalamic responses to stress by modifying CRF and NMDA receptor function

The chronic inability of alcoholics to effectively cope with relapse-inducing stressors has been linked to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and corticotropin-releasing factor (CRF) signaling. However, the cellular mechanisms responsible for this dysregulation are yet to be identified. After exposure of male Sprague Dawley rats to chronic intermittent ethanol (CIE; 5–6 g/kg orally for 35 doses over 50 days) or water, followed by 40–60 days of protracted withdrawal, we investigated CIE effects on glutamatergic synaptic transmission, stress-induced plasticity, CRF- and ethanol-induced NMDAR inhibition using electrophysiological recordings in parvocellular neurosecretory cells (PNCs) of the paraventricular nucleus. We also assessed CIE effects on hypothalamic mRNA expression of CRF-related genes using real-time polymerase chain reaction, and on HPA axis function by measuring stress-induced increases in plasma adrenocorticotropic hormone, corticosterone, and self-grooming. In control rats, ethanol-mediated inhibition of NMDARs was prevented by CRF1 receptor (CRFR1) blockade with antalarmin, while CRF/CRFR1-mediated NMDAR blockade was prevented by intracellularly-applied inhibitor of phosphatases PP1/PP2A, okadaic acid, but not the selective striatal-enriched tyrosine protein phosphatase inhibitor, TC-2153. CIE exposure increased GluN2B subunit-dependent NMDAR function of PNCs. This was associated with the loss of both ethanol- and CRF-mediated NMDAR inhibition, and loss of stress-induced short-term potentiation of glutamatergic synaptic inputs, which could be reversed by intracellular blockade of NMDARs with MK801. CIE exposure also blunted the hormonal and self-grooming behavioral responses to repeated restraint stress. These findings suggest a cellular mechanism whereby chronic alcohol dysregulates the hormonal and behavioral responses to repetitive stressors by increasing NMDAR function and decreasing CRFR1 function.

Preclinical in vivo characterization of lemborexant (E2006), a novel dual orexin receptor antagonist for sleep/wake regulation.

Study ObjectivesTo present results from in vivo studies underlying the preclinical development of lemborexant (E2006), a novel dual orexin (hypocretin) receptor antagonist for sleep/wake regulation.MethodsRodent (wild-type rats and wild-type and orexin neuron-deficient [orexin/ataxin-3 Tg/+] mice) studies were performed to evaluate the effects of single-dose oral lemborexant (1–300 mg/kg) on orexin-induced increases in plasma adrenocorticotropic hormone (ACTH), locomotor activity, vigilance state measures (wakefulness, nonrapid eye movement [non-REM] sleep, rapid eye movement [REM] sleep), ethanol-induced anesthesia, and motor coordination, and the effects of multiple-dose oral lemborexant (30 mg/kg) on vigilance state measures. Active comparators were almorexant and zolpidem. Pharmacokinetics were assessed after single-dose lemborexant in mice and rats.ResultsLemborexant prevented the orexin-promoted increase in ACTH in rats, therefore demonstrating inhibition of the orexin signaling pathway. Furthermore, lemborexant promoted sleep in wild-type mice and rats. Lemborexant promoted REM and non-REM sleep at an equal rate (there was no change in the REM sleep ratio). In contrast, zolpidem reduced REM sleep. The sleep-promoting effect of lemborexant was mediated via the orexin-peptide signaling pathway as demonstrated by a lack of sleep promotion in orexin neuron-deficient mice. Chronic dosing was not associated with a change in effect size or sleep architecture immediately postdosing. Lemborexant did not increase the sedative effects of ethanol or impair motor coordination, showing good safety margin in animals. Pharmacokinetic/pharmacodynamic data for mice and rats were well aligned.ConclusionsThese findings supported further clinical evaluation (ongoing at this time) of lemborexant as a potential candidate for treating insomnia and other sleep disorders.

Corticotrophin-releasing factor mediates vasoactive intestinal peptide-induced hypophagia and changes in plasma parameters

Vasoactive intestinal peptide (VIP) and corticotrophin-releasing factor (CRF) are anorexigenic neuropeptides that act in the hypothalamus to regulate food intake. Intracerebroventricular (ICV) microinjection of VIP promotes increased plasma adrenocorticotrophic hormone (ACTH) and corticosterone, indicating that VIP activates hypothalamic-pituitary-adrenal axis. The aim of this study was to evaluate the interaction between VIP and CRF, by verifying the effects of ICV administration of VIP on the activity of neurons and CRF mRNA expression in paraventricular nucleus of hypothalamus (PVN). In addition, it was evaluated the effects of pretreatment with CRF type 1 receptor (CRFR1) antagonist (Antalarmin, ANT) or CRF type 2 receptor (CRFR2) antagonist (Antisauvagine-30, AS30) on VIP-induced changes on food intake and plasma parameters of male rats. Compared to Saline group, VIP increased not only the number of Fos-related antigens (FRA)-immunoreactive neurons in the PVN but also CRF mRNA levels in this nucleus. Both ANT and AS30 treatment attenuated the inhibition of food intake promoted by VIP, ANT showing a more pronounced effect. Both antagonists also attenuated VIP-induced reduction and enhancement of free fatty acids and corticosterone plasma levels, respectively, and only AS30 was able to attenuate the hyperglycemia. These results suggest that CRF is an important mediador of VIP effects on energy balance, and CRFR1 and CRFR2 are involved in these responses.

Intravenous Corticotropin-releasing Hormone Administration Increases Esophageal Electrical Sensitivity in Healthy Individuals.

Background/AimsWhen a person is experiencing stress, corticotropin-releasing hormone (CRH) can modulate gut physiologies, such as visceral sensation or gastrointestinal motility, and its intravenous administration mimics stress-induced physiological changes. However, the influence of CRH on the esophagus is yet unknown. Accordingly, we investigated whether intravenous CRH administration increases esophageal sensitivity to electrical stimulation in healthy Japanese subjects.MethodsTwenty healthy subjects were recruited. We quantified the initial perception threshold (IPT) every 15 minutes after CRH injection. Venous blood was collected with a cannula, and both plasma adrenocorticotropic hormone (ACTH) and cortisol were measured at pre-stimulation, 0, 30, 60, 90, and 120 minutes. The results from each time point were compared against a baseline IPT obtained before electrical stimulation was initiated.ResultsWhen compared to the baseline IPT value (16.9 ± 4.5), CRH significantly decreased electrical threshold of the esophagus at 30, 45, 60, 75 minutes (14.1 ± 4.2, 13.1 ± 5.0, 12.1 ± 5.7, 14.0 ± 5.8 minutes, P < 0.01, respectively) after CRH injection, suggesting that CRH increased esophageal sensitivity to the electrical stimulus. CRH also significantly increased plasma ACTH levels at 30 minutes (50.3 ± 17.7, P < 0.01), and cortisol levels at 30 minutes (22.0 ± 6.7 minutes, P < 0.01) and 60 minutes (20.3 ± 6.7 minutes, P < 0.01) after CRH injection, when compared to the pre-stimulation ACTH and cortisol values.ConclusionIntravenous CRH administration increased esophageal electrical sensitivity in normal subjects, emphasizing the important role of stress in esophageal sensitivity.

Corticotropin-releasing hormone and copeptin as acute stress markers in serial cerebrospinal fluid – first evidence for non-response during insulin hypoglycemia test

Background: During stress, arginine vasopressin (AVP) and corticotropin-releasing hormone (CRH) can act as potent hypothalamic stimulators of the hypothalamic pituitary adrenocortical (HPA) axis. Recently, plasma CT-proAVP, also termed copeptin, was found to be a stable and sensitive surrogate marker for AVP release. A valid assessment of both CRH and copeptin in cerebrospinal fluid (CSF) might directly quantify an individual’s current stress level. Here we investigated how concentrations of CRH and copeptin in CSF alter during insulin-induced hypoglycemia test (IHT) - which has been shown to activate both hypothalamic AVP and CRH - and hypothesized an increase of both.Methods: Five healthy young men were studied from 08:00 until 14:00 after over-night fasting. They received an i.v. injection of human insulin (0.1 IE/kg body weight) at 11:02. CSF samples were drawn from a subarachnoidal catheter every 20 minutes from 10:40 to 14:00 for the measurement of CSF CRH and CSF copeptin. Plasma adrenocorticotropic hormone (ACTH) and cortisol were analyzed in parallel.Results: Data could be assessed in three of five subjects, of which two responded to IHT by showing glucose levels of < 40 mg/dl and clinical symptoms (sweating). Despite a 17-fold, respectively 11-fold increase of plasma ACTH, neither our hypothesized increase of CSF CRH nor of CSF copeptin was seen in these two responders.Conclusions: This is the first study investigating CSF CRH and CSF copeptin in man during acute stress. Copeptin had not been measured in CSF before. Our results support recent speculations that CSF CRH is not a measure of hypothalamic but rather extrahypothalamic CRH (non-HPA CRH). Further research on copeptin in CSF is needed.

Antidepressant and anxiolytic profiles of newly synthesized arginine vasopressin V1B receptor antagonists: TASP0233278 and TASP0390325

Vasopressin V1B receptor antagonists may be effective for the treatment of depression and anxiety and the objective of this study was to characterize the pharmacological profiles of two newly synthesized arginine vasopressin receptor 1B (V1B receptor) antagonists, TASP0233278 and TASP0390325. We investigated the in vitro profiles of TASP0233278 and TASP0390325. In addition, the effect of TASP0390325 on the increase in plasma adrenocorticotropic hormone (ACTH) levels induced by corticotropin-releasing factor (CRF)/desmopressin (dDAVP) was investigated. We also investigated the antidepressant and anxiolytic profiles of TASP0233278 and TASP0390325 in animal models. Both TASP0233278 and TASP0390325 showed a high affinity and potent antagonist activity for V1B receptors. Oral administration of TASP0390325 antagonized the increase in plasma ACTH levels induced by CRF/dDAVP in rats, indicating that TASP0390325 blocks the anterior pituitary V1B receptor in vivo. Oral administration of TASP0233278 or TASP0390325 also exerted antidepressant effects in two models of depression (a forced swimming test and an olfactory bulbectomy model). Moreover, TASP0233278 improved depressive-like behaviour induced by repeated treatment with corticosterone, a model that has been shown to be resistant to treatment with currently prescribed antidepressants. In addition to depression models, TASP0233278 or TASP0390325 exerted anxiolytic effects in several anxiety models (social interaction, elevated plus-maze, stress-induced hyperthermia, separation-induced ultrasonic vocalization and sodium lactate-induced panic-like responses in panic-prone rats). TASP0233278 and TASP0390325 are potent and orally active V1B receptor antagonists with antidepressant and anxiolytic activities in rodents.

Cardiac adverse effects of naloxone-precipitated morphine withdrawal on right ventricle: Role of corticotropin-releasing factor (CRF) 1 receptor

Opioid addiction is associated with cardiovascular disease. However, mechanisms linking opioid addiction and cardiovascular disease remain unclear. This study investigated the role of corticotropin-releasing factor (CRF) 1 receptor in mediating somatic signs and the behavioural states produced during withdrawal from morphine dependence. Furthermore, it studied the efficacy of CRF1 receptor antagonist, CP-154,526 to prevent the cardiac sympathetic activity induced by morphine withdrawal. In addition, tyrosine hydroxylase (TH) phosphorylation pathways were evaluated. Like stress, morphine withdrawal induced an increase in the hypothalamic–pituitary–adrenal (HPA) axis activity and an enhancement of noradrenaline (NA) turnover. Pre-treatment with CRF1 receptor antagonist significantly reduced morphine withdrawal-induced increases in plasma adrenocorticotropic hormone (ACTH) levels, NA turnover and TH phosphorylation at Ser31 in the right ventricle. In addition, CP-154,526 reduced the phosphorylation of extracellular signal-regulated kinase (ERK) after naloxone-precipitated morphine withdrawal. In addition, CP-154,526 attenuated the increases in body weight loss during morphine treatment and suppressed some of morphine withdrawal signs. Altogether, these results support the idea that cardiac sympathetic pathways are activated in response to naloxone-precipitated morphine withdrawal suggesting that treatment with a CRF1 receptor antagonist before morphine withdrawal would prevent the development of stress-induced behavioural and autonomic dysfunction in opioid addicts.

Mechanisms Underlying the Increased Plasma ACTH Levels in Chronic Psychosocially Stressed Male Mice

Mice exposed to chronic subordinate colony housing (CSC, 19 days), an established paradigm for chronic psychosocial stress, show unaffected basal morning plasma corticosterone (CORT) concentrations, despite enlarged adrenal glands and an increased CORT response to an acute heterotypic stressor. In the present study we investigate the mechanisms underlying these phenomena at the level of the pituitary. We show that both basal and acute stressor-induced (forced swim (FS), 6 min) plasma adrenocorticotropic hormone (ACTH) concentrations, the number of total and corticotroph pituitary cells, and relative protein expression of pituitary mineralocorticoid receptor and FK506-binding protein 51 was increased in CSC compared with single-housed control (SHC) mice, while relative corticotropin releasing hormone (CRH) receptor 1 (CRH-R1) and glucocorticoid receptor protein expression was down-regulated. Relative pituitary pro-opiomelanocortin and arginine vasopressin (AVP) receptor 1b (AVPR-1b) protein expression, FS (6 min)-induced ACTH secretion in dexamethasone-blocked mice, and the number of AVP positive magnocellular and parvocellular neurons in the paraventricular hypothalamic nucleus (PVN) was unaffected following CSC. Taken together, the data of the present study indicate that 19 days of CSC result in pituitary hyperactivity, under both basal and acute heterotypic stress conditions. Although further studies have to assess this in detail, an increased number of pituitary corticotrophs together with unaffected relative pituitary AVPR-1b and decreased CRH-R1 protein expression following CSC suggests that pituitary hyperdrive is mediated by newly formed corticotrophs that are more sensitive to AVP than CRH. Moreover, our data indicate that changes in PVN AVP and negative feedback inhibition seem not to play a major role in pituitary hyperactivity following CSC.

Neurobiological consequences of acute footshock stress: effects on tyrosine hydroxylase phosphorylation and activation in the rat brain and adrenal medulla

Stress activates selected neuronal systems in the brain and this leads to activation of a range of effector systems. Our aim was to investigate some of the relationships between these systems under basal conditions and over a 40-min period in response to footshock stress. Specifically, we investigated catecholaminergic neurons in the locus coeruleus (LC), ventral tegmental area and medial prefrontal cortex (mPFC) in the brain, by measuring tyrosine hydroxylase (TH) protein, TH phosphorylation and TH activation. We also measured the effector responses by measuring plasma adrenocorticotrophic hormone, corticosterone, glucose and body temperature as well as activation of adrenal medulla protein kinases, TH protein, TH phosphorylation and TH activation. The LC, ventral tegmental area and adrenal medulla all had higher basal levels of Ser19 phosphorylation and lower basal levels of Ser31 phosphorylation than the mPFC, presumably because of their cell body versus nerve terminal location, while the adrenal medulla had the highest basal levels of Ser40 phosphorylation. Ser31 phosphorylation was increased in the LC at 20 and 40 min and in the mPFC at 40 min; TH activity was increased at 40 min in both tissues. There were significant increases in body temperature between 10 and 40 min, as well as increases in plasma adrenocorticotropic hormone at 20 min and corticosterone and glucose at 20 and 40 min. The adrenal medulla extracellular signal-regulated kinase 2 was increased between 10 and 40 min and Ser31 phosphorylation was increased at 20 min and 40 min. Protein kinase A and Ser40 phosphorylation were increased only at 40 min. TH activity was increased between 20 and 40 min. TH protein and Ser19 phosphorylation levels were not altered in any of the brain regions or adrenal medulla over the first 40 min. These findings indicate that acute footshock stress leads to activation of TH in the LC, pre-synaptic terminals in the mPFC and adrenal medullary chromaffin cells, as well as changes in activity of the hypothalamic-pituitary-adrenal axis.

Hypothalamic and Pituitary Clusterin Modulates Neurohormonal Responses to Stress

Clusterin is a sulfated glycoprotein abundantly expressed in the pituitary gland and hypothalamus of mammals. However, its physiological role in neuroendocrine function is largely unknown. In the present study, we investigated the effects of intracerebroventricular (ICV) administration of clusterin on plasma pituitary hormone levels in normal rats. Single ICV injection of clusterin provoked neurohormonal changes seen under acute stress condition: increased plasma adrenocorticotropic hormone (ACTH), corticosterone, GH and prolactin levels and decreased LH and FSH levels. Consistently, hypothalamic and pituitary clusterin expression levels were upregulated following a restraint stress, suggesting an involvement of endogenous clusterin in stress-induced neurohormonal changes. In the pituitary intermediate lobe, clusterin was coexpressed with proopiomelanocortin (POMC), a precursor of ACTH. Treatment of clusterin in POMC expressing AtT-20 pituitary cells increased basal and corticotropin-releasing hormone (CRH)-stimulated POMC promoter activities and intracellular cAMP levels. Furthermore, clusterin treatment triggered ACTH secretion from AtT-20 cells in a CRH-dependent manner, indicating that increased clusterin under stressful conditions may augment CRH-stimulated ACTH production and release. In summary, hypothalamic and pituitary clusterin may function as a modulator of neurohormonal responses under stressful conditions.

Influence of chronic stress on brain corticosteroid receptors and HPA axis activity

BackgroundDisruption of the glucocorticoid negative feedback system evoked in animals by chronic stress can be induced by downregulation of glucocorticoid receptors (GRs) in several brain regions. In the present study, the dynamics of the changes in GRs, in brain structures involved in stress reactions, prefrontal cortex, hippocampus and hypothalamus was compared with the peripheral hypothalamo-pituitary-adrenocortical (HPA) axis hormones response to chronic stress. MethodsRats were exposed to 10min restraint or restrained twice a day for 3, 7or 14 days, and 24h after the last stress session exposed to homotypic stress for 10min. Control rats were not restrained. After rapid decapitation at 0, 1, 2, and 3h after stress termination, trunk blood for plasma adrenocorticotropic hormone (ACTH) and corticosterone determinations was collected and prefrontal cortex, hippocampus and hypothalamus were excised and frozen. Plasma hormones were determined using commercially available kits and glucocorticoids and mineralocorticoids protein levels in brain structure samples were determined by western blot procedure. ResultsRestraint stress alone significantly decreased glucocorticoid receptor (GR) level in prefrontal cortex and hippocampus, and increased mineralocorticoid receptor (MR) level in hypothalamus. Prior repeated stress for 3 days significantly increased GR protein level in hippocampus and diminished that level in hypothalamus in 7 days stressed rats. Acute stress-induced strong increase in plasma ACTH and corticosterone levels decreased to control level after 1 or 2h, respectively. Prior repeated stress for 3 days markedly diminished the fall in plasma ACTH level and repeated stress for 7 days moderately deepened this decrease. Plasma ACTH level induced by homotypic stress in rats exposed to restraint for 3, 7, and 14 days did not markedly differ from its control level, whereas plasma corticosterone response was significantly diminished. The fast decrease of stress-induced high plasma ACTH and corticosterone levels was accompanied by a parallel decline of GR level only in prefrontal cortex but not in the hippocampus or hypothalamus. ConclusionsComparison of the dynamics of changes in plasma ACTH and corticosterone level with respective alterations in GR and MR in brain structures suggests that the buffering effect of repeated stress depends on the period of habituation to stress and the brain structure involved in regulation of these stress response.

Central Administration of Aminoprocalcitonin Inhibits Food Intake and Stimulates the Hypothalamic‐Pituitary‐Adrenal Axis in Rats via the Corticotrophin‐Releasing Factor System

Aminoprocalcitonin (N-PCT), a neuroendocrine peptide derived from procalcitonin, reduces food intake and body weight when administered centrally in rats. We have recently shown that N-PCT is expressed in brain areas known to be involved in energy homeostasis, including the paraventricular nucleus (PVN) of the hypothalamus, which contains a prominent population of corticotrophin-releasing factor (CRF)-synthesising neurones. CRF plays a pivotal role in the regulation of the hypothalamic-pituitary adrenal (HPA) axis and food intake. However, little is known about functional interactions of N-PCT and CRF. In the present study, we found endogenous N-PCT protein in the rat PVN. We also showed N-PCT immunoreactivity in PVN co-localised with NeuN, a neuronal marker, or glial fibrillary acidic protein, an astrocyte marker. Double staining immunohistochemistry revealed that N-PCT co-localised with CRF in parvocellular neurones of the PVN. Intracerebroventricular N-PCT administration increased CRF mRNA and content in the hypothalamus, suggesting that N-PCT stimulates the HPA axis and suppresses food intake and body weight via CRF-dependent pathways. In keeping with this, i.c.v. co-injection of D-Phe-CRF(12-41), a CRF receptor antagonist, significantly attenuated N-PCT-induced reduction in food intake and body weight in a dose-dependent manner. Furthermore, i.c.v. administration of N-PCT increased plasma adrenocorticotrophic hormone and corticosterone concentrations and induced the expression of Fos protein, a marker of neuronal activity, in parvocellular CRF neurones. These data collectively support the hypothesis that N-PCT inhibits food intake and body weight and stimulates the HPA axis via CRF-mediated pathways.

Prevention of gut leakiness by a probiotic treatment leads to attenuated HPA response to an acute psychological stress in rats

Intestinal barrier impairment is incriminated in the pathophysiology of intestinal gut disorders associated with psychiatric comorbidity. Increased intestinal permeability associated with upload of lipopolysaccharides (LPS) translocation induces depressive symptoms. Gut microbiota and probiotics alter behavior and brain neurochemistry. Since Lactobacillus farciminis suppresses stress-induced hyperpermeability, we examined whether (i) L. farciminis affects the HPA axis stress response, (ii) stress induces changes in LPS translocation and central cytokine expression which may be reversed by L. farciminis, (iii) the prevention of "leaky" gut and LPS upload are involved in these effects. At the end of the following treatments female rats were submitted to a partial restraint stress (PRS) or sham-PRS: (i) oral administration of L. farciminis during 2 weeks, (ii) intraperitoneal administration of ML-7 (a specific myosin light chain kinase inhibitor), (iii) antibiotic administration in drinking water during 12 days. After PRS or sham-PRS session, we evaluated LPS levels in portal blood, plasma corticosterone and adrenocorticotropic hormone (ACTH) levels, hypothalamic corticotropin releasing factor (CRF) and pro-inflammatory cytokine mRNA expression, and colonic paracellular permeability (CPP). PRS increased plasma ACTH and corticosterone; hypothalamic CRF and pro-inflammatory cytokine expression; CPP and portal blood concentration of LPS. L. farciminis and ML-7 suppressed stress-induced hyperpermeability, endotoxemia and prevented HPA axis stress response and neuroinflammation. Antibiotic reduction of luminal LPS concentration prevented HPA axis stress response and increased hypothalamic expression of pro-inflammatory cytokines. The attenuation of the HPA axis response to stress by L. farciminis depends upon the prevention of intestinal barrier impairment and decrease of circulating LPS levels.

Atrazine does not induce pica behavior at doses that increase hypothalamic–pituitary–adrenal axis activation and cause conditioned taste avoidance

Previous work has shown that a single oral administration of atrazine (ATR), a chlorotriazine herbicide, causes rapid increases in plasma adrenocorticotropic hormone (ACTH), serum corticosterone (CORT) and progesterone. The mechanism for these effects is unknown. To test whether administration of ATR causes hypothalamic–pituitary–adrenal (HPA) axis activation through the production of a generalized stress response resulting from gastrointestinal distress, we conducted both conditioned taste avoidance (CTA) and pica behavior experiments. Body temperature data were also collected to detect the presence of stress-induced hyperthermia. Adult male Wistar rats were given a single oral dose of ATR (0, 5, 25, 50, 100, or 200mg/kg) or the primary ATR metabolite diamino-s-chlorotriazine (DACT; 135mg/kg). Increases were observed in ACTH (LOEL, 12.5mg/kg), CORT (LOEL, 5mg/kg) and progesterone (LOEL, 5mg/kg) 15min following a single dose of ATR. DACT (135mg/kg) increased ACTH (1.3-fold), CORT (2.9-fold) and progesterone (1.9-fold) above vehicle control concentrations, but the magnitude of the responses was much lower than that observed for an equal molar dose of ATR (200mg/kg; 7.0, 9.0 and 11.0-fold above ACTH, CORT, progesterone controls, respectively). CTA results demonstrated conditioned taste avoidance to ATR, with a NOEL of 5mg/kg. Animals dosed with DACT developed avoidance responses comparable to the highest dose of ATR. In the pica experiment, lower doses (5–50mg/kg) of ATR had no effect on pica behavior, as measured 6 and 24h post-dosing, nor did DACT. However, the highest dose of ATR (200mg/kg) did induce pica behavior at both time points. No differences in body temperature were observed. Overall, results indicate that increases in ACTH and CORT secretion following administration of ATR occur at doses that are without effect on the display of pica behavior, indicating that the HPA-axis activation caused by ATR is not likely the result of gastrointestinal distress.

Complex Actions of Estradiol-3-Sulfate in Late Gestation Fetal Brain

The most abundant form of estrogen circulating in fetal plasma is sulfo-conjugated estrogen; for example, estradiol-3-sulfate (E(2)SO(4)) is more highly abundant than estradiol (E(2)). The present study investigated the ontogeny of the deconjugating (steroid sulfatase [STS]) and conjugating (estrogen sulfotransferase [STF]) enzymes in ovine fetal brain and tested the hypothesis that treatment with E(2)SO(4) would alter the expression of one or both enzymes. Steroid sulfatase was more highly expressed than STF, and both changed as a function of gestational age. Estradiol-3-sulfate infused intracerebroventricularly (icv) significantly increased plasma adrenocorticotropic hormone (ACTH) and cortisol concentrations. Plasma E(2) and E(2)SO(4) were increased, and brain expression of estrogen receptor α was decreased. The proteins STS and STF were up- and downregulated, respectively. Pituitary proopiomelanocortin (POMC) and follicle-stimulating hormone (FSH) and hypothalamic corticotrophin-releasing hormone (CRH) messenger RNA (mRNA) was decreased. We conclude that E(2)SO(4) has complex actions on the fetal brain, which might involve deconjugation by STS, but that the net result of direct E(2)SO(4) icv infusion is more complex than can be accounted for by infusion of E(2) alone.