Stress-related Peptide Research Articles

Effects of physical activity in child and adolescent depression and anxiety: role of inflammatory cytokines and stress-related peptide hormones.

Depression and anxiety are the most common mental illnesses affecting children and adolescents, significantly harming their well-being. Research has shown that regular physical activity can promote cognitive, emotional, fundamental movement skills, and motor coordination, as a preventative measure for depression while reducing the suicide rate. However, little is known about the potential role of physical activity in adolescent depression and anxiety. The studies reviewed in this paper suggest that exercise can be an effective adjunctive treatment to improve depressive and anxiety symptoms in adolescents, although research on its neurobiological effects remains limited.

A Phase 2, Single-Arm, Open-Label Clinical Trial on Adjuvant Peptide-Based Vaccination in Dogs with Aggressive Hemangiosarcoma Undergoing Surgery and Chemotherapy.

To test the antitumor effect and safety of peptide-based anticancer vaccination in dogs with hemangiosarcoma undergoing the standard of care (SOC; surgery and doxorubicin), canine hemangiosarcoma cells were infected with Salmonella typhi Ty21a to release immunogenic endoplasmic reticulum stress-related peptides into the extracellular milieu via CX43 hemichannels opening. The infected tumor cell secretome constituted the vaccine. Following the SOC, dogs with biologically aggressive hemangiosarcoma were vaccinated a total of five times, once every 3 weeks, and were followed up with serial imaging. A retrospective population of dogs undergoing the SOC alone served as controls. The primary endpoints were the time to progression (TTP) and overall survival (OS), and the secondary endpoints were toxicity and immune responses. A total of 28 dogs were vaccinated along with the SOC, and 32 received only the SOC. A tumor-specific humoral response along with a vaccine-specific T-cell response was observed. Toxicity did not occur. The TTP and OS were significantly longer in vaccinated versus unvaccinated dogs (TTP: 195 vs. 160 days, respectively; p = 0.001; OS: 276 vs. 175 days, respectively; p = 0.002). One-year survival rates were 35.7% and 6.3% for vaccinated and unvaccinated dogs, respectively. In dogs with hemangiosarcoma undergoing the SOC, the addition of a peptide-based vaccine increased the TTP and OS, while maintaining a safe profile. Moreover, vaccinated dogs developed a tumor-specific response, supporting the feasibility of future phase three studies.

Circulating levels of mitochondrial oxidative stress-related peptides MOTS-c and Romo1 in stable COPD: A cross-sectional study.

MOTS-c and Romo1 are mitochondrial peptides that are modulated by oxidative stress. No previous studies have explored circulating levels of MOTS-c in patients with chronic obstructive pulmonary disease (COPD). We enrolled 142 patients with stable COPD and 47 smokers with normal lung function in an observational cross-sectional study. We assessed serum levels of both MOTS-c and Romo1 and associated these findings with clinical characteristics of COPD. Compared with smokers with normal lung function, patients with COPD had lower levels of MOTS-c (p = 0.02) and higher levels of Romo1 (p = 0.01). A multivariate logistic regression analysis revealed that above-median MOTS-c levels were positively associated with Romo1 levels (OR 1.075, 95% CI 1.005-1.150, p = 0.036), but no association was found with other COPD characteristics. Below-median levels of circulating MOTS-c were associated with oxygen desaturation (OR 3.25 95% CI 1.456-8.522, p = 0.005) and walking <350 meters (OR 3.246 95% CI 1.229-8.577, p = 0.018) in six-minute walk test. Above-median levels of Romo1 were positively associated with current smoking (OR 2.756, 95% CI 1.133-6.704, p = 0.025) and negatively associated with baseline oxygen saturation (OR 0.776 95% CI 0.641-0.939, p = 0.009). Reduced levels of circulating MOTS-c and increased levels of Romo1 were detected in patients diagnosed with COPD. Low levels of MOTS-c were associated with oxygen desaturation and poorer exercise capacity using 6 min walk test. Romo1 was associated with current smoking and baseline oxygen saturation. www.clinicaltrials.gov; No.: NCT04449419; URL: www.clinicaltrials.gov. Date of registration: June 26, 2020.

Genetic Tagging Uncovers a Robust, Selective Activation of the Thalamic Paraventricular Nucleus by Adverse Experiences Early in Life

BackgroundEarly-life adversity (ELA) is associated with increased risk for mood disorders, including depression and substance use disorders. These disorders are characterized by impaired reward-related behaviors, suggesting compromised operations of reward-related brain circuits. However, the brain regions engaged by ELA that mediate these enduring consequences of ELA remain largely unknown. In an animal model of ELA, we identified aberrant reward-seeking behaviors, a discovery that provides a framework for assessing the underlying circuits. MethodsEmploying TRAP2 (targeted recombination in active populations) male and female mice, in which neurons activated within a defined time frame are permanently tagged, we compared ELA- and control-reared mice, assessing the quantity and distribution of ELA-related neuronal activation. After validating the TRAP2 results using native c-Fos labeling, we defined the molecular identity of this population of activated neurons. ResultsWe uniquely demonstrated that the TRAP2 system is feasible and efficacious in neonatal mice. Surprisingly, the paraventricular nucleus of the thalamus was robustly and almost exclusively activated by ELA and was the only region distinguishing ELA from typical rearing. Remarkably, a large proportion of ELA-activated paraventricular nucleus of the thalamus neurons expressed CRF1, the receptor for the stress-related peptide, corticotropin-releasing hormone, but these neurons did not express corticotropin-releasing hormone itself. ConclusionsThe paraventricular nucleus of the thalamus, an important component of reward circuits that is known to encode remote, emotionally salient experiences to influence future motivated behaviors, encodes adverse experiences as remote as those occurring during the early postnatal period and is thus poised to contribute to the enduring deficits in reward-related behaviors consequent to ELA.

Repeated cocaine or methamphetamine treatment alters astrocytic CRF2 and GLAST expression in the ventral midbrain.

Dopamine neurons in the substantia nigra (SN) and ventral tegmental area (VTA) play a central role in the reinforcing properties of abused drugs including methamphetamine and cocaine. Chronic effects of psychostimulants in the SN/VTA also involve non-dopaminergic transmitters, including glutamate and the stress-related peptide corticotropin-releasing factor (CRF). In the SN/VTA, astrocytes express a variety of membrane-bound neurotransmitter receptors and transporters that influence neurotransmission. CRF receptor type 2 (CRF2) activity in the VTA is important for stress-induced relapse and drug-seeking behaviour, but the localization of its effects is incompletely understood. Here, we first identified CRF2 transcript in astrocytes of the SN/VTA using RNA-Seq in Aldh1l1;NuTRAP mice and confirmed it using in situ hybridization (RNAscope) in wild-type mice. We then used immunofluorescence to quantify the astrocytic marker protein S100β, glial-specific glutamate/aspartate transporter GLAST, and CRF2 in the SN/VTA following 12 days of treatment (i.p.) with methamphetamine (3 mg/kg), cocaine (10mg/kg), or saline. We observed a significant decrease in GLAST immunofluorescence in brains of psychostimulant treated mice compared with saline controls. In addition, we observed increased labelling of CRF2 in drug treated groups, a decrease in the number of S100β positive cells, and an increase of co-staining of CRF2 with both S100β and tyrosine hydroxylase (dopamine neurons). Our results suggest a significant interaction between CRF2, GLAST, and astrocytes in the midbrain that emerges with repeated exposure to psychostimulants. These findings provide rationale for future investigation of astrocyte-based strategies for altering cellular and circuit function in response to stress and drug exposure.

Neurobiology: Novel peptide pathways impact threat discrimination

Discriminating dangerous predictive stimuli from non-threatening stimuli is vital for maintaining optimal behavioral strategies. A new study finds that novel stress-related peptide pathways to the dopaminergic midbrain play a fundamental role in threat generalization.

Altered mRNA Levels of Stress-Related Peptides in Mouse Hippocampus and Caudate-Putamen in Withdrawal after Long-Term Intermittent Exposure to Tobacco Smoke or Electronic Cigarette Vapour.

Nicotine addiction is a severe public health problem. The aim of this study was to investigate the alterations in key neurotransmissions after 60 days of withdrawal from seven weeks of intermittent cigarette smoke, e-cigarette vapours, or an e-cigarette vehicle. In the nicotine withdrawal groups, increased depressive and anxiety/obsessive–compulsive-like behaviours were demonstrated in the tail suspension, sucrose preference and marble burying tests. Cognitive impairments were detected in the spatial object recognition test. A significant increase in Corticotropin-releasing factor (Crf) and Crf1 mRNA levels was observed, specifically after cigarette withdrawal in the caudate-putamen nucleus (CPu). The nociceptin precursor levels were reduced by cigarette (80%) and e-cigarette (50%) withdrawal in the CPu. The delta opioid receptor showed a significant reduction in the hippocampus driven by the exposure to an e-cigarette solubilisation vehicle, while the mRNA levels doubled in the CPu of mice that had been exposed to e-cigarettes. Withdrawal after exposure to e-cigarette vapour induced a 35% Bdnf mRNA decrease in the hippocampus, whereas Bdnf was augmented by 118% by cigarette withdrawal in the CPu. This study shows that long-term withdrawal-induced affective and cognitive symptoms associated to lasting molecular alterations in peptidergic signalling may determine the impaired neuroplasticity in the hippocampal and striatal circuitry.

Effects of stress-related peptides on chloride secretion in the mouse proximal colon.

Stress increases intestinal secretion and exacerbates symptoms of irritable bowel syndrome (IBS). Peripherally derived corticotropin-releasing factor (CRF) is known to mediate stress-induced intestinal secretion, presumably by activation of CRF1 receptors in the gut. The present study aimed to ascertain the role of CRF2 activation in intestinal secretion by three other members of CRF peptide family, urocortin (UCN) 1-3, in wild type (WT) and CRF2 knockout (Crhr2-/- ) mice. Mucosal/submucosal preparations from proximal colon of WT and Crhr2-/- mice of both sexes were mounted in Ussing chambers for measurement of short-circuit current (Isc ) as an indicator of ion secretion. Male mice demonstrated a significantly higher baseline Isc than female in both WT and Crhr2-/- genotypes. CRF and UCN1-3 (1μM) caused greater increases in colonic Isc (ΔIsc ) in male than female. Colonic Isc response to the selective CRF1 agonist, stressin1, was similar in both sexes. In male mice, the selective CRF2 agonists (UCN2 and UCN3) caused significantly greater ΔIsc than CRF and stressin1. UCN2- and UCN3-evoked ΔISC was significantly reduced in preparations pretreated with the selective CRF2 antagonist antisauvagine-30 and in Crhr2-/- mice. The prosecretory effects of urocortins were due to increases in Cl- secretion and involved enteric neurons and mast cells. The findings revealed sex differences in baseline colonic secretion and responses to stress-related peptides. CRF2 receptors play a more prominent role in colonic secretion in male mice. The greater baseline secretion and responses to UCNs may contribute to the higher prevalence of diarrhea-predominant IBS in males.

The Combination of Cholecystokinin and Stress Amplifies an Inhibition of Appetite, Gastric Emptying, and an Increase in c-Fos Expression in Neurons of the Hypothalamus and the Medulla Oblongata.

Cholecystokinin (CCK) had been the first gastrointestinal hormone known to exert anorexic effects. CCK had been inferred to contribute to the onset of functional dyspepsia (FD) symptoms. To understand the pathophysiology of FD, the roles of stress have to be clarified. In this study, we aimed to clarify the influence of stress on the action of cholecystokinin (CCK) on appetite and gastric emptying. Using rats, stress was simulated by giving restraint stress or intraperitoneal injection of the stress-related peptide hormone urocortin 1 (UCN1). The effects of CCK and restraint stress, alone or in combination, on food intake and gastric motility were examined, and c-Fos expression in the neurons of appetite control network in the central nervous system was assessed by immunohistochemical staining. CCK inhibited food intake and gastric emptying in a dose-dependent manner. Food intake for 1h was significantly lower with UCN1 (2nmol/kg) than with the saline control. Restraint stress amplified the suppressive effects of CCK on food intake for 1h and on gastric emptying. With regard to brain function, the CCK induced c-Fos expression in the neurons of the nucleus tractus solitarius and paraventricular nucleus of the hypothalamus was markedly and significantly amplified by the addition of restraint stress with CCK. The results suggested that stress might amplify the anorexic effects of CCK through activation of the nuclei that comprise the brain neuronal network for satiation; this might play a role in the pathogenesis of the postprandial distress syndromes of functional dyspepsia.

Urocortin 1: A putative excitatory neurotransmitter in the enteric nervous system.

Urocortin 1 (Ucn1), a stress-related peptide, is a member of the corticotropin-releasing factor (CRF) family and acts as a CRF1 receptor agonist. Ucn1 and CRF1 receptor immunoreactivity are present in the enteric nervous system (ENS), and Ucn1 elicits contraction of colonic muscle strips. Considering these findings, we have hypothesized that Ucn1 acts as an excitatory neurotransmitter in the ENS. The present study was conducted to determine whether exogenously applied Ucn1 causes contractions, whether it participates in neurally mediated contraction, and whether it is released from the ENS of the rat colon. Isometric tension of the rat colonic muscle strips (middle to distal colon) in a longitudinal direction was measured. The effects of Ucn1 on phasic contractions were examined in the absence and presence of antalarmin (CRF1 receptor antagonist), tetrodotoxin (TTX), and atropine. The effects of antalarmin on electrical field stimulation (EFS)-induced contractions were examined in the absence and presence of atropine. Ucn1 peptide in the bath solution was measured after EFS using an EIA kit. Ucn1 caused a significant and dose-dependent increase in phasic contractions. These effects were completely inhibited by antalarmin, TTX, and atropine. EFS-induced contractions were inhibited by antalarmin. Atropine markedly reduced EFS-induced contractions, and antalarmin did not decrease these contractions further. EFS elicited a significant increase in the concentration of Ucn1 in the bath solution, and this increase was completely inhibited by TTX. These results suggest that Ucn1 acts as an excitatory neurotransmitter in the ENS enhancing the cholinergic neurotransmission.

Evaluation of Serum Urocortin 2 Levels in Patients with Hypertension.

Urocortin 2 (UCN2), is an endogenous stress-related peptide belonging to the corticotropin-releasing factor (CRF) family, has a major role in the pathogenesis of congestive heart failure, ischemic heart disease, and hypertension. To investigate the role of UCN2 levels in patients with hypertension (HTN). Serum UCN2 levels measured by ELISA were compared between patients with HTN (n = 86) and nonHTN (n = 53). Eighty-six patients with HTN [median age 66 (45-76); 38 men] and 53 patients with non-HTN [median age 62 (40-80); 39 men] were included into this study. Serum UCN2 (5.17ng/ml; IQR, 1.26-11.68ng/ml vs 0.79ng/ml; IQR, 0.07-4.10ng/ml, p < 0.0005) levels were found significantly elevated in patients with HTN compared to nonHTN control group.Concentrations of serum UCN2 were positively correlated with left ventricle mass index to body surface area (LV mass index to BSA, r = 0.20, p = 0.03), LV mass index to height2.7 (r = 0.28, p = 0.002) and body mass index (r = 0.24, p = 0.008). Additionally, logistic regression analysis was performed to UCN2, uric acid, creatinine, glomerular filtration rate, age, body mass index, coronary artery disease and diabetes mellitus which are the potential confounders of hypertension. According to logistic regression analysis serum UCN2 values were found out as an independent predictor of HTN. UCN2 levels, correlated with LV mass index were increased in HTN patients compared to nonHTN patients. These data provide evidence that there could be a relationship between high concentrations of UCN2 and HTN. UCN2 may appear as a promising choice of HTN treatment in the future.

Neurobiology of Aggressive Behavior-Role of Autoantibodies Reactive With Stress-Related Peptide Hormones.

Adrenocorticotropic hormone together with arginine vasopressin and oxytocin, the neuropeptides regulating the stress response and the hypothalamic-pituitary-adrenal axis activity, are known to modulate aggressive behavior. The functional role of the adrenocorticotropic hormone immunoglobulin G autoantibodies in peptidergic signaling and motivated behavior, including aggression, has been shown in experimental and in vitro models. This review summarizes some experimental data implicating autoantibodies reactive with stress-related peptides in aggressive behavior.

Role of corticotropin-releasing factor on bladder function in rats with psychological stress

Stress-related peptide corticotropin-releasing factor (CRF) and CRF-related peptides are distributed in the peripheral viscera such as the bladder. We investigated the contribution of psychological stress (PS) and CRF on bladder function. Male rats received sham stress (SS) or PS using a communication box method for 120 min every day for 7 days. One group of rats received the intraperitoneal CRF-R1 antagonist antalarmin for 7 days during stress exposure. Mean voided volume per micturition was significantly lower in PS rats compared to SS rats, which was antagonized by antalarmin treatment. Increases in plasma and bladder CRF, and mRNA expressions of bladder CRF, CRF-R1, and M2/3 muscarinic receptors, were found in PS rats. CRF did not influence bladder contraction in itself; however, stress increased the response of muscarinic contraction of bladder strips. These changes were antagonized by antalarmin treatment. In conclusion, PS reinforces M3 receptor-mediated contractions via CRF-R1, resulting in bladder storage dysfunction.

Comparison of Colonic Baseline Ion Secretion and Responses to Stress‐related Peptides between Male and Female Mice

Background and AimsSex plays an important role in the symptoms of irritable bowel syndrome (IBS) and responses to treatment. Constipation‐predominant IBS (IBS‐C) is more prevalent in women, whereas diarrhea‐predominant IBS (IBS‐D) is more common in men. Stress has been shown to increase intestinal ion secretion and may exacerbate symptoms in IBS‐D. Most of the previous preclinical studies investigating the effects of stress on gut function were performed in male animals. The aim of the present study was to determine if there was a sex difference in baseline ion secretion in the mouse colon and/or its responses to stress‐related peptides, including corticotrophin releasing hormone (CRF), urocortin 1 (Ucn1), Ucn2, and Ucn3.MethodsAdult C57BL/6J mice (47 males and 20 females) were used in the present study. Mucosa/submucosa preparations from the proximal colon were mounted in Ussing flux chambers for measurement of short‐circuit current (Isc) as an indicator of mucosal ion secretion.ResultsMale mice were found to exhibit a significantly (p &lt; 0.05) higher baseline Isc (70.90 ± 4.84 μA/cm2, n = 47) in the proximal colon than females (52.92 ± 4.40 μA/cm2, n = 20). In addition, male mice exhibited a greater increase in colonic Isc (ΔIsc) than did female mice in response to 1 μM of CRF (10.26 ± 1.31 μA/cm2 vs. 4.59 ± 1.21 μA/cm2, n = 5/group, p &lt; 0.05), 1 μM of Ucn1 (16.65 ± 2.23 μA/cm2 vs. 6.80 ± 1.16 μA/cm2, n = 5/group, p &lt; 0.01), 1 μM of Ucn2 (21.76 ± 4.58 μA/cm2 vs. 6.72 ± 0.57 μA/cm2, n = 5/group, p &lt; 0.05), or 1 μM of Ucn3 (41.41 ± 8.91 μA/cm2 vs. 7.86 ± 1.47 μA/cm2, n = 5, p &lt; 0.01). Colonic Isc response to the selective CRF1 receptor agonist, stressin I (1 μM) was similar in male and female mice (10.19 ± 2.19 μA/cm2 vs. 7.08 ± 5.16 μA/cm2, n = 4–5/group, p &gt; 0.05). In male mice, Ucn3 caused a significantly higher ΔIsc than stressin I, CRF, Ucn1, or Ucn2. Contrastingly, female mice displayed a similar and weaker ΔIsc response to these peptides.ConclusionsMarked sex differences were observed in colonic baseline ion secretion and responses to stress‐related peptides. Male mice demonstrated a significantly higher baseline ion secretion in the proximal colon when compared with their female counter parts. In addition, CRF, Ucn1, Unc2, and Ucn3 evoked a greater increase in colonic ion secretion in male mice than female mice. Ucn3 is more efficacious than the other stress‐related peptides to evoke ion secretion in the male mouse colon, suggesting a predominant role of the CRF2 receptors in stimulation colonic ion secretion in males. Female mice, however, exhibited low level responses to these stress‐related peptides, and no significant differences were seen between these peptides‐evoked responses. The results suggest that the greater colonic baseline ion secretion and responses to stress‐related peptides in male mice may contribute to the high prevalence of IBS‐D in males.Support or Funding InformationNIH R15 DK097460‐01A1 (SL) and UWL graduate research service and educational leadership grant (AK). Howard Hua is a summer research fellow from Wheeler High School, Marietta, GA.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Tu1681 - Stress and Stress-Related Peptide Amplify the Anorexic Actions of Cholecystokinin

Tu1681 - Stress and Stress-Related Peptide Amplify the Anorexic Actions of Cholecystokinin

Acetaldehyde, Motivation and Stress: Behavioral Evidence of an Addictive ménage à trois.

Acetaldehyde (ACD) contributes to alcohol’s psychoactive effects through its own rewarding properties. Recent studies shed light on the behavioral correlates of ACD administration and the possible interactions with key neurotransmitters for motivation, reward and stress-related response, such as dopamine and endocannabinoids. This mini review article critically examines ACD psychoactive properties, focusing on behavioral investigations able to unveil ACD motivational effects and their pharmacological modulation in vivo. Similarly to alcohol, rats spontaneously drink ACD, whose presence is detected in the brain following chronic self-administration paradigm. ACD motivational properties are demonstrated by operant paradigms tailored to model several drug-related behaviors, such as induction and maintenance of operant self-administration, extinction, relapse and punishment resistance. ACD-related addictive-like behaviors are sensitive to pharmacological manipulations of dopamine and endocannabinoid signaling. Interestingly, the ACD-dopamine-endocannabinoids relationship also contributes to neuroplastic alterations of the NPYergic system, a stress-related peptide critically involved in alcohol abuse. The understanding of the ménage-a-trois among ACD, reward- and stress-related circuits holds promising potential for the development of novel pharmacological approaches aimed at reducing alcohol abuse.

Interaction of Isoflurane, Tumor Necrosis Factor-α and β-Amyloid on Long-term Potentiation in Rat Hippocampal Slices.

The relationship between inhalational anesthetics such as isoflurane and cognitive impairment in the elderly is controversial. Both β-amyloid peptide (Aβ), associated with Alzheimer disease, and tumor necrosis factor-α (TNF-α), a proinflammatory stress-related peptide, impair the synaptic function. We hypothesized that transient exposure to isoflurane and these peptides would impair synaptic function, manifest as a depression of long-term potentiation (LTP) and paired pulse facilitation (PPF), in the rat hippocampus. Hippocampal slices were prepared from 3- to 4-week-old male Wistar rats. Preliminary experiments identified minimal concentrations of Aβ1-42 peptide and TNF-α that produced statistically detectable suppressing effects on LTP (600 nM Aβ1-42 and 5 ng/mL TNF-α). These concentrations of peptides were applied to slices alone, with 1.5% isoflurane, or in combination for 1 hour and then washed out. Measurements of LTP (field excitatory postsynaptic potentials [fEPSPs]) from neurons in the CA1 area by stimulation of the Schaffer-Collateral pathway were made after high-frequency stimulation (100 Hz, 1 second). Analysis of variance with correction for multiple comparisons was used to compare LTP under steady-state conditions and averaged for the 40- to 60-minute period after LTP induction. EPSP amplitude after LTP induction was 155% ± 9% of baseline and was not affected by isoflurane exposure and washout (150% ± 4% of baseline, P = .47). Both Aβ1-42 and TNF-α reduced LTP by approximately 15% compared with control (129% ± 7% and 131% ± 11% of baseline respectively, means ± SD, both P < .001). When Aβ1-42 was combined with isoflurane, LTP was not impaired (151% ± 9% of control, P = .85), but isoflurane had no effect on LTP depression caused by TNF-α or a combination of Aβ and TNF-α. Brief exposure to isoflurane prevents rather than impairs the decrease in LTP caused by Aβ1-42 in rat hippocampus. In contrast, isoflurane had no effect on synaptic impairment caused by TNF-α or a combination of TNF-α and Aβ. Although this is an in vitro study and translation to clinical medicine requires additional work, the interactions of isoflurane, Aβ, and TNF-α revealed here could have implications for patients with Alzheimer disease or perioperative neuroinflammation.

A Stress-Related Peptide Bombesin Centrally Induces Frequent Urination through Brain Bombesin Receptor Types 1 and 2 in the Rat.

Stress exacerbates symptoms of bladder dysfunction including overactive bladder and bladder pain syndrome, but the underlying mechanisms are unknown. Bombesin-like peptides and bombesin receptor types 1 and 2 (BB1 and BB2, respectively) in the brain have been implicated in the mediation/integration of stress responses. In this study, we examined effects of centrally administered bombesin on micturition, focusing on their dependence on 1) the sympathoadrenomedullary system (a representative mechanism activated by stress exposure) and 2) brain BB receptors in urethane-anesthetized (1.0-1.2 g/kg, i.p.) male rats. Intracerebroventricularly administered bombesin significantly shortened intercontraction intervals (ICI) at both doses (0.1 and 1 nmol/animal) without affecting maximal voiding pressure. Bombesin at 1 nmol induced significant increments of plasma noradrenaline and adrenaline levels, which were both abolished by acute bilateral adrenalectomy. On the other hand, adrenalectomy showed no effects on the bombesin-induced shortening of ICI. Much lower doses of bombesin (0.01 and 0.03 nmol/animal, i.c.v.) dose-dependently shortened ICI. Pretreatment with either a BB1 receptor antagonist (BIM-23127; d-Nal-cyclo[Cys-Tyr-d-Trp-Orn-Val-Cys]-Nal-NH2; 3 nmol/animal, i.c.v.) or a BB2 receptor antagonist (BEA; H-d-Phe-Gln-Trp-Ala-Val-Gly-His-Leu-NHEt; 3 nmol/animal, i.c.v.), respectively, suppressed the BB (0.03 nmol/animal, i.c.v.)-induced shortening of ICI, whereas each antagonist by itself (1 and 3 nmol/animal, i.c.v.) had no significant effects on ICI. Bombesin (0.03 nmol/animal, i.c.v.) significantly reduced voided volume per micturition and bladder capacity without affecting postvoid residual volume or voiding efficiency. These results suggest that brain bombesin and BB receptors are involved in facilitation of the rat micturition reflex to induce bladder overactivity, which is independent of the sympathoadrenomedullary outflow modulation.

Brain opioid and nociceptin receptors are involved in regulation of bombesin-induced activation of central sympatho-adrenomedullary outflow in the rat

Previously, we reported that central administration of bombesin, a stress-related peptide, elevated plasma levels of catecholamines (noradrenaline and adrenaline) in the rat. The sympatho-adrenomedullary system, which is an important component of stress responses, can be regulated by the central opioid system. In the present study, therefore, we examined the roles of brain opioid receptor subtypes (µ, δ, and κ) and nociceptin receptors, originally identified as opioid-like orphan receptors, in the bombesin-induced activation of central sympatho-adrenomedullary outflow using anesthetized male Wistar rats. Intracerebroventricularly (i.c.v.) administered bombesin-(1nmol/animal) induced elevation of plasma catecholamines was significantly potentiated by pretreatment with naloxone (300 and 1000µg/animal, i.c.v.), a non-selective antagonist for µ-, δ-, and κ-opioid receptors. Pretreatment with cyprodime (100µg/animal, i.c.v.), a selective antagonist for µ-opioid receptors, also potentiated the bombesin-induced responses. In contrast, pretreatment with naltrindole (100µg/animal, i.c.v.) or nor-binaltorphimine (100µg/animal, i.c.v.), a selective antagonist for δ- or κ-opioid receptors, significantly reduced the elevation of bombesin-induced catecholamines. In addition, pretreatment with JTC-801 (30 and 100µg/animal, i.c.v.) or J-113397 (100µg/animal, i.c.v.), which are selective antagonists for nociceptin receptors, also reduced the bombesin-induced responses. These results suggest that brain µ-opioid receptors play a suppressive role and that brain δ-, κ-opioid, and nociceptin receptors play a facilitative role in the bombesin-induced elevation of plasma catecholamines in the rat. Thus, in the brain, these receptors could play differential roles in regulating the activation of central sympatho-adrenomedullary outflow.

Role of adrenomedullin in the cerebrospinal fluid-contacting nucleus in the modulation of immobilization stress

The contribution of the cerebrospinal fluid-contacting nucleus (CSF-contacting nucleus) and adrenomedullin (ADM) to the developmental modulation of stressful events remains controversial. This study explored the effects of endogenous ADM in the CSF-contacting nucleus on immobilization of stress-induced physiological parameter disorders and glucocorticoid hormone releasing hormone (CRH), rat plasma corticosterone expression, and verification of such effects by artificially lowering ADM expression in the CSF-contacting nucleus by targeted ablation of the nucleus. Immunohistochemical experiments showed that ADM-like immunoreactivity and the calcitonin receptor-like receptor (CRLR) marker were localized in the CSF-contacting nucleus. After 7 continuous days of chronic immobilization stress (CIS), animals exhibited anxiety-like behavior. Also, an increase in serum corticosterone, and enhanced expression of ADM in the CSF-contacting nucleus were observed, following activation by CIS. The intracerebroventricular (i.c.v.) administration of the ADM receptor antagonist AM22–52 significantly reduced ADM in the CSF-contacting nucleus, additionally, blocked the effects of ADM, meaning the expression of CRH in the hypothalamic paraventricular nucleus (Pa) and serum corticosterone level were increased, and the physiological parameters of the rats became correspondingly deteriorated. Additionally, the i.c.v. administration of cholera toxin subunit B-saporin (CB-SAP), a cytotoxin coupled to a cholera toxin subunit, completely eliminated the CSF-contacting nucleus, worsening the reaction of the body to CIS. The collective results demonstrated that ADM acted as a stress-related peptide in the CSF-contacting nucleus, and its lower expression and blocked effects in the nucleus contributed to the deterioration of stress-induced physiologic parameter disorders as well as the excessive expressions of stress-related hormones which were part of the hypothalamic–pituitary–adrenal (HPA) axis.