r-121919 and antalarmin

Mounting evidence suggests that chronic stress can alter brain structure and function and promote the development of neuropsychiatric disorders, such as depression and Alzheimer's disease. Although the results of several studies have indicated that aged brains are more vulnerable to chronic stress, it remains unknown whether antagonists of a key stress regulator, the corticotrophin releasing factor receptor 1 (CRF1), can prevent stress-induced anxiety and memory deficits in animal models. In this study, we evaluated the potential benefits of two CRF1 antagonists, R121919 and antalarmin, for preventing stress-induced anxiety-related behavioral and memory deficits and neurodegeneration in aged rats. We stressed rats using isolation-restraint for 3 months starting from the 18 months of age. Subsets of animals were administrated either R121919 or antalarmin through food chow for 3 months, followed by a series of behavioral, biochemical and morphological analyses. We found that stressed aged rats displayed body weight losses and increased corticosterone levels, as well as anxiety-related behaviors and memory deficits. Additionally, chronic stress induced a loss of cortical dendritic spines and synapses. However, R121919 and antalarmin both prevented stress-induced behavioral changes including anxiety-related behaviors and memory deficits and prevented synapse loss, perhaps through reversing HPA axis dysfunction. These results suggest that CRF1 antagonists may hold promise as a potential therapy for preventing stress-induced anxiety and memory deficits in aged individuals.

Topics: Age Factors; Animals; Anxiety; Behavior; Behavior, Animal; Corticotropin-Releasing Hormone; Depression; Disease Models, Animal; Female; Hypothalamo-Hypophyseal System; Male; Pituitary-Adrenal System; Pyrimidines; Pyrroles; Rats; Rats, Sprague-Dawley; Receptors, Corticotropin-Releasing Hormone; Stress, Psychological; Synapses

Previous studies indicate that psychosocial stressors could accelerate amyloid-β (Aβ) levels and accelerate plaque deposition in mouse models of Alzheimer disease (AD). Stressors enhanced the release of corticotrophin-releasing factor (CRF), and exogenous CRF administration mimicked the effects of stress on Aβ levels in mouse models of AD. However, whether CRF receptor 1 (CRF1) antagonists could influence the stress-induced acceleration of an AD-like process in mouse models has not been well studied.. We sought to examine whether CRF1 antagonists inhibit the effects of isolation stress on tissue Aβ levels, Aβ plaque deposition, and behaviors related to anxiety and memory in Tg2576 mice, and to investigate the molecular mechanism underlying such effects.. Cohorts of Tg2576 mouse pups were isolated or group-housed at 21 days of age, and then the subgroups of these cohorts received daily intraperitoneal injections of the CRF1 antagonists, antalarmin or R121919 (5, 10, and 20 mg/kg), or vehicle for 1 week. Other cohorts of Tg2576 mouse pups were isolated or group-housed at 21 days of age, and then at 4 months of age, subgroups of these mice were administered antalarmin (20 mg/kg) or vehicle in their drinking water for 6 months. Finally, cultured primary hippocampal neurons from regular Tg2576 pups (P0) were incubated with CRF (0.1, 1, and 10 nM), antalarmin (100 nM) or H-89 (1 μM) for 48 h. Brain tissues or cultured neurons were collected for histological and biochemical analyses, and behavioral measures were collected in the cohorts of mice that were chronically stressed.. Administration of antalarmin at 20 mg/kg dose for 1 week significantly reduced Aβ1-42 levels in isolation stressed mice. Administration of antalarmin for 6 months significantly decreased plasma corticosterone levels, tissue Aβ1-42 levels, and Aβ plaque deposition in the brain and blocked the effects of isolation stress on behaviors related to anxiety and memory. Finally, incubation of neurons with 100 nM antalarmin inhibited the ability of 10 nM CRF to increase Aβ1-42 levels and protein kinase A IIβ expression. The effect of CRF1 on Aβ1-42 levels was also diminished by treatment with H-89, a c-AMP/PKA inhibitor.. These results suggest that CRF1 antagonists can slow an AD-like process in Tg2576 mice and that the c-AMP/PKA signaling pathway may be involved in this effect.

Topics: Alzheimer Disease; Amyloid beta-Protein Precursor; Animals; Corticotropin-Releasing Hormone; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Disease Models, Animal; Hippocampus; Male; Memory; Mice; Mice, Transgenic; Neurons; Plaque, Amyloid; Pyrimidines; Pyrroles; Receptors, Corticotropin-Releasing Hormone; Signal Transduction

Exposure and/or sensitivity to stress have been implicated as conferring risk for development of Alzheimer's disease (AD). Although the basis for such a link remains unclear, we previously reported differential involvement of corticotropin-releasing factor receptor (CRFR) 1 and 2 in acute stress-induced tau phosphorylation (tau-P) and solubility in the hippocampus. Here we examined the role of CRFRs in tau-P induced by repeated stress and the structural manifestations of altered tau solubility. Robust tau-P responses were seen in WT and CRFR2 null mice exposed to repeated stress, which were sustained at even 24 h after the final stress exposure. A portion of phosphorylated tau in these mice was sequestered in detergent-soluble cellular fractions. In contrast, CRFR1 and CRFR double-KO mice did not exhibit repeated stress-induced alterations in tau-P or solubility. Similarly, treatment with CRFR1 antagonist attenuated repeated stress-induced tau-P. Using histochemical approaches in a transgenic CRFR1 reporter mouse line, we found substantial overlap between hippocampal CRFR1 expression and cells positive for phosphorylated tau after exposure to repeated stress. Ultrastructural analysis of negatively stained extracts from WT and CRFR2 null mice identified globular aggregates that displayed positive immunogold labeling for tau-P, as well as conformational changes in tau (MC1) seen in early AD. Given that repeated stress exposure results in chronic increases in hippocampal tau-P and its sequestration in an insoluble (and potentially prepathogenic) form, our data may define a link between stress and an AD-related pathogenic mechanism.

Topics: Animals; Blotting, Western; Dentate Gyrus; Detergents; Female; Fluorescent Antibody Technique; Green Fluorescent Proteins; Hippocampus; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Microscopy, Immunoelectron; Neurons; Phosphorylation; Pyrimidines; Pyrroles; Receptors, Corticotropin-Releasing Hormone; Solubility; Stress, Psychological; tau Proteins

Alcohol dependence is characterized by excessive alcohol consumption, loss of control over intake, and the presence of a withdrawal syndrome, which includes both motivational and physical symptoms. Similar to human alcoholics, ethanol-dependent animals display enhanced anxiety-like behaviors and enhanced ethanol self-administration during withdrawal, effects hypothesized to result from a dysregulation of corticotropin-releasing factor (CRF) stress systems. Here, we used an animal model of ethanol dependence to test the effects of CRF(1) receptor antagonists on excessive ethanol self-administration in dependent rats.. Wistar rats, trained to orally self-administer ethanol, were exposed intermittently to ethanol vapors to induce ethanol dependence. Nondependent animals were exposed to control air. Following a 2-hour period of withdrawal, dependent and nondependent animals were systemically administered antalarmin, MJL-1-109-2, or R121919 (CRF(1) antagonists) and ethanol self-administration was measured.. The nonpeptide, small molecule CRF(1) antagonists selectively reduced excessive self-administration of ethanol in dependent animals during acute withdrawal. The antagonists had no effect on ethanol self-administration in nondependent rats.. These data demonstrate that CRF(1) receptors play an important role in mediating excessive ethanol self-administration in dependent rats, with no effect in nondependent rats. CRF(1) antagonists may be exciting new pharmacotherapeutic targets for the treatment of alcoholism in humans.

Topics: Alcoholism; Animals; Behavior, Animal; Central Nervous System Depressants; Conditioning, Operant; Corticotropin-Releasing Hormone; Disease Models, Animal; Dose-Response Relationship, Drug; Ethanol; Hormone Antagonists; Male; Pyrimidines; Pyrroles; Rats; Rats, Wistar; Self Administration; Triazines

Corticotropin-releasing factor (CRF) is a neurotransmitter in Barrington's nucleus neurons. These neurons can coregulate parasympathetic tone to the bladder (to modulate micturition) and brain noradrenergic activity (to affect arousal). To identify the role of CRF in the regulation of micturition, the effects of CRF agonists and antagonists on urodynamics in the unanesthetized rat were characterized. Rats were implanted with bladder and intrathecal or intraperitoneal catheters under isoflurane anesthesia. Cystometry was performed in the unanesthetized, unrestrained state at least 24 h later. In some cases, cortical electroencephalographic activity (EEG) was recorded simultaneously to assess arousal state. During cystometry, the state of arousal often shifted between waking and sleeping and urodynamic function changed depending on the state. Micturition threshold, bladder capacity, and micturition volume were all increased during sleep. The CRF1/CRF2 receptor agonists CRF and urocortin 2 increased bladder capacity and micturition volume in awake but not in sleeping rats. Conversely, the CRF1 receptor antagonists antalarmin and NBI-30775 increased urinary frequency and decreased bladder capacity in awake rats. The present results demonstrate a profound effect of the state of arousal on urodynamic function and suggest that simultaneous monitoring of EEG and cystometry may provide a useful model for studying nocturnal enuresis and other urinary disorders. In addition, the results provide evidence for an inhibitory influence of CRF in the spinal pathway on micturition. Targeting the CRF system in the spinal cord may provide a novel approach for treating urinary disorders.

Topics: Animals; Arousal; Corticotropin-Releasing Hormone; Electroencephalography; Hormone Antagonists; Injections, Spinal; Male; Movement; Neuropeptides; Peptide Fragments; Pyrimidines; Pyrroles; Rats; Rats, Sprague-Dawley; Receptors, Corticotropin-Releasing Hormone; Sleep; Urocortins; Urodynamics; Wakefulness

Exposure to stressors that elicit fear and feelings of hopelessness can cause severe vagal activation leading to bradycardia, syncope, and sudden death. These phenomena though documented, are difficult to diagnose, treat clinically, and prevent. Therefore, an animal model incorporating these cardiovascular conditions could be useful. The present study examined 'sinking' during a 2-h swim stress, a phenomenon that occurs in 50% of rats during 25 degrees C water exposure. Concurrent measurements of body temperature, immobility, heart rate (HR), and PR interval (a measure of vagal activity) were made. Neither decreases in immobility nor variations in hypothermia during swim were correlated with sinking. Bradycardia was more severe in sinking rats (average minimum HR+/-SEM; 143+/-13 vs 247+/-14; p<0.01), and PR interval was elevated (p<0.0001). To examine potential modulation of vagal activity during stress, corticotropin-relasing factor (CRF) receptor antagonists (antalarmin, R121919 and astressin B), a glucocorticoid receptor antagonist (RU486), and a peripherally acting cholinergic antagonist (methylatropine nitrate) were administered. The centrally acting CRF antagonist, antalarmin (32 mg/kg), produced elongation of the PR interval (p<0.0001), robust bradycardia (135+/-18; p<0.001), and increased sinking (92%; p<0.05), and methylatropine nitrate (3.2 mg/kg) blocked these effects. Corroborating these data, two different CRF antagonists, R121919 (30 mg/kg) and astressin B (intracerebroventricular (i.c.v.), 0.03 mug/rat) increased sinking to 100%. RU486 (20 mg/kg) blocked HPA axis negative feedback and decreased percent sinking to 25%. From these studies, we concluded that sinking during a 2-h water exposure was a result of extreme vagal hyperactivity. Furthermore, stress-induced CRF release may serve to protect against elevated cardiac vagal activity.

Topics: Animals; Bradycardia; Cholinergic Antagonists; Corticotropin-Releasing Hormone; Death, Sudden, Cardiac; Disease Models, Animal; Exercise Tolerance; Fatigue; Heart Rate; Hypothalamo-Hypophyseal System; Hypothermia, Induced; Male; Mifepristone; Peptide Fragments; Psychomotor Agitation; Pyrimidines; Pyrroles; Rats; Rats, Sprague-Dawley; Receptors, Corticotropin-Releasing Hormone; Stress, Psychological; Swimming; Vagus Nerve; Vagus Nerve Diseases

The role of positive vs negative ethanol reinforcement in ethanol intake of Sardinian alcohol-preferring (sP) rats is unclear.. To test the hypothesis that spontaneous ethanol self-administration of sP rats was sensitive to the opioid receptor antagonist naltrexone, whereas withdrawal-induced, but not spontaneous, ethanol self-administration would be sensitive to corticotropin-releasing factor(1) (CRF(1)) antagonists, implicating differential roles for positive and negative reinforcement, respectively.. Male sP rats operantly (FR1, 30 min/day) self-administered ethanol (10% v/v) until responding stabilized. One group (n=11) was made ethanol dependent through intermittent ethanol vapor exposure. Both nondependent (n = 10) and dependent rats received the CRF(1) antagonist LWH-63 (5, 10, and 20 mg/kg, s.c.). Separate nondependent sP rats (n = 10) received the opioid antagonist naltrexone (16, 50, 150, and 450 microg/kg, s.c.). Finally, CRF(1) antagonists (MJL-1-109-2, LWH-63, and R121919) were studied for their actions on home-cage ethanol drinking in nondependent sP rats (n = 6-8/group) under continuous, limited-access, or stressed conditions.. Naltrexone potently reduced ethanol self-administration in nondependent sP rats. LWH-63 reduced heightened ethanol self-administration of vapor-sensitive, dependent sP rats. CRF(1) antagonists did not reduce ethanol intake in nondependent sP rats. R121919 (10 mg/kg, s.c.) retained antistress activity in sP rats, blunting novelty stress-induced suppression of ethanol intake.. Spontaneous ethanol self-administration of sP rats was opioid dependent with CRF(1) receptors implicated in withdrawal-induced drinking. Opioid and CRF(1) receptors play different roles in ethanol reinforcement and perhaps the ethanol addiction cycle. Such distinctions may apply to subtypes of alcoholic patients who differ in their motivation to drink and ultimately treatment response.

Topics: Alcohol Drinking; Animals; Behavior, Addictive; Central Nervous System Agents; Drinking; Ethanol; Male; Naltrexone; Narcotic Antagonists; Pyrimidines; Pyrroles; Rats; Rats, Inbred Strains; Receptors, Corticotropin-Releasing Hormone; Reinforcement, Psychology; Self Administration; Stress, Psychological; Triazines

Exposure to extreme stress has been suggested to produce long-term, detrimental alterations in the hypothalamic-pituitary-adrenal (HPA) axis leading to the development of mental disorders such as depression. Therefore, compounds that block the effects of stress hormones were investigated as potential therapeutics for depression.. In the present study, we compared the potential antidepressant-like effects of four CRF antagonists, antalarmin, CP154,526, R121919, and LWH234 (at 3, 10, and 30 mg/kg i.p., 60 min prior to the forced swim test) and the corresponding effect on swim-induced HPA activation to better elucidate the relation between HPA activity and antidepressant activity.. The antidepressant-like effects of the CRF antagonists and known antidepressants were determined in the rat forced swim test, and blood samples were obtained before and after swimming for the evaluation of adrenocorticotropin-releasing hormone (ACTH) levels.. Antalarmin, CP154,526, and R121919 did not produce antidepressant-like effects in the forced swim test although these compounds decreased swim-induced increases in ACTH to various extents. In contrast, LWH234 reduced immobility in the forced swim test, without altering the swim-stress-induced ACTH response. However, this compound antagonized restraint-induced ACTH release.. These data suggest that reducing stress-induced increases in HPA activity alone may not be sufficient to produce antidepressant-like activity; however, reductions in HPA activity may contribute to antidepressant actions of some treatments. In addition, it is proposed that CRF antagonists may alter differentially the HPA axis depending on the type of stressor used or behavioral measure evaluated.

Topics: Adrenocorticotropic Hormone; Animals; Antidepressive Agents; Corticotropin-Releasing Hormone; Hypothalamo-Hypophyseal System; Male; Pituitary-Adrenal System; Pyrimidines; Pyrroles; Rats; Rats, Sprague-Dawley; Restraint, Physical; Stress, Psychological; Swimming; Triazoles

The development of selective corticotropin-releasing factor type-1 (CRF1) receptor antagonists represents a potential novel treatment for depression. These studies evaluated CRF1 receptor antagonists for antidepressant-like activity in mice. Subchronic dosing of both R 121919 (3-[6-(dimethylamino)-4-methyl-pyrid-3-yl]-2,5-dimethyl-N,N-dipropyl-pyrazolo[2,3-a]pyrimidin-7-amine) and DMP 696 (4-(1,3-dimethoxyprop-2-ylamino)-2,7-dimethyl-8-(2,4-dichlorophenyl)-pyrazolo[1,5-a]-1,3,5-triazine) significantly decreased immobility time in the tail suspension test (at 30 and at 3 and 10 mg/kg, i.p., respectively). These antidepressant-like effects were observed at doses that did not impair general locomotor activity. Neither antalarmin (N-butyl-N-ethyl-[2,5,6-trimethyl-7-(2,4,6)trimethylphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]amine) nor DMP 904 (4-(3-pentylamino)-2,7-dimethyl-8-(2-methyl-4-methoxyphenyl)-pyrazolo-[1,5-a]-pyrimidine) had an effect indicative of antidepressant-like activity. These results suggest that the tail suspension assay may have utility to identify CRF1 receptor antagonists with antidepressant-like activity. Moreover, the results lend support to the theory that some nonpeptidic CRF1 receptor antagonists may possess antidepressant-like activity and therefore represent a promising novel pharmacotherapeutic strategy in the treatment of depression.

Topics: Animals; Antidepressive Agents; Clorgyline; Desipramine; Dose-Response Relationship, Drug; Fluoxetine; Hindlimb Suspension; Male; Mice; Morpholines; Motor Activity; Paroxetine; Pyrazoles; Pyrimidines; Pyrroles; Reboxetine; Receptors, Corticotropin-Releasing Hormone; Selegiline; Swimming; Tranylcypromine; Triazines