Dual orexin receptor antagonists increase sleep and cataplexy in wild type mice

Abstract Orexin receptor antagonists are clinically useful for treating insomnia, but thorough blockade of orexin signaling could cause narcolepsy-like symptoms. Specifically, while sleepiness is a desirable effect, an orexin antagonist could also produce cataplexy, sudden episodes of muscle weakness often triggered by strong, positive emotions. In this study, we examined the effects of dual orexin receptor antagonists (DORAs), lemborexant (E2006) and almorexant, on sleep–wake behavior and cataplexy during the dark period in wild-type (WT) mice and prepro-orexin knockout (OXKO) mice. In WT mice, lemborexant at 10 and 30 mg/kg quickly induced NREM sleep in a dose-dependent fashion. In contrast, lemborexant did not alter sleep–wake behavior in OXKO mice. Under the baseline condition, cataplexy was rare in lemborexant-treated WT mice, but when mice were given chocolate as a rewarding stimulus, lemborexant dose-dependently increased cataplexy. Almorexant produced similar results. Collectively, these results demonstrate that DORAs potently increase NREM and REM sleep in mice via blockade of orexin signaling, and higher doses can cause cataplexy when co-administered with a likely rewarding stimulus.

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Vigilance states, EEG spectra, and cortical temperature in the guinea pig

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1993.264.6.r1125 ◽

1993 ◽

Vol 264 (6) ◽

pp. R1125-R1132 ◽

Cited By ~ 6

Author(s):

I. Tobler ◽

P. Franken ◽

K. Jaggi

Keyword(s):

Guinea Pig ◽

Rem Sleep ◽

Guinea Pigs ◽

Process Model ◽

Dark Period ◽

Nrem Sleep ◽

Light Period ◽

Recording Time ◽

Cortical Temperature ◽

Eeg Power

Vigilance states, electroencephalogram (EEG) power spectra (0.25-25.0 Hz), and cortical temperature (TCRT) were obtained in nine guinea pigs for 24 h in a 12:12-h light-dark (LD 12:12) schedule. Sleep was markedly polyphasic and fragmented and amounted to 32% of recording time, which is a low value compared with sleep in other rodents. There was 6.8% more sleep in the light period than in the dark period. EEG power density in non-rapid eye movement (NREM) sleep showed no significant temporal trend within the light or the dark period. The homeostatic aspects of sleep regulation, as proposed in the two-process model, can account for the slow-wave activity (SWA) pattern also in the guinea pig: The small 24-h amplitude of the sleep-wakefulness pattern resulted in a small, 12% decline of SWA within the light period. In contrast to more distinctly nocturnal rodents, SWA in the dark period was not higher than in the light period. TCRT showed no difference between the light and the dark period. TCRT in REM sleep and waking was higher than TCRT in NREM sleep. TCRT increased after the transition from NREM sleep to either REM sleep or waking, and decreased in the last minute before the transition and after the transition from waking to NREM sleep. Motor activity measured in six animals for 11 days in constant darkness showed no apparent rhythm in three animals and a significant circadian rhythm in three others. Our data support the notion that guinea pigs exhibit only a weak circadian rest-activity rhythm.

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Effects of Ruscus extract on muscarinic receptors: Is there a role for endothelium derived relaxing factors on macromolecular permeability protection and microvascular diameter changes?

Clinical Hemorheology and Microcirculation ◽

10.3233/ch-201019 ◽

2021 ◽

pp. 1-17

Author(s):

Maria das Graças C. de Souza ◽

Fatima Z. G. A. Cyrino ◽

Fernando L. Sicuro ◽

Eliete Bouskela

Keyword(s):

Muscarinic Receptors ◽

Cheek Pouch ◽

Protective Effects ◽

Cox Inhibitors ◽

Nos Inhibitors ◽

Dose Dependent Fashion ◽

Oxide Synthase ◽

Macromolecular Permeability ◽

Dose Dependent ◽

Higher Doses

BACKGROUND: Protective effects of Ruscus extract on macromolecular permeability depend on its capacity to stimulate muscarinic receptors on endothelial cells and induce the release of endothelium derived relaxing factors (EDRFs). OBJECTIVE: To investigate if these effects depend only on activation of muscarinic receptors or EDRFs release are also necessary. We have also investigated the participation of Ruscus extract on muscarinic-induced release of EDRFs on microvascular diameters. METHODS: Hamsters were treated daily during two weeks with Ruscus extract (50, 150 and 450 mg/kg/day) and then macromolecular permeability induced by histamine and arteriolar and venular diameters after cyclooxygenase (COX) and nitric oxide synthase (NOS) inhibitors: indomethacin and Nω-Nitro-L-arginine (LNA), respectively applied topically at 10–8M, 10–6M and 10–4M were observed on the cheek pouch preparation. RESULTS: Ruscus extract decreased macromolecular permeability in a dose-dependent fashion and did not affect microvascular diameters. NOS and COX inhibitors enhanced this effect. NOS inhibition reduced arteriolar diameter and COX blocking decreased arteriolar and venular diameters at the lowest dose and increased them at higher doses of Ruscus extract. CONCLUSION: The protective effect of Ruscus extract on macromolecular permeability seems to be mediated only via muscarinic receptors. Muscarinic activation attenuated vasoconstrictive tone through cyclooxygenase-independent endothelium derived relaxing factors.

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Chaperone Coexpression Plasmids: Differential and Synergistic Roles of DnaK-DnaJ-GrpE and GroEL-GroES in Assisting Folding of an Allergen of Japanese Cedar Pollen, Cryj2, inEscherichia coli

Applied and Environmental Microbiology ◽

10.1128/aem.64.5.1694-1699.1998 ◽

1998 ◽

Vol 64 (5) ◽

pp. 1694-1699 ◽

Cited By ~ 260

Author(s):

Kazuyo Nishihara ◽

Masaaki Kanemori ◽

Masanari Kitagawa ◽

Hideki Yanagi ◽

Takashi Yura

Keyword(s):

Japanese Cedar ◽

Wild Type ◽

E Coli ◽

Model Protein ◽

Dose Dependent Fashion ◽

In The Wild ◽

Japanese Cedar Pollen ◽

K 12 ◽

Cedar Pollen ◽

Dose Dependent

ABSTRACT Plasmids that can be used for controlled expression of the DnaK-DnaJ-GrpE and/or GroEL-GroES chaperone team were constructed in order to facilitate assessment of the effects of these chaperone teams on folding or assembly of recombinant proteins in Escherichia coli. A typical pACYC184-based plasmid which was obtained could express the major DnaK-DnaJ-GrpE and GroEL-GroES chaperone teams from separate promoters when l-arabinose and tetracycline, respectively, were added in a dose-dependent fashion. The model protein used to determine whether this system was useful was an allergen of Japanese cedar pollen, Cryj2, which was unstable when it was produced in E. coli K-12. The effects of chaperone coexpression on the folding, aggregation, and stability of Cryj2 were examined in the wild type and in several mutant bacteria. Coexpression of the DnaK-DnaJ-GrpE and/or GroEL-GroES chaperone team at appropriate levels resulted in marked stabilization and accumulation of Cryj2 without extensive aggregation. Experiments performed with mutants that lack each of the chaperone proteins (DnaK, DnaJ, GrpE, GroEL, and GroES) or heat shock transcription factor ς32 revealed that both chaperone teams are critically involved in Cryj2 folding but that they are involved in distinct ways. In addition, it was observed that the two chaperone teams have synergistic roles in preventing aggregation of Cryj2 in the absence of ς32 at certain temperatures.

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Effects of suboptimal levels of extracellular calcium on the regulation of the cyclic AMP phosphodiesterase-inhibitor system and membrane differentiation in Dictyostelium discoideum

Journal of Cell Science ◽

10.1242/jcs.90.4.691 ◽

1988 ◽

Vol 90 (4) ◽

pp. 691-700 ◽

Cited By ~ 1

Author(s):

M.B. Coukell ◽

A.M. Cameron

Keyword(s):

Cyclic Amp ◽

Dictyostelium Discoideum ◽

Cyclic Gmp ◽

Phosphodiesterase Inhibitor ◽

Wild Type ◽

Cyclic Amp Phosphodiesterase ◽

Dose Dependent Fashion ◽

Inhibitor System ◽

Membrane Bound ◽

Dose Dependent

When starved wild-type amoebae of Dictyostelium discoideum were washed and incubated in 1 mM-EGTA, their ability to induce soluble cyclic AMP phosphodiesterase (PD) activity in response to either millimolar cyclic AMP or a series of nanomolar cyclic AMP pulses was reduced by 55–75%. Supplementation of EGTA-treated cells with exogenous Ca2+ stimulated PD induction in a dose-dependent fashion (EC50 = 100–200 nM free extracellular Ca2+), and enzyme production was maximal at about 1 microM free Ca2+. Ca2+ depletion also strongly impaired production of the phosphodiesterase inhibitor (PDI). In contrast, other than delaying their appearance by about 1 h, EGTA had little effect on the induction by cyclic AMP pulses of cell surface markers such as contact sites A and membrane-bound PD activity. Similar changes in both the soluble and membrane activities were observed with strain NP368, a mutant that overproduces cyclic GMP when stimulated by cyclic AMP. Thus, Ca2+ depletion does not appear to inhibit PD and PDI production by reducing intracellular cyclic GMP. To determine whether Ca2+ depletion alters signal transduction, two mutants that produce the soluble PD activities constitutively were examined. Suboptimal concentrations of free extracellular Ca2+ were found to inhibit PD production in these cells to the same degree and with the same concentration dependence as low Ca2+ inhibited PD induction by cyclic AMP in wild-type cells. These results suggest that Ca2+ depletion by EGTA probably inhibits PD and PDI production indirectly by perturbing an intracellular Ca2+ pool(s) rather than by altering a surface cyclic AMP-receptor-mediated process.

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Ectopic expression of UBX and ABD-B proteins during Drosophila embryogenesis: competition, not a functional hierarchy, explains phenotypic suppression

Development ◽

10.1242/dev.116.4.841 ◽

1992 ◽

Vol 116 (4) ◽

pp. 841-854 ◽

Cited By ~ 13

Author(s):

M.L. Lamka ◽

A.M. Boulet ◽

S. Sakonju

Keyword(s):

Ectopic Expression ◽

Homeotic Genes ◽

Wild Type ◽

Homeodomain Proteins ◽

Regulatory Interactions ◽

M Proteins ◽

Dose Dependent Fashion ◽

Functional Hierarchy ◽

Dose Dependent ◽

Similar Stage

The Abdominal-B (Abd-B) gene, a member of the bithorax complex (BX-C), specifies the identities of parasegments (PS) 10–14 in Drosophila. Abd-B codes for two structurally related homeodomain proteins, ABD-B m and ABD-B r, that are expressed in PS10-13 and PS14-15, respectively. Although ABD-B m and r proteins have distinct developmental functions, ectopic expression of either protein during embryogenesis induces the development of filzkorper and associated spiracular hairs, structures normally located in PS13, at ectopic sites in the larval thorax and abdomen. These results suggest that other parasegmental differences contribute to the phenotype specified by ABD-B r activity in PS14. Both ABD-B m and r repress the expression of other homeotic genes, such as Ubx and abd-A, in PS10-14. However, the importance of these and other cross-regulatory interactions among homeotic genes has been questioned. Since ectopic UBX protein apparently failed to transform abdominal segments, Gonzalez-Reyes et al. (Gonzalez-Reyes, A., Urquia, N., Gehring, W.J., Struhl, G. and Morata, G. (1990). Nature 344, 78–80) proposed a functional hierarchy in which ABD-A and ABD-B activities override UBX activity. We tested this model by expressing UBX and ABD-B m proteins ectopically in wild-type and BX-C-deficient embryos. Ectopic ABD-B m does not prevent transformations induced by ectopic UBX. Instead, ectopic UBX and ABD-B m proteins compete for the specification of segmental identities in a dose-dependent fashion. Our results support a quantitative competition among the homeotic proteins rather than the existence of a strict functional hierarchy. Therefore, we suggest that cross-regulatory interactions are not irrelevant but are important for repressing the expression of competing homeotic proteins. To explain the apparent failure of ectopic UBX to transform the abdominal segments, we expressed UBX at different times during embryonic development. Our results show that ectopic UBX affects abdominal cuticular identities if expressed during early stages of embryogenesis. In later embryonic stages, abdominal segments become resistant to transformation by ectopic UBX while thoracic segments remain susceptible. Head segments also show a similar stage-dependent susceptibility to transformation by ectopic UBX in early embryogenesis but become resistant in later stages. These results suggest that abdominal and head identities are determined earlier than are thoracic identities.

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Antagonism of corticotropin-releasing hormone alters serotonergic-induced changes in brain temperature, but not sleep, of rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00074.2005 ◽

2005 ◽

Vol 289 (4) ◽

pp. R1116-R1123 ◽

Cited By ~ 5

Author(s):

Luca Imeri ◽

Susanna Bianchi ◽

Mark R. Opp

Keyword(s):

Body Temperature ◽

Time Course ◽

Dark Period ◽

Brain Temperature ◽

Nrem Sleep ◽

Corticotropin Releasing Hormone ◽

Light Onset ◽

Releasing Hormone ◽

The Impact ◽

Higher Doses

Serotonin is involved in many physiological processes, including the regulation of sleep and body temperature. Administration into rats of low doses (25, 50 mg/kg) of the 5-HT precursor l-5-hydroxytryptophan (5-HTP) at the beginning of the dark period of the 12:12-h light-dark cycle initially increases wakefulness. Higher doses (75, 100 mg/kg) increase nonrapid eye movement (NREM) sleep. The initial enhancement of wakefulness after low-dose 5-HTP administration may be a direct action of 5-HT in brain or due to 5-HT-induced activation of other arousal-promoting systems. One candidate arousal-promoting system is corticotropin-releasing hormone (CRH) and the hypothalamic-pituitary-adrenal axis. Serotonergic activation by 5-HTP at the beginning of the dark period also induces hypothermia. Because sleep and body temperature are influenced by circadian factors, one aim of this study was to determine responses to 5-HTP when administered at a different circadian time, the beginning of the light period. Results obtained show that all doses of 5-HTP (25–100 mg/kg) administered at light onset initially increase wakefulness; NREM sleep increases only after a long delay, during the subsequent dark period. Serotonergic activation by 5-HTP at light onset induces hypothermia, the time course of which is biphasic after higher doses (75, 100 mg/kg). Intracerebroventricular pretreatment with the CRH receptor antagonist α-helical CRH does not alter the impact of 5-HTP on sleep-wake behavior but potentiates the hypothermic response to 50 mg/kg 5-HTP. These data suggest that serotonergic activation by peripheral administration of 5-HTP may modulate sleep-wake behavior by mechanisms in addition to direct actions in brain and that circadian systems are important determinants of the impact of serotonergic activation on sleep and body temperature.

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Induction of narcolepsy-like symptoms by orexin receptor antagonists in mice

SLEEP ◽

10.1093/sleep/zsab043 ◽

2021 ◽

Author(s):

Mahesh K Kaushik ◽

Kosuke Aritake ◽

Yoan Cherasse ◽

Aya Imanishi ◽

Takashi Kanbayashi ◽

...

Keyword(s):

Eye Movement ◽

Sleep Onset ◽

Nrem Sleep ◽

Rapid Eye Movement ◽

Wild Type ◽

Receptor Antagonists ◽

Experimental Animals ◽

Hypothalamic Neuropeptides

Abstract Orexins/hypocretins are hypothalamic neuropeptides that promote and stabilize wakefulness by binding to the orexin receptor type-1 (OX1R) and type-2 (OX2R). Disruption of orexinergic signaling results in the sleep disorder narcolepsy in mice, rats, dogs, and humans. The orexin receptor antagonist suvorexant promotes sleep by blocking both OX1R and OX2R. Whereas suvorexant has been clinically approved for the treatment of insomnia because it is well tolerated in experimental animals as well as in human patients, a logical question remains as to why orexin receptor antagonists do not induce overt narcolepsy-like symptoms. Here we show that acute and chronic suvorexant promotes both rapid eye movement (REM) and non-rapid eye movement (NREM) sleep without inducing cataplexy in mice. Interestingly, chronic suvorexant increases OX2R mRNA and decreases orexin mRNA and peptide levels, which remain low long after termination of suvorexant administration. When mice are chronically treated with suvorexant and then re-challenged with the antagonist after a 1-week washout, however, cataplexy and sleep-onset REM (SOREM) are observed, which are exacerbated by chocolate administration. Heterozygous orexin knockout mice, with lower brain orexin levels, show cataplexy and SOREM after acute suvorexant administration. Furthermore, we find that acute suvorexant can induce cataplexy and SOREM in wild-type mice when co-administered with chocolate under stress-free (temporally anesthetized) conditions. Taken together, these results suggest that suvorexant can inhibit orexin synthesis resulting in susceptibility to narcolepsy-like symptoms in mice under certain conditions.

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Dose-dependent inhibition of cold air-induced bronchoconstriction by atropine

Journal of Applied Physiology ◽

10.1152/jappl.1982.53.1.169 ◽

1982 ◽

Vol 53 (1) ◽

pp. 169-174 ◽

Cited By ~ 59

Author(s):

D. Sheppard ◽

J. Epstein ◽

M. J. Holtzman ◽

J. A. Nadel ◽

H. A. Boushey

Keyword(s):

Base Line ◽

Muscarinic Agonist ◽

Cold Air ◽

Dependent Inhibition ◽

Dose Dependent Fashion ◽

Dose Dependent Inhibition ◽

Airway Tone ◽

Maximal Reduction ◽

Dose Dependent ◽

Higher Doses

We undertook a study to demonstrate whether inhalation of atropine could inhibit cold air-induced bronchoconstriction in a dose-dependent fashion. In seven subjects with asthma we assessed the effects of placebo and of various doses of inhaled atropine (0.1313;2.08 mg) on a base-line specific airway resistance (sRaw) and on the increase in sRaw produced by 5 min of voluntary eucapnic hyperventilation with subfreezing air at -17 degrees C. We also assessed the effect of the lowest doses of atropine on the increase in sRaw produced by five breaths of 1.0% metacholine. Atropine in doses of 0.13 or 0.26 mg caused a maximal reduction in base-line sRaw and completely inhibited the effect of 1.0% methacholine on sRaw, but it did not inhibit the bronchomotor response to cold air. Higher doses of atropine did inhibit the effect of cold air on sRaw in a dose-dependent fashion. The dose of atropine required to inhibit this effect of cold air varied with the increase in sRaw produced by cold air after placebo. These results suggest that cold air causes bronchoconstriction through vagal pathways and that higher doses of antimuscarinic agents are required to inhibit vagally mediated bronchoconstriction than those required to reduce base-line airway tone or to inhibit the effects of a large dose of an inhaled muscarinic agonist.

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Bax Loss Impairs Myc-Induced Apoptosis and Circumvents the Selection of p53 Mutations during Myc-Mediated Lymphomagenesis

Molecular and Cellular Biology ◽

10.1128/mcb.21.22.7653-7662.2001 ◽

2001 ◽

Vol 21 (22) ◽

pp. 7653-7662 ◽

Cited By ~ 116

Author(s):

Christine M. Eischen ◽

Martine F. Roussel ◽

Stanley J. Korsmeyer ◽

John L. Cleveland

Keyword(s):

Transgenic Mice ◽

Tumor Suppressors ◽

P53 Mutations ◽

Wild Type ◽

Dose Dependent Fashion ◽

Induced Apoptosis ◽

Apoptotic Effects ◽

Dose Dependent ◽

Mdm2 Overexpression ◽

Selection Of

ABSTRACT The ARF and p53 tumor suppressors mediate Myc-induced apoptosis and suppress lymphoma development in Eμ-myc transgenic mice. Here we report that the proapoptotic Bcl-2 family member Bax also mediates apoptosis triggered by Myc and inhibits Myc-induced lymphomagenesis. Bax-deficient primary pre-B cells are resistant to the apoptotic effects of Myc, and Bax loss accelerates lymphoma development in Eμ-myc transgenics in a dose-dependent fashion. Eighty percent of lymphomas arising in wild-type Eμ-myc transgenics have alterations in the ARF-Mdm2-p53 tumor suppressor pathway characterized by deletions inARF, mutations or deletions of p53, and overexpression of Mdm2. The absence of Bax did not alter the frequency of biallelic deletion of ARF in lymphomas arising in Eμ-myc transgenic mice or the rate of tumorigenesis in ARF-null mice. Furthermore, Mdm2 was overexpressed at the same frequency in lymphomas irrespective ofBax status, suggesting that Bax resides in a pathway separate from ARF and Mdm2. Strikingly, lymphomas fromBax-null Eμ-myc transgenics lackedp53 alterations, whereas 27% of the tumors inBax +/− Eμ-myctransgenic mice contained p53 mutations or deletions. Thus, the loss of Bax eliminates the selection ofp53 mutations and deletions, but not ARF deletions or Mdm2 overexpression, during Myc-induced tumorigenesis, formally demonstrating that Myc-induced apoptotic signals through ARF/Mdm2 and p53 must bifurcate: p53 signals through Bax, whereas this is not necessarily the case for ARF and Mdm2.

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