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Torkzadeh-Mahani S, Abbasnejad M, Raoof M, Aarab G, Esmaeili-Mahani S, Lobbezoo F. Age-dependent down-regulation of orexin receptors in trigeminal nucleus caudalis correlated with attenuation of orexinergic analgesia in rats. Exp Gerontol 2023; 183:112321. [PMID: 37898178 DOI: 10.1016/j.exger.2023.112321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 10/09/2023] [Accepted: 10/25/2023] [Indexed: 10/30/2023]
Abstract
Aging is related to a variety of physiological organ changes, including central and peripheral nervous systems. It has been reported that the orexin signaling has a potential analgesic effect in different models of pain, especially inflammatory pulpal pain. However, the age-induced alteration in dental pain perception and orexin analgesia has not yet been fully elucidated. Here, we tested that how aging may change the effect of orexin-A on nociceptive behaviors in a rat dental pulp pain model. The expression levels of orexin receptors and the nociceptive neuropeptides substance P (SP) and calcitonin-related gene peptide (CGRP) were also assessed in the trigeminal nucleus caudalis (TNC) of young and aged rats. Dental pulp pain was induced by intradental application of capsaicin (100 μg). The immunofluorescence technique was used to evaluate the expression levels. The results show less efficiency of orexin-A to ameliorate pain perception in aged rats as compared to young rats. In addition, a significant decrease in the number of orexin 1 and 2 receptors was observed in the TNC of aged as compared to young rats. Dental pain-induced SP and CGRP overexpression was also significantly inhibited by orexin-A injection into the TNC of young animals. In contrast, orexin-A could not produce such effects in the aged animals. In conclusion, the older age-related reduction of the antinociceptive effect of orexin may be due to the downregulation of its receptors and inability of orexin signaling to inhibit the expression of nociceptive neuropeptides such as SP and CGRP in aged rats.
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Affiliation(s)
- Shima Torkzadeh-Mahani
- Department of Orofacial Pain and Dysfunction, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran
| | - Mehdi Abbasnejad
- Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran
| | - Maryam Raoof
- Department of Orofacial Pain and Dysfunction, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
| | - Ghizlane Aarab
- Department of Orofacial Pain and Dysfunction, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Saeed Esmaeili-Mahani
- Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran
| | - Frank Lobbezoo
- Department of Orofacial Pain and Dysfunction, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
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2
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Abdelmissih S. A Bitter Experience That Enlightens the Future: COVID-19 Neurological Affection and Perspectives on the Orexigenic System. Cureus 2022; 14:e30788. [DOI: 10.7759/cureus.30788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2022] [Indexed: 11/06/2022] Open
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3
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Priyadarsini N, Nanda P, Devi S, Mohapatra S. Sarcopenia: An Age-Related Multifactorial Disorder. Curr Aging Sci 2022; 15:209-217. [PMID: 35249518 DOI: 10.2174/1874609815666220304194539] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 12/22/2021] [Accepted: 12/28/2021] [Indexed: 11/22/2022]
Abstract
Sarcopenia is an emerging clinical entity characterized by a gradual decline in skeletal muscle mass and strength that accompanies the normal aging process. It has been noted that sarcopenia is associated with various adverse health outcomes in the geriatric population like prolonged hospital admission, disability, poor quality of life, frailty, and mortality. Factors involved in the development of age-related sarcopenia include anorexia, alteration in the hormone levels, decreased neural innervation, low blood flow to the muscles, cytokine dysregulation, altered mitochondrial activity, genomic instability, intracellular proteolysis, and insulin resistance. Understanding the mechanism may help develop efficient preventive and therapeutic strategies which can improve the quality of life in elderly individuals. Thus, the objective of the present article is to review the literature regarding the mechanism involved in the development of sarcopenia in aged individuals.
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Affiliation(s)
- Nibedita Priyadarsini
- Department of Physiology, All India Institute of Medical Sciences, Bhubaneswar, India
| | - Pranati Nanda
- Department of Physiology, All India Institute of Medical Sciences, Bhubaneswar, India
| | - Sujata Devi
- Department of Medicine, All India Institute of Medical Sciences, Bhubaneswar, India
| | - Subarna Mohapatra
- Department of Physiology, All India Institute of Medical Sciences, Bhubaneswar, India
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4
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Muthmainah M, Gogos A, Sumithran P, Brown RM. Orexins (hypocretins): The intersection between homeostatic and hedonic feeding. J Neurochem 2021; 157:1473-1494. [PMID: 33608877 DOI: 10.1111/jnc.15328] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 02/11/2021] [Accepted: 02/15/2021] [Indexed: 12/11/2022]
Abstract
Orexins are hypothalamic neuropeptides originally discovered to play a role in the regulation of feeding behaviour. The broad connections of orexin neurons to mesocorticolimbic circuitry suggest they may play a role in mediating reward-related behaviour beyond homeostatic feeding. Here, we review the role of orexin in a variety of eating-related behaviour, with a focus on reward and motivation, and the neural circuits driving these effects. One emerging finding is the involvement of orexins in hedonic and appetitive behaviour towards palatable food, in addition to their role in homeostatic feeding. This review discusses the brain circuitry and possible mechanisms underlying the role of orexins in these behaviours. Overall, there is a marked bias in the literature towards studies involving male subjects. As such, future work needs to be done to involve female subjects. In summary, orexins play an important role in driving motivation for high salient rewards such as highly palatable food and may serve as the intersection between homeostatic and hedonic feeding.
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Affiliation(s)
- Muthmainah Muthmainah
- The Florey Institute of Neuroscience and Mental Health, Mental Health Research Theme, Parkville, Melbourne, Vic., Australia.,The Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Vic., Australia.,Department of Anatomy, Faculty of Medicine, Universitas Sebelas Maret, Surakarta, Indonesia
| | - Andrea Gogos
- The Florey Institute of Neuroscience and Mental Health, Mental Health Research Theme, Parkville, Melbourne, Vic., Australia
| | - Priya Sumithran
- Department of Medicine (Austin), University of Melbourne, Heidelberg, Vic., Australia.,Department of Endocrinology, Austin Health, Heidelberg, Vic., Australia
| | - Robyn M Brown
- The Florey Institute of Neuroscience and Mental Health, Mental Health Research Theme, Parkville, Melbourne, Vic., Australia.,The Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, Melbourne, Vic., Australia
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5
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The Role of Ventromedial Hypothalamus Receptors in the Central Regulation of Food Intake. Int J Pept Res Ther 2020. [DOI: 10.1007/s10989-020-10120-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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6
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Stanojlovic M, Pallais Yllescas JP, Mavanji V, Kotz C. Chemogenetic activation of orexin/hypocretin neurons ameliorates aging-induced changes in behavior and energy expenditure. Am J Physiol Regul Integr Comp Physiol 2019; 316:R571-R583. [PMID: 30726119 PMCID: PMC6589608 DOI: 10.1152/ajpregu.00383.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 01/30/2019] [Accepted: 01/30/2019] [Indexed: 02/07/2023]
Abstract
Aging affects numerous physiological processes, as well as behavior. A large number of these processes are regulated, at least partially, by hypothalamic orexin neurons, and orexin tone may decrease with normal aging. In this study, we hypothesized that designer receptors exclusively activated by designer drugs (DREADD) stimulation of orexin neuronal activity will ameliorate the effect of aging on behavioral and metabolic alterations in young and middle-aged mice. DREADD targeting was achieved by stereotaxic injection of AAV vectors (AAV2-hSyn-DIO-hM3D(Gq)-mCherry) into the lateral hypothalamus of 5- and 12-mo old orexin-cre female mice and was confirmed by immunohistochemistry (IHC) analysis of orexin A and mCherry expression. After recovery, animals were subjected to a behavioral test battery consisting of the elevated plus maze (EPM), open field (OFT), and novel object recognition tests (NORT) to assess effects of aging on anxiety-like behavior, general locomotion, and working memory. A comprehensive laboratory animal monitoring system (CLAMS) was used to measure spontaneous physical activity (SPA) and energy expenditure (EE). The results indicate that activation of orexin neurons mitigates aging-induced reductions in anxiety-like behavior in middle-aged mice (P < 0.005) and increases locomotion in both young and middle-aged mice (P < 0.05). Activation of orexin neurons increases SPA (P < 0.01) and EE (P < 0.005) in middle-aged mice, restoring the levels to that observed in young animals. Results from this study identify orexin neurons as potential therapeutic targets for age-related impairments in cognitive and anxiety-related behavior, and energy balance.
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Affiliation(s)
- Milos Stanojlovic
- Integrative Biology and Physiology, University of Minnesota , Minneapolis, Minnesota
| | | | - Vijaya Mavanji
- Minneapolis Veterans Affairs Health Care System, Geriatric Research Education and Clinical Center , Minneapolis, Minnesota
| | - Catherine Kotz
- Integrative Biology and Physiology, University of Minnesota , Minneapolis, Minnesota
- Minneapolis Veterans Affairs Health Care System, Geriatric Research Education and Clinical Center , Minneapolis, Minnesota
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Naidoo N, Zhu J, Galante RJ, Lian J, Strus E, Lee A, Keenan BT, Pack AI. Reduction of the molecular chaperone binding immunoglobulin protein (BiP) accentuates the effect of aging on sleep-wake behavior. Neurobiol Aging 2018; 69:10-25. [PMID: 29843048 DOI: 10.1016/j.neurobiolaging.2018.04.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 04/05/2018] [Accepted: 04/23/2018] [Indexed: 12/17/2022]
Abstract
Sleep and wake quality, quantity, and architecture become modified with aging. Sleep and wake quality decline coinciding with increased fragmentation of both states across aging. We have previously shown that this age-related decline in sleep-wake quality is associated with increased endoplasmic reticular (ER) stress and decreased expression of the major ER chaperone binding immunoglobulin protein (BiP). BiP, also known as glucose-regulated protein 78, plays a key role in controlling the cellular response to ER stress, acting as a regulator of a protein homeostatic signaling pathway known as the unfolded protein response. Induction of BiP during cellular stress is part of an adaptive prosurvival mechanism. Here, using mice heterozygous for BiP, we investigated the effect of reduced BiP expression on sleep-wake behavior across aging; complete knockdown of BiP is embryonic lethal. We report that BiP heterozygosity accentuates the aging sleep-wake phenotype. Sleep and wake fragmentation was more pronounced in the BiP heterozygotes across the 3 ages examined. In mice lacking 1 functional copy of BiP, we observed an age-related significant reduction in wake bout duration and increase in wake bout numbers during the active period, as well as an increase in non rapid eye movement and rapid eye movement bout numbers accompanied by reduced bout durations of both non rapid eye movement and rapid eye movement during the sleep period. In addition, we observed increased ER stress in orexin neurons and occurrence of aggregates immunopositive for orexin at the terminals and projections of orexin neurons in the middle-aged BiP heterozygotes. Taken together, our data indicate that a reduction in the molecular chaperone BiP impacts sleep architecture across aging and that orexin processing is likely to be affected.
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Affiliation(s)
- Nirinjini Naidoo
- Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; Division of Sleep Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Jingxu Zhu
- Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Raymond J Galante
- Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jie Lian
- Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Ewa Strus
- Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Amy Lee
- Department of Biochemistry and Molecular Biology, University of Southern California, Keck, School of Medicine, USC Norris Comprehensive Cancer Center, Los Angeles, CA, USA
| | - Brendan T Keenan
- Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Allan I Pack
- Center for Sleep and Circadian Neurobiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; Division of Sleep Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Wysokiński A, Sobów T, Kłoszewska I, Kostka T. Mechanisms of the anorexia of aging-a review. AGE (DORDRECHT, NETHERLANDS) 2015; 37:9821. [PMID: 26232135 PMCID: PMC5005824 DOI: 10.1007/s11357-015-9821-x] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 07/22/2015] [Indexed: 05/05/2023]
Abstract
Many, even healthy, older people fail to adequately regulate food intake and experience loss of weight. Aging-associated changes in the regulation of appetite and the lack of hunger have been termed as the anorexia of aging. The etiology of the anorexia of aging is multi-factorial and includes a combination of physiological changes associated with aging (decline in smell and taste, reduced central and peripheral drive to eat, delayed gastric emptying), pathological conditions (depression, dementia, somatic diseases, medications and iatrogenic interventions, oral-health status), and social factors (poverty, loneliness). However, exact mechanisms of the anorexia of aging remain to be elucidated. Many neurobiological mechanisms may be secondary to age-related changes in body composition and not associated with anorexia per se. Therefore, further studies on pathophysiological mechanisms of the anorexia of aging should employ accurate measurement of body fat and lean mass. The anorexia of aging is associated with protein-energy malnutrition, sarcopenia, frailty, functional deterioration, morbidity, and mortality. Since this symptom can lead to dramatic consequences, early identification and effective interventions are needed. One of the most important goals in the geriatric care is to optimize nutritional status of the elderly.
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Affiliation(s)
- Adam Wysokiński
- Department of Old Age Psychiatry and Psychotic Disorders, Medical University of Lodz, Czechosłowacka 8/10, 92-216, Łódź, Poland,
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Nixon JP, Mavanji V, Butterick TA, Billington CJ, Kotz CM, Teske JA. Sleep disorders, obesity, and aging: the role of orexin. Ageing Res Rev 2015; 20:63-73. [PMID: 25462194 DOI: 10.1016/j.arr.2014.11.001] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 09/19/2014] [Accepted: 11/14/2014] [Indexed: 02/03/2023]
Abstract
The hypothalamic neuropeptides orexin A and B (hypocretin 1 and 2) are important homeostatic mediators of central control of energy metabolism and maintenance of sleep/wake states. Dysregulation or loss of orexin signaling has been linked to narcolepsy, obesity, and age-related disorders. In this review, we present an overview of our current understanding of orexin function, focusing on sleep disorders, energy balance, and aging, in both rodents and humans. We first discuss animal models used in studies of obesity and sleep, including loss of function using transgenic or viral-mediated approaches, gain of function models using exogenous delivery of orexin receptor agonist, and naturally-occurring models in which orexin responsiveness varies by individual. We next explore rodent models of orexin in aging, presenting evidence that orexin loss contributes to age-related changes in sleep and energy balance. In the next section, we focus on clinical importance of orexin in human obesity, sleep, and aging. We include discussion of orexin loss in narcolepsy and potential importance of orexin in insomnia, correlations between animal and human studies of age-related decline, and evidence for orexin involvement in age-related changes in cognitive performance. Finally, we present a summary of recent studies of orexin in neurodegenerative disease. We conclude that orexin acts as an integrative homeostatic signal influencing numerous brain regions, and that this pivotal role results in potential dysregulation of multiple physiological processes when orexin signaling is disrupted or lost.
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Armbruszt S, Figler M, Ábrahám H. Stability of CART peptide expression in the nucleus accumbens in aging. ACTA BIOLOGICA HUNGARICA 2015; 66:1-13. [PMID: 25740434 DOI: 10.1556/abiol.66.2015.1.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aging is accompanied by changes of several anorexigenic and orexigenic neuropeptides expressed in various brain areas that control food intake and these changes correlate with senescent anorexia. During aging expression of cocaine- and amphetamine-regulated transcript (CART) peptide was reported to be reduced in the hypothalamic nuclei related to food intake. Although CART peptide is abundant in the nucleus accumbens that also plays a crucial role in the food intake regulation, no data is available about the CART peptide expression in this region through aging. In the present study, CART peptide immunoreactivity was compared in the nucleus accumbens of young adult (4- and 7-month-old) middle-aged (15-month-old) and aging (25-32-month-old) Long-Evans rats. The density of CART-immunoreactive cells and axon terminals in the nucleus accumbens was measured with computer-aided densitometry. CART-immunodensity was similar in the old rats and in the younger animals without significant difference between age groups. In addition, no gender-difference was observed when CART-immunoreactivities in the nucleus accumbens of male and female animals were compared. Our results indicate that CART peptide expression in the nucleus accumbens is stable in adults and does not change with age.
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Affiliation(s)
- Simon Armbruszt
- University of Pécs Institute of Nutritional Sciences and Dietetics, Faculty of Health Sciences Pécs Hungary
| | - Mária Figler
- University of Pécs Institute of Nutritional Sciences and Dietetics, Faculty of Health Sciences Pécs Hungary
| | - Hajnalka Ábrahám
- University of Pécs Central Electron Microscopic Laboratory, Faculty of Medicine Pécs Hungary
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Hunt NJ, Rodriguez ML, Waters KA, Machaalani R. Changes in orexin (hypocretin) neuronal expression with normal aging in the human hypothalamus. Neurobiol Aging 2015; 36:292-300. [DOI: 10.1016/j.neurobiolaging.2014.08.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 07/30/2014] [Accepted: 08/04/2014] [Indexed: 11/29/2022]
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Zink AN, Perez-Leighton CE, Kotz CM. The orexin neuropeptide system: physical activity and hypothalamic function throughout the aging process. Front Syst Neurosci 2014; 8:211. [PMID: 25408639 PMCID: PMC4219460 DOI: 10.3389/fnsys.2014.00211] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 10/07/2014] [Indexed: 12/18/2022] Open
Abstract
There is a rising medical need for novel therapeutic targets of physical activity. Physical activity spans from spontaneous, low intensity movements to voluntary, high-intensity exercise. Regulation of spontaneous and voluntary movement is distributed over many brain areas and neural substrates, but the specific cellular and molecular mechanisms responsible for mediating overall activity levels are not well understood. The hypothalamus plays a central role in the control of physical activity, which is executed through coordination of multiple signaling systems, including the orexin neuropeptides. Orexin producing neurons integrate physiological and metabolic information to coordinate multiple behavioral states and modulate physical activity in response to the environment. This review is organized around three questions: (1) How do orexin peptides modulate physical activity? (2) What are the effects of aging and lifestyle choices on physical activity? (3) What are the effects of aging on hypothalamic function and the orexin peptides? Discussion of these questions will provide a summary of the current state of knowledge regarding hypothalamic orexin regulation of physical activity during aging and provide a platform on which to develop improved clinical outcomes in age-associated obesity and metabolic syndromes.
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Affiliation(s)
- Anastasia N Zink
- Graduate Program in Neuroscience, School of Medicine, University of Minnesota Minneapolis, MN, USA
| | | | - Catherine M Kotz
- Graduate Program in Neuroscience, School of Medicine, University of Minnesota Minneapolis, MN, USA ; GRECC (11G), Minneapolis VA Healthcare System Minneapolis, MN, USA ; Department of Food Science and Nutrition, University of Minnesota Saint Paul, MN, USA
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Quarta D, Smolders I. Rewarding, reinforcing and incentive salient events involve orexigenic hypothalamic neuropeptides regulating mesolimbic dopaminergic neurotransmission. Eur J Pharm Sci 2014; 57:2-10. [DOI: 10.1016/j.ejps.2014.01.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 01/19/2014] [Indexed: 12/22/2022]
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Wang ZH, Ni XL, Li JN, Xiao ZY, Wang C, Zhang LN, Tong L, Dong HL. Changes in plasma orexin-A levels in sevoflurane-remifentanil anesthesia in young and elderly patients undergoing elective lumbar surgery. Anesth Analg 2014; 118:818-22. [PMID: 24651236 DOI: 10.1213/ane.0000000000000109] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND Delayed emergence from general anesthesia frequently occurs in elderly patients, but the reason is not clear. Orexin has been shown to be involved in arousal from general anesthesia. In this study, we examined plasma orexin-A levels in both elderly and young patients during the anesthesia arousal cycle. METHODS We recruited 41 patients scheduled for elective lumbar surgery and eventually evaluated 34 patients. Patients were divided into a young group (age 30-55, N = 16) and an elderly group (age 65-77, N = 18). Anesthesia with sevoflurane-remifentanil was titrated to maintain the Bispectral Index between 45 and 65. The times from stopping anesthesia to eyes opening and extubation were recorded. Arterial blood was collected, and plasma orexin-A was determined by radioimmunoassay at the following 4 time points: preanesthesia (T0), 1 hour after anesthesia induction (T1), emergence (5 minutes after tracheal extubation) (T2), and 30 minutes after tracheal extubation (T3). RESULTS The times from stopping anesthesia to eyes opening and tracheal extubation were both significantly longer in the elderly group than in the young group (P = 0.004, P = 0.01, respectively). Basal (T0) orexin-A levels were higher in the elderly group than in the young group (T0, 26.13 ± 1.25 vs 17.9 ± 1.30 pg/mL, P < 0.0001). Plasma orexin-A levels did not change during induction of anesthesia in either group but significantly increased at T2 (vs T0, P <0.0001) in both elderly (35.0 ± 1.7 pg/mL) and young (29.2 ± 1.9 pg/mL) groups. Orexin-A levels were significantly higher in the elderly than in the young group at T1, T2, and T3. CONCLUSION Plasma orexin-A levels are not responsible for the delayed emergence from general anesthesia in elderly patients.
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Affiliation(s)
- Zhi-Hua Wang
- From the Department of Anesthesiology, Xijing Hospital, Fourth Military Medical University, Shaanxi, China
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Thompson MD, Xhaard H, Sakurai T, Rainero I, Kukkonen JP. OX1 and OX2 orexin/hypocretin receptor pharmacogenetics. Front Neurosci 2014; 8:57. [PMID: 24834023 PMCID: PMC4018553 DOI: 10.3389/fnins.2014.00057] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Accepted: 03/12/2014] [Indexed: 01/01/2023] Open
Abstract
Orexin/hypocretin peptide mutations are rare in humans. Even though human narcolepsy is associated with orexin deficiency, this is only extremely rarely due to mutations in the gene coding prepro-orexin, the precursor for both orexin peptides. In contrast, coding and non-coding variants of the OX1 and OX2 orexin receptors have been identified in many human populations; sometimes, these have been associated with disease phenotype, although most confer a relatively low risk. In most cases, these studies have been based on a candidate gene hypothesis that predicts the involvement of orexins in the relevant pathophysiological processes. In the current review, the known human OX1/HCRTR1 and OX2/HCRTR2 genetic variants/polymorphisms as well as studies concerning their involvement in disorders such as narcolepsy, excessive daytime sleepiness, cluster headache, polydipsia-hyponatremia in schizophrenia, and affective disorders are discussed. In most cases, the functional cellular or pharmacological correlates of orexin variants have not been investigated—with the exception of the possible impact of an amino acid 10 Pro/Ser variant of OX2 on orexin potency—leaving conclusions on the nature of the receptor variant effects speculative. Nevertheless, we present perspectives that could shape the basis for further studies. The pharmacology and other properties of the orexin receptor variants are discussed in the context of GPCR signaling. Since orexinergic therapeutics are emerging, the impact of receptor variants on the affinity or potency of ligands deserves consideration. This perspective (pharmacogenetics) is also discussed in the review.
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Affiliation(s)
- Miles D Thompson
- University of Toronto Epilepsy Research Program, Department of Pharmacology, University of Toronto Toronto, ON, Canada
| | - Henri Xhaard
- Faculty of Pharmacy, Centre for Drug Research, University of Helsinki Helsinki, Finland
| | - Takeshi Sakurai
- Department of Molecular Neuroscience and Integrative Physiology, Faculty of Medicine, Kanazawa University Kanazawa, Japan
| | | | - Jyrki P Kukkonen
- Biochemistry and Cell Biology, Department of Veterinary Biosciences, University of Helsinki Helsinki, Finland
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Wang W, Pan Y, Li Q, Wang L. Orexin: a potential role in the process of obstructive sleep apnea. Peptides 2013; 42:48-54. [PMID: 23313149 DOI: 10.1016/j.peptides.2013.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 12/28/2012] [Accepted: 01/02/2013] [Indexed: 02/07/2023]
Abstract
Obstructive sleep apnea (OSA) is a complicated disease with an unrecognized mechanism. Obesity, sex, age, and smoking have been found to be independent correlates of OSA. Orexin (also named hypocretin) mainly secreted by lateral hypothalamus neurons has a wide array of biological functions like regulating sleep, energy levels and breathing. Several clinical studies found ties between orexin and OSA. Because of the close correlation between orexin and obesity, sex, age and smoking (which are the key risk factors for OSA patients), we hypothesize that orexin may play a key role in the pathogenesis of OSA.
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Affiliation(s)
- Wei Wang
- Institute of Stomatology, Nanjing Medical University, Department of Orthodontics, Affiliated Hospital of Stomatology, Nanjing Medical University, Nanjing 210029, China
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Gotter AL, Webber AL, Coleman PJ, Renger JJ, Winrow CJ. International Union of Basic and Clinical Pharmacology. LXXXVI. Orexin Receptor Function, Nomenclature and Pharmacology. Pharmacol Rev 2012; 64:389-420. [DOI: 10.1124/pr.111.005546] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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Stanley EM, Fadel J. Aging-related deficits in orexin/hypocretin modulation of the septohippocampal cholinergic system. Synapse 2012; 66:445-52. [PMID: 22213437 PMCID: PMC3292656 DOI: 10.1002/syn.21533] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 11/22/2011] [Accepted: 12/17/2011] [Indexed: 12/20/2022]
Abstract
The medial septum (MS) of the basal forebrain contains cholinergic neurons that project to the hippocampus, support cognitive function, and are implicated in age-related cognitive decline. Hypothalamic orexin/hypocretin neurons innervate and modulate basal forebrain cholinergic neurons and provide direct inputs to the hippocampus. However, the precise role of orexin in modulating hippocampal cholinergic transmission--and how these interactions are altered in aging--is unknown. Here, orexin A was administered to CA1 and the MS of young (3-4 months) and aged (27-29 months) Fisher 344/Brown Norway rats, and hippocampal acetylcholine efflux was analyzed by in vivo microdialysis. At both infusion sites, orexin A dose-dependently increased hippocampal acetylcholine in young, but not aged rats. Moreover, immunohistochemical characterization of the MS revealed no change in cholinergic cell bodies in aged animals, but a significant decrease in orexin fiber innervation to cholinergic cells. These findings indicate that: (1) Orexin A modulates hippocampal cholinergic neurotransmission directly and transsynaptically in young animals, (2) Aged animals are unresponsive to orexin A, and (3) Aged animals undergo an intrinsic reduction in orexin innervation to cholinergic cells within the MS. Alterations in orexin regulation of septohippocampal cholinergic activity may contribute to age-related dysfunctions in arousal, learning, and memory.
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Affiliation(s)
- Emily M Stanley
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, USA
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Affiliation(s)
- J E Morley
- Division of Geriatric Medicine, Saint Louis University School of Medicine, St. Louis, MO 63104, USA.
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Ghezzi AC, Cambri LT, Botezelli JD, Ribeiro C, Dalia RA, de Mello MAR. Metabolic syndrome markers in wistar rats of different ages. Diabetol Metab Syndr 2012; 4:16. [PMID: 22541367 PMCID: PMC3482597 DOI: 10.1186/1758-5996-4-16] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 04/27/2012] [Indexed: 01/04/2023] Open
Abstract
In recent decades, metabolic syndrome has become a public health problem throughout the world. Longitudinal studies in humans have several limitations due to the invasive nature of certain analyses and the size and randomness of the study populations. Thus, animal models that are able to mimic human physiological responses could aid in investigating metabolic disease. Thus, the present study was designed to analyze metabolic syndrome markers in albino Wistar rats (Rattus norvegicus) of different ages. The following parameters were assessed at two (young), four ( adult), six (adult), and twelve (mature) months of age: glucose tolerance (glucose tolerance test); insulin sensitivity (insulin tolerance test); fasting serum glucose, triglycerides, total cholesterol, HDL cholestero, and LDL cholesterol concentrations; glucose uptake in isolated soleus muscle; and total lipid concentration in subcutaneous, mesenteric, and retroperitoneal adipose tissue. We found that aging triggered signs of metabolic syndrome in Wistar rats. For example, mature rats showed a significant increase in body weight that was associated. In addition, mature rats showed an increase in the serum concentration of triglycerides, total cholesterol, and LDL cholesterol, which is characteristic of dyslipidemia. There was also an increase in serum glucose compared with the younger groups of animals. Therefore, aging Wistar rats appear to be an interesting model to study the changes related to metabolic syndrome.
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Affiliation(s)
- Ana Carolina Ghezzi
- Department of Physical Education, São Paulo State University (UNESP – Universidade Estadual Paulista), Rio Claro, SP, Brazil
| | - Lucieli Teresa Cambri
- Department of Physical Education, São Paulo State University (UNESP – Universidade Estadual Paulista), Rio Claro, SP, Brazil
| | - José Diego Botezelli
- Department of Physical Education, São Paulo State University (UNESP – Universidade Estadual Paulista), Rio Claro, SP, Brazil
| | - Carla Ribeiro
- Department of Physical Education, São Paulo State University (UNESP – Universidade Estadual Paulista), Rio Claro, SP, Brazil
| | - Rodrigo Augusto Dalia
- Department of Physical Education, São Paulo State University (UNESP – Universidade Estadual Paulista), Rio Claro, SP, Brazil
| | - Maria Alice Rostom de Mello
- Department of Physical Education, São Paulo State University (UNESP – Universidade Estadual Paulista), Rio Claro, SP, Brazil
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21
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Hypothalamic Control of Sleep in Aging. Neuromolecular Med 2012; 14:139-53. [DOI: 10.1007/s12017-012-8175-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Accepted: 02/10/2012] [Indexed: 12/23/2022]
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22
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Poirier J, Semple H, Davies J, Lapointe R, Dziwenka M, Hiltz M, Mujibi D. Double-blind, vehicle-controlled randomized twelve-month neurodevelopmental toxicity study of common aluminum salts in the rat. Neuroscience 2011; 193:338-62. [DOI: 10.1016/j.neuroscience.2011.05.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 05/04/2011] [Indexed: 10/18/2022]
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23
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Akimoto Y, Kanai S, Ohta M, Akimoto S, Uematsu H, Miyasaka K. Age-associated reduction of stimulatory effect of ghrelin on food intake in mice. Arch Gerontol Geriatr 2011; 55:238-43. [PMID: 21958715 DOI: 10.1016/j.archger.2011.09.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 09/05/2011] [Accepted: 09/06/2011] [Indexed: 10/17/2022]
Abstract
Aging is associated with a progressive decrease in appetite and food intake. We focused on the age-associated changes of the stimulatory effect of the appetite-regulating peptide, ghrelin. Food intake and the concentrations of acyl ghrelin and desacyl ghrelin in the plasma and in the stomach were measured with and without overnight fasting in young and old mice. Moreover, the food intake in response to the intraperitoneal administration of graded doses of acyl ghrelin was compared between young and old mice. Fasting drives food intake in young mice, but not in old mice. The concentrations of acyl ghrelin and desacyl ghrelin in the plasma and in the stomach were higher in the old mice than in the young mice. Food intake did not increase in old mice when stimulated by the administration of 1-3 nmol of acyl ghrelin, which could produce a significant increase in food intake in young mice. In conclusion, food intake did not increase in old mice after either overnight fasting or the administration of acyl ghrelin. The release and synthesis of ghrelin seem to be rather higher in old mice compared to young mice. These increases might be the results of compensation for the decline of receptor (and/or post-receptor) functions.
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Affiliation(s)
- Yosuke Akimoto
- Section of Gerodontology, Department of Gerodontology, Division of Gerontology and Gerodontology, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
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24
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Kessler BA, Stanley EM, Frederick-Duus D, Fadel J. Age-related loss of orexin/hypocretin neurons. Neuroscience 2011; 178:82-8. [PMID: 21262323 DOI: 10.1016/j.neuroscience.2011.01.031] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 01/11/2011] [Accepted: 01/15/2011] [Indexed: 12/15/2022]
Abstract
Aging is associated with many physiological alterations-such as changes in sleep patterns, metabolism and food intake-suggestive of hypothalamic dysfunction, but the effects of senescence on specific hypothalamic nuclei and neuronal groups that mediate these alterations is unclear. The lateral hypothalamus and contiguous perifornical area (LH/PFA) contains several populations of neurons, including those that express the neuropeptides orexin (hypocretin) or melanin-concentrating hormone (MCH). Collectively, orexin and MCH neurons influence many integrative homeostatic processes related to wakefulness and energy balance. Here, we determined the effect of aging on numbers of orexin and MCH neurons in young adult (3-4 months) and old (26-28 months) Fisher 344/Brown Norway F1 hybrid rats. Aged rats exhibited a loss of greater than 40% of orexin-immunoreactive neurons in both the medial and lateral (relative to the fornix) sectors of the LH/PFA. MCH-immunoreactive neurons were also lost in aged rats, primarily in the medial LH/PFA. Neuronal loss in this area was not global as no change in cells immunoreactive for the pan-neuronal marker, NeuN, was observed in aged rats. Combined with other reports of altered receptor expression or behavioral responses to exogenously-administered neuropeptide, these data suggest that compromised orexin (and, perhaps, MCH) function is an important mediator of age-related homeostatic disturbances of hypothalamic origin. The orexin system may represent a crucial substrate linking homeostatic and cognitive dysfunction in aging, as well as a novel therapeutic target for pharmacological or genetic restoration approaches to preventing or ameliorating these disturbances.
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Affiliation(s)
- B A Kessler
- University of South Carolina School of Medicine, Department of Pharmacology, Physiology and Neuroscience, 6439 Garners Ferry Road Columbia, SC 29208, USA
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Akimoto S, Miyasaka K. Age-associated changes of appetite-regulating peptides. Geriatr Gerontol Int 2010; 10 Suppl 1:S107-19. [PMID: 20590826 DOI: 10.1111/j.1447-0594.2010.00587.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Aging is associated with a progressive decrease in appetite and food intake. The reasons for the decline in food intake are multifactorial, and relate to both peripheral and central mechanisms. Current studies about the regulation of food intake suggest that there are many central mediators that control the appetite. To determine the mechanism of age-associated decrease in appetite and food intake, we focused on the age-associated changes of the suppressing and stimulatory effect of some appetite-regulating peptides. At first, we examined cholecystokinin (CCK), one of the typical appetite-suppressing factors. Although sensitivity to CCK is enhanced in old animals, the mechanism underlying this effect has not been elucidated. Next, we focused on the appetite-stimulating peptides, orexin-A, neuropeptide Y (NPY) and ghrelin, which are known to play a critical role in food intake. To determine the age-associated decrease in appetite and food intake, we compared the stimulatory effect of intracerebroventricular administration of orexin-A, NPY and ghrelin. We report the studies of the age-associated changes of appetite-regulating peptides in this review.
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Affiliation(s)
- Saeko Akimoto
- Tokyo Metropolitan Institute of Gerontology, Tokyo Kasei University, Itabashiku, Tokyo, Japan
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Morairty SR, Wisor J, Silveira K, Sinko W, Kilduff TS. The wake-promoting effects of hypocretin-1 are attenuated in old rats. Neurobiol Aging 2009; 32:1514-27. [PMID: 19781813 DOI: 10.1016/j.neurobiolaging.2009.07.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 06/01/2009] [Accepted: 07/27/2009] [Indexed: 11/16/2022]
Abstract
Disruption of sleep is a frequent complaint among elderly humans and is also evident in aged laboratory rodents. The neurobiological bases of age-related sleep/wake disruption are unknown. Given the critical role of the hypocretins in sleep/wake regulation, we sought to determine whether the wake-promoting effect of hypocretin changes with age in Wistar rats, a strain in which age-related changes in both sleep and hypocretin signaling have been reported. Intracerebroventricular infusions of hypocretin-1 (10 and 30 μg) significantly increased wake time relative to vehicle in both young (3 mos) and old (25 mos) Wistar rats. However, the magnitude and duration of the wake-promoting effects were attenuated with age. An increase of parameters associated with homeostatic sleep recovery after sleep deprivation, including non-rapid eye movement (NR) sleep time, NR delta power, the ratio of NR to rapid eye movement (REM) sleep, and NR consolidation, occurred subsequent to Hcrt-induced waking in young but not old rats. ICV infusions of hypocretin-2 (10 and 30 μg) produced fewer effects in both young and old rats. These data demonstrate that activation of a major sleep/wake regulatory pathway is attenuated in old rats.
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27
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Behavioral and metabolic effects of central injections of orexins/hypocretins in pigeons (Columba livia). ACTA ACUST UNITED AC 2008; 147:9-18. [DOI: 10.1016/j.regpep.2007.12.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2007] [Revised: 11/08/2007] [Accepted: 12/09/2007] [Indexed: 11/22/2022]
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28
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Silveyra P, Lux-Lantos V, Libertun C. Both orexin receptors are expressed in rat ovaries and fluctuate with the estrous cycle: effects of orexin receptor antagonists on gonadotropins and ovulation. Am J Physiol Endocrinol Metab 2007; 293:E977-85. [PMID: 17638707 DOI: 10.1152/ajpendo.00179.2007] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Orexins are peptides controlling feeding, sleep, and neuroendocrine functions. They are synthesized by the hypothalamus with projections throughout the brain. Orexins and their orexin 1 (OX(1)) and orexin 2 receptors (OX(2)) are present outside the central nervous system. Here the expression of preproorexin (PPO), OX(1), and OX(2) was studied in rat ovaries. PPO, OX(1), and OX(2) were determined by quantitative real-time RT-PCR in ovaries of cycling Sprague-Dawley rats on all days of the cycle. Serum hormones and food consumption were determined. Ovarian OX(1) and OX(2) expression was then studied after ovulation blockade with Cetrorelix or Nembutal. Finally, proestrous rats were treated at 1400 and 1900 with a selective OX(1) antagonist (SB-334867-A) and/or a selective OX(2) antagonist (JNJ-10397049), and hormone levels, ovulation, and ovarian histology were studied. Both receptors' expression increased in the ovary between 1700 and 2300 of proestrus exclusively, in coincidence with hormone peaks, but not with the dark-light cycle or food intake. PPO was not detected. Cetrorelix or Nembutal prevented the increases of OX(1) and OX(2) while blunting gonadotropin peaks. SB-334867-A and JNJ-10397049, alone or combined, decreased serum gonadotropins and reduced ova number the following morning; ovaries showed a bloody (hyperemic and/or hemorrhagic) reaction with more preovulatory follicles and less corpora lutea. Here we demonstrate for the first time an increased ovarian expression of both OX(1) and OX(2), only during proestrous afternoon, and its hormone dependence but not dependence on the dark-light cycle. Two new receptor antagonists reduced proestrous gonadotropins and/or ova number while producing ovarian structural changes.
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Affiliation(s)
- Patricia Silveyra
- Instituto de Biología y Medicina Experimental-Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Argentina
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Downs JL, Dunn MR, Borok E, Shanabrough M, Horvath TL, Kohama SG, Urbanski HF. Orexin neuronal changes in the locus coeruleus of the aging rhesus macaque. Neurobiol Aging 2006; 28:1286-95. [PMID: 16870307 DOI: 10.1016/j.neurobiolaging.2006.05.025] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Revised: 04/18/2006] [Accepted: 05/19/2006] [Indexed: 11/28/2022]
Abstract
Orexin neuropeptides regulate arousal state and excite the noradrenergic locus coeruleus (LC), so it is plausible that an age-related loss of orexin neurons and projections to the LC contributes to poor sleep quality in elderly humans and nonhuman primates. To test this hypothesis we examined orexin B-immunoreactivity in the lateral hypothalamic area (LHA) and the LC of male rhesus macaques (Macaca mulatta) throughout the life span. Orexin perikarya, localized predominantly in the LHA, showed identical distribution patterns irrespective of age. Similarly, orexin neuron number and serum orexin B concentrations did not differ with age. In contrast, orexin B-immunoreactive axon density in the LC of old animals was significantly lower than that observed in the young or adult animals. Furthermore, the age-related decline was associated with a significant decrease in tyrosine hydroxylase (TH) mRNA in the LC, despite no change in TH-immunoreactive neuron number. Taken together, these data suggest that age-related decreases in excitatory orexin innervation to the noradrenergic LC may contribute to the etiology of poor sleep quality in the elderly.
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Affiliation(s)
- Jodi L Downs
- Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, United States
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Kotz CM, Mullett MA, Wang C. Diminished feeding responsiveness to orexin A (hypocretin 1) in aged rats is accompanied by decreased neuronal activation. Am J Physiol Regul Integr Comp Physiol 2005; 289:R359-R366. [PMID: 15879054 DOI: 10.1152/ajpregu.00717.2004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Orexin A is produced in caudal lateral, posterior, perifornical, and dorsomedial hypothalamic areas. Orexin A in the rostro-dorsal lateral hypothalamic area (rLHa) stimulates feeding and activates several feeding-regulatory brain areas. We hypothesized that aging diminishes feeding and c-Fos-immunoreactivity (c-Fos-ir; marker of neuronal activation) response to orexin A. Young (3 mo), middle-aged (12 mo), and old (24 mo) male Fischer 344 rLHa-cannulated rats were injected with orexin A (0.5, 1, and 2 nmol). Food intake was measured at 1, 2, and 4 h. c-Fos-ir in hypothalamic, limbic, and hindbrain regions was measured in two additional sets of rLHa-orexin A injected rats. In a separate study, orexin A effects on feeding and c-Fos-ir were measured in 6-mo-old rats. Orexin A significantly elevated feeding in rats aged 3, 6, and 12 mo in the 0-1 and 1-2- h time intervals, whereas in old rats this was significant in the 1-2 h time interval only. At 1 h, 6-8 (of 14) brain areas showed elevated c-Fos-ir in response to orexin A in 3- and 6-mo-old rats, but 24-mo-old rats exhibited attenuated or absent c-Fos-ir response in all brain regions except the hypothalamic paraventricular nucleus (PVN) and rostral nucleus of the solitary tract (rNTS). Orexin A did not elevate c-Fos-ir in 3-mo-old rats at 2 h after injection, whereas the PVN and mediodorsal thalamic nucleus (MD) showed elevated c-Fos-ir at 2 h in 24-mo-old rats. These data suggest that delayed and diminished feeding responses in old animals may be due to ineffective neural signaling and implicate the orexin A network as one feeding system affected by aging.
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Affiliation(s)
- Catherine M Kotz
- Veterans Affairs Medical Center, GRECC (11G), One Veterans Drive, Minneapolis, MN 55417, USA.
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Akimoto-Takano S, Sakurai C, Kanai S, Hosoya H, Ohta M, Miyasaka K. Differences in the appetite-stimulating effect of orexin, neuropeptide Y and ghrelin among young, adult and old rats. Neuroendocrinology 2005; 82:256-63. [PMID: 16721031 DOI: 10.1159/000092754] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 02/21/2006] [Indexed: 11/19/2022]
Abstract
Aging is associated with a progressive decrease in appetite and food intake. The appetite-stimulating peptides orexin A, neuropeptide Y (NPY) and ghrelin are known to play a critical role in food intake. In this study, the stimulatory effect of intracerebroventricular administration of these peptides on food intake was compared among young (4 months old), adult (11 months old) and old (24-27 months old) male Wistar rats. A stainless steel cannula was implanted stereotactically into the left lateral ventricle. After a 7-day recovery period, different doses of orexin A (0.25-3 nmol), NPY and ghrelin (0.03-1 nmol) were injected into the left lateral ventricle without anesthesia. Food consumption was measured at 1, 2 and 4 h after injection. We also examined the plasma levels of acylated and desacyl ghrelin in young and old rats by ELISA. Intracerebroventricular administration of orexin A and NPY stimulated food intake in young and adult rats, but no effects were observed at any dose in old rats. Ghrelin increased food intake in a dose-dependent manner in all groups, and the effect of ghrelin was reduced with advancing age. Neither the acylated nor the desacyl plasma ghrelin level differed significantly between young and old rats. In conclusion, the orexigenic effect of the peptides orexin A, NPY and ghrelin decreased in old rats, and this reduction may have been responsible for the age-related decrease in food intake.
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Affiliation(s)
- Saeko Akimoto-Takano
- Department of Clinical Physiology, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
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