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Liddle TA, Majumdar G, Stewart C, Bain MM, Stevenson TJ. Dissociating Mechanisms That Underlie Seasonal and Developmental Programs for the Neuroendocrine Control of Physiology in Birds. eNeuro 2024; 11:ENEURO.0154-23.2023. [PMID: 38548332 PMCID: PMC11007308 DOI: 10.1523/eneuro.0154-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 12/14/2023] [Accepted: 12/19/2023] [Indexed: 04/12/2024] Open
Abstract
Long-term programmed rheostatic changes in physiology are essential for animal fitness. Hypothalamic nuclei and the pituitary gland govern key developmental and seasonal transitions in reproduction. The aim of this study was to identify the molecular substrates that are common and unique to developmental and seasonal timing. Adult and juvenile quail were collected from reproductively mature and immature states, and key molecular targets were examined in the mediobasal hypothalamus (MBH) and pituitary gland. qRT-PCR assays established deiodinase type 2 (DIO2) and type 3 (DIO3) expression in adults changed with photoperiod manipulations. However, DIO2 and DIO3 remain constitutively expressed in juveniles. Pituitary gland transcriptome analyses established that 340 transcripts were differentially expressed across seasonal photoperiod programs and 1,189 transcripts displayed age-dependent variation in expression. Prolactin (PRL) and follicle-stimulating hormone subunit beta (FSHβ) are molecular markers of seasonal programs and are significantly upregulated in long photoperiod conditions. Growth hormone expression was significantly upregulated in juvenile quail, regardless of photoperiodic condition. These findings indicate that a level of cell autonomy in the pituitary gland governs seasonal and developmental programs in physiology. Overall, this paper yields novel insights into the molecular mechanisms that govern developmental programs and adult brain plasticity.
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Affiliation(s)
- Timothy Adam Liddle
- Laboratory of Seasonal Biology, School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Gaurav Majumdar
- Department of Zoology, University of Allahabad, Allahabad, India
| | - Calum Stewart
- Laboratory of Seasonal Biology, School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Maureen M Bain
- Laboratory of Seasonal Biology, School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Tyler John Stevenson
- Laboratory of Seasonal Biology, School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
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Stevenson TJ, Liddle TA, Stewart C, Marshall CJ, Majumdar G. Neural programming of seasonal physiology in birds and mammals: A modular perspective. Horm Behav 2022; 142:105153. [PMID: 35325691 DOI: 10.1016/j.yhbeh.2022.105153] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 01/30/2022] [Accepted: 03/07/2022] [Indexed: 11/17/2022]
Abstract
Most animals in the temperate zone exhibit robust seasonal rhythms in neuroendocrine, physiological and behavioral processes. The integration of predictive and supplementary environmental cues (e.g., nutrients) involves a series of discrete, and interconnected brain regions that span hypothalamic, thalamic, mesencephalic, and limbic regions. Species-specific adaptive changes in these neuroendocrine structures and cellular plasticity have likely evolved to support seasonal life-history transitions. Despite significant advances in our understanding of ecological responses to predictive and supplementary environmental cues, there remains a paucity of literature on how these diverse cues impact the underlying neural and cellular substrates. To date, most scientific approach has focused on neuroendocrine responses to annual changes in daylength, referred to as photoperiod, due to the robust physiological changes to light manipulations in laboratory settings. In this review, we highlight the relatively few animal models that have been effectively used to investigate how predictive day lengths, and supplementary cues are integrated across hypothalamic nuclei, and discuss key findings of how seasonal rhythms in physiology are governed by adaptive neuroendocrine changes. We discuss how specific brain regions integrate environmental cues to form a complex multiunit or 'modular' system that has evolved to optimize the timing of seasonal physiology. Overall, the review aims to highlight the existence of a modular network of neural regions that independently contribute to timing seasonal physiology. This paper proposes that a multi-modular neuroendocrine system has evolved in which independent neural 'units' operate to support species-specific seasonal rhythms.
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Affiliation(s)
- Tyler J Stevenson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom.
| | - Timothy A Liddle
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom
| | - Calum Stewart
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom
| | - Christopher J Marshall
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom
| | - Gaurav Majumdar
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow G61 1QH, United Kingdom
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Onishi KG, Prendergast BJ, Stevenson TJ. Trait-specific effects of exogenous triiodothyronine on cytokine and behavioral responses to simulated systemic infection in male Siberian hamsters. Horm Behav 2019; 110:90-97. [PMID: 30826308 DOI: 10.1016/j.yhbeh.2019.02.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 11/21/2022]
Abstract
Seasonal changes in day length enhance and suppress immune function in a trait-specific manner. In Siberian hamsters (Phodopus sungorus) winter-like short days (SDs) increase blood leukocyte concentrations and adaptive T cell dependent immune responses, but attenuate innate inflammatory responses to simulated infections. Thyroid hormone (TH) signaling also changes seasonally and has been implicated in modulation of the reproductive axis by day length. Immunologically, TH administration in long days (LD) enhances adaptive immune responses in male Siberian hamsters, mimicking effects of SDs. This experiment tested the hypothesis that T3 is also sufficient to mimic the effects of SD on innate immune responses. Adult male hamsters housed in LDs were pretreated with triiodothyronine (T3; 1 μg, s.c.) or saline (VEH) daily for 6 weeks; additional positive controls were housed in SD and received VEH, after which cytokine, behavioral, and physiological responses to simulated bacterial infection (lipopolysaccharide; LPS) were evaluated. SD pretreatment inhibited proinflammatory cytokine mRNA expression (i.e. interleukin 1β, nuclear factor kappa-light-chain-enhancer of activated B cells). In addition, the magnitude and persistence of anorexic and cachectic responses to LPS were also lower in SD hamsters, and LPS-induced inhibition of nest building behavior was absent in SD. T3 treatments failed to affect behavioral (food intake, nest building) or somatic (body mass) responses to LPS in LD hamsters, but one CNS cytokine response to LPS (e.g., hypothalamic TNFα) was augmented by T3. Together these data implicate thyroid hormone signaling in select aspects of innate immune responses to seasonal changes in day length.
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Affiliation(s)
- Kenneth G Onishi
- Department of Psychology, Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, USA.
| | - Brian J Prendergast
- Department of Psychology, Institute for Mind and Biology, University of Chicago, Chicago, IL 60637, USA
| | - Tyler J Stevenson
- Inst. Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, UK
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Peliciari-Garcia RA, Bargi-Souza P, Young ME, Nunes MT. Repercussions of hypo and hyperthyroidism on the heart circadian clock. Chronobiol Int 2017; 35:147-159. [PMID: 29111822 DOI: 10.1080/07420528.2017.1388253] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Myocardial gene expression and metabolism fluctuate over the course of the day in association with changes in energy supply and demand. Time-of-day-dependent oscillations in myocardial processes have been linked to the intrinsic cardiomyocyte circadian clock. Triiodothyronine (T3) is an important modulator of heart metabolism and function. Recently, our group has reported time-of-day-dependent rhythms in cardiac T3 sensitivity, as well as, T3-mediated acute alterations on core clock components. Hypo and hyperthyroidism are the second most prevalent endocrine disease worldwide. Considering the importance of the cardiomyocyte circadian clock and T3 to cardiac physiology, the aim of this study was to investigate the consequences of chronic hypo and hyperthyroidism on 24-h rhythms of circadian clock genes in the heart. Hypo and hyperthyroidism was induced in rats by thyroidectomy (Tx) and i.p. injections of supraphysiological dose of T3, respectively. Here we report alterations in mRNA levels of the major core clock components (Bmal1, Per2, Nr1d1, and Rora) for both experimental conditions (with the exception of Per2 during hyperthyroid condition). Oscillations in mRNA levels of key glucose and fatty-acid metabolism genes known to be clock controlled (Pdk4, Ucp3, Acot1, and Cd36) were equally affected by the experimental conditions, especially during the hypothyroid state. These findings suggest that chronic alterations in thyroid status significantly impacts 24-h rhythms in circadian clock and metabolic genes in the heart. Whether these perturbations contribute toward the pathogenesis of cardiac dysfunction associated with hypo and hyperthyroidism requires further elucidation.
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Affiliation(s)
- Rodrigo A Peliciari-Garcia
- a Morphophysiology & Pathology Sector, Department of Biological Sciences , Federal University of São Paulo , Diadema , Brazil.,b Department of Physiology and Biophysics , Institute of Biomedical Sciences-I, University of São Paulo , São Paulo , Brazil
| | - Paula Bargi-Souza
- b Department of Physiology and Biophysics , Institute of Biomedical Sciences-I, University of São Paulo , São Paulo , Brazil
| | - Martin E Young
- c Division of Cardiovascular Diseases, Department of Medicine , University of Alabama at Birmingham , Birmingham , AL , USA
| | - Maria Tereza Nunes
- b Department of Physiology and Biophysics , Institute of Biomedical Sciences-I, University of São Paulo , São Paulo , Brazil
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Peliciari-Garcia RA, Prévide RM, Nunes MT, Young ME. Interrelationship between 3,5,3´-triiodothyronine and the circadian clock in the rodent heart. Chronobiol Int 2016; 33:1444-1454. [PMID: 27661292 DOI: 10.1080/07420528.2016.1229673] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Triiodothyronine (T3) is an important modulator of cardiac metabolism and function, often through modulation of gene expression. The cardiomyocyte circadian clock is a transcriptionally based molecular mechanism capable of regulating cardiac processes, in part by modulating responsiveness of the heart to extra-cardiac stimuli/stresses in a time-of-day (TOD)-dependent manner. Although TOD-dependent oscillations in circulating levels of T3 (and its intermediates) have been established, oscillations in T3 sensitivity in the heart is unknown. To investigate the latter possibility, euthyroid male Wistar rats were treated with vehicle or T3 at distinct times of the day, after which induction of known T3 target genes were assessed in the heart (4-h later). The expression of mRNA was assessed by real-time quantitative polymerase chain reaction (qPCR). Here, we report greater T3 induction of transcript levels at the end of the dark phase. Surprisingly, use of cardiomyocyte-specific clock mutant (CCM) mice revealed that TOD-dependent oscillations in T3 sensitivity were independent of this cell autonomous mechanism. Investigation of genes encoding for proteins that affect T3 sensitivity revealed that Dio1, Dio2 and Thrb1 exhibited TOD-dependent variations in the heart, while Thra1 and Thra2 did not. Of these, Dio1 and Thrb1 were increased in the heart at the end of the dark phase. Interestingly, we observed that T3 acutely altered the expression of core clock components (e.g. Bmal1) in the rat heart. To investigate this further, rats were injected with a single dose of T3, after which expression of clock genes was interrogated at 3-h intervals over the subsequent 24-h period. These studies revealed robust effects of T3 on oscillations of both core clock components and clock-controlled genes. In summary, the current study exposed TOD-dependent sensitivity to T3 in the heart and its effects in the circadian clock genes expression.
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Affiliation(s)
- Rodrigo Antonio Peliciari-Garcia
- a Department of Biological Sciences , Federal University of São Paulo , Diadema.,b Institute of Biomedical Sciences-I, Department of Physiology and Biophysics , University of São Paulo , São Paulo , SP , Brazil
| | - Rafael Maso Prévide
- b Institute of Biomedical Sciences-I, Department of Physiology and Biophysics , University of São Paulo , São Paulo , SP , Brazil
| | - Maria Tereza Nunes
- b Institute of Biomedical Sciences-I, Department of Physiology and Biophysics , University of São Paulo , São Paulo , SP , Brazil
| | - Martin Elliot Young
- c Department of Medicine, Division of Cardiovascular Diseases , University of Alabama at Birmingham , Birmingham , AL , USA
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Nassar M, Halle I, Plagemann A, Tzschentke B. Detection of long-term influence of prenatal temperature stimulation on hypothalamic type-II iodothyronine deiodinase in juvenile female broiler chickens using a novel immunohistochemical amplification protocol. Comp Biochem Physiol A Mol Integr Physiol 2015; 179:120-4. [PMID: 25289994 DOI: 10.1016/j.cbpa.2014.09.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Revised: 08/05/2014] [Accepted: 09/29/2014] [Indexed: 12/25/2022]
Abstract
It has been clearly shown that early environmental stimulation may have long-lasting influence on body functions. Because of the strong relationship between thermoregulation and other homeostatic linked physiological parameters, perinatal thermal manipulation will also have an impact on other body functions like reproduction. As a maturation stimulant for later reproductive performance, hypothalamic type-2 iodothyronine deiodinase (Dio2) expression was investigated in 35day old immature female broilers with and without embryonic temperature stimulation. For the first time, human-specific Dio2 primary antibodies combined with additional amplification enabled the immunohistochemical detection of hypothalamic Dio2 protein in birds. The novel protocol includes an additional amplification step involving swine-anti-rabbit/mouse/goat antibodies against both goat anti-Dio2 primary and rabbit anti-goat biotinylated secondary commercial antibodies in the standard diaminobenzidine protocol. However, significant Dio2 expression was exclusively found in perinatally short-term temperature stimulated hens. Caudal but not rostral hypothalamic slices revealed that elevating incubation temperature by 1°C for 2h daily, from day 18 of embryonic development until hatching, induced a statistical significant expression of Dio2 within the subcommisural organ and the median eminence. This ample expression of Dio2 protein within caudal but not rostral hypothalamic slices of embryonic temperature stimulated chickens, leads to the assumption of a novel physiological prospective for embryonic thermal manipulation involving the suppression of thyroid hormone and the boosting of hypothalamic Dio2-induced FSH secretion to considerably advance the age of photoinduced egg production. It could be also of practicable relevance for broiler breeder females, and needs further investigations.
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Affiliation(s)
- Maaly Nassar
- Humboldt University of Berlin, Institute of Biology, Philippstr. 13, 10115 Berlin, Germany.
| | - Ingrid Halle
- Friedrich-Loeffler-Institute for Animal Health, Institute of Animal Nutrition, 38226 Braunschweig, Germany.
| | - Andreas Plagemann
- Charité Unversitätsmedizin Berlin, Campus Virchow-Klinikum, Department of Obstetrics, Division of Perinatal Programming, Augustenburger Platz, 113353 Berlin, Germany.
| | - Barbara Tzschentke
- Humboldt University of Berlin, Institute of Biology, Philippstr. 13, 10115 Berlin, Germany.
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Cassone VM. Avian circadian organization: a chorus of clocks. Front Neuroendocrinol 2014; 35:76-88. [PMID: 24157655 PMCID: PMC3946898 DOI: 10.1016/j.yfrne.2013.10.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 07/18/2013] [Accepted: 10/09/2013] [Indexed: 12/24/2022]
Abstract
In birds, biological clock function pervades all aspects of biology, controlling daily changes in sleep: wake, visual function, song, migratory patterns and orientation, as well as seasonal patterns of reproduction, song and migration. The molecular bases for circadian clocks are highly conserved, and it is likely the avian molecular mechanisms are similar to those expressed in mammals, including humans. The central pacemakers in the avian pineal gland, retinae and SCN dynamically interact to maintain stable phase relationships and then influence downstream rhythms through entrainment of peripheral oscillators in the brain controlling behavior and peripheral tissues. Birds represent an excellent model for the role played by biological clocks in human neurobiology; unlike most rodent models, they are diurnal, they exhibit cognitively complex social interactions, and their circadian clocks are more sensitive to the hormone melatonin than are those of nocturnal rodents.
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Affiliation(s)
- Vincent M Cassone
- Department of Biology, University of Kentucky, Lexington, KY 40506, United States.
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Sánchez E, Singru PS, Wittmann G, Nouriel SS, Barrett P, Fekete C, Lechan RM. Contribution of TNF-alpha and nuclear factor-kappaB signaling to type 2 iodothyronine deiodinase activation in the mediobasal hypothalamus after lipopolysaccharide administration. Endocrinology 2010; 151:3827-35. [PMID: 20501675 PMCID: PMC2940536 DOI: 10.1210/en.2010-0279] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 04/28/2010] [Indexed: 11/19/2022]
Abstract
To determine whether signaling through TNF and/or nuclear factor-kappaB contributes to bacterial lipopolysaccharide (LPS)-induced activation of type 2 iodothyronine deiodinase (D2) in tanycytes lining the floor and infralateral walls of the third ventricle, the effect of a TNF antagonist on D2 gene expression and LPS-induced Ikappa-Balpha expression in tanycytes were studied. Animals treated with soluble, rat, polyethylene glycol-conjugated TNF receptor type 1 (4 mg/kg body weight) before a single ip injection of LPS showed a significant reduction in circulating IL-6 levels but no effect on LPS-induced D2 mRNA in the majority of tanycytes with the exception of a subpopulation of alpha tanycytes in the wall of the third ventricle. LPS induced a rapid increase in Ikappa-Balpha mRNA in the pars tuberalis and a delayed response in alpha tanycytes but absent in all other tanycyte subsets. The LPS-induced increase in Ikappa-Balpha in the pars tuberalis was associated with increased TSHbeta gene expression in this tissue, but cAMP response element-binding protein (CREB) phosphorylation was observed only in a subset of alpha tanycytes. These data suggest that TNF and nuclear factor-kappaB signaling are not the primary, initiating mechanisms mediating the LPS-induced D2 response in tanycytes, but may contribute in part to sustaining the LPS-induced D2 response in a subset of alpha tanycytes. We hypothesize that in addition to TSH, other factors derived from the pars tuberalis may contribute to LPS-induced D2 activation in tanycytes.
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Affiliation(s)
- Edith Sánchez
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Tufts Medical Center, Boston, Massachusetts 02111, USA
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Kumar P, Pati AK, Mohan J, Sastry KVH, Tyagi JS, Chaturvedi CM. Effects of Simulated Hypo‐ and Hyper‐Reproductive Conditions on the Characteristics of Circadian Rhythm in Hypothalamic Concentration of Serotonin and Dopamine and in Plasma Levels of Thyroxine, Triiodothyronine, and Testosterone in Japanese Quail,Coturnix coturnix japonica. Chronobiol Int 2009; 26:28-46. [DOI: 10.1080/07420520802697882] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Shiga S, Numata H. Roles of PER immunoreactive neurons in circadian rhythms and photoperiodism in the blow fly, Protophormia terraenovae. ACTA ACUST UNITED AC 2009; 212:867-77. [PMID: 19252004 DOI: 10.1242/jeb.027003] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Several hypothetical models suggest that the circadian clock system is involved in the photoperiodic clock mechanisms in insects. However, there is no evidence for this at a neuronal level. In the present study, whether circadian clock neurons were involved in photoperiodism was examined by surgical ablation of small area in the brain and by immunocytochemical analysis in the blow fly Protophormia terraenovae. Five types of PER-immunoreactive cells, dorsal lateral neurons (LN(d)), large ventral lateral neurons (l-LN(v)), small ventral lateral neurons (s-LN(v)), lateral dorsal neurons (DN(l)) and medial dorsal neurons (DN(m)) were found, corresponding to period-expressing neurons in Drosophila melanogaster. Four l-LN(v)s and four s-LN(v)s were bilaterally double-labelled with antisera against pigment-dispersing factor (PDF) and PER. When the anterior base of the medulla in the optic lobe, where PDF-immunoreactive somata (l-LN(v) and s-LN(v)) are located, was bilaterally ablated, 55% of flies showed arrhythmic or obscure activity patterns under constant darkness. Percentages of flies exhibiting a rhythmic activity pattern decreased along with the number of small PDF-immunoreactive somata (i.e. s-Ln(v)). When regions containing small PDF somata (s-LN(v)) were bilaterally ablated, flies did not discriminate photoperiod, and diapause incidences were 48% under long-day and 55% under short-day conditions. The results suggest that circadian clock neurons, s-LN(v)s, driving behavioural rhythms might also be involved in photoperiodism, and that circadian behavioural rhythms and photoperiodism share neural elements in their underlying mechanisms.
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Affiliation(s)
- Sakiko Shiga
- Department of Biology and Geosciences, Graduate School of Science, Osaka City University, Sumiyoshi, Osaka 558-8585, Japan.
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Dardente H, Birnie M, Lincoln GA, Hazlerigg DG. RFamide-related peptide and its cognate receptor in the sheep: cDNA cloning, mRNA distribution in the hypothalamus and the effect of photoperiod. J Neuroendocrinol 2008; 20:1252-9. [PMID: 18752651 DOI: 10.1111/j.1365-2826.2008.01784.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Photoperiodic responses enable animals to adapt their physiology to predictable patterns of seasonal environmental change. In mammals, this depends on pineal melatonin secretion and effects in the hypothalamus, but the cellular and molecular substrates of its action are poorly understood. The recent identification of a mammalian orthologue of the avian gonadotrophin-inhibitory hormone gene has led to interest in its possible involvement in seasonal breeding. In long-day breeding Syrian hamsters, hypothalamic RFamide-related peptide (RFRP) expression is increased by exposure to long photoperiod. Because, opposite to hamsters, sheep are short-day breeders, we predicted that a conserved role in mammalian reproductive activation would decrease RFRP expression in sheep under a long photoperiod. We cloned the ovine RFRP cDNA and examined its expression pattern in Soay sheep acclimated to a 16 : 8 h or 8 : 16 h light /dark cycle (LP and SP, respectively). RFRP was expressed widely in the sheep hypothalamus and increased modestly overall with exposure to LP. Interestingly, RFRP expression in the ependymal cells surrounding the base of the third ventricle was highly photoperiodic, with levels being undetectable in animals held on SP but consistently high under LP. These data are inconsistent with a conserved reproductive role for RFRP across mammals. Additionally, we cloned the ovine homologue of the cognate RFRP receptor, rfr-2 (NPFF1) and found localised expression in the suprachiasmatic nuclei and in the pars tuberalis. Taken together, these data strengthen the emerging view that interplay between ependymal cells and the pars tuberalis might be important for the seasonal timing system.
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Affiliation(s)
- H Dardente
- School of Biological Sciences, Aberdeen University, Scotland, UK.
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Paul MJ, Zucker I, Schwartz WJ. Tracking the seasons: the internal calendars of vertebrates. Philos Trans R Soc Lond B Biol Sci 2008; 363:341-61. [PMID: 17686736 PMCID: PMC2606754 DOI: 10.1098/rstb.2007.2143] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Animals have evolved many season-specific behavioural and physiological adaptations that allow them to both cope with and exploit the cyclic annual environment. Two classes of endogenous annual timekeeping mechanisms enable animals to track, anticipate and prepare for the seasons: a timer that measures an interval of several months and a clock that oscillates with a period of approximately a year. Here, we discuss the basic properties and biological substrates of these timekeeping mechanisms, as well as their reliance on, and encoding of environmental cues to accurately time seasonal events. While the separate classification of interval timers and circannual clocks has elucidated important differences in their underlying properties, comparative physiological investigations, especially those regarding seasonal prolactin secretions, hint at the possibility of common substrates.
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Affiliation(s)
- Matthew J Paul
- Department of Neurology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
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Bertin A, Houdelier C, Richard-Yris MA, Guyomarc'h C, Lumineau S. Stable individual profiles of daily timing of migratory restlessness in European quail. Chronobiol Int 2007; 24:253-67. [PMID: 17453846 DOI: 10.1080/07420520701283685] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Temporal characteristics of migratory behavior in birds are usually studied at the species and population levels, and rarely at the individual level. Variations among species and populations of the seasonal onset of migratory behavior have been widely investigated, but very little is known about its daily organization or whether birds are conservative in their behavior. The determination of intra- and inter-individual variability is important for the study of genetic variations and can reveal the existence of different adaptation capacities within populations. This laboratory study analyzed intra- and inter-individual variability of daily initiation and time course of nocturnal restlessness in partial-migrant European quail (Coturnix coturnix coturnix). Thirty-five quail were selected randomly from a captive stock, and their spring activity was recorded under natural daylenghs. Eighteen of the thirty-five quail presented behavioral profiles of migrant birds. Migrant birds initiated their nocturnal activity punctually, and the time courses of the nocturnal activity of 88% of them revealed intra-individual stability over six consecutive nights. All birds initiated their nocturnal activity after sunset and civil twilight, and they were more active at the beginning than the middle or end of the night, suggesting that their drive to migrate could be synchronized with particular skylight conditions. For the first time, stable individual profiles in the daily time course of migratory restlessness are shown. These results support previous findings concerning biological rhythms of quail and raise questions concerning the timing of migratory behavior.
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Affiliation(s)
- Aline Bertin
- UMR CNRS 6552, Ethologie-Evolution-Ecologie, Université de Rennes 1, Rennes cedex, France.
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