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Gorman MR. Temporal organization of pineal melatonin signaling in mammals. Mol Cell Endocrinol 2020; 503:110687. [PMID: 31866317 DOI: 10.1016/j.mce.2019.110687] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 12/13/2019] [Accepted: 12/14/2019] [Indexed: 12/20/2022]
Abstract
In mammals, the pineal gland is the sole endocrine source of melatonin, which is secreted according to daily and seasonal patterns. This mini-review synthesizes the established endocrine actions of melatonin in the following temporal contexts. Melatonin is a strictly regulated output of the circadian timing system, but under certain conditions, may also entrain the circadian pacemaker and clocks in peripheral tissues. As the waveform of nightly melatonin secretion varies seasonally, melatonin provides a hormonal representation of the time of year. The duration of elevated melatonin secretion regulates reproductive physiology and other seasonal adaptations either by entraining a circannual rhythm or by inducing seasonal responses directly. An entrainment action of nightly melatonin on clock gene expression in the pars tuberalis of the anterior pituitary may partly underly its mechanistic role as a photoperiodic switch. Melatonin has important functions developmentally to regulate multiple physiological systems and program timing of puberty. Endogenous melatonergic systems are disrupted by modern lifestyles of humans through altered circadian entrainment, acute suppression by light and self-administration of pharmacological melatonin. Non-endocrine actions of locally synthesized melatonin fall outside of the scope of this mini-review.
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Affiliation(s)
- Michael R Gorman
- Departments of Psychology and Center for Circadian Biology, University of California, San Diego, La Jolla, CA, 92093-0109, USA.
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Uchiwa T, Takai Y, Tashiro A, Furuse M, Yasuo S. Exposure of C57BL/6J mice to long photoperiod during early life stages increases body weight and alters plasma metabolomic profiles in adulthood. Physiol Rep 2017; 4:4/18/e12974. [PMID: 27650252 PMCID: PMC5037922 DOI: 10.14814/phy2.12974] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 08/24/2016] [Indexed: 01/21/2023] Open
Abstract
Perinatal photoperiod is an important regulator of physiological phenotype in adulthood. In this study, we demonstrated that postnatal (0–4 weeks old) exposure of C57BL/6J mice to long photoperiod induced persistent increase in body weight until adulthood, compared with the mice maintained under short photoperiod. The expression of peroxisome proliferator‐activated receptor δ, a gene involved in fatty acid metabolism, was decreased in 10‐week‐old mice exposed to long photoperiod during 0–4 or 4–8 weeks of age. Plasma metabolomic profiles of adult mice exposed to a long photoperiod during the postnatal period (0–4 LD) were compared to those in the mice exposed to short photoperiod during the same period. Cluster analysis revealed that both carbon metabolic pathway and nucleic acid pathway were altered by the postnatal photoperiod. Levels of metabolites involved in glycolysis were significantly upregulated in 0–4 LD, suggesting that the mice in 0–4 LD use the glycolytic pathway for energy expenditure rather than the fatty acid oxidation pathway. In addition, the mice in 0–4 LD exhibited high levels of purine metabolites, which have a role in neuroprotection. In conclusion, postnatal exposure of C57BL/6J mice to long photoperiod induces increase in body weight and various changes in plasma metabolic profiles during adulthood.
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Affiliation(s)
- Tatsuhiro Uchiwa
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Yusuke Takai
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Ayako Tashiro
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Mitsuhiro Furuse
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Shinobu Yasuo
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
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3
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Petri I, Diedrich V, Wilson D, Fernández-Calleja J, Herwig A, Steinlechner S, Barrett P. Orchestration of gene expression across the seasons: Hypothalamic gene expression in natural photoperiod throughout the year in the Siberian hamster. Sci Rep 2016; 6:29689. [PMID: 27406810 PMCID: PMC4942572 DOI: 10.1038/srep29689] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 06/23/2016] [Indexed: 01/17/2023] Open
Abstract
In nature Siberian hamsters utilize the decrement in day length following the summer solstice to implement physiological adaptations in anticipation of the forthcoming winter, but also exploit an intrinsic interval timer to initiate physiological recrudescence following the winter solstice. However, information is lacking on the temporal dynamics in natural photoperiod of photoperiodically regulated genes and their relationship to physiological adaptations. To address this, male Siberian hamsters born and maintained outdoors were sampled every month over the course of one year. As key elements of the response to photoperiod, thyroid hormone signalling components were assessed in the hypothalamus. From maximum around the summer solstice (late-June), Dio2 expression rapidly declined in advance of physiological adaptations. This was followed by a rapid increase in Mct8 expression (T3/T4 transport), peaking early-September before gradually declining to minimum expression by the following June. Dio3 showed a transient peak of expression beginning late-August. A recrudescence of testes and body mass occurred from mid-February, but Dio2 expression remained low until late-April of the following year, converging with the time of year when responsiveness to short-day length is re-established. Other photoperiodically regulated genes show temporal regulation, but of note is a transient peak in Gpr50 around late-July.
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Affiliation(s)
- Ines Petri
- University of Veterinary Medicine Hannover, Buenteweg 17, 30559 Hannover, Germany
| | - Victoria Diedrich
- University of Veterinary Medicine Hannover, Buenteweg 17, 30559 Hannover, Germany
| | - Dana Wilson
- Rowett Institute for Nutrition and Health, University of Aberdeen, Greenburn Road Bucksburn, Aberdeen AB21 9SB, UK
| | - José Fernández-Calleja
- Rowett Institute for Nutrition and Health, University of Aberdeen, Greenburn Road Bucksburn, Aberdeen AB21 9SB, UK
| | - Annika Herwig
- Zoological Institute, University of Hamburg, Martin-Luther-King-Platz 3, D-20146 Hamburg, Germany
| | - Stephan Steinlechner
- University of Veterinary Medicine Hannover, Buenteweg 17, 30559 Hannover, Germany
| | - Perry Barrett
- Rowett Institute for Nutrition and Health, University of Aberdeen, Greenburn Road Bucksburn, Aberdeen AB21 9SB, UK
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Abstract
Seasonal clocks (e.g., circannual clocks, seasonal interval timers) permit anticipation of regularly occurring environmental events by timing the onset of seasonal transitions in reproduction, metabolism, and behavior. Implicit in the concept that seasonal clocks reflect adaptations to the local environment is the unexamined assumption that heritable genetic variance exists in the critical features of such clocks, namely, their temporal properties. These experiments quantified the intraspecific variance in, and heritability of, the photorefractoriness interval timer in Siberian hamsters ( Phodopus sungorus), a seasonal clock that provides temporal information to mechanisms that regulate seasonal transitions in body weight. Twenty-seven families consisting of 54 parents and 109 offspring were raised in a long-day photoperiod and transferred as adults to an inhibitory photoperiod (continuous darkness; DD). Weekly body weight measurements permitted specification of the interval of responsiveness to DD, a reflection of the duration of the interval timer, in each individual. Body weights of males and females decreased after exposure to DD, but 3 to 5 months later, somatic recrudescence occurred, indicative of photorefractoriness to DD. The interval timer was approximately 5 weeks longer and twice as variable in females relative to males. Analyses of variance of full siblings revealed an overall intraclass correlation of 0.71 ± 0.04 (0.51 ± 0.10 for male offspring and 0.80 ± 0.06 for female offspring), suggesting a significant family resemblance in the duration of interval timers. Parent-offspring regression analyses yielded an overall heritability estimate of 0.61 ± 0.2; h2 estimates from parent-offspring regression analyses were significant for female offspring (0.91 ± 0.4) but not for male offspring (0.35 ± 0.2), indicating strong additive genetic components for this trait, primarily in females. In nature, individual differences, both within and between sexes, in the timekeeping properties of seasonal interval timers, and a strong heritable basis thereof, would provide ample substrate for selection to rapidly influence seasonal clocks. Balancing selection in environments where the onset of spring conditions varies from year to year could maintain genetic variance in interval timers and yield interval timers tuned to the local environment.
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Weil ZM, Borniger JC, Cisse YM, Abi Salloum BA, Nelson RJ. Neuroendocrine control of photoperiodic changes in immune function. Front Neuroendocrinol 2015; 37:108-18. [PMID: 25456047 PMCID: PMC4402123 DOI: 10.1016/j.yfrne.2014.10.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 10/07/2014] [Accepted: 10/09/2014] [Indexed: 12/29/2022]
Abstract
Seasonal variation in immune function putatively maximizes survival and reproductive success. Day length (photoperiod) is the most potent signal for time of year. Animals typically organize breeding, growth, and behavior to adapt to spatial and temporal niches. Outside the tropics individuals monitor photoperiod to support adaptations favoring survival and reproductive success. Changes in day length allow anticipation of seasonal changes in temperature and food availability that are critical for reproductive success. Immune function is typically bolstered during winter, whereas reproduction and growth are favored during summer. We provide an overview of how photoperiod influences neuronal function and melatonin secretion, how melatonin acts directly and indirectly to govern seasonal changes in immune function, and the manner by which other neuroendocrine effectors such as glucocorticoids, prolactin, thyroid, and sex steroid hormones modulate seasonal variations in immune function. Potential future research avenues include commensal gut microbiota and light pollution influences on photoperiodic responses.
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Affiliation(s)
- Zachary M Weil
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA.
| | - Jeremy C Borniger
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Yasmine M Cisse
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Bachir A Abi Salloum
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Randy J Nelson
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
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Gracceva G, Herde A, Groothuis TGG, Koolhaas JM, Palme R, Eccard JA. Turning Shy on a Winter's Day: Effects of Season on Personality and Stress Response inMicrotus arvalis. Ethology 2014. [DOI: 10.1111/eth.12246] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Giulia Gracceva
- Behavioural Physiology; Institute of Behavioural Neurosciences; University of Groningen; Groningen The Netherlands
- Behavioural Biology; Institute of Behavioural Neurosciences; University of Groningen; Groningen The Netherlands
| | - Antje Herde
- Department of Animal Ecology; Institute of Biochemistry and Biology; University of Potsdam; Potsdam Germany
| | - Ton G. G. Groothuis
- Behavioural Biology; Institute of Behavioural Neurosciences; University of Groningen; Groningen The Netherlands
| | - Jaap M. Koolhaas
- Behavioural Physiology; Institute of Behavioural Neurosciences; University of Groningen; Groningen The Netherlands
| | - Rupert Palme
- Institute for Medical Biochemistry; University of Veterinary Medicine; Vienna Austria
| | - Jana A. Eccard
- Department of Animal Ecology; Institute of Biochemistry and Biology; University of Potsdam; Potsdam Germany
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Monecke S, Amann B, Lemuth K, Wollnik F. Dual control of seasonal time keeping in male and female juvenile European hamsters. Physiol Behav 2014; 130:66-74. [DOI: 10.1016/j.physbeh.2014.03.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 03/13/2014] [Indexed: 01/19/2023]
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Walton JC, Weil ZM, Nelson RJ. Influence of photoperiod on hormones, behavior, and immune function. Front Neuroendocrinol 2011; 32:303-19. [PMID: 21156187 PMCID: PMC3139743 DOI: 10.1016/j.yfrne.2010.12.003] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2010] [Revised: 11/30/2010] [Accepted: 12/03/2010] [Indexed: 01/26/2023]
Abstract
Photoperiodism is the ability of plants and animals to measure environmental day length to ascertain time of year. Central to the evolution of photoperiodism in animals is the adaptive distribution of energetically challenging activities across the year to optimize reproductive fitness while balancing the energetic tradeoffs necessary for seasonally-appropriate survival strategies. The ability to accurately predict future events requires endogenous mechanisms to permit physiological anticipation of annual conditions. Day length provides a virtually noise free environmental signal to monitor and accurately predict time of the year. In mammals, melatonin provides the hormonal signal transducing day length. Duration of pineal melatonin is inversely related to day length and its secretion drives enduring changes in many physiological systems, including the HPA, HPG, and brain-gut axes, the autonomic nervous system, and the immune system. Thus, melatonin is the fulcrum mediating redistribution of energetic investment among physiological processes to maximize fitness and survival.
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Affiliation(s)
- James C Walton
- Department of Neuroscience, The Ohio State University Medical Center, Columbus, OH 43210, USA.
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Butler MP, Turner KW, Park JH, Schoomer EE, Zucker I, Gorman MR. Seasonal regulation of reproduction: altered role of melatonin under naturalistic conditions in hamsters. Proc Biol Sci 2010; 277:2867-74. [PMID: 20444712 DOI: 10.1098/rspb.2010.0396] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The seasonal reproductive cycle of photoperiodic rodents is conceptualized as a series of discrete melatonin-dependent neuroendocrine transitions. Least understood is the springtime restoration of responsiveness to winter-like melatonin signals (breaking of refractoriness) that enables animals to once again respond appropriately to winter photoperiods the following year. This has been posited to require many weeks of long days based on studies employing static photoperiods instead of the annual pattern of continually changing photoperiods under which these mechanisms evolved. Maintaining Siberian hamsters under simulated natural photoperiods, we demonstrate that winter refractoriness is broken within six weeks after the spring equinox. We then test whether a history of natural photoperiod exposure can eliminate the requirement for long-day melatonin signalling. Hamsters pinealectomized at the spring equinox and challenged 10 weeks later with winter melatonin infusions exhibited gonadal regression, indicating that refractoriness was broken. A photostimulatory effect on body weight is first observed in the last four weeks of winter. Thus, the seasonal transition to the summer photosensitive phenotype is triggered prior to the equinox without exposure to long days and is thereafter melatonin-independent. Distinctions between photoperiodic and circannual seasonal organization erode with the incorporation in the laboratory of ecologically relevant day length conditions.
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Affiliation(s)
- Matthew P Butler
- Department of Integrative Biology and, University of California, , Berkeley, CA 94720, USA.
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Butler MP, Paul MJ, Turner KW, Park JH, Driscoll JR, Kriegsfeld LJ, Zucker I. Circadian rhythms of photorefractory siberian hamsters remain responsive to melatonin. J Biol Rhythms 2008; 23:160-9. [PMID: 18375865 DOI: 10.1177/0748730407312949] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Short day lengths increase the duration of nocturnal melatonin (Mel) secretion, which induces the winter phenotype in Siberian hamsters. After several months of continued exposure to short days, hamsters spontaneously revert to the spring-summer phenotype. This transition has been attributed to the development of refractoriness of Mel-binding tissues, including the suprachiasmatic nucleus (SCN), to long-duration Mel signals. The SCN of Siberian hamsters is required for the seasonal response to winter-like Mel signals, and becomes refractory to previously effective long-duration Mel signals restricted to this area. Acute Mel treatment phase shifts circadian locomotor rhythms of photosensitive Siberian hamsters, presumably by affecting circadian oscillators in the SCN. We tested whether seasonal refractoriness of the SCN to long-duration Mel signals also renders the circadian system of Siberian hamsters unresponsive to Mel. Males manifesting free-running circadian rhythms in constant dim red light were injected with Mel or vehicle for 5 days on a 23.5-h T-cycle beginning at circadian time 10. Mel injections caused significantly larger phase advances in activity onset than did the saline vehicle, but the magnitude of phase shifts to Mel did not differ between photorefractory and photosensitive hamsters. Similarly, when entrained to a 16-h light/8-h dark photocycle, photorefractory and photosensitive hamsters did not differ in their response to Mel injected 4 h before the onset of the dark phase. Activity onset in Mel-injected hamsters was masked by light but was revealed to be significantly earlier than in vehicle-injected hamsters upon transfer to constant dim red light. The acute effects of melatonin on circadian behavioral rhythms are preserved in photorefractory hamsters.
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Affiliation(s)
- Matthew P Butler
- Department of Integrative Biology, University of California, Berkeley, CA, USA.
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Butler MP, Trumbull JJ, Turner KW, Zucker I. Timing of puberty and synchronization of seasonal rhythms by simulated natural photoperiods in female Siberian hamsters. Am J Physiol Regul Integr Comp Physiol 2007; 293:R413-20. [PMID: 17491109 DOI: 10.1152/ajpregu.00216.2007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The timing of puberty is a critical life history trait of short-lived species; spring-born individuals mature rapidly and breed in the season of birth, whereas young born in mid- to late summer delay puberty until the next spring. The cues that govern the transition from rapid to delayed maturation in natural populations remain unknown. To identify ecologically relevant photoperiod cues that control timing of puberty, we monitored nine cohorts of female Siberian hamsters ( Phodopus sungorus) born every 2 wk from 4 wk before to 12 wk after the summer solstice in a simulated natural photoperiod (SNP). Hamsters born by the summer solstice underwent rapid somatic growth and achieved puberty that summer; among females born 2–4 wk after the solstice, some delayed puberty by many weeks, whereas others manifested early puberty. Hamsters born 6 or more weeks after the solstice generally delayed puberty until the following spring. The transition from accelerated to delayed pubertal development in the SNP occurred at day lengths that induce early puberty when presented as static photoperiods. Despite differences in timing of birth and timing of puberty, fall and subsequent spring seasonal events occurred at similar calendar dates in all cohorts. We found no evidence that prenatal photoperiod history influenced postnatal development of female hamsters. Considered together with a parallel study on males, the present findings point to sex differences in responsiveness to natural photoperiod variations. In both sexes, incrementally changing photoperiods exert a strong organizing effect on seasonal rhythms.
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Affiliation(s)
- Matthew P Butler
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
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Butler MP, Turner KW, Park JH, Butler JP, Trumbull JJ, Dunn SP, Villa P, Zucker I. Simulated natural day lengths synchronize seasonal rhythms of asynchronously born male Siberian hamsters. Am J Physiol Regul Integr Comp Physiol 2007; 293:R402-12. [PMID: 17428890 DOI: 10.1152/ajpregu.00146.2007] [Citation(s) in RCA: 17] [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
Photoperiodism research has relied on static day lengths and abrupt transitions between long and short days to characterize the signals that drive seasonal rhythms. To identify ecologically relevant critical day lengths and to test the extent to which naturally changing day lengths synchronize important developmental events, we monitored nine cohorts of male Siberian hamsters (Phodopus sungorus) born every 2 wk from 4 wk before to 12 wk after the summer solstice in a simulated natural photoperiod (SNP). SNP hamsters born from 4 wk before to 2 wk after the solstice underwent rapid somatic and gonadal growth; among those born 4-6 wk after the solstice, some delayed puberty by many weeks, whereas others manifested early puberty. Hamsters born eight or more weeks after the solstice failed to undergo early testicular development. The transition to delayed development occurred at long day lengths, which induce early puberty when presented as static photoperiods. The first animals to delay puberty may do so predominantly on the basis of postnatal decreases in day length, whereas in later cohorts, a comparison of postnatal day length to gestational day length may contribute to arrested development. Despite differences in timing of birth and timing of puberty, autumn gonadal regression and spring gonadal and somatic growth occurred at similar calendar dates in all cohorts. Incrementally changing photoperiods exert a strong organizing effect on seasonal rhythms by providing hamsters with a richer source of environmental timing cues than are available in simple static day lengths.
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Affiliation(s)
- Matthew P Butler
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
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Weil ZM, Pyter LM, Martin LB, Nelson RJ. Perinatal photoperiod organizes adult immune responses in Siberian hamsters (Phodopus sungorus). Am J Physiol Regul Integr Comp Physiol 2006; 290:R1714-9. [PMID: 16410397 DOI: 10.1152/ajpregu.00869.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Individuals of many nontropical rodent species display reproductive, immunological, and somatic responses to day length. In general, short day (SD) lengths inhibit reproduction and enhance immune function in the laboratory when all other conditions are held constant. Most studies to date have focused on seasonal variation in immune function in adulthood. However, perinatal photoperiods also communicate critical day length information and serve to establish a developmental trajectory appropriate for the time of year. Nontropical rodents born early in the breeding season undergo rapid reproductive development, presumably to promote mating success during their first reproductive season. Rodents born late in the breeding season suspend somatic growth and puberty until the following vernal breeding season. We tested the hypothesis that perinatal day lengths have similar enduring effects on the immune system of rodents. Siberian hamsters (Phodopus sungorus) were maintained prenatally and until weaning (21 days) in either SDs (8 h light:16 h dark) or long days (LD) (16 h light:8 h dark), then they were weaned into either the opposite photoperiod or maintained in their natal photoperiod, forming four groups (LD-LD, LD-SD, SD-LD, and SD-SD). After 8-wk in these conditions, cell-mediated immune activity was compared among groups. SD-SD hamsters of both sexes enhanced immune function relative to all other groups. The reproductive effects of perinatal photoperiod were not evident by the end of the experiment; circulating testosterone and cortisol sampled at the end of the experiment reflected the postweaning, but not the perinatal photoperiod. This experiment demonstrates long-lasting organizational effects of perinatal photoperiod on the rodent immune system and indicates that photoperiod-induced changes in the immune system are dissociable from changes in the reproductive system.
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Affiliation(s)
- Zachary M Weil
- Department of Neuroscience, and Institute for Behavioral Medicine Research, The Ohio State University, Columbus, OH 43210, USA.
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Prendergast BJ, Mosinger B, Kolattukudy PE, Nelson RJ. Hypothalamic gene expression in reproductively photoresponsive and photorefractory Siberian hamsters. Proc Natl Acad Sci U S A 2002; 99:16291-6. [PMID: 12456888 PMCID: PMC138604 DOI: 10.1073/pnas.232490799] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2002] [Indexed: 01/27/2023] Open
Abstract
An interval timing mechanism in the brain governs reproduction in seasonally breeding mammals by triggering refractoriness to inhibitory short photoperiods during midwinter. The neural mechanisms responsible for the timing and induction of photorefractoriness by this seasonal clock are unknown. Using cDNA microarrays and RT-PCR, we identified a class of genes encoding thyroxine (T4)-binding proteins (transthyretin, T4-binding globulin, albumin) whose expression is associated with reproductive refractoriness to short day lengths. Down-regulation of these genes was associated with reduced hypothalamic T4 uptake, which was reversed by long-day photoperiod treatments that restored responsiveness to short days. Circulating T4 concentrations did not vary with states of photoresponsiveness in euthyroid hamsters, but blockade of thyroid function accelerated the onset of photorefractoriness to short days. These data link changes in gene expression in the hypothalamus to the functional output of a seasonal clock. Reproductive inhibition in short days depends on T4 only late in the nonbreeding season. Down-regulation of genes encoding T4-binding proteins in the hypothalamus during this interval may restrict access of a static T4 signal to hypothalamic target tissues that regulate reproduction, thereby timing annual transitions in reproductive function. Hypothalamic autoregulation of T4 influx may constitute a critical cellular process involved in the generation and expression of seasonal reproductive rhythms and suggests a previously undescribed mechanism by which neural targets gain access to peripheral hormones.
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Affiliation(s)
- Brian J Prendergast
- Departments of Psychology and Neuroscience, and Biochemistry and Medical Biochemistry and Neurobiotechnology Center, Ohio State University, Columbus, OH 43210, USA.
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