Note: Intro -- Series Preface -- Volume Preface -- Contents -- 1: Photoperiodism and Circannual Timing: Introduction and Historical Perspective -- 1.1 Introduction -- Box 1.1 Why There Are Seasons on Earth -- 1.1.1 Seasonality, Human Evolution and Culture -- 1.1.2 Seasonality in Human Health and Disease -- Box 1.2 Seasonal Variation in Reproduction in Man -- 1.2 Seasonality Is the Norm for Vertebrates -- Box 1.3 Seasonal Cycles in the Siberian Hamster, a Widely Studied Animal Model -- 1.3 Photoperiodism -- 1.3.1 Early Studies (1900-1950) -- Box 1.4 Photorefractoriness as Part of Innate Circannual Rhythmicity -- 1.3.2 Photoperiodism and Circadian Oscillators (1960s) -- 1.3.3 Photoreceptors for PTM (1970s) -- 1.3.4 Melatonin and Melatonin Receptors (1980-1990s) -- 1.3.5 Circadian Clock Gene Expression in the PT (2000-Present) -- 1.4 Circannual Timing -- 1.4.1 Discovery of Circannual Timing (1950-1970s) -- 1.4.2 Interaction with the Circadian System -- 1.4.3 Entrainment of Circannual Rhythms -- 1.4.4 Circannual Chronotypes -- 1.4.5 Circannual Pacemakers 2000-Present -- References -- Further Recommended Reading -- 2: The Pars Tuberalis and Seasonal Timing -- 2.1 Introduction -- 2.2 Photoperiodic and Circannual Species -- 2.3 Melatonin, the Photoperiodic Response and Circannual Rhythms -- 2.4 Anatomy of the Pars Tuberalis -- 2.5 Thyroid Hormone and Seasonal Rhythms -- 2.6 The Pars Tuberalis as the Missing Link Between Photoperiod Input and TH Output -- 2.7 Circadian Circuits Driving the Response to Melatonin in the Pars Tuberalis -- 2.8 Prolactin and Seasonal Rhythms -- 2.9 Evolutionary Conservation in the Photoperiodic Response and Anatomical Structures -- References -- Recommended Further Reading -- 3: Tanycytes and Their Pivotal Role in Seasonal Physiological Adaptations -- 3.1 Introduction -- 3.1.1 Structure of Tanycytes. , 3.1.2 Tanycytes as a Barrier Between the Periphery and Hypothalamus -- 3.2 Tanycytes as a Neural Stem Cell Niche -- 3.3 Animal Models for Studying Seasonal Changes in Tanycyte Function -- 3.4 Thyroid Hormone as the Common Denominator to Seasonal Physiological Responses -- 3.5 Regulation of Thyroid Hormone Availability -- 3.5.1 Deiodinase Enzymes -- 3.5.2 Thyroid Hormone Transporters -- 3.6 Regulated Non-thyroid Hormone Signalling Genes Present in Tanycytes -- 3.6.1 Metabolic Sensing -- 3.6.2 Hypophysiotrophic Hormone Gatekeeping -- 3.6.3 Retinoic Acid Signalling -- 3.7 Tanycytes: A Seasonal Neural Stem Cell Niche -- 3.8 Regulation of Tanycyte Functions in a Natural Environment -- 3.9 Perspectives -- References -- Further Recommended Reading -- 4: Epigenetic Mechanisms in Developmental and Seasonal Programs -- 4.1 Introduction -- 4.2 Epigenetic Enzyme Families and Mode of Action -- 4.3 Epigenetic Modifications and Developmental Programs -- 4.4 Animal Models of Seasonal Rhythms -- 4.5 Epigenetic Modifications and Seasonal Programs -- 4.6 Variations of a Common Theme? Similarities Between Developmental and Seasonal Programs -- 4.7 Summary -- References -- Recommended Further Reading -- 5: Plasticity of Neuroendocrine Mechanisms Regulating Seasonal Reproduction in Sheep -- 5.1 Introduction -- 5.2 Secondary Modulators of Seasonal Reproduction -- 5.2.1 Social Factors -- 5.2.2 Metabolic Status -- Box 1 Sheep as an Integrated Model of Seasonal Processes in Mammals -- 5.3 Seasonal Fluctuations of Blood Brain Barrier Permeability -- 5.3.1 Blood Brain Barrier -- 5.3.2 Access of Peripheral Molecules to the Brain -- 5.3.3 Seasonal Variation in CSF Production -- 5.3.4 Modulation of Tight Junction Composition by Photoperiod -- 5.3.5 Impact of Polychlorinated Biphenyls (PCBs) on BBB Permeability. , 5.4 Plasticity of Neuropeptidergic Systems Involved in the Control of Seasonal Reproduction -- 5.4.1 Kisspeptin Neurons -- 5.4.2 Neurons Involved in Food Intake -- 5.5 Plasticity Mechanisms Involved in Seasonal Reproduction in Sheep -- 5.5.1 Morphological Reorganizations -- 5.5.2 Seasonal Fluctuations of Neurogenesis and Cell Fate -- 5.6 Perspectives -- References -- Recommended Further Reading -- 6: Clocks and Calendars in Birds -- 6.1 Introduction -- 6.2 Light Input Pathways in Birds -- 6.3 Avian Circadian System -- 6.4 The Role of Melatonin -- 6.5 Diversity and Plasticity of Circadian Organization -- 6.6 Circannual Rhythms -- Box 1. Effects of Migration on Experienced Daylength -- 6.7 Photoperiodism and Neuroendocrine Annual Regulators -- Box 2. Evidence of Circadian Involvement in Photoperiodic Timekeeping -- 6.8 Clocks and Calendars in a Changing World -- References -- Further Recommended Reading -- 7: Calendar Timing in Teleost Fish -- 7.1 Introduction -- 7.2 Seasonal Biology in Teleosts -- 7.2.1 Timer-Independent Seasonal Biology -- 7.2.2 Timer-Dependent Seasonal Biology: Anticipation of Seasonal Change -- Text Box 1 The Anadromous Life Cycle of the Atlantic Salmon -- 7.2.3 Timer-Dependent Seasonal Biology: Circannual Rhythms -- 7.2.4 Timer Properties -- 7.3 Photoperiodism in Teleosts -- 7.4 The Teleost Circadian Clock -- 7.5 Seasonal Neuroendocrine Cascade in Teleosts -- 7.6 The Saccus Vasculosus -- 7.7 Conclusions -- References -- Further Recommended Reading -- 8: Action of Light on the Neuroendocrine Axis -- 8.1 Introduction -- 8.2 The Neuroendocrine Axis -- 8.3 The Mammalian Circadian Timing System -- 8.3.1 Light Regulation of Circadian Rhythms: The Photic Phase Response Curve (PRC) -- 8.4 The Retinohypothalamic Tract -- 8.4.1 Photoreceptors of the RHT: Role of Melanopsin -- 8.4.2 Neurotransmitters of the RHT. , 8.5 Impact of Light on Clock Function and Neuroendocrine Regulation: Circadian Regulation and Masking -- 8.6 Effects of Artificial Light at Night (ALAN) on the Neuroendocrine Axis -- 8.7 Perspectives -- References -- Recommended Further Reading -- 9: Seasons, Clocks and Mood -- 9.1 Introduction -- 9.1.1 Intrinsic Clocks -- 9.2 Seasons and Mood -- 9.3 Seasons and Clocks -- 9.4 Clocks and Mood -- 9.5 Conclusion -- References -- Further Recommended Reading -- 10: Photoperiodic Modulation of Clock Gene Expression in the SCN -- 10.1 Introduction -- 10.1.1 Photoperiodic Modulation of Physiological Functions -- 10.1.2 Photoperiodic Regulation of Pineal Function -- 10.2 Suprachiasmatic Nuclei Are the Central Circadian Clock Directly Entrained by External Light/Dark Cycles -- 10.3 Photoperiodic Modulation of Output Rhythmicity within the SCN -- 10.3.1 Photoperiod Controls the SCN Output Rhythms at the Systemic Level -- 10.3.2 Photoperiod Modulates Specific SCN Regions -- 10.3.3 Photoperiodic Modulation of the Photic Sensitivity in the SCN Core Region -- 10.3.4 Photoperiodic Modulation of the Neuronal Activity in the SCN Shell Region -- 10.3.5 Photoperiod Modulates the Cellular Network Properties -- 10.4 Photoperiodic Modulation of the SCN Molecular Clock -- 10.4.1 Molecular Mechanism of the Mammalian Clock -- 10.4.2 Photic Entrainment of the Molecular Clock -- 10.4.3 Photoperiodic Modulation of the Molecular Clock -- 10.4.4 Photoperiod Reprograms the Phases of Cellular Oscillators -- 10.5 Summary and Perspectives -- References -- Further Recommended Reading -- 11: Circadian Timekeeping in the Suprachiasmatic Nucleus: Genes, Neurotransmitters, Neurons, and Astrocytes -- 11.1 Introduction: Clocks and Calendars -- 11.2 Cell-Autonomous Circadian Timekeeping in Mammals: TTFLs. , 11.3 The SCN as the Principal Circadian Clock and the Hierarchical Organization of Timekeeping in Mammals -- Text Box 1: Intrinsically Photoreceptive Retinal Ganglion Cells, Melanopsin, and Circadian Entrainment by Light -- 11.4 The Importance of Neural Circuit-Level Interactions in Circadian Timekeeping by the SCN -- 11.5 Daily and Seasonal Entrainment of the SCN Pacemaker -- 11.6 Neurons, the TTFL, and Circadian Timekeeping in the SCN Circuit -- Text Box 2: Amber Suppression for Translational Switching of Protein Expression -- 11.7 Are there Pacemaker Neurons in the SCN Circuit? -- 11.8 Neurons Are Not the Only Pacemakers in the SCN Circuit: The Contribution of Astrocytes -- 11.9 Astrocytically Released Glutamate Synchronizes Activity of SCN Neurons -- 11.10 Perspectives -- References -- Glossary -- Index.