Seasonal changes in plasma testosterone, thyroxine, and cortisol levels in wild rabbits (Oryctolagus cuniculus algirus) of Zembra island

Saad, Moncef Ben; Baylé, J.D.

doi:10.1016/0016-6480(85)90218-7

Cited by 14 publications

(7 citation statements)

References 9 publications

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“…This results in uncoupled oxidative phosphorylation and finally non-shivering thermogenesis (202–204, 210, 211). It is therefore not surprising that mammals, typical examples for homeotherm animals (endotherm thermoregulators), usually exhibit elevated serum concentrations of T4 and T3 in winter and during hypothermia as long as they are sufficiently fed (212, 213). Increased concentrations of TSH and/or thyroid hormones in cold seasons and during hypothermia have also been described in humans (214–217).…”

Section: Thyroid Allostasis In Various Physiological and Pathologicalmentioning

confidence: 99%

Thyroid Allostasis–Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming

Hoermann²,

et al. 2017

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The hypothalamus–pituitary–thyroid feedback control is a dynamic, adaptive system. In situations of illness and deprivation of energy representing type 1 allostasis, the stress response operates to alter both its set point and peripheral transfer parameters. In contrast, type 2 allostatic load, typically effective in psychosocial stress, pregnancy, metabolic syndrome, and adaptation to cold, produces a nearly opposite phenotype of predictive plasticity. The non-thyroidal illness syndrome (NTIS) or thyroid allostasis in critical illness, tumors, uremia, and starvation (TACITUS), commonly observed in hospitalized patients, displays a historically well-studied pattern of allostatic thyroid response. This is characterized by decreased total and free thyroid hormone concentrations and varying levels of thyroid-stimulating hormone (TSH) ranging from decreased (in severe cases) to normal or even elevated (mainly in the recovery phase) TSH concentrations. An acute versus chronic stage (wasting syndrome) of TACITUS can be discerned. The two types differ in molecular mechanisms and prognosis. The acute adaptation of thyroid hormone metabolism to critical illness may prove beneficial to the organism, whereas the far more complex molecular alterations associated with chronic illness frequently lead to allostatic overload. The latter is associated with poor outcome, independently of the underlying disease. Adaptive responses of thyroid homeostasis extend to alterations in thyroid hormone concentrations during fetal life, periods of weight gain or loss, thermoregulation, physical exercise, and psychiatric diseases. The various forms of thyroid allostasis pose serious problems in differential diagnosis of thyroid disease. This review article provides an overview of physiological mechanisms as well as major diagnostic and therapeutic implications of thyroid allostasis under a variety of developmental and straining conditions.

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Section: Thyroid Allostasis In Various Physiological and Pathologicalmentioning

confidence: 99%

Thyroid Allostasis–Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming

Hoermann²,

et al. 2017

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“…reproduction, metabolism and migration) in a seasonal manner (Farner, 1985;Gwinner, 2003). For instance, circannual reproductive rhythm has been documented for sheep (Karsch et al, 1989), cattle (Philo and Reiter, 1980), European rabbit (Ben Saad and Baylé, 1985) and pig (Love et al, 1993). The annual reproductive rhythm is linked to the circannual oscillation of reproductive hormones, such as gonadotrophin, prolactin, luteinizing hormone, pineal serotonin (5-HT) and testosterone.…”

Section: Research Articlementioning

confidence: 99%

Seasonal oscillation of liver-derived hibernation protein complex in the central nervous system of non-hibernating mammals

Seldin

Byerly

Petersen

et al. 2014

Journal of Experimental Biology

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Mammalian hibernation elicits profound changes in whole-body physiology. The liver-derived hibernation protein (HP) complex, consisting of HP-20, HP-25 and HP-27, was shown to oscillate circannually, and this oscillation in the central nervous system (CNS) was suggested to play a role in hibernation. The HP complex has been found in hibernating chipmunks but not in related nonhibernating tree squirrels, leading to the suggestion that hibernationspecific genes may underlie the origin of hibernation. Here, we show that non-hibernating mammals express and regulate the conserved homologous HP complex in a seasonal manner, independent of hibernation. Comparative analyses of cow and chipmunk HPs revealed extensive biochemical and structural conservations. These include liver-specific expression, assembly of distinct heteromeric complexes that circulate in the blood and cerebrospinal fluid, and the striking seasonal oscillation of the HP levels in the blood and CNS. Central administration of recombinant HPs affected food intake in mice, without altering body temperature, physical activity levels or energy expenditure. Our results demonstrate that HP complex is not unique to the hibernators and suggest that the HP-regulated liver-brain circuit may couple seasonal changes in the environment to alterations in physiology.

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“…Seasonal changes in sexually dimorphic skeletal muscle mass, in association with sharp increases in testosterone levels, have been well-documented in seasonal mammals (Asher and Peterson, 1991;Ben Saad and Bayle, 1985;Field et al, 1985;Forger and Breedlove, 1987;Lincoln, 1971), including primates . Seasonal testosterone rises are also associated with decreased caloric intake due to increased mating effort, although males will increase energy intake in association with seasonal rises in testosterone if calorically supplemented (McMillin et al, 1980).…”

Section: Testosterone and Somatic Energy Allocationmentioning

confidence: 99%

Reproductive ecology and life history of the human male

Bribiescas

2001

Am. J. Phys. Anthropol.

210

117

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Until recently, the reproductive ecology of human males has not been extensively investigated, primarily as a result of the need for a theoretical framework based on the reproductive constraints and energetics of mammalian males. More specifically, male reproductive ecology has necessitated an integrative interpretation of clinical and anthropological data based on the premise that the evolution of human male life histories has involved selection for physiological mechanisms aimed at optimizing trade-offs between survivorship and reproductive effort. This paper attempts to address this gap in our understanding by presenting the current state of male reproductive ecology, including physiologic data from clinical and anthropological investigations as well as recent theoretical developments. Recent investigations outlining population variation in reproductive endocrine function are discussed within the context of potential sources of variation, including energetic expediture, caloric intake, and developmental canalization during adolescence. Additional summaries of male senescence and behavior are presented to provide a complete overview of male life history. Implications of recent anthropological data on contemporary health issues such as prostate cancer and the development of a male contraceptive are also discussed. Finally, several theories are presented that may contribute to our understanding of the evolution of male life histories and reproductive ecology, including theoretical suggestions involving the role of competition, mate choosiness, and potential constraints on male insemination ability, as well as a theory suggesting that male reproductive ecology may be best understood by analyzing energetic allocation decisions between differing somatic tissues that may be indicative of the competing needs for optimizing survivorship and reproductive effort. Directions for future research are finally considered.

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Seasonal changes in plasma testosterone, thyroxine, and cortisol levels in wild rabbits (Oryctolagus cuniculus algirus) of Zembra island

Cited by 14 publications

References 9 publications

Thyroid Allostasis–Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming

Thyroid Allostasis–Adaptive Responses of Thyrotropic Feedback Control to Conditions of Strain, Stress, and Developmental Programming

Seasonal oscillation of liver-derived hibernation protein complex in the central nervous system of non-hibernating mammals

Reproductive ecology and life history of the human male

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