Response of Reptilian Gonad to Melatonin

Haldar-Misra, C.; Thapliyal, J. P.

doi:10.1159/000123256

“…For example, antigonadotropic effects of MEL occur in various species, including the Indian garden lizard (Calotes versicolor), A. carolinensis, the green treefrog (Hyla cinerea), and a teleost (Fundulus similis) (de Vlaming et al 1974;Haldar and Thapliyal 1977;Thapliyal and Misra nee Haldar 1979;Haldar-Misra and Thapliyal 1981;Underwood 1981;reviewed in Mayer et al 1997). These antigonadal effects, in combination with MEL's seasonal rhythm of secretion, are thought to modulate and synchronize reproductive behavior with environmental cues (Underwood 1981(Underwood , 1985aRismiller and Heldmaier 1987;Crews et al 1988;Mendonça et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Melatonin and thermoregulation in ectothermic vertebrates: a review

Lutterschmidt¹,

Lutterschmidt²,

Hutchison³

2003

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Precise behavioral thermoregulation is well documented in many ectothermic vertebrates. However, many complexities involving the influence of the pineal gland and melatonin (MEL) on thermoregulatory behavior, and thus body temperature (T b ), remain unresolved. Although MEL is commonly considered to decrease T b in both endotherms and ectotherms, several ectothermic species do not modulate T b in response to MEL. Furthermore, it is not yet clear how MEL integrates thermoregulatory behavior with environmental stimuli or how it modulates T b . Some inferences about MEL action in endotherms are not applicable to ectotherms. Changes in ectothermic T b are mediated primarily through behavioral modulation (not physiological modulation as in endotherms). Thus, the most likely mechanism underlying MEL's actions on ectothermic T b is adjustment of the temperature set point in the hypothalamus. We provide a review of the literature addressing the effects of MEL on thermoregulatory behavior in ectothermic vertebrates. We also discuss mechanisms underlying MEL's influence on physiological and behavioral processes in ectotherms and hypotheses regarding interspecific differences in pineal complex and MEL function.Résumé : La thermorégulation comportementale chez les vertébrés ectothermes est un phénomène bien connu. Cependant, des relations complexes concernant l'influence de la glande pinéale et de la mélatonine (MEL) sur le comportement thermorégulateur et, par conséquent, sur la température du corps (T b ), restent à préciser. Bien que MEL soit souvent considérée comme facteur de chute de la température T b , aussi bien chez les endothermes que chez les ectothermes, plusieurs espèces ectothermes ne modifient pas leur température T b en réaction à MEL. De plus, il reste encore à établir comment la mélatonine intègre le comportement thermorégulateur et les stimulus environnementaux et comment elle cause des modulations de la température T b . Certaines conclusions au sujet de l'action de MEL chez les endothermes ne se vérifient pas chez les ectothermes. Les modulations de la température T b chez les ectothernes sont comportementales (pas physiologiques comme chez les endothermes). Le mécanisme qui est le plus susceptible de contrôler l'action de MEL sur la température T b ectothermique consiste donc en un ajustement du réglage de la tempéra-ture dans l'hypothalamus. Nous proposons ici une revue de la littérature sur les effets de MEL sur le comportement themorégulateur des vertébrés ectothermes. Nous examinons les mécanismes qui peuvent être sous-jacents à l'influence qu'exerce MEL sur les processus physiologiques et comportementaux des vertébrés ectothermes et nous discutons des hypothèses expliquant les différences interspécifiques dans le fonctionnement de la glande pinéale et de MEL.[Traduit par la Rédaction] 13 Lutterschmidt et al.

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Daily and Seasonal Rhythms

Underwood

¹

,

Wassmer

²

,

Page

³

1997

Comprehensive Physiology

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The sections in this article are: Daily Rhythms Models and Mechanisms Circadian Pacemaking Systems in Invertebrates Pacemakers in the Arthropod Brain Circadian Pacemakers Outside the Nervous System in Insects Pacemakers in the Gastropod Retina Multioscillator Organization Identification of Output Pathways Circadian Pacemaking Systems in Vertebrates The Mammalian SCN Other Circadian Oscillators in Mammals Hypothalamic Regulation of Circadian Function in Nonmammalian Vertebrates The Pineal Organ Eyes as Clocks Photoreceptor Localization and Mechanisms of Entrainment in Invertebrates Photoreceptive Input: Invertebrates Mechanisms of Regulation of Pacemaker Phase Photoreceptor Localization and Mechanisms of Entrainment in Vertebrates Identification of Photoreceptors Mechanisms of Regulation of Pacemaker Phase Seasonality in Invertebrates Modes of Seasonality Timing of Seasonal Cycles Photoperiodic Time Measurement Mechanisms of Photoperiodic Time Measurement The Photoperiodic Timer The Photoperiodic Counter Anatomical Location of Timers and Counters Photoreceptors Circannual Rhythms Seasonality in Vertebrates Photoperiodic Time Measurement: Models and Experimental Validation Physiological Mechanisms The Pineal and Melatonin: Mammals Mechanisms of Pineal Action The Pineal and Melatonin: Nonmammalian Vertebrates Photoreceptive Inputs: Mammalian Photoreceptive Inputs: Nonmammalian Maternal–Fetal Transfer of Photoperiodic Information Circannual Rhythms Physiological Mechanisms Concluding Comments

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Effects of the pineal gland and melatonin on the metabolism of oocytes in vitro and on ovulation in Bufo arenarum

Atenor

¹

,

Romero

²

,

Brauckmann

³

et al. 1994

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The pineal gland and the hormone melatonin appear to be responsible to some extent for the metabolic behaviour of Bufo arenarum oocytes during the winter. This assumption is supported by the observation that, in isolated mitochondria, both elements stimulate the rate of oxidation of citrate and inhibit that of fumarate, thus raising the oxidizing ratio that relates these parameters (C/F) to values close to or above 1, which is characteristic of these animals in winter. The sensitivity of oocytes to melatonin, in terms of the C/F ratio, varies throughout the year. It is maximal in fall and early winter at a dose of 1.8 micrograms/ml after 30 min treatment, minimal or nonexistent in late winter, and it increases gradually during the spring and summer. The response of oocytes to melatonin is more significant if the animals have been previously injected with a homogenate of homologous hypophysis. A direct metabolic effect of melatonin on oocytes was observed when coelomic oocytes, without follicle cells, responded to hormonal treatment. Both an extract of pineal gland and melatonin inhibit in vitro ovulation, the inhibitory effect of the extract being greater than that of the hormone.

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Response of Reptilian Gonad to Melatonin

Cited by 14 publications

References 9 publications

Melatonin and thermoregulation in ectothermic vertebrates: a review

Melatonin and thermoregulation in ectothermic vertebrates: a review

Daily and Seasonal Rhythms

Effects of the pineal gland and melatonin on the metabolism of oocytes in vitro and on ovulation in Bufo arenarum

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