Circadian rhythm of ERG in Iguana iguana: role of the pineal

In green iguanas, the pineal controls the circadian rhythm of body temperature but not the rhythm of locomotor activity. As part of a program to investigate the characteristics of this multioscillator circadian system, the authors studied the circadian rhythms of the electroretinographic response (E...

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Bibliographic Details
Published inJournal of biological rhythms Vol. 15; no. 2; p. 163
Main Authors Miranda-Anaya, M, Bartell, P A, Yamazaki, S, Menaker, M
Format Journal Article
LanguageEnglish
Published United States 01.04.2000
Subjects
Animals
Circadian Rhythm - physiology
Darkness
Electroretinography
Iguanas - physiology
Photoperiod
Pineal Gland - physiology
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Summary:In green iguanas, the pineal controls the circadian rhythm of body temperature but not the rhythm of locomotor activity. As part of a program to investigate the characteristics of this multioscillator circadian system, the authors studied the circadian rhythms of the electroretinographic response (ERG) and asked whether the pineal gland is necessary for the expression of this rhythm. ERGs from a total of 24 anesthetized juvenile iguanas were recorded under four different conditions: (a) complete darkness (DD), (b) dim light-dark cycles (dLD), (c) constant dim light (dLL), and (d) pinealectomized in DD. Results demonstrate that the b-wave component of the ERG shows a very clear circadian rhythm in DD and that this rhythm persists in dLL and entrains to dLD cycles. The ERG response is maximally sensitive during the subjective day. Pinealectomy does not abolish the circadian rhythm in ERG, demonstrating that the oscillator responsible for the ERG rhythm is located elsewhere.
ISSN:0748-7304
DOI:10.1177/074873040001500210