The pineal organ of teleost fishes

The pineal organ of teleost fishes The pineal organ of teleost fish is a directly photosensory organ that contains photoreceptor cells similar to those of the retina. It conveys photoperiod information to the brain via neural pathways and by release of indoleamines, primarily melatonin, into the circulation. The photoreceptor cells respond to changes in ambient illumination with a gradual modulation of neurotransmission to second-order neurons that innervate various brain centres, and by modulation of indoleamine synthesis. Melatonin is produced rhythmically, and melatonin synthesis may be regulated either directly by ambient photoperiod, or by an endogenous circadian oscillator that is entrained by the photoperiod. During natural conditions, melatonin is produced at highest levels during the night. Although the pineal organ undoubtedly influences a variety of physiological parameters, as assessed by experimental removal of the pineal organ and/or administration of exogenous indoleamines, its role in any physiological situation is not clear cut. The effects of any interference with pineal functions appear to vary with the time of year and experimental photothermal regimes. There are strong indications that the pineal organ is one component in a central neural system that constitutes the photoperiod-responding system of the animal, i.e. the system that is responsible for correct timing of daily and seasonal physiological rhythms. It is important to envisage the pineal organ as a part of this system; it interacts with other photosensory structures (the retina, possibly extraretinal non-pineal photoreceptors) and circadian rhythm generators http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Reviews in Fish Biology and Fisheries Springer Journals

The pineal organ of teleost fishes

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Publisher
Kluwer Academic Publishers
Copyright
Copyright © 1997 by Chapman and Hall
Subject
Life Sciences; Freshwater & Marine Ecology; Zoology
ISSN
0960-3166
eISSN
1573-5184
D.O.I.
10.1023/A:1018483627058
Publisher site
See Article on Publisher Site

Abstract

The pineal organ of teleost fish is a directly photosensory organ that contains photoreceptor cells similar to those of the retina. It conveys photoperiod information to the brain via neural pathways and by release of indoleamines, primarily melatonin, into the circulation. The photoreceptor cells respond to changes in ambient illumination with a gradual modulation of neurotransmission to second-order neurons that innervate various brain centres, and by modulation of indoleamine synthesis. Melatonin is produced rhythmically, and melatonin synthesis may be regulated either directly by ambient photoperiod, or by an endogenous circadian oscillator that is entrained by the photoperiod. During natural conditions, melatonin is produced at highest levels during the night. Although the pineal organ undoubtedly influences a variety of physiological parameters, as assessed by experimental removal of the pineal organ and/or administration of exogenous indoleamines, its role in any physiological situation is not clear cut. The effects of any interference with pineal functions appear to vary with the time of year and experimental photothermal regimes. There are strong indications that the pineal organ is one component in a central neural system that constitutes the photoperiod-responding system of the animal, i.e. the system that is responsible for correct timing of daily and seasonal physiological rhythms. It is important to envisage the pineal organ as a part of this system; it interacts with other photosensory structures (the retina, possibly extraretinal non-pineal photoreceptors) and circadian rhythm generators

Journal

Reviews in Fish Biology and FisheriesSpringer Journals

Published: Oct 22, 2004

References

  • Effect of pinealectomy on the histology of the adrenocortical homologue and plasma cortisol level in the Indian catfish, Heteropneustes fossilis (Bloch.)
    Agha, A.K.; Joy, K.P.
  • Effects of skeleton photoperiods on melatonin secretion in the rainbow trout, Oncorhynchus mykiss (Walbaum)
    Alvariño, J.M.R.; Randall, C.F.; Bromage, N.R.

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