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Effects of light and melatonin treatment on body temperature and melatonin secretion daily rhythms in a diurnal rodent, the fat sand rat.

Abstract

Many mammals display predictable daily rhythmicity in both neuroendocrine function and behavior. The basic rest-activity cycles are usually consistent for a given species and vary from night-active (nocturnal), those mostly active at dawn and dusk (i.e., crepuscular), and to day-active (diurnal) species. A number of daily rhythms are oppositely phased with respect to the light/dark (LD) cycle in diurnal compared with nocturnal mammals, whereas others are equally phased with respect to the LD cycle, regardless of diurnality/nocturnality. Pineal produced melatonin (MLT) perfectly matches this phase-locked feature in that its production and secretion always occurs during the night in both diurnal and nocturnal mammals. As most rodents studied to date in the field of chronobiology are nocturnal, the aim in this study was to evaluate the effect of light manipulations and different photoperiods on a diurnal rodent, the fat sand rat, Psammomys obesus. The authors studied its daily rhythms of body temperature (T(b)) and 6-sulphatoxymelatonin (6-SMT) under various photoperiodic regimes and light manipulations (acute and chronic exposures) while maintaining a constant ambient temperature of 30 degrees C +/- 1 degrees C. The following protocols were used: (A) Control (CON) conditions 12L:12D; (A1) exposure to one light interference (LI) of CON-acclimated individuals for 30 min, 5 h after lights-off; (A2) short photoperiod (SP) acclimation (8L:16D) for 3 wks; (A3) 3 wks of SP acclimation with chronic LI of 15 min, three times a night at 4-h intervals; (A4) chronic exposure to constant dim blue light (470 nm, 30 lux) for 24 h for 3 wks (LL). (B) The response to exogenous MLT administration, provided in drinking water, was measured under the following protocols: (B1) After chronic exposure to SP with LI, MLT was provided once, starting 1 h before the end of photophase; (B2) after a continuous exposure to dim blue light, MLT was provided at 15:00 h for 2 h for 2 wks; (B3) to CON animals, MLT was given intraperitoneally (i.p.) at 14:00 h. The results demonstrate that under CON acclimation, Psammomys obesus has robust T(b) and 6-SMT daily rhythms in which the acrophase (peak time) of T(b) is during the photophase, whereas that of 6-SMT is during scotophase. LI resulted in an elevation of T(b) and a reduction of 6-SMT levels. A significant difference in the response was noted between acute and chronic exposure to LI, particularly in 6-SMT levels, which were lower than CON after LI and higher after chronic LI, implying an acclimation process. Constant exposure to blue light abolished T(b) and 6-SMT rhythms in all the animals. MLT administration resumed the T(b) daily rhythm in these animals, and had a recovery effect on the chronic LI-exposed animals, resulting in a T(b) decrease. Altogether, the authors show in this study the different modifications of T(b) rhythms and MLT levels in response to environmental light manipulations. These series of experiments may serve as a basis for establishing P. obesus as an animal model for further studies in chronobiology.

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  • Authors+Show Affiliations

    ,

    Department of Biology, University of Haifa, Mt. Carmel, Haifa, Israel 31905. hagitsc@research.haifa.ac.il

    ,

    Source

    Chronobiology international 27:7 2010 Aug pg 1401-19

    MeSH

    Animals
    Biological Clocks
    Body Temperature
    Circadian Rhythm
    Gerbillinae
    Humans
    Light
    Male
    Melatonin
    Photoperiod

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    20795883

    Citation

    Schwimmer, Hagit, et al. "Effects of Light and Melatonin Treatment On Body Temperature and Melatonin Secretion Daily Rhythms in a Diurnal Rodent, the Fat Sand Rat." Chronobiology International, vol. 27, no. 7, 2010, pp. 1401-19.
    Schwimmer H, Mursu N, Haim A. Effects of light and melatonin treatment on body temperature and melatonin secretion daily rhythms in a diurnal rodent, the fat sand rat. Chronobiol Int. 2010;27(7):1401-19.
    Schwimmer, H., Mursu, N., & Haim, A. (2010). Effects of light and melatonin treatment on body temperature and melatonin secretion daily rhythms in a diurnal rodent, the fat sand rat. Chronobiology International, 27(7), pp. 1401-19. doi:10.3109/07420528.2010.505355.
    Schwimmer H, Mursu N, Haim A. Effects of Light and Melatonin Treatment On Body Temperature and Melatonin Secretion Daily Rhythms in a Diurnal Rodent, the Fat Sand Rat. Chronobiol Int. 2010;27(7):1401-19. PubMed PMID: 20795883.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Effects of light and melatonin treatment on body temperature and melatonin secretion daily rhythms in a diurnal rodent, the fat sand rat. AU - Schwimmer,Hagit, AU - Mursu,Netta, AU - Haim,Abraham, PY - 2010/8/28/entrez PY - 2010/8/28/pubmed PY - 2010/12/17/medline SP - 1401 EP - 19 JF - Chronobiology international JO - Chronobiol. Int. VL - 27 IS - 7 N2 - Many mammals display predictable daily rhythmicity in both neuroendocrine function and behavior. The basic rest-activity cycles are usually consistent for a given species and vary from night-active (nocturnal), those mostly active at dawn and dusk (i.e., crepuscular), and to day-active (diurnal) species. A number of daily rhythms are oppositely phased with respect to the light/dark (LD) cycle in diurnal compared with nocturnal mammals, whereas others are equally phased with respect to the LD cycle, regardless of diurnality/nocturnality. Pineal produced melatonin (MLT) perfectly matches this phase-locked feature in that its production and secretion always occurs during the night in both diurnal and nocturnal mammals. As most rodents studied to date in the field of chronobiology are nocturnal, the aim in this study was to evaluate the effect of light manipulations and different photoperiods on a diurnal rodent, the fat sand rat, Psammomys obesus. The authors studied its daily rhythms of body temperature (T(b)) and 6-sulphatoxymelatonin (6-SMT) under various photoperiodic regimes and light manipulations (acute and chronic exposures) while maintaining a constant ambient temperature of 30 degrees C +/- 1 degrees C. The following protocols were used: (A) Control (CON) conditions 12L:12D; (A1) exposure to one light interference (LI) of CON-acclimated individuals for 30 min, 5 h after lights-off; (A2) short photoperiod (SP) acclimation (8L:16D) for 3 wks; (A3) 3 wks of SP acclimation with chronic LI of 15 min, three times a night at 4-h intervals; (A4) chronic exposure to constant dim blue light (470 nm, 30 lux) for 24 h for 3 wks (LL). (B) The response to exogenous MLT administration, provided in drinking water, was measured under the following protocols: (B1) After chronic exposure to SP with LI, MLT was provided once, starting 1 h before the end of photophase; (B2) after a continuous exposure to dim blue light, MLT was provided at 15:00 h for 2 h for 2 wks; (B3) to CON animals, MLT was given intraperitoneally (i.p.) at 14:00 h. The results demonstrate that under CON acclimation, Psammomys obesus has robust T(b) and 6-SMT daily rhythms in which the acrophase (peak time) of T(b) is during the photophase, whereas that of 6-SMT is during scotophase. LI resulted in an elevation of T(b) and a reduction of 6-SMT levels. A significant difference in the response was noted between acute and chronic exposure to LI, particularly in 6-SMT levels, which were lower than CON after LI and higher after chronic LI, implying an acclimation process. Constant exposure to blue light abolished T(b) and 6-SMT rhythms in all the animals. MLT administration resumed the T(b) daily rhythm in these animals, and had a recovery effect on the chronic LI-exposed animals, resulting in a T(b) decrease. Altogether, the authors show in this study the different modifications of T(b) rhythms and MLT levels in response to environmental light manipulations. These series of experiments may serve as a basis for establishing P. obesus as an animal model for further studies in chronobiology. SN - 1525-6073 UR - https://www.unboundmedicine.com/medline/citation/20795883/Effects_of_light_and_melatonin_treatment_on_body_temperature_and_melatonin_secretion_daily_rhythms_in_a_diurnal_rodent_the_fat_sand_rat_ L2 - http://www.tandfonline.com/doi/full/10.3109/07420528.2010.505355 DB - PRIME DP - Unbound Medicine ER -