Campbell and Murphy reported recently that3hof bright light (13,000 lux) exposure to the area behind the knee caused phase shifts of the circadian rhythms of both body temperature and saliva melatonin in humans. The authors tested the hypothesis that extraocular photoreception is also involved in the circadian system of the Syrian hamster. Hamsters were bilaterally enucleated (eyes removed), and their backs were shaved. Hamsters with stable free-running rhythms in constant darkness were exposed to direct sunlight for 1 or 3 hours during their subjective night. Intact (control) animals showed phase shifts as expected, but the locomotor activity of enucleated animals was unaffected by the exposure to sunlight. The authors also measured the pineal melatonin content after exposure to sunlight. Pineal melatonin content in intact animals declined markedly as expected, but no decline was observed in the enucleated hamsters. The authors conclude that extraocular phototransduction is not capable of shifting the phase of the hamster's locomotor activity rhythm or of suppressing pineal melatonin synthesis.
Browman LG (1943) The effect of bilateral optic enucleation upon the activity rhythms of the albino rat. J Comp Psychol36:33-36.
2.
Bruce VG (1960) Environmental entrainment of circadian rhythms. Cold Spring Harbor Symp Quant Biol25:29-48.
3.
Bruss RT , Jocobson R, Halberg F, Zander HA, and Bittner JJ (1958) Effects of lighting regimen and blinding upon gross motor activity of mice. Fed Proc17:21-21.
4.
Campbell SS and Murphy PJ (1998) Extraocular circadian phototransduction in humans. Science279:396-399.
5.
Czeisler CA , Shanahan TL, Klerman EB, Martens H, Brotman DJ, Emens JS, Klein T, and Rizzo JF III (1995). Suppression of melatonin secretion in some blind patients by exposure to bright light. N Engl J Med332:6-11.
6.
Foster RG (1998) Shedding light on the biological clock. Neuron20:829-832.
7.
Freedman MS , Lucas RJ, Soni B, von Schantz M, Muñoz M, David-Gray Z, and Foster R (1999) Regulation of mammalian circadian behavior by Non-rod, non-cone, ocular photoreceptors. Science284:502-504.
8.
Groos GA and van der Kooy D (1981) Functional absence of brain photoreceptors mediating entrainment of circadian rhythms adult rats. Experientia37:71-72.
9.
Halberg F , Visscher MB, and Bittner JJ (1954) Relation of visual factors to eosinophil rhythm in mice. Am J Physiol179:515-523.
10.
Hunt JM and Schlosberg H (1939) The influence of illumination upon general activity in normal, blinded, and castrated male white rats. J Comp Psychol28:285-298.
11.
Lockley SW , Skene DJ, Thapan K, English J, Ribeiro D, Haimov I, Hampton S, Middleton B, von Schantz M, and Arendt J (1998) Extraocular light exposure does not suppress plasma melatonin in humans. J Clinical Endocrinology & Metabolism83:3369-3372.
12.
Maywood ES , Hastings MH, Max M, Ampleford E, Menaker M, and Loudon ASI (1993) Circadian and daily rhythms of melatonin in the blood and pineal gland of freerunning and entrained Syrian hamsters. J Endocrinol136:65-73.
13.
Menaker M (1968) Extraretinal light perception in the sparrow: I. Entrainment of the biological clock. Proc Natl Acad Sci USA59:414-421.
14.
Miyamoto Y and Sancar A (1998) Vitamin B2-based blue-light photoreceptors in the retinohypothalamic tract as the photoactive pegments for setting the circadian clock in mammals. Proc Natl Acad Sci USA95:6097-6102.
15.
Mrosovsky N (1996) Locomotor activity and non-photic influences on circadian clocks. Biol Rev71:343-372.
16.
Navaneethakannan K and Kumarasamy P (1986) Absence of extraretinal photic entrainment in a diurnal squirrel (Funambulus palmarum) and a nocturnal mouse (Mus boduga). Indian J Exp Biol24:730-731.
17.
Nelson RJ and Zucker I (1981) Absence of extraocular photoreception in diurnal and nocturnal rodents exposed to direct sunlight. Comp Biochem Physiol69A:145-148.
18.
Oren DA (1996) Humoral phototransduction: Blood is a messenger. The Neuroscientist2:207-210.
19.
Page TL (1982) Extraretinal photoreception in entrainment and photoperiodism in invertebrates. Experientia38:1007-1013.
20.
Provencio I and Foster RG (1995) Circadian rhythms in mice can be regulated by photoreceptors with cone-like characteristics. Brain Res694:183-190.
21.
Richter CP (1968) Inherent twenty-four hour and lunar clocks of a primate—the squirrel monkey. Communications Behav Biol1:305-332.
22.
Roenneberg T and Foster RG (1997) Twilight times: Light and the circadian system. Photochem Photobiol66:549-561.
23.
Snyder SH , Zweig M, Axelrod J, and Fisher JE (1965) Control of the circadian rhythm in serotonin content of the rat pineal gland. Proc Nat Acad Sci USA53:301-305.
24.
Takahashi JS , DeCoursey PJ, Bauman L, and Menaker M (1984) Spectral sensitivity of a novel photoreceptive system mediating entrainment of mammalian circadian rhythms. Nature308:186-188.
25.
Thresher RJ , Vitaterna MH, Miyamoto Y, Kazantsev A, Hsu DS, Petit C, Selby CP, Dawut L, Smithies O, Takahashi JS, and Sancar A (1998) Role of mouse cryptochrome blue-light photoreceptor in circadian photoresponses. Science282:1490-1494.
26.
Underwood H and Groos G (1982) Vertebrate circadian rhythms: Retinal and extraretinal photoreception. Experimentia38:1013-1021.
27.
van der Horst GTJ , Muijtjens M, Kobayashi K, Takano R, Kanno S-I, Takao M, de Wit J, Verkerk A, Eker APM, van Leenen D, Buijs R, Bootsma D, Hoeijmakers JHJ, Yaui A (1999) Mammalian cry1 and cry2 are essential for maintenance of circadian rhythms. Nature398:627-630.
