This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lucas, R. J. Articles by Loudon, A. S. I. Search for Related Content PubMed PubMed Citation Articles by Lucas, R. J. Articles by Loudon, A. S. I. Pubmed/NCBI databases Compound via MeSH Substance via MeSH Hazardous Substances DB HYDROCORTISONE

Free Running Circadian Rhythms of Melatonin, Luteinizing Hormone, and Cortisol in Syrian Hamsters Bearing the Circadian tau Mutation¹

Department of Biology, Imperial College of Science Technology and Medicine (R.J.L.), London, United Kingdom SW7 2AZ; School of Biological Sciences, University of Manchester (J.A.S., A.S.I.L.), Manchester, United Kingdom M13 9PT; and the Department of Biology, National Science Foundation Center for Biological Timing, University of Virginia (J.M.D., M.M.), Charlottesville, Virginia 22903

Address all correspondence and requests for reprints to: Dr. Andrew Loudon, School of Biological Sciences, Stopford Building, University of Manchester, Manchester, United Kingdom M13 9PT. E-mail: andrew.loudon{at}man.ac.uk

The tau mutation of Syrian hamsters induces a robust reduction in the period of circadian activity rhythms, from 24 h (wild-type; tau⁺⁺) to 22 h (heterozygote; tau^S+) and 20 h (homozygous mutant, tau^SS). Here, we examine the effect of this mutation on circadian rhythms of LH, melatonin, and cortisol in ovariectomized hamsters. Free running circadian rhythms were observed in all three hormones. In each genotype, endocrine rhythms were synchronized with concurrently assessed activity rhythms, suggesting a shared period around 20 h in tau^SS, 22 h in tau^S+, and 24 h in tau⁺⁺. Phasing with respect to the activity rhythm was generally similar in tau⁺⁺ and mutant genotypes. However, melatonin concentrations rose significantly earlier in tau^SS than in tau⁺⁺ animals. Explanted pineals from both genotypes exhibited a similar time course of response to norepinephrine administration, suggesting that the phase advance of melatonin production observed in tau^SS in vivo is not a direct effect of the tau mutation within the pinealocyte. The demonstration of reduced period endocrine rhythms in the mutant genotypes extends previous behavioral studies and, together with recent work on rhythmicity in the isolated retina, suggests an ubiquitous influence of the tau mutation on the processes of circadian rhythm generation in this species.

This article has been cited by other articles:

				E. S. Maywood, J. S. O'Neill, J. E. Chesham, and M. H. Hastings Minireview: The Circadian Clockwork of the Suprachiasmatic Nuclei Analysis of a Cellular Oscillator that Drives Endocrine Rhythms Endocrinology, December 1, 2007; 148(12): 5624 - 5634. [Abstract] [Full Text] [PDF]

				M. Hastings, J. S O'Neill, and E. S Maywood Circadian clocks: regulators of endocrine and metabolic rhythms J. Endocrinol., November 1, 2007; 195(2): 187 - 198. [Abstract] [Full Text] [PDF]

				A.S.I. Loudon, Q.J. Meng, E.S. Maywood, D.A. Bechtold, R.P. Boot-Handford, and M.H. Hastings The Biology of the Circadian Ck1{epsilon} tau Mutation in Mice and Syrian Hamsters: A Tale of Two Species Cold Spring Harb Symp Quant Biol, January 1, 2007; 72(0): 261 - 271. [Abstract] [PDF]

				M. J Boden and D. J Kennaway Circadian rhythms and reproduction. Reproduction, September 1, 2006; 132(3): 379 - 392. [Abstract] [Full Text] [PDF]

				H. O. de la Iglesia and W. J. Schwartz Minireview: Timely Ovulation: Circadian Regulation of the Female Hypothalamo-Pituitary-Gonadal Axis Endocrinology, March 1, 2006; 147(3): 1148 - 1153. [Abstract] [Full Text] [PDF]

				C. A. Christian, J. L. Mobley, and S. M. Moenter Diurnal and estradiol-dependent changes in gonadotropin-releasing hormone neuron firing activity PNAS, October 25, 2005; 102(43): 15682 - 15687. [Abstract] [Full Text] [PDF]

				J. Dey, A.-J. F. Carr, F. R. A. Cagampang, A. S. Semikhodskii, A. S. I. Loudon, M. H. Hastings, and E. S. Maywood The tau Mutation in the Syrian Hamster Differentially Reprograms the Circadian Clock in the SCN and Peripheral Tissues J Biol Rhythms, April 1, 2005; 20(2): 99 - 110. [Abstract] [PDF]

				S. Panda and J. B. Hogenesch It's All in the Timing: Many Clocks, Many Outputs J Biol Rhythms, October 1, 2004; 19(5): 374 - 387. [Abstract] [PDF]

				H. O. de la Iglesia, J. Meyer, and W. J. Schwartz Lateralization of Circadian Pacemaker Output: Activation of Left- and Right-Sided Luteinizing Hormone-Releasing Hormone Neurons Involves a Neural Rather Than a Humoral Pathway J. Neurosci., August 13, 2003; 23(19): 7412 - 7414. [Abstract] [Full Text] [PDF]

				W. J. Schwartz, H. O. de la Iglesia, P. Zlomanczuk, and H. Illnerova Encoding Le Quattro Stagioni within the Mammalian Brain: Photoperiodic Orchestration through the Suprachiasmatic Nucleus J Biol Rhythms, August 1, 2001; 16(4): 302 - 311. [Abstract] [PDF]

				N. Cermakian, D. Whitmore, N. S. Foulkes, and P. Sassone-Corsi Asynchronous oscillations of two zebrafish CLOCK partners reveal differential clock control and function PNAS, April 11, 2000; 97(8): 4339 - 4344. [Abstract] [Full Text] [PDF]