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Gonadal responses of the male Syrian hamster to programmed infusions of melatonin are sensitive to signal duration and frequency but not to signal phase nor to lesions of the suprachiasmatic nuclei


, : Gonadal responses of the male Syrian hamster to programmed infusions of melatonin are sensitive to signal duration and frequency but not to signal phase nor to lesions of the suprachiasmatic nuclei. Biology of Reproduction 43(2): 174-182

This study investigated the roles of the melatonin signal and the circadian system in the induction of photoperiodic responses in the male Syrian hamster. Pinealectomized animals received programmed s.c. infusions of saline or melatonin. Saline infusions for 10 h or melatonin for 4 h during the night had no effect on the reproductive axis whereas nightly 10-h infusions of melatonin induced gonadal atrophy. Animals that received 10-h infusions of melatonin arranged such that consecutive daily signals were delivered alternately during the day and night also exhibited gonadal atrophy, whereas melatonin signals delivered every 48 h, exclusively during either the day or night, were without effect. These results demonstrate that the brain is able to read melatonin signals delivered at different phases of the circadian cycle and to use them in combination to generate an appropriate photoperiod response. Melatonin signals lasting 10 h delivered to pinealectomized (PX) animals every 24 h induced gonadal regression. Melatonin delivered at periodicities of 20 h, 23 h, and 25 h also caused gonadal regression infusions every 28 h were without effect, demonstrating that the systems responsive to melatonin are sensitive to signal frequency but do not need to receive the signal on a strictly circadian basis. These results are discussed in the context of the significance of the melatonin-free interval. PX animals that received sham or bilateral lesions of the suprachiasmatic nuclei (SCN) were infused nightly for 10 h with saline or melatonin. Melatonin infusions were equally effective at inducing gonadal atrophy and lowering serum testosterone levels in both sham- and SCN-lesioned animals. These results demonstrate that the SCN are not an essential component of the neural circuits that measure the melatonin signal.

US$19.90

PMID: 2378931

DOI: 10.1095/biolreprod43.2.174


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Bitam, I.; Dittmar, K.; Parola, P.; Whiting, M.F.; Raoult, D., 2010: Fleas and flea-borne diseases. Flea-borne infections are emerging or re-emerging throughout the world, and their incidence is on the rise. Furthermore, their distribution and that of their vectors is shifting and expanding. This publication reviews general flea biology and the...

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Eyndhoven, G.L. van., 1941: Lets over het voorkomen van Mijten op Houtbijen. Entomologische Berichten 's Gravenhage, 10239: 324-331

Zietz Isidore; Andreasen Gordon E.; Cain Joseph C., 1970: Magnetic anomalies from satellite magnetometer. Journal of Geophysical Research: 0, Pages 4007-4015. 1970.

M.Khann C.F., 1971: Increased tumor specific immunogenicity through the use of neuraminidase. Transplantation Proceedings 3(3): 1156-1157

Spendelow, J.A.; Burger, J.; Nisbet, I.C.T.; Nichols, J.D.; Hines, J.E.; Hays, H.; Cormons, G.D.; Gochfeld, M., 1995: Sources of variation in loss rates of color bands applied to adult roseate terns Sterna dougallii in the western North Atlantic. A model-based analysis was done to test several hypotheses concerning the rates of loss butt-ended color bands placed on adult Roseate Terns (Sterna dougallii) in the western North Atlantic. These birds were captured and color banded from 1987-199...

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