+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

Non-photic phase shifting of the circadian activity rhythm of Syrian hamsters: the relative potency of arousal and melatonin

, : Non-photic phase shifting of the circadian activity rhythm of Syrian hamsters: the relative potency of arousal and melatonin. Brain Research 591(1): 20-26

This study investigated the relative potency of melatonin and arousal as Zeitgebers in the non-photic phase shifting of circadian rhythmicity in the adult Syrian hamster. Animals held under dim red light (DD) exhibited robust free-running rhythms of wheel-running activity. Melatonin (1 mg/kg) or ethanolic saline vehicle, delivered manually by subcutaneous injection after removing the animal from its cage, resulted in phase advances of the activity rhythm. This effect was phase dependent, injections at CT 8 and 10 being effective (CT 12 = anticipated activity onset), whereas injection at CT 2, 6, 14 and 20 did not cause a shift. There was no significant difference between the magnitude or timing of phase shifts in response to injections of saline or melatonin. To determine whether the observed shifts were related to arousal of the animals induced by handling, a second group held under DD were fitted with chronic s.c. cannulae so that melatonin solution or vehicle could be delivered remotely at projected CT 10. Neither solution had any effect upon the free-running rhythm. However, when these animals received manual s.c. injection of saline or melatonin solution, they exhibited phase advances similar to those observed in Expt. 1. These results fail to support the hypothesis that melatonin can exert a chemically specific, acute phase-shifting action in the adult Syrian hamster. They do, however, demonstrate the potent effect of arousing stimuli upon the circadian clock in this species.


PMID: 1446229

Other references

Imieliński, L.B.; Kopczyński, S.; Drewniak, K.; Chmielewski, J., 1972: Premature closure of cranial sutures (craniostenosis syndrome). Pediatria Polska 47(8): 1043-1047

Machacek, J.E., 1954: Cooperative seed treatment trials. These treatments were applied to naturally contaminated, infested, or bruised seed, and were tested against wheat bunt, loose smuts of oats and barley, covered smut of oats, seedling blight of wheat, and seed rot of flax. All materials were effect...

Dawnay, N.; Mcewing, R.; Thorpe, R., S.; Ogden, R., 2008: Preliminary data suggests genetic distinctiveness of gyr and saker falcons. The inadequately controlled trade in gyr and saker falcons has lead to saker falcons becoming endangered and both species being CITES listed. However, the phylogenetic relationship between these nominal species is unresolved preventing their mole...

Mohr, S.; Perroud, N.; Gillieron, C.; Brandt, P-Yves.; Rieben, I.; Borras, L.; Huguelet, P., 2011: Spirituality and religiousness as predictive factors of outcome in schizophrenia and schizo-affective disorders. Spirituality and religiousness have been shown to be highly prevalent in patients with schizophrenia. This study assesses the predictive value of helpful vs. harmful use of religion to cope with schizophrenia or schizo-affective disorder at 3 year...

Anonymous, 1954: Western Red Cedar shingle roofs. Tests have shown that the roof under investigation cannot be ignited by a small source of ignition, but that, when involved in a fire, it can distribute brands over a wide area.

Wong, W.; Tompar Tiu, A.P., 1981: A community programme in the Philippines. The project Reaching the Unreached. In 1979, the Philippine Foundation for the Rehabilitation of the Disabled, the Mental Feeding Programme of the Nutrition Center of the Philippines and UNICEF launched a joint project which they named "Reaching the Unreached". Its primary...

Schulz, D.; Rothenhöfer, C.; Faul, A., 1978: Fractionation of human erythrocytes according to their sedimentation behaviour caused by gravity. II. Application for the differential diagnosis of erythroblastosis caused by incompatibility in the abo blood group system. In contrast to Rh-erythroblastosis the diagnosis of A/B0-erythroblastosis by means of serological methods is often impossible. Further biochemical investigations, the demonstration of elevated erythrocyte sedimentation rates in polyvinylpyrrolidon...

Neuman A.; Gillier Pandraud H.; Longchambon F.; Rabinovich D., 1975: Crystal structure of n acetyl alpha d galactosamine. Acta Crystallographica Section B Structural Crystallography & Crystal Chemistry 31(2): 474-477

Madelmont, C.; Michon, G., 1964: Radioactive contamination of milk consumed in the Paris area. Forty-five samples of bulk milk were taken in 8 districts supplying roughly 52% of the Paris area with pasteurized milk. Between April 1961 and Dec. 1962 the range of values (mean for all districts) for radioactive contamination was as follows: -...

Collins, F.H.; Paskewitz, S.M.; Crews-Oyen, A.E., 1991: A genetic study of Plasmodium susceptibility in the African malaria vector Anopheles gambiae. The authors are studying the interaction between malarial parasites and their mosquito hosts by a process based on the genetic selection of lines of the mosquito vector that will not support normal parasite development. The model system being used...