Biomaterial Database

Regulation of melatonin-sensitivity and firing-rate rhythms of hamster suprachiasmatic nucleus neurons: pinealectomy effects. 1993

B Rusak, and G D Yu

Department of Biomedical Sciences, McMaster University, Hamilton, Ont., Canada.

As a test of the origin of the melatonin-sensitivity rhythm recorded from SCN cells in brain slices from intact Syrian hamsters, hamsters were either pinealectomized to remove the influence of endogenous melatonin, or sham operated. Cells from sham-operated hamsters showed a trough in responsiveness during the projected night. Pinealectomy eliminated the daily rhythm of melatonin responsiveness, reduced the proportions of cells responding to melatonin, and raised response thresholds in those cells that did not meet the criterion for responsiveness. Pinealectomy also altered the firing-rate rhythm so that the morning peak in firing rate was not sustained and the nocturnal trough was attenuated, leading to a firing-rate rhythm with reduced amplitude compared to those recorded from sham-operated or intact animals. These results indicate a role for endogenous melatonin in regulating both melatonin sensitivity and the integrity of the SCN firing-rate rhythm, and they suggest why pinealectomy can disrupt circadian organization in some situations.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008550	Melatonin	A biogenic amine that is found in animals and plants. In mammals, melatonin is produced by the PINEAL GLAND. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of SLEEP, mood, and REPRODUCTION. Melatonin is also an effective antioxidant.
D008647	Mesocricetus	A genus in the order Rodentia and family Cricetidae. One species, Mesocricetus auratus or golden hamster is widely used in biomedical research.	Hamsters, Golden,Hamsters, Golden Syrian,Hamsters, Syrian,Mesocricetus auratus,Syrian Golden Hamster,Syrian Hamster,Golden Hamster,Golden Hamster, Syrian,Golden Hamsters,Golden Syrian Hamsters,Hamster, Golden,Hamster, Syrian,Hamster, Syrian Golden,Syrian Hamsters
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D010870	Pineal Gland	A light-sensitive neuroendocrine organ attached to the roof of the THIRD VENTRICLE of the brain. The pineal gland secretes MELATONIN, other BIOGENIC AMINES and NEUROPEPTIDES.	Epiphysis Cerebri,Pineal Body,Corpus Pineale,Gland, Pineal,Pineal Bodies,Pineal Glands
D002940	Circadian Rhythm	The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs or environmental and physiological stimuli.	Diurnal Rhythm,Nyctohemeral Rhythm,Twenty-Four Hour Rhythm,Nycthemeral Rhythm,Circadian Rhythms,Diurnal Rhythms,Nycthemeral Rhythms,Nyctohemeral Rhythms,Rhythm, Circadian,Rhythm, Diurnal,Rhythm, Nycthemeral,Rhythm, Nyctohemeral,Rhythm, Twenty-Four Hour,Rhythms, Circadian,Rhythms, Diurnal,Rhythms, Nycthemeral,Rhythms, Nyctohemeral,Rhythms, Twenty-Four Hour,Twenty Four Hour Rhythm,Twenty-Four Hour Rhythms
D004594	Electrophysiology	The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D006224	Cricetinae	A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.	Cricetus,Hamsters,Hamster
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013493	Suprachiasmatic Nucleus	An ovoid densely packed collection of small cells of the anterior hypothalamus lying close to the midline in a shallow impression of the OPTIC CHIASM.	Hypothalamic Suprachiasmatic Nuclei,Hypothalamic Suprachiasmatic Nucleus,Suprachiasmatic Nuclei,Suprachiasmatic Nuclei, Hypothalamic,Suprachiasmatic Nucleus, Hypothalamic