Biomaterial Database

Modulation of circadian rhythm of discharges of suprachiasmatic nucleus neurons in rat hypothalamic slices by melatonin. 2000

X J Zhou, and X H Jiang, and G D Yu, and Q Z Yin

Laboratory of Neurobiology, Suzhou Medical College, Suzhou 215007, China. zxjsj@yahoo.com

Spontaneous firing of suprachiasmatic nucleus (SCN) neurons and the effect of melatonin (MEL) were examined in hypothalamic slices made from pinealectomized rats or from the rats exposed to constant light. The results are as follows. (1) Under normal light cycle (light dark=12 12), SCN neurons displayed a circadian rhythm in spontaneous discharges. A peak about 8.3 Hz was presented at CT (circadian time) 6 8 and a trough about 3.8 Hz at CT18 20. The circadian rhythm persisted after pinealectomy, but disappeared after constant light exposure. (2) The response of SCN neurons to MEL was mainly inhibitory. Under normal light exposure, the inhibitory proportion was higher during the subjective day with the largest proportion of about 42% at CT8 10, and was lower during the subjective night with the largest proportion of about 26% at CT22 24. Under both constant light exposure and pinealectomy, the circadian rhythm of the response of SCN neurons to MEL disappeared. (3) The inhibitory effect of MEL on spontaneous discharges of SCN neurons was blocked by ML-1 receptor antagonist luzindole, but not by ML-2 receptor antagonist prazosin. The above results suggest that pineal gland, as a regulator of the organization of circadian rhythm, regulates the circadian rhythm of SCN neurons at two responsive time windows (CT8 10 and CT22 24) through high affinity ML-1 receptors in SCN.

UI	MeSH Term	Description	Entries
D007031	Hypothalamus	Ventral part of the DIENCEPHALON extending from the region of the OPTIC CHIASM to the caudal border of the MAMMILLARY BODIES and forming the inferior and lateral walls of the THIRD VENTRICLE.	Lamina Terminalis,Preoptico-Hypothalamic Area,Area, Preoptico-Hypothalamic,Areas, Preoptico-Hypothalamic,Preoptico Hypothalamic Area,Preoptico-Hypothalamic Areas
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.
D008839	Microelectrodes	Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)	Electrodes, Miniaturized,Electrode, Miniaturized,Microelectrode,Miniaturized Electrode,Miniaturized Electrodes
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
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.
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
D017208	Rats, Wistar	A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.	Wistar Rat,Rat, Wistar,Wistar Rats