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Journal ArticleDOI

Precocious entrainment and associated characteristics of activity patterns following pinealectomy and reversal of photoperiod

01 Nov 1970-Physiology & Behavior (Elsevier)-Vol. 5, Iss: 11, pp 1281-1290
TL;DR: The post ΔΦ activity of the p animals differed in showing a sharp differentiation of circadian and photoperiod-dependent segments of activity phase (α), and in having an unusually close temporal relation and suggested dependency to the white-lights-off Zeitgeber during the first days following Δη.
About: This article is published in Physiology & Behavior.The article was published on 1970-11-01. It has received 94 citations till now. The article focuses on the topics: Pinealectomy.
Citations
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Journal ArticleDOI
04 Mar 1983-Science
TL;DR: The pineal gland hormone melatonin may play a role in synchronization of rat circadian rhythms, and the time of day of melatonin administration is crucial in pharmacological experiments.
Abstract: The pineal gland hormone melatonin may play a role in synchronization of rat circadian rhythms. Free-running activity rhythms of the rat were entrained by a daily melatonin injection, with entrainment occurring when the onset of activity coincided with the time of daily injections. When injections were stopped, activity rhythms became free-running again. Thus in pharmacological experiments, the time of day of melatonin administration is crucial.

552 citations

Journal ArticleDOI
TL;DR: The steps taken since melatonin's discovery by Aaron Lerner in 1958 are summarized to functionally characterize, clone, and localize receptors in mammalian tissues, as well as current efforts to discover and develop ligands for treatment of a number of illnesses.
Abstract: The hormone melatonin (5-methoxy- N -acetyltryptamine) is synthesized primarily in the pineal gland and retina, and in several peripheral tissues and organs. In the circulation, the concentration of melatonin follows a circadian rhythm, with high levels at night providing timing cues to target tissues endowed with melatonin receptors. Melatonin receptors receive and translate melatonin's message to influence daily and seasonal rhythms of physiology and behavior. The melatonin message is translated through activation of two G protein-coupled receptors, MT1 and MT2, that are potential therapeutic targets in disorders ranging from insomnia and circadian sleep disorders to depression, cardiovascular diseases, and cancer. This review summarizes the steps taken since melatonin's discovery by Aaron Lerner in 1958 to functionally characterize, clone, and localize receptors in mammalian tissues. The pharmacological and molecular properties of the receptors are described as well as current efforts to discover and develop ligands for treatment of a number of illnesses, including sleep disorders, depression, and cancer.

500 citations

Journal ArticleDOI
TL;DR: The data suggest that the behavioral effects of melatonin, like those on reproduction in seasonally breeding mammals, depend upon an intact circadian system and the SCN.

233 citations

Journal ArticleDOI
TL;DR: The effects of melatonin in rodent behavior are described, focusing on inhibitory effects (sedation, hypnotic activity, pain perception threshold elevation), and direct effects on circadian rhythmicity (entrainment, resynchronization, alleviation of jet-lag symptoms, phase-shifting).

203 citations

Journal ArticleDOI
TL;DR: Experimental data, primarily from studies on the rat, in support of the chronometric approach, include the reinstatement of cyclic feeding patterns after food deprivation; the continuation of circadian pattern of wheel running and nocturnal drinking during food deprivation.

178 citations

References
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Journal ArticleDOI
TL;DR: The timing, resetting and number of active 10-min periods per day or per cycle were unaffected by pinealectomy and shortening of the circadian cycle length in continuous illumination of decreased intensity occurred in all animals with an overt cycle.

69 citations

Book ChapterDOI
TL;DR: This chapter presents the results of seven completed experiments that demonstrate or relate to this disability of the pinealectomized animal and evaluates the significance and possible physiological interrelations of other characteristics of these experimental animals.
Abstract: Pinealectomized rats on a sodium-deficient diet have lower cerebral potassium content than sham-operated or unoperated controls. Consistent and significant differences among these animals in the electrolyte contents of other organs, serum, and urine are not apparent. In long-term pinealectomy with sodium deficiency, an increase in the adrenal weight sometimes occurs. This chapter presents the results of seven completed experiments that demonstrate or relate to this disability of the pinealectomized animal. The chapter discusses the experimental evidence of conditions that may diminish or modify pineal activity. The chapter also evaluates the significance and possible physiological interrelations of other characteristics of these experimental animals. The mammalian pineal's endocrine activity may be primarily centripetal, and the effects on peripheral tissues may possibly result through shifts in relative levels of activity in physiologically counterbalanced brain areas or functional systems.

69 citations

Journal ArticleDOI
TL;DR: The results suggest that the mammalian pineal may be more closely related to general central homeostatic mechanisms than to specific service in transducing photoperiod information to peripheral response systems.

66 citations

Journal ArticleDOI
TL;DR: It remains probable that on a seasonal basis, the pineal's vegetative and homeostatic effects may contribute to the adaptive physiological changes in particular mammalian species under the influence of changes in photoperiod and possibly other environmental factors.
Abstract: The current status of knowledge concerning the mammalian pineal's endocrine effects and the possible mechanisms for their mediation is reviewed and discussed. The diversity, physiological relations, and variability of the pineal's peripheral effects, and the constancy, rapidity, and homeostatic nature of its central and behavioral effects are consistent with the view that the pineal's primary action is on brain tissue. It remains probable that on a seasonal basis, the pineal's vegetative and homeostatic effects may contribute to the adaptive physiological changes in particular mammalian species under the influence of changes in photoperiod and possibly other environmental factors.

42 citations