The pineal gland of the aging rat: Calcium localization and variation in the number of pinealocytes

Humbert, Willy; Pévet, Paul

doi:10.1111/j.1600-079x.1995.tb00137.x

Cited by 24 publications

(10 citation statements)

References 51 publications

(33 reference statements)

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“…Schmid (1993) summarized evidence, further confirmed by Humbert and Pevet (1995), that calcification of pinealocytes results from death or degeneration of the cell itself, thus leading to an overall decrease in pineal activity. Besides, it has been shown that, with age, there is a significant reduction in both melatonin content and the total number of pinealocytes due to a reduction of light pinealocytes, which are known to be functional (Skene et al 1990;Humbert and Pevet 1995). Occurring simultaneously, there is an increase of dark pinealocytes, which are characterized by an intranuclear deposition of calcium and with many signs of degeneration (Schmid et al 1994;Humbert and Pevet 1995).…”

Section: Discussionmentioning

confidence: 89%

“…Besides, it has been shown that, with age, there is a significant reduction in both melatonin content and the total number of pinealocytes due to a reduction of light pinealocytes, which are known to be functional (Skene et al 1990;Humbert and Pevet 1995). Occurring simultaneously, there is an increase of dark pinealocytes, which are characterized by an intranuclear deposition of calcium and with many signs of degeneration (Schmid et al 1994;Humbert and Pevet 1995). With the present data, we may be able to add a link missing so far in the chain of arguments that an increased calcification of the pineal gland represents a decrease in the number of functioning pinealocytes, which results in a decreased ability of the pineal gland to produce melatonin.…”

Section: Discussionmentioning

confidence: 99%

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A New Concept for Melatonin Deficit On Pineal Calcification and Melatonin Excretion

Kunz

1999

Neuropsychopharmacology

138

102

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Even though exogenous melatonin has proven to influence sleep and circadian parameters, low endogenous melatonin is not related to sleep disturbances, nor does it predict response to melatonin replacement therapy. In this manuscript, we present a new concept towards a definition of a melatonin deficit. The purpose of the study was to introduce a marker for an intra-individual decrease in melatonin production. Therefore, we developed a method to quantify the degree of pineal calcification (DOC) usingIn mammals, the circadian timing system has proven to be involved in the daily variation of almost any physiological and psychological variable evaluated so far (Weitzman et al. 1978;Wirz-Justice 1987;Johnson et al. 1992;Dijk and Czeisler 1995;Boivin et al. 1997). The rhythm of the circadian pacemaker comprised in the nuclei suprachiasmatici (SCN) becomes entrained to the environmental 24-hour rhythm, predominantly by two zeitgebers, light and melatonin (Dawson and Armstrong 1996).Melatonin influences the circadian phase in humans inversely compared to light. In particular, this drug delays circadian rhythms when administered in the morning and advances them when administered in the afternoon or early evening according to a phase response curve (PRC), which is nearly opposite in phase to the PRC's for light exposure (Lewy et al. 1992). Melatonin has proven to exert a chronobiotic mode of action (Dawson and Armstrong 1996) by its ability to facilitate the post-flight adaptation to jet-lag (Arendt et al. 1986), to phase advance the sleep of patients suffering from a phase-delay syndrome (Dahlitz et al. 1991;Tzischinsky et al. 1993), and to re-entrain the sleep-wake cycle of patients with a non-24-hour rhythm, such as in the blind, to the environmental light-dark cycle (Arendt et al. 1988;Lapierre and Dumont 1995;McArthur et al. 1996).However, in only one of the clinical studies (Haimov et al. 1995), in which exogenous melatonin proved usefulness, did low endogenous melatonin excretion predict response (Garfinkel et al. 1995;Hughes et al. 1998 Lushington et al. 1998;Youngstedt et al. 1998). Furthermore, normative data as to the amount of melatonin secretion demonstrate a huge inter-individual variability in humans (Dawson et al. 1992;Bergiannaki et al. 1995;Smith et al. 1997). Thus, existing normative data on melatonin excretion in a "healthy population" might only be considered normal in the sense that they are representative for the normal scatter. But since there is yet no pathology that can be attributed to either high or low melatonin levels, "normative" in this context may not necessarily indicate being healthy. The question arises, does a melatonin deficit or a hypopinealism exist at all?In a previously reported pilot-study we showed that the degree of pineal calcification (DOC) correlated positively to the incidence of chronic daytime tiredness as well as the subjective perception of sleep disturbances (Kunz et al. 1998). The basic assumption in that study was the hypothesis that an increasing degree of pineal c...

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

A New Concept for Melatonin Deficit On Pineal Calcification and Melatonin Excretion

Kunz

1999

Neuropsychopharmacology

138

102

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“…As suggested elsewhere [6], reduced activity of the arylalkylamine N -acetyltransferase, linked to an impaired pineal catecholaminergic neurotransmission, could result in diminished or suppressed nocturnal production. Moreover, the aging process leads to pineal gland calcification [35], [36]. Our investigations (unpublished) have shown modifications at the level of the pinealocytes and an accumulation of calcium deposits in both the pineal organ and retina of aged shrews compared to young individuals.…”

Section: Discussionmentioning

confidence: 90%

The Timing of the Shrew: Continuous Melatonin Treatment Maintains Youthful Rhythmic Activity in Aging Crocidura russula

et al. 2009

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BackgroundLaboratory conditions nullify the extrinsic factors that determine the wild expected lifespan and release the intrinsic or potential lifespan. Thus, wild animals reared in a laboratory often show an increased lifespan, and consequently an increased senescence phase. Senescence is associated with a broad suite of physiological changes, including a decreased responsiveness of the circadian system. The time-keeping hormone melatonin, an important chemical player in this system, is suspected to have an anti-aging role. The Greater White-toothed shrew Crocidura russula is an ideal study model to address questions related to aging and associated changes in biological functions: its lifespan is short and is substantially increased in captivity; daily and seasonal rhythms, while very marked the first year of life, are dramatically altered during the senescence process which starts during the second year. Here we report on an investigation of the effects of melatonin administration on locomotor activity of aging shrews.Methodology/Principal Findings1) The diel fluctuations of melatonin levels in young, adult and aging shrews were quantified in the pineal gland and plasma. In both, a marked diel rhythm (low diurnal concentration; high nocturnal concentration) was present in young animals but then decreased in adults, and, as a result of a loss in the nocturnal production, was absent in old animals. 2) Daily locomotor activity rhythm was monitored in pre-senescent animals that had received either a subcutaneous melatonin implant, an empty implant or no implant at all. In non-implanted and sham-implanted shrews, the rhythm was well marked in adults. A marked degradation in both period and amplitude, however, started after the age of 14–16 months. This pattern was considerably delayed in melatonin-implanted shrews who maintained the daily rhythm for significantly longer.ConclusionsThis is the first long term study (>500 days observation of the same individuals) that investigates the effects of continuous melatonin delivery. As such, it sheds new light on the putative anti-aging role of melatonin by demonstrating that continuous melatonin administration delays the onset of senescence. In addition, the shrew appears to be a promising mammalian model for elucidating the precise relationships between melatonin and aging.

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“…Light and dark pinealocytes have also been distinguished in many species, e.g. mouse (Upson et aI., 1976), rat (Johnson, 1980;MiJin et aI., 1990;Humbert and Pevet, 1995), horse (Cozzi, 1986), rabbit (Krakowski and Cieciura 1992), gerbil (Redecker, 1993) and pig (Przybylska, 1989;Lewczuk et al, 1994). However, the nature of the two forms of cells was controversial.…”

Section: Introductionmentioning

confidence: 99%

Cellular Constituents of the Pineal Parenchyma in the Albino Rat: Effect of Different Photoperiods

EI-Fadaly

2004

The Egyptian Journal of Anatomy

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The pineal gland of the aging rat: Calcium localization and variation in the number of pinealocytes

Cited by 24 publications

References 51 publications

A New Concept for Melatonin Deficit On Pineal Calcification and Melatonin Excretion

A New Concept for Melatonin Deficit On Pineal Calcification and Melatonin Excretion

The Timing of the Shrew: Continuous Melatonin Treatment Maintains Youthful Rhythmic Activity in Aging Crocidura russula

Cellular Constituents of the Pineal Parenchyma in the Albino Rat: Effect of Different Photoperiods

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