Limits...
The timing of the shrew: continuous melatonin treatment maintains youthful rhythmic activity in aging Crocidura russula.

Magnanou E, Attia J, Fons R, Boeuf G, Falcon J - PLoS ONE (2009)

Bottom Line: Senescence is associated with a broad suite of physiological changes, including a decreased responsiveness of the circadian system.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.This is the first long term study (>500 days observation of the same individuals) that investigates the effects of continuous melatonin delivery.

View Article: PubMed Central - PubMed

Affiliation: UPMC University of Paris 06, UMR 7628, Banyuls/Mer, France. elodie.magnanou@obs-banyuls.fr

ABSTRACT

Background: Laboratory conditions ify 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 findings: 1) 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.

Conclusions: This 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.

Show MeSH

Related in: MedlinePlus

24 h Melatonin release by the implant.Melatonin implants were individually immersed in 1 mL physiological buffer renewed every 24 hours for up to 130 days. Melatonin concentration measured in the physiological serum are the Mean±SEM (n is indicated under brackets). The data fitted an exponential decay.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2690841&req=5

pone-0005904-g002: 24 h Melatonin release by the implant.Melatonin implants were individually immersed in 1 mL physiological buffer renewed every 24 hours for up to 130 days. Melatonin concentration measured in the physiological serum are the Mean±SEM (n is indicated under brackets). The data fitted an exponential decay.

Mentions: Melatonin measurements were made in four implanted shrews in order to estimate the levels induced by the implant. Plasma levels averaged 50 ng/ml one week after implantation (2 animals), and decreased to 120 pg/ml 3 months later (2 animals). In the in vitro system, melatonin release diminished with time, fitting an exponential decay (Fig. 2). High at the beginning of the experiment, it decreased rapidly during the first ten days and then remained within the same order of magnitude until the end of the survey.


The timing of the shrew: continuous melatonin treatment maintains youthful rhythmic activity in aging Crocidura russula.

Magnanou E, Attia J, Fons R, Boeuf G, Falcon J - PLoS ONE (2009)

24 h Melatonin release by the implant.Melatonin implants were individually immersed in 1 mL physiological buffer renewed every 24 hours for up to 130 days. Melatonin concentration measured in the physiological serum are the Mean±SEM (n is indicated under brackets). The data fitted an exponential decay.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2690841&req=5

pone-0005904-g002: 24 h Melatonin release by the implant.Melatonin implants were individually immersed in 1 mL physiological buffer renewed every 24 hours for up to 130 days. Melatonin concentration measured in the physiological serum are the Mean±SEM (n is indicated under brackets). The data fitted an exponential decay.
Mentions: Melatonin measurements were made in four implanted shrews in order to estimate the levels induced by the implant. Plasma levels averaged 50 ng/ml one week after implantation (2 animals), and decreased to 120 pg/ml 3 months later (2 animals). In the in vitro system, melatonin release diminished with time, fitting an exponential decay (Fig. 2). High at the beginning of the experiment, it decreased rapidly during the first ten days and then remained within the same order of magnitude until the end of the survey.

Bottom Line: Senescence is associated with a broad suite of physiological changes, including a decreased responsiveness of the circadian system.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.This is the first long term study (>500 days observation of the same individuals) that investigates the effects of continuous melatonin delivery.

View Article: PubMed Central - PubMed

Affiliation: UPMC University of Paris 06, UMR 7628, Banyuls/Mer, France. elodie.magnanou@obs-banyuls.fr

ABSTRACT

Background: Laboratory conditions ify 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 findings: 1) 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.

Conclusions: This 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.

Show MeSH
Related in: MedlinePlus