Change in Photoperiodic Cycle Affects Life Span in a Prosimian Primate (Microcebus murinus

Abstract

The lesser mouse lemur, a small prosimian primate, exhibits seasonal rhythms strictly controlled by photoperiodic variations. Exposure to day lengths shorter than 12 h results in complete sexual rest, fattening, lethargy, and reduced behavioral activities; whereas exposure to day lengths greater than 12 h induces sexual activity, an increase in behavioral activities, and high hormonal levels. The objective of this study was to test whether long-term acceleration of seasonal rhythms may affect survival and longevity of this primate. In captivity, acceleration of seasonal rhythms was obtained by exposing the animals to an accelerated photoperiodic regimen consisting of 5 months of long photoperiod followed by 3 months of short photoperiod. The age-specific survival rate in animals exposed from birth to accelerated photoperiodic conditions (n = 89) was compared to the age-specific survival rate of animals maintained under a natural photoperiod (n = 68). Independent of sexes, the mean life span (45.5 +/- 2.1 months) and maximal survival (79.3 +/- 3.3 months) were significantly (p < .01) shortened in mouse lemurs exposed to the accelerated photoperiodic cycle compared to those in animals living under annual photoperiod (63.2 +/- 2.5 and 98 +/- 3.9 months for mean life span and maximal survival, respectively). This reduction of about 30% of life span was not accompanied by a desynchronization of biological rhythms under photoperiodic control and was not related to an increase in reproduction or in duration of time spent in active conditions. However, when the number of seasonal cycles experienced by 1 individual is considered rather than chronological age, the mean life span was 5 seasonal cycles and maximum survival reached 9-10 cycles, independent of sex or of photoperiodic regimen. These results suggest that in mouse lemurs, as in other seasonal mammals, longevity may depend on the expression of a fixed number of seasonal cycles rather than on a fixed biological age.

Distribution of lithostathine in the mouse lemur brain with aging and Alzheimer's-like pathology

“…Three groups were considered: 8 adults (1-4.5 years-old), 6 healthy aged (5-13 years-old) (Perret, 1997) or 6 aged with amyloid plaques (5.5-13 years-old). Grey mouse lemurs were all born and kept in captivity within our breeding colony (Ecole Pratique des Hautes Etudes, license approval N br 34-05-026-FS, France), according to the guidelines of the French Ethical Committee (Decree 87-848) and the European Community Directive (86/609/EEC).…”

Senescence or selective disappearance? Age trajectories of body mass in wild and captive populations of a small-bodied primate

“…Longevity is slightly male-biased in our captive study population [19,45] but strongly female-biased in the wild [30]. Roaming by males during the mating season [41] coincides with increased male mortality and, along with an age-associated increase in risk taking by males [46], probably drives the overall sex bias in longevity in the wild [30].…”

“…For individuals that survive to adulthood (here, to age 12 months or more), the average lifespan in captivity is approximately 5 years [19,45] (maximum in our captive colony was 13.8 years) but only 2 -3 years in the wild (lifespan of at least 10 years recorded in our study population). The annual turnover rate in nature is approximately 50% owing to high levels of EM [30] (mainly reptilian, avian and mammalian predation [47]).…”

Attenuated effect of increased daylength on activity rhythm in the old mouse lemur, a non-human primate

“…Daily exposure to light for longer than 12 h promotes sustained behavioral activity, whereas daily exposure to light for less than 12 h reduces behavioral activity and leads to an increase in fat deposits (Perret, 1992). The life span of this species is about 8 -10 years in captivity (Perret, 1997). Old animals show a decrease in amplitude of the seasonal variations in body mass, sexual hormones (Aujard and Perret, 1998), melatonin ) and DHEA-S Aujard, 2005, 2006).…”