Search tips
Search criteria

Results 1-4 (4)

Clipboard (0)
more »
Year of Publication
Document Types
jtitle_s:("Age (dodr)")
1.  Aging in male primates: reproductive decline, effects of calorie restriction and future research potential 
Age  2008;30(2-3):157-168.
Although less dramatic than in females, male mammals experience decreasing reproductive function during aging. In primates, multiple facets of the hypothalamic-pituitary-gonadal axis show evidence of gradual age-related decline, including behavioral, neuroendocrine and endocrine alterations such as decreased testosterone levels, reduced circulating dehydroepiandrosterone sulfate (DHEAS) levels, increased numbers of sperm abnormalities, and a general decline in physiological responses. In this review we consider a range of age-related changes in males. These measures, including more subtle aging characteristics, are interesting additional indices for detecting the timing of age-related changes in behavioral, neuroendocrine, and endocrine responses. Evidence of potential effects of calorie restriction as an intervention in reproductive aging is also discussed. A discernable decline occurs in both metabolic and reproductive endocrine processes during male aging. This cascade of events includes neuroendocrine and behavioral changes; biomarkers such as circulating DHEAS also show clear age-related decline. The varied changes that occur during male aging are considered in the context of primate aging in general.
PMCID: PMC2527629  PMID: 19424865
Calorie restriction; Male aging; Neuroendocrine systems; Primate; Reproduction
2.  Neuropathological quantification of dtg APP/PS1: neuroimaging, stereology, and biochemistry 
Age  2007;29(2-3):87-96.
Murine models that mimic the neuropathology of Alzheimer’s disease (AD) have the potential to provide insight into the pathogenesis of the disease and lead to new strategies for the therapeutic management of afflicted patients. We used magnetic resonance imaging (MRI), design-based stereology, and high performance liquid chromatography (HPLC) to assess the age-related neuropathology in double transgenic mice that overexpress two AD-related proteins—amyloid precursor protein (APP) and presenilin 1 (PS1)—and age- and gender-matched wild-type (WT) controls. In mice ranging in age from 4–28 months, total volumes of the hippocampal formation (VHF) and whole brain (Vbrain) were quantified by the Cavalieri-point counting method on a systematic-random sample of coronal T2-weighted MRI images; the same stereological methods were used to quantify VHF and Vbrain after perfusion and histological processing. To assess changes in AD-type beta-amyloid (Aβ) plaques, sections from the hippocampal formation and amylgdaloid complex of mice aged 5, 12, and 15 months were stained by Congo Red histochemistry. In aged mice with large numbers of amyloid plaques, systematic-random samples of sections were stained by GFAP immunocytochemistry to assess gender and genotype effects on total numbers of astrocytes. In addition, levels of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and 5-HT metabolites were assayed by HPLC in fresh-frozen samples from neocortex, striatum, hippocampus, and brainstem. We confirmed age-related increases in amyloid plaques, beginning with a few plaques at 5 months of age and increasing densities by 12 and 15 months. At 15 months of age, there were robust genotype effects, but no gender effects, on GFAP-immunopositive astrocytes in the amygdaloid complex and hippocampus. There were no effects on monoamine levels in all brain regions examined, and no volume changes in hippocampal formation or whole brain as quantified on either neuroimages or tissue sections. Strong correlations were present between volume estimates from MRI images and histological sections, with about 85% reduction in mean VHF or mean Vbrain between MRI and processed histological sections. In summary, these findings show that the double transgenic expression of AD-type mutations is associated with age-related increases in amyloid plaques and astrocytosis; however, this model does not recapitulate the cortical atrophy or neurochemical changes that are characteristic of AD.
PMCID: PMC2267662  PMID: 19424834
MRI; Alzheimer’s disease; Hippocampal formation; Amygdala; Unbiased stereology
3.  Aging in birds 
Age  2006;27(4):iii-v.
PMCID: PMC3455883
4.  Age-related differences in nest defense in common terns: Relationship to other life-history parameters 
Age  2006;27(4):297-305.
The Common Tern (Sterno hirundo) is a long-lived colonial nesting seabird. Previous studies have shown that chick growth and fledging success vary with age of the parental pair and with laying date, with older parents and those nesting earlier being more successful. This study investigated the dependence of breeding performance and one aspect of behavior, defense against conspecifics, on age and laying date. Nest defense behavior was evaluated by recording individual responses to a mirror placed 20 cm from the nest, simulating an unfamiliar intruder within the territory. Most study birds were of known age (3–21 years) from banding as chicks; they were divided into three groups: ≥12, 8–11 and ≤seven years. Responses to the mirror were examined during incubation and at the time of hatching. Older birds nested earlier than younger birds. Chicks reared by older parents gained mass more quickly and survived better than chicks of younger parents. Using a composite score reflecting both the intensity and duration of aggressive responses to the mirror, older birds responded more strongly than younger birds during incubation, but responses were similar at the time of hatching. Older birds reduced their aggressive responses between incubation and hatching, while younger birds increased their responses. We suggest that this contributes to the greater success of older birds, because younger birds expend more time and energy on territorial defense at a time when they need to feed chicks. Our findings are consistent with previous studies and show that Common Tern colonies are finely structured by age and laying date; older and earlier-nesting birds are superior to younger and later birds on several measures of performance. This study suggests that finely-tuned nest defense behavior is one component of the superior performance of old birds.
PMCID: PMC3455885  PMID: 23598663
age; chick growth; common tern; nest defense; productivity; seabird

Results 1-4 (4)