Visit our Expo - Redox and Inflammation signaling 2012

Session XII : Cell death and neurodegenerative diseases Poster XII, 2
Age-related decline of synaptic turnover as an early event in neurodegeneration
Carlo Bertoni-Freddari, Patrizia Fattoretti, Belinda Giorgetti, Yessica Grossi, Marta
Balietti, Tiziana Casoli, Giuseppina Di Stefano, *Gemma Perretta
Neurobiology of Aging Laboratory, INRCA Research Department, Via Birarelli 8,
60121 Ancona, Italy Email: c.bertoni@inrca.it and *Istituto di Neurobiologia e
Medicina Molecolare-CNR, S.p Anguillarese km 1.3, 00060 Roma, Italy
The changes of synaptic ultrastructure in the frontal (FC) and temporal (TC) cortex were
investigated in adult and aged monkeys (Macaca fascicularis), by means of quantitative
morphometry, in order to assess the potential role of age-related synaptic deterioration in
neurodegeneration. The average synaptic size (S), the synaptic numeric density (Nv: number
of synapses/cubic micron of tissue), the synaptic surface density (Sv: overall area of synaptic
junctional zones/cubic micron of tissue) and the number of synapses/neuron (Syn/Neur) were
semiautomatically measured by a computer-assisted image analysis system. The results of FC
evaluation revealed no significant differences of Nv and Sv between adult and old monkeys,
while S was significantly increased in the aged animals. In TC, Sv did not show changes due
to age, while Nv was significantly decreased and S was significantly increased in aged
monkeys. The fraction (%) of perforated junctions was similar in FC and TC of the adult
animals, while it was decreased by 22.6% in TC vs. FC in the old monkeys. A percent
distribution of S showed that the fraction of enlarged synapses (>0.20 square micron) was
higher in TC than in FC regardless of the age of the animals (21.3% vs.16.9% in adult and
33.9% vs. 26.0% in aged monkeys, respectively). The comparison between data from adult
and old TC revealed that the increase was markedly higher in aged monkeys (i.e. 33.9% vs.
21.3%). In these animals, Syn/Neur was significantly decreased by 14.1% in TC, whereas it
was not significantly reduced in FC (- 4.4%). Sv, Nv, S and Syn/Neur are morphometric
parameters currently adopted to estimate the ongoing rearrangements of synaptic
ultrastructure to react to environmental stimuli. Our findings provide evidence of an agerelated
decline of synaptic plasticity in the brain of aged monkeys that is significant in TC.
According to current literature data on synaptic structural dynamics, this decay might
represent an early and subtle alteration able to trigger the development of senile plaques and
neurodegenerative events.
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