Ricerc@Sapienza

Abstract
Background: In recent years, mechanistic, epidemiologic, and interventional studies have indicated beneficial
effects of omega-3 polyunsaturated fatty acids (n-3 PUFA) against brain aging and age-related cognitive decline,
with the most consistent effects against Alzheimer’s disease (AD) confined especially in the early or prodromal
stages of the pathology.
In the present study, we investigated the action of n-3 PUFA supplementation on behavioral performances and
hippocampal neurogenesis, volume, and astrogliosis in aged mice subjected to a selective depletion of basal
forebrain cholinergic neurons. Such a lesion represents a valuable model to mimic one of the most reliable
hallmarks of early AD neuropathology.
Methods: Aged mice first underwent mu-p75-saporin immunotoxin intraventricular lesions to obtain a massive
cholinergic depletion and then were orally supplemented with n-3 PUFA or olive oil (as isocaloric control) for 8
weeks. Four weeks after the beginning of the dietary supplementation, anxiety levels as well as mnesic, social, and
depressive-like behaviors were evaluated. Subsequently, hippocampal morphological and biochemical analyses and
n-3 PUFA brain quantification were carried out.
Results: The n-3 PUFA treatment regulated the anxiety alterations and reverted the novelty recognition memory
impairment induced by the cholinergic depletion in aged mice. Moreover, n-3 PUFA preserved hippocampal
volume, enhanced neurogenesis in the dentate gyrus, and reduced astrogliosis in the hippocampus. Brain levels of
n-3 PUFA were positively related to mnesic abilities.
Conclusions: The demonstration that n-3 PUFA are able to counteract behavioral deficits and hippocampal
neurodegeneration in cholinergically depleted aged mice promotes their use as a low-cost, safe nutraceutical tool
to improve life quality at old age, even in the presence of first stages of AD.
Keywords: Aging, Cholinergic system, Omega-3 fatty acids, Memory deficits, Diet, Alzheimer’s disease