Calorie restriction produces a general slowing of the progression of degenerative aging and creates sweeping changes at all levels of metabolism. Thus it should not be a surprise to find protective effects no matter how deep you dive into the biochemistry of calorie restricted laboratory animals. Here's one of the many more detailed examples, looking at the abundances of receptors known to be important in brain function:

The effects of aging and long-term caloric restriction, on the regulation of neuropeptide Y (NPY) Y(1), Y(2) and Y(5) receptors subtypes, was studied in 20-month-old male rats fed ad libitum (AL) or submitted to a 40% caloric restriction for 12 months.

In the brain of 3-month-old AL rats, the distribution and densities of Y(1), Y(2) and Y(5) receptors were in agreement with previous reports. In the brain of 20-month-old AL rats, a decrease of NPY receptor subtype densities in regions having important physiological functions such as the cingulate cortex, hippocampus and dentate gyrus, thalamus and hypothalamus was observed.

In contrast, caloric restriction had multiple effects. It induced specific decreases of Y(1)-receptor densities in the dentate gyrus, thalamic and hypothalamic nuclei and lateral hypothalamic area and Y(2)-receptor densities in the suprachiasmatic nucleus of hypothalamus. Moreover, it prevented the age-induced increase in Y(1)-receptor densities in the ventromedial hypothalamic nucleus and decrease in the mediodorsal thalamic nucleus, and increased Y(2)-receptor densities in the CA2 subfield of the hippocampus.

These results indicate that caloric restriction not only counteracts some of the deleterious effects of aging on NPY receptor subtype densities but exerts specific effects of its own. The overall impact of the regulation of NPY receptor subtypes in the brain of old calorie-restricted rats may protect the neural circuits involved in pain, emotions, feeding and memory functions.

Link: http://www.ncbi.nlm.nih.gov/pubmed/23410741

Source:
http://www.fightaging.org/archives/2013/03/calorie-restriction-protective-of-specific-brain-mechanisms.php