When longevity becomes chemistry: Why rodent brains lack neuromelanin
Background: The biology of neuromelanin (NMel) is linked to Parkinson's disease, in which pigment accumulation and release contribute to dopaminergic cell loss. Rodent brains lack detectable levels of NMel, despite possessing the molecular machinery required for its synthesis. The basis for this absence remains unknown. Objectives: To determine whether long-living rodents accumulate NMel and to…
Rodent brains lack the pigmentation compound neuromelanin (NMel), despite possessing the necessary molecular machinery to produce it. The reason for this absence has remained a mystery. Researchers sought to investigate whether long-living rodents accumulate NMel and whether lifespan constraints are the cause of its absence in mice and rats.
To answer these questions, the scientists performed histological stains on brain samples of mole rats of varying ages. The aim was to detect any pigmentation in catecholaminergic centers and determine the chemical makeup of pigmented neurons. The results of their study revealed that mole rats do exhibit clear age-dependent NMel accumulation, beginning after two years of age. The highest levels of pigmentation were found in the neurons of the locus coeruleus.
The researchers concluded that the accumulation of NMel is a slow kinetic process that necessitates extended longevity. In common laboratory rodents, such as mice and rats, the brains remain unpigmented simply because they do not live long enough to reach detectable levels of NMel.
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