Increased whole cerebellar serotonin in aged C57BL/6 mice.

Mobility and locomotor impairments have high prevalence, morbidity, and significant mortality in older adult populations. Cerebellar functional changes have been implicated in the pathogenesis of these age-related mobility and gait deficits unrelated to stroke, Parkinson's disease, or degenerative joint disease. We thus examined total cerebellar glutamate, glutamine, GABA, glycine, dopamine, norepinephrine, tryptophan, serotonin, alanine, threonine, and asparagine content from male 2-3-month (young, n = 6) and 21-24-month-old (aged, n = 6) C57BL/6 mice. Neurotransmitter and amino acid concentrations were determined by high-performance liquid chromatography followed with mass spectroscopy. We found a significant increase in cerebellar serotonin in aged versus young mice, but otherwise no significant phenotypic differences in measured neurotransmitter concentrations. Applying current thought about cerebellar aging and cerebellar serotonergic systems, we consider how this age-related increase in cerebellar serotonin may contribute to gait ataxia.