An age-related decline in striatal taurine is correlated with a loss of dopaminergic markers

Taurine is present in high concentration in the mammalian brain and is know n to decline with aging. The present studies examined the relationship betw een the loss of striatal neurotransmitters and spatial learning ability in aged male Long-Evans rats. The effects of intrahippocampal infusions of neu rotrophic factors-nerve growth factor (NGF) and brain-derived neurotrophic factor-were also examined for their ability to ameliorate the age-related d ecline in brain amino acid content. Taurine content was found to be signifi cantly reduced in the striatum of aged rats (26 months old) that were impai red in spatial learning performance when compared to young unimpaired rats (5 months old). Aged rats that were behaviorally unimpaired had more modest reductions in taurine. Striatal dopamine content was also significantly re duced in aged learning-impaired rats. There was a significant (p < 0.001) c orrelation (r = 0.61) between the striatal content of taurine and dopamine, but no such correlation was found for other striatal transmitters (glutama te, serotonin, norepinephrine), Treatment with neurotrophins had little eff ect on the age-related decline in striatal amino acids, although NGF treatm ent did improve spatial learning. These studies suggest (1) a link between age-related declines in striatal dopamine and taurine and (2) that NGF-indu ced improvement in spatial learning is not related to mechanisms involving changes in taurine or glutamate content. (C) 1999 Elsevier Science Inc.