Increases In Attention Set Shift Performance in aged male rats: Taurine As A Nootropic

Abstract

The global population is continuing to age more than ever before, while at the same time increasing the rates of age-related cognitive dementias and associated neurodegenerative disorders. This situation has directed researchers to examine the potential for cognitive enhancing drugs to ameliorate or forestall the naturally occurring age-dependent decline in cognitive functions that accompanying aging. The present study examined in aged male rats (i.e., 1-year of age) that were randomly assigned to either a Control water of 0.05% Taurine water (i.e., for 1-month) prior to being subjected to the Neuwirth-BrownTM Attention Set-Shift Test (ASST; a very sensitive test for cognitive functions of the frontal lobes’ flexibility and evaluation of perseverative behaviors) and were compared to a group of young male rats (i.e., 3-4 months old). The Old Control rats unfortunately due to age-related cognitive impairments could either not complete simple discrimination training (66.67%) or the simple discrimination during test day 1 (33%). Interestingly, the age-matched Old Control+Taurine rats were able to complete the ASST training (i.e., faster latency) and testing (i.e., similar amount of trials to completion) at rates comparable to the Young Control rats. The data suggest that taurine (i.e., a GABA receptor agonist) serves as a nootropic (i.e., cognitive enhancing drug) in an aging rodent model through recovery of fronto-executive functional behaviors in the ASST with brain imaging evidence showing taurine-dependent increases in dopamine fluorescent tagged neurons in the olfactory bulbs and prefrontal cortical areas that regulate fronto-executive functions. It is thought that since aging reduces the level of GABA (i.e., the main inhibitory neurotransmitter in the brain) and less inhibition can result in impulsive decision making, that taurine may serve to compensate and replenish GABA levels in the aging brain, which in part, could explain the cognitive improvements in this animal model of aging. This work shows that taurine may prove to be an effective nootropic to be prescribed in aging populations to forestall cognitive dysfunctions in the elderly by increasing GABAergic tone and Dopaminergic signals underlying more regulated inhibition and motivation.