Question

Why is GABA different when youre younger vs. when youre older?

Answer 1

Gamma amino butyric acid or GABA is produced by glutamic acid decarboxylase or GAD. It is released in synapse when the neuronal membrane depolarizes. It acts via GABA-A and GABA-B receptors.

It has been seen that GABA levels decline with age in hippocampus, frontal and parietal regions. This decline in GABA levels is due to loss of grey matter fraction. Decreased production of GABA along with either/or degradation of GABAergic inhibitory interneurons are seen to be primary reasons in animal studies for differences in GABA in young and old people. Lower GABA levels also led to decrease in reactive inhibition in older individuals. These reduced levels of GABA are linked to reduced synthesis of GABA at presynaptic level.

There have also been reports suggesting that ageing alters the expression of regional GABA-AR subunit. In aged mice, it has been seen, that there is loss of R1 subunit of GABA-BR in prefrontal cortex and hippocampus. This result in generation of reduced inhibitory currents that causes learning deficits and memory. There has also been evidence of decreased expression of α2 subunit of GABA-AR around soma, proximal dendrites and CA1 and CA3 pyramidal cells. Further, intracortical inhibition circuits get altered as people age.