Comparing the inferior colliculus of young and old gerbils (Meriones unguiculatus) with an emphasis on GABA.

Indicators of an age-dependent down-regulation of GABA (gamma amino butyric acid) have been well-documented in the inferior colliculus (IC) of several rat strains. In the present study, we performed a quantitative light microscopic analysis of GABA-immunostained IC sections to characterize the effect of age on the cross-sectional area of the IC, the number and density of GABAergic cells and the expression of GABA in gerbils. Compared to young gerbils, a significant shrinkage of the IC but no loss of GABAergic cells was found resulting in an increased density of GABAergic cells in old gerbils. The expression of GABA in neurons and the neuropil of the IC did not differ between young and old gerbils. The results in the gerbil differ considerably from age-dependent changes described for the rat IC, showing clear species-specific differences.