Fig. 2

Effect of ageing on ADORA2A gene expression in human peripheral blood cells. a Quantification of ADORA2A mRNA fold change in cells of young, middle-aged and older adults as well as centenarians. ADORA2A mRNA level for each sample was normalized to ACTB signal (internal control) and relative to the mean normalized value of ADORA2A gene expression in young adults group. Error bars represent S.E.M. of the means obtained in each group (n = 13 per young adults; n = 12 per middle-aged adults; n = 11 per older adults; n = 21 per centenarian group). ** (p < 0.01) and **** (p < 0.0001) indicate statistically significant differences between older adults and the rest of groups. b ADORA2A mRNA fold change in different subgroups of a centenarians. ^{¤ ¤ ¤ ¤} (p < 0.0001) indicates significant differences between centenarian’s subgroups, overexpressed (n = 7) and underexpressed (n = 14). ^{# # #} (p < 0.001) and ^{# # # #} (p < 0.0001) denote highly significant differences between the subgroup of overexpressed centenarians and young as well as middle-aged adults groups of a, respectively. ^♦ (p < 0.05) and ^{♦ ♦ ♦ ♦} (p < 0.0001) mean statistical differences between the subgroup of underexpressed centenarians and the rest of groups of a. The p values were determined by Mann–Whitney test