Value of depletion (enhancement) of the central oxygen abundance Δ(O/H)₀ (the difference between the mean value of the oxygen abundances 12+log(O/H) in spaxels with galactocentric distances within 0.1 R₂₅ and the value of the central intersect oxygen abundance estimated from the radial abundance gradient based on spaxels with galactocentric distances within 0.2–0.8 R₂₅) as a function of ΔPA (panel a) and as a function of stellar mass of the galaxy (panel b). The circles represent data for galaxies with large ΔPA and without signs of ah interaction while the plus signs show galaxies with large ΔPA and with signs of an interaction. The crosses denote galaxies with small (no) ΔPA from Pilyugin et al. (2019). The dashed line marks a ΔPA of zero, and the dotted lines show the ±0.05 values. Panel c: histograms of Δ(O/H)₀ for galaxies with ΔPA < 20° (solid line) and for galaxies with ΔPA > 20° (dashed line).