  We derive the nitrogen and oxygen abundances in the Narrow Line Regions
(NLRs) of a sample of 38 local ($z \: < \: 0.4$) Seyfert~2 nuclei. For that, we
consider narrow optical emission line intensities and direct estimates of the
electron temperatures ($T_{\rm e}$-method). We find nitrogen abundances in the
range $7.6 \: < \: \rm 12+log(N/H) \: < \: 8.6$ (mean value $8.06\pm0.22$) or
$\rm 0.4 \: < \: (N/N_{\odot}) \: < 4.7$, in the metallicity regime $8.3 \: <
\: \rm 12+log(O/H) \: < \: 9.0$. Our results indicate that the dispersion in
N/H abundance for a fixed O/H value in AGNs is in agreement with that for disc
\ion{H}{ii} regions with similar metallicity. We show that Seyfert~2 nuclei
follow a similar (N/O)-(O/H) relation to the one followed by star-forming
objects. Finally, we find that active galaxies called as 'nitrogen-loud'
observed at very high redshift ($z \: > \: 5$) show N/O values in consonance
with those derived for local NLRs. This result indicates that the main
star-formation event is completed in the early evolution stages of active
galaxies.
