  In this work, we investigated the nitrogen and oxygen abundances in a sample
of galaxies with Low Ionization Nuclear Emission Regions (LINERs) in their
nucleus. Optical spectroscopic data (3 600 - 10 000 {\AA}) of 40 LINERs from
the Mapping Nearby Galaxies (MaNGA) survey were considered. Only objects
classified as retired galaxies, i.e. whose main ionization sources are
post-Asymptotic Giant Branch (pAGB) stars, were selected. The abundance
estimates were obtained through detailed photoionization models built with the
cloudy code to reproduce a set of observational emission line intensities
ratios of the sample. Our results show that LINERs have oxygen and nitrogen
abundances in the ranges of $ 8.0 \leq 12+\log(O/H) \leq 9.0$ (mean value
$8.74\pm 0.27$) and $7.6 \leq 12+\log(N/H) \leq 8.5$ (mean value $8.05\pm
0.25$), respectively. About 70% of the sample have oversolar O/H and N/H
abundances. Our abundance estimates are in consonance with those for Seyfert 2
nuclei and H ii regions with the highest metallicity, indicating that these
distinct object classes show similar enrichment of the interstellar medium
(ISM). The LINERs in our sample are located in the higher N/O region of the N/O
versus O/H diagram, showing an expected negative correlation between these two
parameters. These results suggest that these LINERs mainly exhibit a secondary
nitrogen production and could be acting some other mechanisms that deviate them
from the usual theoretical secondary nitrogen production curve and the H ii
regions observations. However, we did not find any evidence in our data able to
support the literature suggested mechanisms. On the other hand, our results
show that LINERs do not present any correlation between the N/O abundances and
the stellar masses of the hosting galaxies.
