Effects of acetaminophen exposure on behavior and erythrocyte nuclear morphology of juvenile Oreochromis niloticus

Abstract

The occurrence of pharmaceuticals in the environment can have undesirable effects on nontarget animals, including fish. The present experiment assessed the effects of subchronic exposure to waterborne acetaminophen (N-acetyl-p-aminophenol) (APAP) on selected behavioral aspects (physical avoidance response, ventilation rate, and food detection rate) and erythrocyte nuclear abnormality (ENA) in juvenile Oreochromis niloticus. Two groups of fish were exposed to APAP dissolved in aged municipal water (T₁: 2 mg/L and T₂: 10 mg/L) for 8 weeks in three replicates (n = 7 fish per tank), alongside a control group (C) without APAP. APAP-exposed fish spent significantly (p < .05) longer time to detect food (T₁: 32.6 ± 4.55 s and T₂: 39.6 ± 4.66 s) compared to the control group (19.9 ± 2.46 s). Both APAP-exposed groups exhibited attenuated physical avoidance responses (76.7%, 68.7%, and 87.3% in T₁, T₂, and C, respectively) and a lower mean ventilation rate compared to the control group (194.5 ± 15.5, 179.1 ± 11.6, and 233.2 ± 19.0 per min in T₁, T₂, and C, respectively). The frequency occurrence of ENA types such as bi-nucleated, notched nuclei, lobed nuclei, and blebbed nuclei (except micronuclei) was significantly higher (p < .05) in APAP-exposed groups compared to the control, with more pronounced effects in the T₂ group. The study concludes that APAP exposure prompts significant alterations in behavior and erythrocyte nuclear morphology, emphasizing the value of monitoring and regulating the entry of pharmaceuticals, including APAP, into aquatic environments to prevent unintended effects on non-target organisms like Oreochromis niloticus.

Graphical Abstract

Keywords:

• Aquatic toxicology
• behavior
• acetaminophen
• oreochromis niloticus
• ENA

Acknowledgements

The authors thank the Department of Zoology, Faculty of Science, for providing all wet laboratory facilities and Faculty of Fisheries and Marine Science Technology for providing microimaging facilities. Previous version of this article has been made available as a preprint, Effects of Acetaminophen Exposure on Behavior, Erythrocyte Nuclear Morphology and Gill Histology of Juvenile Oreochromis Niloticus (Nile Tilapia), available at https://doi.org/10.2139/ssrn.4279439.

Author contributions

D. D. S. Dissanayaka contributed to writing, reviewing and editing, experimental maintenance and statistical analysis. K. B. S. Gunawickrama contributed to conceptualization, editing, funding acquisition and project administration. S. H. N. P. Gunawickrama contributed to conceptualization and review. T. N. Dharmapriya contributed to reviewing and statistical analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

This work was supported by the grant RU/SF/RP/2017/06 from the University of Ruhuna for partial funding.