Elevated CYP1A expression detected in pinfish collected from a coastal lagoon in the southern Texas Gulf Coast: indicative of exposure to microplastics or pollutants?

The marine environment is increasingly polluted by anthropogenic wastes, notably plastic debris. This debris breaks down into smaller pieces, known as microplastics. When consumed by marine organisms, microplastics cause various physiological effects. In this study, we sought to determine a link between ingested microplastics and cytochrome P450-1A (CYP1A) expression in fish liver. To achieve this goal, we collected pinfish from five sites in Lower Laguna Madre (LLM, a large coastal lagoon), analyzed stomach contents, excised liver tissues, and performed immunohistochemical analysis to determine CYP1A expression. Microplastics were not discovered in the stomach/intestine of pinfish, though plastic debris was present at various stages of decomposition within sampling sites. Hepatic CYP1A expression was significantly higher in pinfish collected from four of five sampling sites when compared to fish in laboratory conditions. These results imply that pinfish, as well as other organisms, may be exposed to pollutants other than microplastics in LLM.