Early Physiological and Biochemical Responses to Short-Term Oral Exposure to Microplastic Particles in Male Wistar Rats

While various disturbances in organisms have been reported following long-term oral exposure to small plastic particles (microplastic particles, MPs), the effects of acute, short-term encounters remain underrepresented in scientific research. In this study, adult male Wistar rats were orally gavaged with MPs of three different sizes (~41 µm, 70 µm, or 106 µm; dose: 35 mg/kg), originating from poly(ethylene terephthalate) (PET) bottles. Twenty-four hours post-exposure, the impact on overall health indicators, including food and water intake, sensorimotor function and clinical signs of toxicity, in addition to serum biochemical markers related to organ function and oxidative stress, were assessed. Although no overt sensorimotor impairments or visible toxicity signs were observed in all MPs-treated groups, several investigated biochemical parameters were significantly altered. Water intake was also modified, whereas reduced food intake occurred only in the group treated with median-sized MPs, suggesting that acute exposure to MPs can lead to early physiological and biochemical responses. The obtained results, compared to the data extracted by using machine-learning (ML) tools and GPT-5 model within the available literature, highlighted the importance of investigating the acute effects of MPs, which may precede or contribute to long-term health consequences.