*Article* **Immunohistochemical Expression (IE) of Oestrogen Receptors in the Intestines of Prepubertal Gilts Exposed to Zearalenone**

**Magdalena Gaj˛ecka 1,\* , Iwona Otrocka-Domagała <sup>2</sup> , Paweł Brzuzan <sup>3</sup> , Michał D ˛abrowski <sup>1</sup> , Sylwia Lisieska-Zołnierczyk ˙ <sup>4</sup> , Łukasz Zielonka <sup>1</sup> and Maciej Tadeusz Gaj˛ecki <sup>1</sup>**


**Abstract:** This study was conducted to determine if a low monotonic dose of zearalenone (ZEN) affects the immunohistochemical expression (IE) of oestrogen receptor alpha (ERα) and oestrogen receptor beta (ERβ) in the intestines of sexually immature gilts. Group C (control group; n = 18) gilts were given a placebo. Group E (experimental group; n = 18) gilts were dosed orally with 40 µg ZEN /kg body weight (BW), each day before morning feeding. Samples of intestinal tissue were collected post-mortem six times. The samples were stained to analyse the IE of ERα and Erβ in the scanned slides. The strongest response was observed in ERα in the duodenum (90.387—average % of cells with ERα expression) and in ERβ in the descending colon (84.329—average % of cells with ERβ expression); the opposite response was recorded in the caecum (2.484—average % of cells with ERα expression) and the ascending colon (2.448—average % of cells with ERα expression); on the first two dates of exposure, the digestive tract had to adapt to ZEN in feed. The results of this study, supported by a mechanistic interpretation of previous research findings, suggest that ZEN performs numerous functions in the digestive tract.

**Keywords:** zearalenone; immunohistochemistry; oestrogen receptors; gilts before puberty

**Key Contribution:** Qualitative changes were manifested by a shift in oestrogen receptor expression levels from absorption level 0 to 3; particularly in ERβ expression in the descending colon.
