Effects of berberine on a rat model of chronic stress and depression via gastrointestinal tract pathology and gastrointestinal flora profile assays.

Chronic stress and depression are challenging conditions to treat, owing to their complexity and lack of clinically available and effective therapeutic agents. The aim of the present study was to investigate the mechanism by which berberine acts, by examining alterations to gastrointestinal tract histopathology and flora profile in a rat model, following the induction of stress. Research associating gastrointestinal flora and depression has increased, thus, the present study hypothesized that stress induces depression and changes in the gastrointestinal system. The chronic mild stress rat model was previously established based on a set of 10 chronic unpredictable stress methods. In the present study, the measurements of body weight, behavior, gastrointestinal tract histopathology and gastrointestinal flora profile were collected in order to elucidate understanding of chronic stress and depression in this region. In the present study, induced stress and the resulting depression was demonstrated to significantly decrease the body weight and sucrose preference of rats, as well as significantly increasing traverse time, vertical movement time, grooming time and motionless time in an open‑field test. Following modeling and subsequent treatment with low or high doses of berberine, the measurements were significantly different when compared with unstressed rats. Berberine appears to reverse the physical damage brought about by stress within the gastric mucosa and intestinal microvilli of the stomach, ileum, cecum and colon. Using enterobacterial repetitive intergenic consensus sequence‑based polymerase chain reaction analysis, several distinctive bands disappeared following modeling; however, novel distinctive bands appeared in response to the graded berberine treatment. In conclusion, the present study identified that high concentrations of berberine markedly protects rats from various symptoms of chronic stress and depression, with the potential of facilitating treatment within clinical practice.