Chronic administration of SUMO‑1 has negative effects on novel object recognition memory as well as cell proliferation and neuroblast differentiation in the mouse dentate gyrus

Post‑translational modifications have been associated with developmental and aging processes, as well as in the pathogenesis of certain diseases. The present study aimed to investigate the effects of small ubiquitin‑like modifier 1 (SUMO‑1) on hippocampal dependent memory function, cell proliferation and neuroblast differentiation. To facilitate the delivery of SUMO‑1 into hippocampal neurons, a transactivator of transcription (Tat)‑SUMO‑1 fusion protein was constructed and mice were divided into two groups: A vehicle (Tat peptide)‑treated group and a Tat‑SUMO‑1‑treated group. The vehicle or Tat‑SUMO‑1 was administered intraperitoneally to 7‑week‑old mice once daily for 3 weeks, and a novel object recognition test was conducted following the final treatment; the animals were sacrificed 2 h following the test for further analysis. Administration of Tat‑SUMO‑1 significantly decreased exploration of a new object in a novel object recognition test compared with mice in the vehicle‑treated group. In addition, cell proliferation and neuroblast differentiation analyses (based on Ki67 and doublecortin immunohistochemistry, respectively) revealed that the administration of Tat‑SUMO‑1 significantly reduced cell proliferation and neuroblast differentiation in the dentate gyrus. These results suggested that chronic supplementation of Tat‑SUMO‑1 affects hippocampal functions by decreasing cell proliferation and neuroblast differentiation in the mouse dentate gyrus.