Metformin treatment during neonatal period rescues hippocampal neurogenesis in the BTBR T+Itpr3tf/J mouse model of autism

Abstract

Objective To investigate the effects of metformin (MET) treatment during early postnatal period on hippocampal neurogenesis of neonatal BTBR T+Itpr3tf/J (BTBR) mouse model of autism. Methods Healthy C57BL/6J (C57) and BTBR male pups were randomly divided into C57 normal saline group (C57+NS), C57 MET treatment group (C57+MET), BTBR+NS, and BTBR+MET group, with 5 animals in each group. From postnatal day 7 (P7) to P14, MET (200 mg/kg) or normal saline (same volume of sterile saline solution) were intraperitoneally injected into the corresponding mice, once per day. In 2 h after the last injection on P14, all mice were sacrificed, and the brains were collected and sliced coronally. Fluorescent immunostaining was performed to detect the expression of 5-bromo-2'-deoxyuridine (BrdU), Ki67, Sox2/GFAP and Prox1 in the dentate gyrus (DG). Results On P14, the numbers of BrdU-labeled cells and Ki67-labeled cells were significantly less in the DG of BTBR+NS group than the C57+NS group (P < 0.05), while the numbers were obviously increased in BTBR+MET group than the C57+MET group (P < 0.05). Although there were remarkably less Sox2 and GFAP double-positive cells (neural stem cells) and Prox1-positive cells (newborn neurons) in BTBR+NS group than the C57+NS group (P < 0.05), the 2 kinds of cells were increased obviously in BTBR+MET group than the BTBR+NS group (P < 0.05). However, MET treatment showed no effect on the hippocampal neurons, and there were no significant differences in the numbers of BrdU-, Ki67-, Sox2/GFAP- and Prox1-labeled cells between the C57+MET and C57+NS groups. Conclusion MET treatment in early postnatal period significantly improves the defects of hippocampal neurogenesis, and promotes the proliferation of hippocampal DG neurons and neural stem cells in BTBR mice.

Keywords

• metformin
• autism
• neurogenesis
• hippocampus
• mice