Indomethacin reverses decreased hippocampal cell proliferation in streptozotocin-induced diabetic mice

Diabetes in humans and animals is accompanied by chronic low-grade inflammation, which could be a possible mediator of developing neuropathology and neurobehavioral deficits. The objective of the present study determined if decreasing inflammation could reverse diabetes-induced decreases in hippocampal cell proliferation, one aspect of hippocampal neurogenesis. C57BL/6J mice were made diabetic by administering streptozotocin (STZ; 195 mg/kg). STZ mice or vehicle controls received chronic treatment with the non-steroidal anti-inflammatory drug indomethacin (2 mg/kg for 14 days). Levels of glucose, corticosterone and cytokines were measured from plasma, cell proliferation was measured using BrdU incorporation in the hippocampus and TNF-αR1 and TNF-αR2 mRNA was measured using real-time PCR. STZ-induced diabetes increased plasma levels of glucose and corticosterone and decreased body weight. Cell proliferation in the hippocampus was reduced in diabetic mice by 50 %. The decreased level of cell proliferation was reversed by chronic treatment with indomethacin without changes to corticosterone and glucose levels. Plasma TNF-α levels increased in diabetic mice and were normalized by indomethacin treatment whereas IL-1 and IL-6 levels were unchanged by diabetes or indomethacin. In contrast, plasma levels of the cytokines IL-10 and IFN-gamma decreased in diabetic mice and were not affected by indomethacin treatment. STZ-induced diabetes decreased hippocampal expression of TNF-αR2 but not TNF-αR1 mRNA. Indomethacin ameliorated the effects of STZ on hippocampal neurogenesis independent of corticosterone and glycemic control, possibly by mediating the proinflammatory cytokine TNF-α. Inflammation is a potential novel pharmacological target for alleviating neurobehavioral complications arising from diabetes.