Manal A. Othman, Nagi M. Bakhit, Aisha Rashid, Yasin Tayem
Type 2 diabetes (T2D) is considered one of the metabolic conditions which may lead to degeneration of the central nervous system. The blood brain barrier (BBB) is recently recognized as a target that might be compromised in T2D. The pericyte and tight junction proteins, are major components of the BBB, that might be affected by diabetes. This may result in hyperpermeability of the BBB to toxic or hazardous substances, and this might affect its integrity. The current study addresses the effect of T2D on the BBB dysfunction and the role of caffeine to improve this condition. A rat model of T2D was used by feeding the rats with high calorie diet and injecting them with a single lower dose of streptozotocin. Diabetic rats were given caffeine orally for 5 weeks. At the end of the experiment (8 weeks), the rats were sacrificed, and their brains were processed for general histology and immunohistochemistry. The following markers were used: α-smooth muscle actin (α-SMA), occludin (tight junction protein) and transforming growth factor β1 (TGF-β1). There were degenerative changes in the cytoarchitecture of the CA1 area of the hippocampus. Immunohistochemistry revealed decrease in immunostaining of α-SMA and occludin and increase in TGF-β1 immunostaining, in diabetic rats. Caffeine intake resulted in improvement of the degenerative changes and reversal of the expression of the immunohistochemical markers. This study investigated the structural changes of the BBB in T2D, manifested by disruption of pericytes and tight junctions, with improvement of these findings after administration of caffeine.