PROBLEM TO BE SOLVED: To provide a substance that suppresses a breakage of the blood-brain barrier.SOLUTION: A Claudin-5 expression promoter comprises chlorogenic acid or a salt thereof as an active ingredient. A brain HMGB1 expression inhibitor comprises chlorogenic acid or a salt thereof as an active ingredient. A blood-brain barrier protecting agent comprises chlorogenic acid or a salt thereof as an active ingredient. An agent for preventing or ameliorating dysfunction of the blood-brain barrier comprises chlorogenic acid or a salt thereof as an active ingredient.SELECTED DRAWING: NoneCOPYRIGHT: (C)2020,JPO&INPIT【課題】血液脳関門の破綻を抑制する物質の提供。【解決手段】クロロゲン酸類又はその塩を有効成分とするＣｌａｕｄｉｎ－５発現促進剤。クロロゲン酸類又はその塩を有効成分とする脳内ＨＭＧＢ１発現抑制剤。クロロゲン酸類又はその塩を有効成分とする血液脳関門保護剤。クロロゲン酸類又はその塩を有効成分とする血液脳関門の機能低下の予防又は改善剤。【選択図】なし
