PROBLEM TO BE SOLVED: To provide a pharmaceutical composition that is applicable to symptoms and diseases caused by abnormal interaction between a TrkB protein and a BDNF in vivo.SOLUTION: Provided is a pharmaceutical composition comprising, as an active ingredient, a peptide or protein containing a specific partial sequence selected from an extracellular region among amino acid sequences constituting a TrkB protein. Specifically, the pharmaceutical composition comprises, as an active ingredient, a peptide or protein that includes any one of the amino acid sequences shown by the following 1) or 2) and that interacts with a BDNF, and competitively with a TrkB protein. 1) An amino acid sequence represented by SEQ ID NO 4 or SEQ ID NO 10 in the sequence listing； 2) an amino acid sequence obtained by substituting, deleting, adding, or introducing one or more amino acids in the amino acid sequence shown in 1) above. Furthermore, the pharmaceutical composition of the present invention can exert its effect as a drug more continuously by forming it into a liposome-bound preparation.SELECTED DRAWING: Figure 11COPYRIGHT: (C)2020,JPO&INPIT【課題】生体内においてＴｒｋＢタンパク質とＢＤＮＦとが異常に相互作用することに起因する症状や疾患に適用可能な医薬組成物を提供する。【解決手段】ＴｒｋＢタンパク質を構成するアミノ酸配列のうち、細胞外領域から選択される特定の部分配列を含むペプチド又はタンパク質を有効成分とする医薬組成物による。具体的には以下の１）又は２）に示すいずれかのアミノ酸配列を含み、ＴｒｋＢタンパク質と競合的にＢＤＮＦと相互作用するペプチド又はタンパク質を有効成分とする医薬組成物による。１）配列表の配列番号４又は配列番号１０に示すアミノ酸配列；２）上記１）に示すアミノ酸配列のうち、１～複数個のアミノ酸が、置換、欠失、付加又は導入されてなるアミノ酸配列。更には、さらに本発明の医薬組成物は、リポソーム結合型の製剤とすることで、より継続的に医薬としての効果を発揮しうる。【選択図】図１１
