Ethylnitrosourea誘発ラット脳腫瘍における局所血流量の変化

REGIONAL BLOOD FLOW IN THE ETHYLNITROSOUREA INDUCED RAT GLIOMA

I．はじめに

　Ethylnitrosourea （ENU）を用いた実験脳腫瘍については，これまでに多くの知見が発表されている^{1,3,7〜9,16〜20）}。このモデルの利点は，脳に手術的侵襲を加えることなく，高率にラット神経膠腫を発生しうることであり^{3，8,9,16）}，これにより腫瘍発生後の各段階で，腫瘍および周囲脳組織の生理学的，生化学的検索を行なうことができる。

　今回私達はこれらENU誘発ラット脳腫瘍の腫瘍内および近接脳組織内の局所血流量をautoradiographyを用いて測定し，腫瘍の増殖にともなう腫瘍内血管新生の役割について検討した。また制癌剤の脳腫瘍内へのとり込みとの関連についても考察した。

Regional cerebral blood flow of rat brains bearing ethylnitrosourea induced glioma of various size was investigated with ¹⁴C-antipyrine autoradiography. In the small tumors (<2mm in diameter), blood flow was uniformly reduced when compared to the adjacent brain. Even in tiny tumors (0.3-0.4mm in diameter), reduction in blood flow was evident. In the medium (2-4mm in diameter) and large (>4mm in diameter) tumors, the blood flow in-creased in the viable center of the tumor and decreased in the necrosis and peripheral edge. High blood flow in the viable center may be attributable to the neovascularization of the tumor. Blood flow in the brain tissue adjacent to medium and large tumors was lower than control brain tissue probably due to local edema. This reduction in blood flow may be partly attributable to the appearances of the focal neurologic deficits. The result obtained may provide some information about growth regula-tion of glioma and also pharmacokinetic delivery of chemotherapeutic drugs to the malignant brain tumors.