コレステロール食誘発性家兎粥状動脈硬化症におけるelastaseの中枢神経組織内のカルシウム増加抑制作用について

THE INHIBITORY EFFECT OF ELASTASE ON CALCIUM INCREASE IN BRAIN AND SPINAL CORD OF RABBITS WITH ATHEROSCLEROSIS INDUCED BY CHOLESTEROL-RICH DIET

　抄録　中枢神経組織で（CNS）の変性にカルシウム（Ca）が関与することが指摘されている。この研究はコレステロール誘発性粥状動脈硬化症家兎の肝，腎，CNSにおける石灰沈着に対してelastaseのCa増加抑制作用について検討したものである。25匹雄性家兎を6群に分け，次の3群は，家兎標準食群（A），1.5％コレステロール食群（B），1.5％コレステロール食＋elastase450EL．　U／kg／day腹腔内投与群（C）として，3カ月間飼育した。残りの3群は，家兎標準食群（D），0.67％コレステロール食群（E），0.67％コレステロール食＋elastase450EL．　U／kg／day腹腔内投与群（F）として6カ月間飼育した。各々規定期間飼育後，コレステロール食で飼育された4群はKritchevskyにより記載された粥状動脈硬化症が作成された。肝，腎，CNSのCa含有量は放射化分析法で測定され，（F）群の小脳と脊髄のCa含有量は（E）群のそれらに比較して有意に減少した。この結果，elastaseはコレステロール食誘発性粥状動脈硬化症でのCNSにおける緩徐なCa量の増加を抑制する作用をもつことが示唆された。

The aim of present experiment was to investi-gate the decalcified effects of exogenous elastase in liver, kidney and central nervous system (CNS) of rabbits with atherosclerosis experimentally in-duced by the modified procedure of Kritchevsky et al. Twenty five male rabbits, weighing appro-ximately 2 kg, were divided into 6 groups. Animals were fed for 3 months with standard diet (group A), standard diet containing 1.5% cholesterol (group B) and 1. 5% cholesterol-rich diet plus intraperitoneal (ip) daily administration of elastase 450 EL. U/kg (group C). Another groups were kept for 6 months with standard diet (group D), standard diet containing O. 67% cholesterol (group E) and O. 67% cholesterol-rich diet plus same dose of elastase (group F). The rabbits treated with cholesterol-rich diet were confirmed to be induced atherosclerosis biochemically as well as histologi-cally. All groups were maintained under these conditions for experimental periods and allowed tap water. After 3 and 6 months, blood collected by cardiocentesis using ether anesthesia and then sacrificed to remove CNS and internal organs. Blood had stood for 1 hour at room temperature. Serum was separated by centrifugation at 3, 000 rpm for 10 min to determine total cholesterol, triglyceride, phospholipids, HDL-cholesterol, andso on. Calcium contents in the cerebral frontal lobe, cerebellum, pons, spinal cord, liver and kidney were measured by neutron activation analysis method. In this experiment the ameliora-tion of atherosclerosis by ip administration of elastase was ascertained. In rabbits given chole-sterol-rich diet, calcium content in CNS tissues was higher than that of another tissues andparalleled to a rise of serum cholesterol level. Calcium contents in cerebellum and spinal cord in group F significantly decreased as compared with those of group E. These results indicate that exogenous elastase has decalcified effects on the calcium deposition in CNS tissues of rabbits with experimental atherosclerosis.