薬剤によるイヌの脈絡膜壁紙部の病変

抄録

Young beagles were given orally a synthesized chymotrypsin inhibitor (FK-401) at doses of 100, 300, and 600 mg/kg/day for 35 days. Ophthalmoscopic observation revealed discoloration of the tapetum lucidum in one out of six dogs given 300 mg/kg, and in four out of eight dogs given 600 mg/kg. No changes were observed in the electroretinogram. Swelling of tapetal cells and vacuolation of arteriolae were observed in light microscopy, and enlargement of the tapetal rods was observed in electron microscopy. The tapetal discoloration induced by FK-401 at 600 mg/kg was irreversible during the 8-week recovery period. We concluded that the mechanism of tapetal discoloration was different from that produced by a zinc chelator or by beta-adrenergic blocking agents. The tapetum lucidum discoloration might be related to vacuolation of the tapetal cells. Our results suggest that retinal function could be disordered by longterm administration of FK-401. However, tapetal change was considered to be of no significance in species that do not have a tapetum lucidum.