ZINC-DEFICIENCY INCREASES INFARCT SIZE FOLLOWING PERMANENT MIDDLE CEREBRAL-ARTERY OCCLUSION IN RATS

In view of the potential relationship between cerebral ischemia and zi nc status, this study was designed to examine whether dietary zinc-def iciency would affect the outcome of focal cerebral ischemia in rats. F orty-five male Sprague-Dowley rats were randomly divided into five gro ups: (1) eight rats received a semi-purified zinc-deficient diet conta ining less than 0.38mg/100g of zinc for 1 week (ZD-1w);(2) eleven rats received the same diet as described as above for 2 weeks (ZD-2w); (3) ten rats, named pair-fed control group (PF-2w), received a zinc-suppl emented diet and matched by the amount of diet equal to that consumed by ZD-2w group for 2 weeks; (4) ad libitum-fed control group received the same diet as taken by PF-2w animals for 1 week (AF-1w, n=6) and (5 ) the remaining 10 rats were named as no-fed (NF) group, in which the rats were directly subjected to cerebral ischemia without entering the feeding process. After experiencing the dieting stage for 1 or 2 week s, or without (NF group), respectively, the animals were subjected to permanent occlusion of the middle cerebral artery (MCA). Plasma zinc c oncentration and the cerebral infarct volume were determined at 24 hou rs of ischemia. The final level of zinc in NF and AF-1w rats was 139+/ -5 and 127+/-6 mu g/100 ml, respectively. The zinc-deficient diet redu ced the concentration by 52% in ZD-1w and by 64% in ZD-2w group. The i ncrement in infarct size in ZD-1w group was inconspicuous. However, tr eatment with zinc-deficient diet for 2 weeks increased the total infar ct volume by 118%, 88%, 58% and 47% as compared with NF, AF-1w, PF-2w and ZD-1w rats, respectively. Especially, the cortical infarct volume (206+/-35 mm(3)) in ZD-2w group was 98-227% larger than those in the o ther groups (p<0.05, respectively). In conclusion, dietary zinc-defici ency increases infarct size following permanent MCA occlusion in rats. In addition, the aggravation of cerebral ischemia may depend on the s everity of zinc-deficiency, duration and the timing of dietary restric tion. Copyright (C) 1997 Elsevier Science Inc.