Effect of manganese on heat stress protein synthesis of new-born rats

AIM: To study the effect of manganese (Mn) on heat stressprotein 70 (HSP70) synthesis in the brain and liver of new-bom rats whose mother-rats were exposed to Mn.METHODS: 32 female rats were randomly divided into fourgroups. One group was administrated with physiologicalsaline only as control group, the other three groups wereadministrated with 7.5, 15 and 30 mg@ kg-1 manganesechloride (MnCl2) by intraperitioneal injection every two daysfor two weeks. After delivery, the mother-rats receivedMnCl2 unceasingly for a week with the same method. Thenthe contents of Mn、 Zn、 Cu and Fe in the livers of the new-bom rats were determined by atomic absorptionspectroscopy; The level of HSP70 in the brains and thelivers of the new-born rats as detected by Westsrn-dot-blotting, and the SOD activities were measuredsimultaneously.RESULTS: The contents of Mn in the livers of new-bom ratsof the experimental groups(respective 1.38 ± 0.18, 2.73 ±0.65, 3.44 ± 0.89μg @ g-1) were significantly increasedcompared with the control group(0.88 ± 0.18μg@ g-1; p ＜0.01); The contents of Fe in the livers of new-bom rats of 15and 30 mg@ kg-1 experimental groups (426 ± 125,572 ± 175μg@g-1, respectively) were significantly increased comparedwith the control group(286±42μg@g-1; P＜0.05); the levelsof Zn in the livers of the new-bom rats of three experimentalgroups( 254 ± 49, 263 ± 47, 213 ± 28μg@ g-1, respectively)were lower than those of the control group(335 ± 50μg@g-1;respective P＜0.05, P＜0.01); and the levels of Cu showedno significant difference among the four groups (threeexperimental groups: 75 ± 21, 68 ± 241 and 78 ± 18μg@g-1;control group: 83 ± 9μg@ g-1; p ＞ 0.05). There was asignificant increase in the levels of HSP70 in the brains ofnew-bom rats of the 30 mg@kg-1 group (19.5 × 103 ± 1.3 ×103A; control group: 14.3 × 103 ± 1.4 × 103A; P＜ 0.01),andthe levels of HSP70 in the livers of new-bom rats of threeexperinental groups(respective 19.6 × 103 ± 3.9 × 103A, 18.5× 103 ± 3.8 × 103A, 22.4 × 103 ± 1.9 × 103A ) also increasedthan control group(13.3 × 103 ± 1.0 × 103A; P ＜ 0.01), butthe SOD activities showed no significant difference amongbrains of the four groups (experimental groups: 5.04 ± 0.43,4.83±0.48, 4.60±0.84 ku@g-1; control group: 4.91 ± 0.37ku@g-1; P＞ 0.05). The SOD activities in the livers of 15mg@kg-1 group(5.41 ± 0.44 ku@g-1) was lower than the controlgroup(5.95±0.36 ku@g-1; P＜0.05).CONCLUSION: While mother-rats were exposed tomanganese, the metabolisms of Mn、Zn and Fe of new- bornrats in the livers were influenced and were situated in astress status, thus HSP70 syntheses is induced in the brainsand livers of new-bom rats, but the mechanism of this effectin the developmental toxicity of Mn remains to he furtherstudied.

AIM:To study the effect of manganese(Mn)on heat stress protein 70(HSPT0)synthesis in the brain and liver of new- born rats whose mother-rats were exposed to Mn. METHODS:32 female rats were randomly divided into four groups.One group was administrated with physiological saline only as control group,the other three groups were administrated with 7.5,15 and 30 mg·kg^(-1)manganese chloride(MnCl_2)by intraperitioneal injection every two days for two weeks.After delivery,the mother-rats received MnCl_2 unceasingly for a week with the same method.Then the contents of Mn,Zn,Cu and Fe in the livers of the new- born rats were determined by atomic absorption spectroscopy;The level of HSPT0 in the brains and the livers of the new-born rats as detected by Western-dot- blotting,and the SOD activities were measured simultaneously. RESULTS:The contents of Mn in the livers of new-born rats of the experimental groups(respective 1.38±0.18,2.73± 0.65,3.44±0.89μg·g^(-1))were significantly increased compared with the control group(0.88±0.18μg·g^(-1);P< 0.01);The contents of Fe in the livers of new-born rats of 15 and 30 mg·kg^(-1)experimental groups(426±125,572±175μg· g^(-1),respectively)were significantly increased compared with the control group(286±42μg·g^(-1);p<0.05);the levels of Zn in the livers of the new-born rats of three experimental groups(254±49,263±47,213±28μg·g^(-1),respectively) were lower titan those of the control group(335±50μg·g^(-1); respective P<0.05,P<0.01);and the levels of Cu showed no significant difference among the four groups(three experimental groups:75±21,68±241 and 78±18μg·g^(-1); control group:83±9μg·g^(-1);P>0.05).There was a significant increase in the levels of HSP70 in the brains of new-born rats of the 30 mg·kg^(-1)group(19.5×10~3±1.3× 10~3A;control group:14.3×10~3±1.4×10~3A;P<0.01),and the levels of HSPT0 in the livers of new-born rats of three experimental groups(respective 19.6×10~3±3.9×10~3A,18.5 ×10~3±3.8×10~3A,22.4×10~3±1.9×10~3A)also increased than control group(13.3×10~3±1.0×10~3A;P<0.01),but the SOD activities showed no significant difference among brains of the four groups(experimental groups:5.04±0.43, 4.83±0.48,4.60±0.84 ku·g^(-1);control group:4.91±0.37ku ·g^(-1);P>0.05).The SOD activities in the livers of 15mg. kg^(-1)group(5.41±0.44 ku·g^(-1))was lower than the control group(5.95±0.36 ku·g^(-1);P<0.05). CONCLUSION:While mother-rats were exposed to manganese,the metabolisms of Mn、Zn and Fe of new-born rats in the livers were influenced and were situated in a stress status,thus HSP70 syntheses is induced in the brains and livers of new-born rats,but the mechanism of this effect in the developmental toxicity of Mn remains to be further studied.