Experimental Study Of Protective Effects Of L-Arginine On Liver Of Heat Exposed Mice

Objective: To inquire into the effects of L-Arginine (L-Arg) on liver of heat stressed mouse and its possible mechanism.Methods: The effects of L-Arginine on heat acclimatization: 36 mice (Kunming, male, 18-22g) were divided into 3 groups in random. One group was gavaged to water(for control), and the other two groups were gavaged to L-Arginine with 1.0mg/g.bw and 1.5 mg/g.bw respectively. In each group, 6 mice were exposed to 38℃ for 2h as heat acclimatization group , and the other 6 mice were put to 22℃ as normal temperature group for control after they were gavaged to water or L-arginine till the former was acclimated ten days later. On the 11 day, all mice were exposed to 42℃ for 50min.We measured the body weight and rectal temperature of the mice before and after heat treatment, observed the mices respiratory frequency, movement and salivary secretion in the process of heat stress. Then we inquire into the effects of L-Arginine on the expression of HSP70 in liver and activity of alanine aminotransferase(ALT) in serum. The effects of L-Arginine on causing death of heat treated mice: 54 mice (Kunming ,male, 18-22g) were divided 3 group (n=18) which were gavaged to water, 1.0 mg/g.bw and 2.0 mg/g.bw respectively, an hour later being exposed to 42℃ for heat stress to death. We measuring their rectal temperature per 15min, noted the time when there had been 9 mice died in each group. Then we inquire into the effects of L-Arginine on the level of HSP70 ,NO and MDA in liver. Results:1. The effects of L-Arginine on mice of heat acclimatization: a. The body weight increases significantly supplemented with L-Arginine than that of the group gavaged to water(P<0.05), but there is no significant difference between the two groups supplemented with L-Arg(P>0.05). b. There are significant differences between the group gavaged to water and the two groups gavaged to L-Arginine in the content of HSP70 in liver after 42℃ treatment(P<0.05) , but there is no significant difference between the twogroups supplemented with L-Arginine(P>0.05). c. The activity of ALT in serum of the group gavaged to 1.0mg/g.bw and 2.0 mg/g.bw is significantly lowered than that of the group gavaged to water (P<0.05) , but there is no significant difference between the two former groups (P>0.05). 2. The effects of L-Arginine on causing death of heat treated mice: a. The rising ratio of rectal temperature is significant lower in the groups supplemented with L-Arg than that of the group gavaged to water(P<0.05), but there is no significant difference between the two groups supplemented with L-Arg(P>0.05). The 50% lethal time and the survival time for the group supplemented with 1.0 mg/g.bw is the longest within the three groups, and that of the group gavaged to 2.0 mg/g.bw is the shortst. The survival time limit significantly extends in the group gavaged to 1.0 mg/g.bw than that of the two other groups (P<0.05). b. The expressed level of HSP70 in liver is significant lower in the group gavaged to water than that of the other two groups(P<0.05), but there is no significant differences between the latter two groups(P>0.05), the difference between in the production of NO in liver between the three groups is significant (P<0.05), the lowest is the group gaveged to water, and the highest is the group gavaged to L-Arg in 2.0 mg/g.bw. There is a significant difference between the group supplemented with water and the other two groups gavaged to L-Arg in content of MDA(P<0.05), but there is no significant differences between the two latter groups(P>0.05). Conclusions: Suitable dose of L-Arginine supply may play such roles as listed below:1. Inducing the increase of the body weight.2. Reiforcing the expression of HSP70.3. Lowering the activity of ALT in serum.4. Extending the survival time limit of the causing death of heat treated mice, improving the content of NO in liver, potentiating the ability of the liver to tolerate the lipid peroxidation-MDA.