The regulatory effects of arginine on hepatic insulin-like growth factor-1 secretion in rats and its implication / 中华烧伤杂志

<p><b>OBJECTIVE</b>To explore the regulatory effect of arginine on the secretion of hepatic insulin-like growth factor-1 (IGF-I), and the mechanism of enhancing the immune function by arginine.</p><p><b>METHODS</b>Wistar rats were randomly divided into normal control (NC), wound control (WC), and wound with arginine (Arg) groups, with 8 rats in each group. The rats in WC and Arg groups were inflicted with soft tissue trauma on the back. The rats in Arg group were fed a diet supplemented with 5% arginine for one week, while those in NC and WC groups were fed with glycine. The serum contents of arginine, ornithine, growth factor (GH), NO and IGF-I were determined 7 days after feeding. T cell proliferation and IGF-I mRNA expression in hepatic tissue were also measured. Meanwhile, the rat hepatocytes were cultured in serum-free medium containing different concentrations of arginine. The supernatant was collected for the determination of IGF-I level.</p><p><b>RESULTS</b>1). There was no obvious difference of the serum level of arginine and ornithine between NC and WC groups (P > 0.05), but the contents of them were obviously higher in the Arg group compared with other two groups (P < 0.01). 2). No difference in the serum GH level was found among all the groups (P > 0.05), but the serum NO content in WC and Arg groups was significantly lower than that in NC group (P < 0.01), and the serum IGF-I content in WC group decreased obviously compared with that in NC group (P < 0.01). 3). The thymocyte proliferation rate in WC group was also markedly lower than that in NC group (P < 0.01), but that in Arg group was improved compared with WC group (P < 0.01). 4). The expression of hepatic IGF-I mRNA: The relative value of IGF-I mRNA was 1.19 +/- 0.06, 1.08 +/- 0.06 and 1.29 +/- 0.06 in NC, WC and Arg, respectively, while the value in WC was lower than that in NC (P < 0.05) group, and that in Arg group was much higher than that in WC group (P < 0.01). 5). The IGF-I level in the supernatant of cultured hepatocytes: When Arg concentration was 0.0750, 0.7500, 7.5000 mmol/L in the culture medium, the IGF-I level in the supernatant of hepatic cell medi-um was obviously higher than that in the medium without arginine (P < 0.01). Although IGF-I level decreased in the culture medium with arginine in the dose of 37.5000 mmol/L, it was still obviously higher than that in the medium without arginine (P < 0.01).</p><p><b>CONCLUSION</b>Arginine could also produce the immune enhancing effect by stimulating hepatic IGF-I secretion.</p>

Effect of zinc on the corticosterone-induced injury of primary cultured rat hippocampal neurons / 生理学报

The effect of zinc on the damage of primary cultured hippocampal neurons induced by corticosterone (CORT) was studied. Neuronal injury and expression of NMDA receptor subunits (NR1,NR2A,NR2B) mRNA were detected by using in situ staining and RT-PCR, respectively. Neurons treated with 5 micromol/L CORT for 24 h showed decreased survival rates and increased apoptotic rates compared with the controls; co-application of CORT and 10 or 100 micromol/L Zn(2+) attenuated apoptotic rates while 250 micromol/L Zn(2+) worsened CORT-induced neuronal injury. Expression of NR1, NR2B mRNA in neurons treated by 5 micromol/L CORT for 24 h was significantly increased, while those concurrently added with 10 or 100 micromol/L Zn(2+) showed no changes. No statistic difference in NR2A mRNA was obtained under any treatment. These results suggest that zinc can bilaterally regulate neuronal injuries induced by CORT, among while NMDA receptors probably play an important role.

Effects of stress on hippocampal Glu-NMDAR pathway in rats and mechanism of zinc protection / 中国应用生理学杂志

<p><b>AIM</b>To observe the effects of stress on Glu uptake and NMDAR of hippocampus synaptosome in rats with different zinc status.</p><p><b>METHODS</b>Stress model was established by photoelectric stimulus. The behaviors of rats were tested in open-field case. 3H-L-Glu was taken as radioligand to detect the NMDAR binding. Glu uptake was determined with radioimmunoassay.</p><p><b>RESULTS</b>Compared with CT rats, ZD rats performed less movement in open-field test, both Bmax of NMDAR and 3H-L-Glu uptake of hippocampus in these rats were significantly decreased. Compared with corresponding non-stressed groups, the stressed groups appeared longer latency and less movement in open-field test. Increased Bmax of NMDAR and decreased 3H-L-Glu uptake were observed in all stressed rats, but only in SZD rats these indices showed statistical difference.</p><p><b>CONCLUSION</b>Abnormal behaviors of rats induced by photoelectric stress were observed in open-field test, which was more serious in zinc deficiency rats. It is supposed that the Glu-NMDAR pathway is involved in the process of stress reaction. As it shows in our experiment, the changes of Bmax of NMDAR and 3H-L-Glu uptake of hippocampus synaptosome seems to be a part of the mechanisms of stress action.</p>

Na+/H+ antiporter and plant salt tolerance / 生物工程学报

Na+/H+ antiporter plays an important role in mechanisms of the plant salt tolerance, it extrudes Na+ from cell energized by the proton gradient generated by the plasm membrane H(+)-ATPase and/or compartmentalizes Na+ in vacuole energized by the proton gradient generated by the vacuolar membrane H(+)-ATPase and H(+)-PPiase. This review mainly discusses the latest progress in the study of Na+/H+ antiporter in plant and yeast at molecular level.