Effects of chronic multiple stress on learning and memory and the expression and phosphorylation of cerebral ERK of rats / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To study the effect of chronic multiple stress on learning and memory, and the expression and activation of cerebral extracellular signal-regulated protein kinase (ERK) 1/2 of rats in vivo.</p><p><b>METHODS</b>Ninety male SD rats were divided randomly into control group and stress group. Rats in stress group were stressed everyday by one of the seven stressors including cold exposure, foot shock, white noise, restraint, tail hung up, sleep deprivation, and level shake, and then the ability of learning and memory was determined by Morris water maze test. Serum corticosterone (CORT) level was determined by radioimmunoassay kit. Western blot was performed to determine the expression and phosphorylation of ERK in hippocampus and prefrontal cortex of the brain.</p><p><b>RESULTS</b>The escape latencies of stressed rats were substantially longer than those of the controls in the water maze test (P < 0.01) except a transient recovery at the end of the third week after the stress. The stress also resulted in significantly higher serum CORT level and decreased P-ERK level in hippocampus and prefrontal cortex (PFC) (P < 0.01). Similarly, transient elevation of both CORT and P-ERK levels were observed at the end of the third week.</p><p><b>CONCLUSION</b>Chronic multiple stress can lead to impaired learning and memory by decreasing the phosphorylation of ERK in the hippocampus and PFC. The partial recovery of learning and memory, CORT and P-ERK levels at the end of the third week may due to the adaptation of the rats to stressors.</p>

The effects of acute fear stress on emotional behaviors, plasmic hormone levels and the activation of cerebral Erk1/2 of rats / 中国应用生理学杂志

<p><b>AIM</b>To study the effect of acute fear stress on emotional behaviors, Hormone levels, and the expression and activation of cerebra Erk1/2 of rats in vivo.</p><p><b>METHODS</b>Fourty eight male SD rats were divided randomly into control group and stress group. Rats of stress group received 30 min' s acute stress including foot shock and white noise, and then the emotional behaviors were observed. The hormone level in plasm and brain was determined by spectrophotofluorometry and radioimmunoassay kit. In the following experiments, Western blot was performed to determine the expression and phosphorylation of extracellular signal-regulated protein kinase (Erk) of four different regions of the brain.</p><p><b>RESULTS</b>Rats tested after acute fear stress displayed substantial decreases in open-field activity, increases in resistance to capture, and increases in fright reaction (P < 0.01). The stress also resulted in significantly higher plasmic and cerebral noradrenaline, corticosteroid, 5-hydroxytryptamine levels, and lower adrenomedulin level in comparison with the control (P < 0.01) after stress. At the time point of 0 min and 30 min after stress, the phosphorylation of Erk1/2 were increased in all four brain regions examined (hippocampus, striatum, prefrontal cortex and cerebellum).</p><p><b>CONCLUSION</b>Acute fear stress can induce abnormalities of emotional behaviors, such as behavioral habits, anxiety and defense, startle and delayed adaptation to startle, as well as the alteration of hormone levels. The phosphorylation of Erk1/2 may play a role in the abnormality of emotional behaviors of rats induced by acute fear stress.</p>

Effects of infrasound exposure on several enzymes activities of spleen and liver in rats / 中国应用生理学杂志

<p><b>AIM</b>To investigate the changes of several enzymes activities in the spleen and liver of rats after exposure to 8 Hz 130 dB infrasound for different time.</p><p><b>METHODS</b>Thirty-five male SD rats were randomly divided into five groups. Rats of group 1 served as control, rats from group 2 to 5 were exposed to 8 Hz 130 dB infrasound, 2 hours per day, for 1 wk, 2 wk, 3 wk, and 4 wk, respectively. The changes of enzymes activities in spleen and liver of rats were observed.</p><p><b>RESULTS</b>Monoamine oxidase activities in spleen were significantly increased at 1 wk and 2 wk, it was decreased at 3 wk, and increased again at 4 wk (P < 0.05). There were no changes in the liver compared with the control group. Glutathione peroxides activities in spleen were significantly increased at 4 wk (P < 0.05) and it also increased in liver at 1 wk (P < 0.05). Superoxide dismutase activities in spleen were increased significantly from 1 wk to 4 wk, but there were no markedly changes in liver. The level of malondialdehyde in spleen were increased at 3 wk and 4 wk. In the liver, it were increased at 1 wk and 2 wk, and decreased at 3 wk, but it increased again at 4 wk (P < 0.05).</p><p><b>CONCLUSION</b>The results indicated that lipid peroxidation and oxygen free radicals in spleen and liver were increased after infrasound exposure and it might induce the damage in tissue or cells.</p>

Effects of vitamin D analogue EB1089 on proliferation and apoptosis of hepatic carcinoma cells / 中华预防医学杂志

<p><b>OBJECTIVE</b>This study aimed at investigating the effects of vitamin D analogue EB1089 on the proliferation and apoptosis of hepatic carcinoma cells.</p><p><b>METHODS</b>Hepatic carcinoma cell strain G(2) (Hep-G(2)) in which prominent vitamin D receptor (VDR) mRNA could be expressed and the cell strain T (HCC-T) negative in VDR gene expression were incubated in culture media with 100 nmol/L, 10 nmol/L and 1 nmol/L EB1089 for 2 d, 4 d and 6 d, respectively. Survival and proliferation of the cells were detected by blue tetrazolium colorimetric test and plate clone-forming test, the VDR mRNA expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) and apoptosis of the cells was detected by flow cytometry (FCM) and electron microscopy.</p><p><b>RESULTS</b>EB1089 could inhibit the proliferation of hepatocellular cell line Hep-G(2) that expressed prominent vitamin D receptor mRNA, the inhibitory rate is 17.5% approximately 72.1%. On the other hand, EB1089 had no anti-proliferative effect on hepatocellular cell line HCC-T in which the gene expression of vitamin D receptors was negative. The electron microscope results showed that EB1089 could induce apoptosis of hepatocarcinoma cells and the percentages of apoptotic cells measured by flow cytometer was 21.4%. Cell cycle progression was blocked at G(1) phase with EB1089.</p><p><b>CONCLUSION</b>EB1089 could inhibit proliferation of human Hep-G(2), probably through VDR, and induce apoptosis of the cells.</p>