Effects of retinol acid and triiodothyronine on alleviating the impairment of cognitive function by sleep deprivation / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To explore the effects of retinol acid (RA) and triiodothyronine (T3) on alleviating the impairment of cognitive function by sleep deprivation (SD).</p><p><b>METHODS</b>Male Wistar rats were divided into 4 groups: control group (C group), sleep deprivation group (SD group), sleep deprivation + RA group (SD + RA group) and sleep deprivation + T3 group (SD + T3 group). Open field test (OFT) was used to observe the nervous behavior of the rats after SD and electrophysiological brain stereotactic method was used to test long-term potentiation (LTP) in dentate gyrus (DG) of the rats. Ng protein expression was determined by Western blot.</p><p><b>RESULTS</b>Compared with the SD group, the number of crossing in OFT, the changes of amplitude of population spike (PS) and the expression of Ng protein in hippocampus were higher significantly in the SD + RA and SD + T3 groups. All of these had not significant difference comparing with the C group.</p><p><b>CONCLUSION</b>RA and T3 may alleviate the restrain state of neural system after SD by augmenting the expression of Ng protein in hippocampus.</p>

Effects of Polychlorinated Biphenyls on the Development of Neuronal Cells in Growth Period; Structure-Activity Relationship

Polychlorinated biphenyls (PCBs) are accumulated in our body through food chain and cause a variety of adverse health effects including neurotoxicities such as cognitive deficits and motor dysfunction. In particular, neonates are considered as a high risk group for the neurotoxicity of PCBs exposure. The present study attempted to analyze the structure-activity relationship among PCB congeners and the mechanism of PCBs-induced neurotoxicity. We measured total protein kinase C (PKC) activities, PKC isoforms, reactive oxygen species (ROS), and induction of neurogranin (RC-3) and growth associated protein-43 (GAP-43) mRNA in cerebellar granule cells of neonatal rats with phorbol 12, 13-dibutyrate ([3H]PDBu) binding assay, western blot, ROS assay, and reverse transcription PCR (RT-PCR) analysis respectively following the different structural PCBs exposure. Only non-coplanar PCBs showed a significant increase of total PKC-alpha and betaII activity as measured with [3H]PDBu binding assay. ROS were more increased with non-coplanar PCBs than coplanar PCBs. The mRNA levels of RC-3 and GAP-43 were more induced with non-coplanar PCBs than coplanar PCBs, indicating that these factors may be useful biomarkers for differentiating non-coplanar PCBs from coplanar PCBs. Non-coplanar PCBs may be more potent neurotoxic congeners than coplanar PCBs. This study provides evidences that non-coplanar PCBs, which have been neglected in the risk assessment processes, should be added in the future to improve the quality and accuracy of risk assessment on the neuroendocrinal adverse effects of PCBs exposures.

Prenatal restraint stress decreases neurogranin expression in rat offspring hippocampus / 生理学报

Neurogranin, a neuron-specific postsynaptic protein, has been considered to play an important role in synaptic plasticity and learning and memory. The present study aimed to investigate the effects of prenatal restraint stress on neurogranin expression in rat offspring hippocampus. Pregnant rats were given a restraint stress (3 times a day for 7 d, 45 min each time) at the late stage of gestation except that in the control group. The offspring rats were divided into four groups: female control group, male control group, female stress group and male stress group. Expression of neurogranin was determined by immunohistochemistry and Western blot. The results showed that neurogranin-positive immunostaining was detected in all areas of the hippocampus. The staining density was stronger in the CA1 and CA3 regions than that in the dentate gyrus (DG) region. Western blot assay showed that neurogranin protein level in female and male prenatal stressed offspring was significantly lower than that in the controls (P<0.01). Neurogranin level was significantly lower in the female stress group than that in the male stress group, whereas there was no significant gender difference in the control group. Immunohistochemical data further confirmed these results. The present study provides evidence that prenatal restraint stress induces gender-dependent decrease in neurogranin expression in the offspring hippocampus. The prenatal restraint stress-induced decrease in neurogranin expression in the hippocampus might be associated with the deficit in spatial learning and memory reported previously.

Intervention of selenium on neurogranin expression in filial cerebrum of mice with excess iodine / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the effects of excess iodine intake on neurogranin expression in cerebrum of filial mice and the intervention of selenium.</p><p><b>METHODS</b>Sixty BALB/c mice were divided randomly into four groups with different drinking water: control group (tap water, NC), excess iodine group (3000 microg/L I, EL +), supplementing selenium group (200 microg/L Se, Se +) and the excess iodine plus selenium (3000 microg/L + I 200 microg/L Se, EI + Se +) group. The mice were mated at the end of the fourth month. Serum T4 and T3 were determined on postnatal day 14 and 28. The expression level of neurogranin in filial cerebrum was measured by immunohistochemistry and Western blot.</p><p><b>RESULTS</b>Serum T4 level in EI (68.78 +/- 11.10 nmol/ L) + was lower significantly than that in NC (100.85 +/- 11.47 nmol/ L) and EI + Se + (93.15 +/- 12.10 nmol/ L) on postnatal day 14. Western blot analysis showed that the relative level of neurogranin in EI + (0.621 +/- 0.041) was lower than that in NC (0.841 +/- 0.039) and EI + Se + (0.781 +/- 0.029) on postnatal day 14 (P < 0.05). No significant difference in serum T4 and neurogranin level between four groups on postnatal day 28.</p><p><b>CONCLUSION</b>Excess iodine intake might change the expression of neurogranin in filial cerebrum and the selenium supplementation might alleviate it.</p>

Effects of early intervention on learning and memory in young rats of marginal vitamin A deficiency and it's mechanism / 中华儿科杂志

<p><b>OBJECTIVE</b>In recent years, some experiments on vitamin A-deprived animals reveal a progressive and ultimately profound impairment of hippocampal CA1 area's long-term potentiation and these losses are fully reversible by dietary vitamin A replenishment in vivo. Our previous study revealed that marginal vitamin A deficiency (MVAD) beginning from embryonic period impairs learning, memory and long-term potentiation (LTP) in young rats. But the losses might not be reversible if the vitamin A supplementation is late, especially when the critical period of hippocampus development is missed. The present study aimed to observe the recovery of learning and memory in vitamin A marginally deficient young rats after early intervention with vitamin A supplementation and begin to study the mechanism.</p><p><b>METHODS</b>Rats were divided into control, MVAD, vitamin A intervention 1 (VAI1) and VAI2 groups in this study. In control group (10 young rats) the dams and pups were fed with normal diet (VA 6500 U/kg). In MVAD group (19 young rats) the dams and pups were fed with MVAD diet (VA 400 U/kg). In VAI1 group (10 young rats) the dams were fed with MVAD diet till day 14 of pregnancy, then were fed with normal diet and the pups were fed with normal diet. In VAI2 group (13 young rats) the dams were fed with MVAD diet till delivery, then were fed with normal diet and the pups were fed with normal diet too. All the young rats were killed at the age of 7 weeks. During the last week of the experiment, the shuttle box active avoidance reaction tests were carried out. At week 7, the hippocampal CA1 LTP was detected by electrophysiological technique. The expression of RAR-alpha, RAR-beta, RXR-beta, RXR-gamma, RC3 and tTG mRNA was detected by using semi-quantified RT-PCR in hippocampus.</p><p><b>RESULTS</b>(1) The times to reach the learning standard in MVAD group (45.6 +/- 12.1) were more than those in control group (17.1 +/- 4.4) (P < 0.01), in both VAI1 group (20.8 +/- 3.1) and VAI2 group (22.1 +/- 4.0) were more than those in group MVAD (P < 0.01), and there were no significant differences among groups VAI1, VAI2 and control (P > 0.05) in active avoidance reaction tests. (2) The changes of field excitatory postsynaptic potentials (fEPSP) slope for MVAD group [(22.9 +/- 9.4)%] and VAI2 group [(39.1 +/- 4.33)%] were less than that of control group [(57.5 +/- 27.3)%], respectively (P < 0.05). No significant difference was found between VAI1 and control group (P > 0.05). (3) The expression of RAR-beta and RXR-beta mRNA decreased by 48.72% and 37.84% respectively (P < 0.05) compared with control, but the expression of RAR-beta mRNA in group VAI1 was higher than that in group MVAD (P = 0.065). The expression of RC3 mRNA in MVAD group was lower than that in control (P = 0.061) and RAR-alpha mRNA in MVAD group was higher than that in control (P = 0.061). The expression of RXR-gamma and tTG mRNA had no significant difference among different groups as determined with semi-quantified RT-PCR in hippocampus.</p><p><b>CONCLUSION</b>Early vitamin A intervention may make the impaired learning and memory behavior due to marginal vitamin A deficiency recover to the normal level in young rats, but lip losses in group VAI2 might not be reversible. Vitamin A may modulate the expression of RC3 mRNA by affecting RAR-alpha, RAR-beta and RXR-beta to influence the LTP, learning and memory.</p>

Hypermethylation Status of NRGN and OLFM1 Promoter Regionsin Glioblastomas Cell Lines

Glioblastomas are the most malignant astrocytic tumors and the most common brain tumors, representing 50 to 60% of allastrocytic tumors. In a previous study, Marie et al (2005) using SAGE and cDNA microarray analyses, followed by real-time PCRvalidation in additional tumor samples, identified potential markers for astrocytomas with distinct levels of malignancy. In thepresent study, we evaluated if the hypoexpression of two of these genes - Neurogranin (NRGN) and Olfactomedin (OLFM1) – isrelated to the hypermethylation of their promoter regions. CpGs islands were identified in the promoter regions of both genesand tumour cell lines (A172 and T98G) were submitted to 5 Aza dC treatment. The treatment was able to induct the expression(1.8 to 8.9 folds) of both genes. Nevertheless, the association between NRGN and OLFM1 hypoexpression and CpG islandhypermethylation could not be established because the CpGs dinucleotides present in the promoter region of these genes wereunmethylated when evaluated by sequencing.

Effects of PCB Congeners in Rodent Neuronal Cells in Culture

We attempted to analyze the mechanism of polychlorinated biphenyl (PCB) -induced neurotoxicity and identify the target molecules in the neuronal cells for PCBs. Since the developing neuron is particularly sensitive to PCB-induced neurotoxicity, we isolated cerebellar granule cells derived from 7-day old Sprague Dawley (SD) rats and grew cells in culture for additional 7 days to mimic PND-14 conditions. Only non-coplanar PCBs at a high dose showed a significant increase of total protein kinase C (PKC) activity at phobol 12, 13-dibutyrate ([3H]PDBu) binding assay, indicating that non-coplanar PCBs are more neuroactive than coplanar PCBs in neuronal cells. PKC isozymes were immunoblotted with the selected monoclonal antibodies. PKC-alpha, delta, and epsilon were activated with non-coplanar PCB exposure. Receptor for activated C kinase-1 (RACK-1), anchoring protein for activated PKC, was more induced with exposure to coplanar PCBs than non-coplanar PCBs. Reverse transcription PCR (RT-PCR) analysis showed induction of neurogranin (RC-3) and growth associated protein-43 (GAP-43) mRNA with non-coplanar PCBs. The results indicate that these factors may be useful biomarkers for differentiating non-coplanar PCBs from coplanar PCBs. The present study demonstrated that non-coplanar PCBs are more neuroactive congeners than coplanar PCBs.