AIMTo study the effects of vitamin E on stress-induced impairments in hippocampus of rats.

METHODSTwenty four male Wistar rats were randomly allocated into four groups: control, stress, control+ VE, stress+ VE. The rat stress model was built by restraining for 6 h/d,21 d. The long-term potentiation was induced in rat hippocampal dentate gyrus (DG) by high-frequency test stimulation.

RESULTSCompared with control group, the rats suffered from restraint stress showed that the number of crossing in open-field test and the content of glucocorticoids in plasma was significantly increased, the changes of amplitude of population spike (PS) were significantly lower. After VE supplementation in stress rats, the indices mentioned above were significantly improved.

CONCLUSIONOpportune supplementation of vitamin E may improve the brain function under stress.

Animals ; Dentate Gyrus ; drug effects ; physiology ; Electric Stimulation ; Hippocampus ; drug effects ; physiology ; Long-Term Potentiation ; drug effects ; Male ; Rats ; Rats, Wistar ; Stress, Physiological ; Vitamin E ; pharmacology

Long-term potentiation (LTP) is thought as a generative mechanism underlying learning and memory via storing information in central nervous system. Electro-neurophysiological assay for LTP is generally used in screening the drugs that can facilitate learning and memory. By using in vivo LTP technique, isolichenin was found to facilitate LTP induction by a tetanic stimulation (20 pulses/100 Hz) in dentate gyrus. This tetanic stimulation by itself, however, cannot induce LTP. Previous study showed the reagent being able to facilitate LTP-induction, like methanol extract of saffron (MES), usually can antagonize the inhibiting effect of 30% ethanol on LTP induction (30 pulses/60 Hz). Isolichenin may also fall into such kind of drugs. Interestingly, comparatively study showed that isolichenin failed to antagonize the inhibiting effect of 30% ethanol on LTP induction (30 pulses/60 Hz). This result indicates a different unknown mechanism existing in the effect of isolichenin on LTP or memory formation.
Animals ; Crocus ; chemistry ; Dentate Gyrus ; drug effects ; physiology ; Long-Term Potentiation ; drug effects ; physiology ; Male ; Plant Extracts ; pharmacology ; Polysaccharides ; pharmacology ; Rats ; Rats, Wistar

Inducible cyclooxygenase-2 (COX-2) has received much attention because of its role in neuro-inflammation and synaptic plasticity. Even though COX-2 levels are high in healthy animals, the function of this factor in adult neurogenesis has not been clearly demonstrated. Therefore, we performed the present study to compare the effects of pharmacological and genetic inhibition of COX-2 on adult hippocampal neurogenesis. Physiological saline or the same volume containing celecoxib was administered perorally every day for 5 weeks using a feeding needle. Compared to the control, pharmacological and genetic inhibition of COX-2 reduced the appearance of nestin-immunoreactive neural stem cells, Ki67-positive nuclei, and doublecortin-immunoreactive neuroblasts in the dentate gyrus. In addition, a decrease in phosphorylated cAMP response element binding protein (pCREB) at Ser133 was observed. Compared to pharmacological inhibition, genetic inhibition of COX-2 resulted in significant reduction of neural stem cells, cell proliferation, and neuroblast differentiation as well as pCREB levels. These results suggest that COX-2 is part of the molecular machinery that regulates neural stem cells, cell proliferation, and neuroblast differentiation during adult hippocampal neurogenesis via pCREB. Additionally, genetic inhibition of COX-2 strongly reduced neural stem cell populations, cell proliferation, and neuroblast differentiation in the dentate gyrus compared to pharmacological inhibition.
Animals ; Celecoxib/*pharmacology ; Cell Differentiation/drug effects/physiology ; Cell Proliferation/drug effects/physiology ; Cyclooxygenase 2/*genetics/metabolism ; Cyclooxygenase 2 Inhibitors/*pharmacology ; Dentate Gyrus/drug effects/*physiology ; Male ; Mice ; Mice, Knockout ; Neural Stem Cells/drug effects/physiology ; Neurogenesis/drug effects

AIMTo observe the effect of adenosine A, receptor antagonist on synaptic transmission in the dentate gyrus of hippocampus and its relations with NMDA receptor.

METHODSUsing electrophysiological technique to record the long-term potentiation (LTP), the relation between selective adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and NMDA receptor agonist/antagonist, in both basic synaptic transmission and 200 Hz high-frequency stimulation (HFS) induced LTP of the dentate gyrus of hippocampus in anesthetized rats, was studied.

RESULTSDPCPX (6 mg x L(-1), 5 microL, icv) or NMDA (0.2 mg x L(-1), 5 microL, icv) was shown not to affect the synaptic transmission in the dentate gyrus in rats. DPCPX was found not to affect the keeping of LTP induced by HFS after icv NMDA. But the basic synaptic transmission and the magnitude of LTP induced by HFS in the dentate gyrus after icv NMDA could be enhanced significantly by icv DPCPX in advance. DPCPX could not affect the magnitude of LTP inhibited by AP5 (0.5 mg x L(-1), 5 microL) NMDA receptor antagonist, but the inhibitory effect of AP5 on LTP could be antagonized by icv DPCPX in advance.

CONCLUSIONThe selective adenosine A1 receptor antagonist DPCPX could not affect the synaptic transmission in the dentate gyrus of hippocampus, but could significantly enhance the effect of NMDA receptor in both basic synaptic transmission and HFS induced LTP in the dentate gyrus of hippocampus in anesthetized rats.

2-Amino-5-phosphonovalerate ; pharmacology ; Adenosine A1 Receptor Antagonists ; Animals ; Dentate Gyrus ; drug effects ; physiology ; Long-Term Potentiation ; drug effects ; Male ; N-Methylaspartate ; pharmacology ; Rats ; Rats, Wistar ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors ; Synaptic Transmission ; drug effects ; Xanthines ; pharmacology

In this study, we determined how rosiglitazone (RSG) differentially affected hippocampal neurogenesis in mice fed a low-fat diet (LFD) or high-fat diet (HFD; 60% fat). LFD and HFD were given to the mice for 8 weeks. Four weeks after initiating the LFD and HFD feeding, vehicle or RSG was administered orally once a day to both groups of mice. We measured cell proliferation and neuroblast differentiation in the subgranular zone of the dentate gyrus using Ki67 and doublecortin (DCX), respectively, as markers. In addition, we monitored the effects of RSG on the levels of DCX and brain-derived neurotrophic factor (BDNF) in hippocampal homogenates. At 8 weeks after the LFD feeding, the numbers of Ki67- and DCX-positive cells as well as hippocampal levels of DCX and BDNF were significantly decreased in the RSG-treated group compared to the vehicle-treated animals. In contrast, the numbers of Ki67- and DCX-positive cells along with hippocampal levels of DCX and BDNF in the HFD fed mice were significantly increased in the RSG-treated mice compared to the vehicle-treated group. Our data demonstrate that RSG can modulate the levels of BDNF, which could play a pivotal role in cell proliferation and neuroblast differentiation in the hippocampal dentate gyrus.
Animals ; Blotting, Western ; Brain-Derived Neurotrophic Factor/metabolism ; Cell Differentiation/*drug effects ; Cell Proliferation/drug effects ; Dentate Gyrus/growth & development/physiology ; Diet, Fat-Restricted ; *Diet, High-Fat ; Hippocampus/growth & development/physiology ; Hypoglycemic Agents/*pharmacology ; Immunohistochemistry ; Ki-67 Antigen/metabolism ; Male ; Mice, Inbred C57BL ; Microtubule-Associated Proteins/metabolism ; Neurogenesis/*drug effects ; Neuropeptides/metabolism ; Thiazolidinediones/*pharmacology

AIMTo investigate effects of (-), (+)-7-hydroxy-clausenamide (7-OH-Clau) on basal synaptic transmission in the dentate gyrus of anesthetized rats.

METHODSExtracellular recording of the population spike (PS) of hippocampal dentate gyrus following application of low-frequency stimulation (1/30 Hz, 1.0 mA).

RESULTSFifteen, thirty and sixty minutes after intracerebroventricular (icv) administration of an estimated final brain concentration of 2 x 10(-6) mol.L-1, (-)-7-OH-Clau caused over 30% increase relative to basal PS amplitude before administration, and 27%-41% increase relative to vehicle control (P < 0.05), while (+)-7-OH-Clau exhibited 18%-25% and 11%-20% decrease in the PS amplitude when compared with basal PS amplitude and vehicle control (P < 0.05), respectively.

CONCLUSIONThe basal synaptic transmission in the dentate gyrus of the rat hippocampus can be potentiated by (-)-7-OH-Clau and attenuated by (+)-7-OH-Clau, indicating that there was a stereoselective difference between the two enantiomers in the modulation of synaptic responses and plasticity.

Action Potentials ; drug effects ; Animals ; Dentate Gyrus ; drug effects ; physiology ; Drugs, Chinese Herbal ; isolation & purification ; pharmacology ; Excitatory Postsynaptic Potentials ; drug effects ; Injections, Intraventricular ; Lactams ; isolation & purification ; pharmacology ; Lignans ; isolation & purification ; pharmacology ; Male ; Plants, Medicinal ; chemistry ; Rats ; Rats, Sprague-Dawley ; Rutaceae ; chemistry ; Stereoisomerism ; Synaptic Transmission ; drug effects