摘要:

GINSENG total saponins (GTS) injected intracere-broventricularly (i.c.v.) at doses of 0.1–1 μg inhibited the i.c.v. injection stress-induced plasma corticosterone levels in mice. The inhibitory action of GTS was blocked by co-administered NG-nitro-L-arginine methyl ester (L-NAME; 1.5 μg, i.c.v.), an inhibitor of nitric oxide synthase (NOS). Of the ginsenosides Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, 20(S)-Rg3and 20(R)-Rg3injected i.c.v. at doses of 0.01–1 μg, 20(S)-Rg3and Rc significantly inhibited the i.c.v. injection stress-induced plasma corticosterone levels. The inhibitory actions of 20(S)-Rg3and Rc were blocked by co-administered L-NAME (1.5 μg, i.c.v.). These results suggest that GTS, 20(S)-Rg3and Rc may inhibit the i.c.v. injection stress-induced hypothalamo-pituitary-adrenal response by inducing NO production in the brain.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THIS study was designed to investigate the effects of endomorphin 1 and 2, recently identified μ-opioid receptor selective peptides, on food intake and anxiety in non-food-deprived mice. The intracerebroventricular (i.c.v.) injection of either endomorphin 1 or 2 (0.03–30 nmol) increased food intake in a dose-related manner. A significant increase was observed 20 min after i.c.v. injection of endomorphin 1 or 2 and continued for 4 h. In the elevated plus maze test, the i.c.v. injection of endomorphin 1 (30 nmol) significantly decreased the normal preference for the closed arms. These results suggest that endomorphin produces orexigenic and anxiolytic effects, and that the μ-opioid receptor contributes to the regulation of feeding and anxiety in mice.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

USING a modified method of focal ischemic preconditioning (FIP) followed by permanent middle cerebral artery occlusion (MCAO), we studied the effects of ischemic tolerance on infarct volume. The FIP was achieved by obstructing the blood flow into the MCA using miniature clamps at two points simultaneously. The first point was proximal to its origin and the second was where it intersects the middle cerebral vein. In rats subjected to three short conditioning periods (3 × 3 min with 7 min reperfusion between occlusions), there were significant reductions in the infarct volume in the cerebral cortex induced by the subsequent MCAO in FIP-treated rats compared with sham-operated controls. This rapid FIP-induced ischemic tolerance to subsequent MCAO occurred within 1 day and lasted for 5 days. Tissue lipid peroxidation in the cortex was significantly reduced for up to 2 days after FIP. In contrast, lipid peroxidation increased rapidly after MCAO. A significant reduction in this increase was observed in FIP-treated rats, suggesting a correlation with the subsequent reduction in the infarct volume.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

RECENT studies investigated the pattern of visual exploration along the horizontal axis in patients with neglect. They found a deviated distribution of activity with the centre shifted −150° to the right of the body's mid-sagittal plane. The present study reports comparable observations concerning tactile exploration of space in neglect. We found the whole distribution of patients' exploratory hand movements shifted towards the right. The median activity lay 17.7 cm right of the body's mid-sagittal plane. The frequency of tactile exploration decreased towards the periphery of peripersonal space on the right and the left side. The findings are in clear contrast to the predictions of the attentional gradient model of neglect. They rather favour a deviation of the whole frame for exploratory behaviour towards a new equilibrium on the right. The character of this frame appears to be supramodal in that it determines the distribution of exploratory movements irrespective of whether the subject explores the surround visually or tactually.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE examined whether endothelin-1 (ET-1), a potent vasoconstrictive peptide secreted in high concentration by metastatic prostate cancer cells, produces endothelin receptor-dependent pain behavior when applied to rat sciatic nerve. ET-1 (200–800 μM) applied to the epineurial surface of rat sciatic nerve produced reliable, robust, unilateral hindpaw flinching lasting 60 min. Preemptive systemic morphine completely blocked this effect in a naloxone-reversible manner, suggesting that this behavior was pain-related. Equipotent doses of epineurially applied epinephrine had no effect, suggesting that ET-1 effects are on tissue sites other than sciatic nerve microvessels. Prior and co-administration of BQ-123, an endothelin-A (ETA) receptor antagonist, also blocked ET-1-induced hindpaw flinching establishing that pain behavior induced by ET-1 application to rat sciatic nerve is ETAreceptor mediated.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ACTIVATION in numerous regions of the brain is likely to be involved in the complex neural network function of pain perception. To detect the cortical representation during nonpainful and painful stimuli, which were presented using electrical finger stimulation in six normal right-handed male volunteers, we performed echo-planar functional magnetic resonance imaging (fMRI). Using a 1.5-T MR system that scanned the supratentorial region of the brain, we obtained multislice BOLD-based functional MR images with single-shot gradient-echo echo-planar imaging (EPI). The data show that dispersed brain regions are activated during painful stimulation, and especially demonstrate the significance of the SII-insular region in pain perception.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE effect of oxidative stress on myogenic cells with expanded CTG repeats in the myotonin protein kinase (MtPK) gene was investigated using MtPK cDNA-transformants in order to investigate the disease process underlying myotonic dystrophy. We employed methylmercury as a model for reagents that produce reactive oxygen species (ROS). Mutant MtPK cDNA transformants containing 46 CTG repeats treated with 1 μM methylmercury for 24 h underwent cell death showing the characteristics of apoptosis. In contrast, methylmercury-induced cytotoxicity was weaker in wild type MtPK cDNA transformants. Antioxidants such as N-acetyl-L-cysteine and trolox suppressed methylmercury-induced apoptosis, indicating that the intracellular generation of ROS plays an important role. These studies suggest that expanded CTG repeats in MtPK increase the susceptibility of cells to oxidative stress.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

AT present it is not clear how instrumental actions arise. In our experiments the molluskHelixreceived an aversive stimulus when one of its neurons did not generate an action potential in response to a conditioned stimulus. The appearance of an aversive stimulus did not depend on the generation or failure of a spike in the control neuron. Although the trained and the control neurons were not coupled and did not connect directly by synapses, the magnitudes of the conditioned responses of both the trained and the control neurons depended on the relationship between the nearest previous neuronal responses and the rapidity of their change. These relationships changed several times during learning, and depended on the initial excitability of the control neurons. The trial-and-error method may have revealed itself at the neuronal level.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE Brn-3a POU family transcription factor activates a number of neuronal promoters which are repressed by the closely related Brn-3b factor. Although transcriptional activation by mutant forms of Brn-3a/Brn-3b can occur with a number of different amino acids at position 22 of the POU homeodomain, an isoleucine at this position is of critical importance for transcriptional repression. In addition, this isoleucine residue can mediate an interaction with the herpes simplex virus Vmw65 regulatory protein whereas the valine found in Brn-3a cannot do so. Thus, position 22 in the homeodomain plays a critical role in the function of neuronally expressed POU factors by controlling their interaction with viral and cellular co-activator/co-repressor proteins.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

5-[125I]iodo-3-(2(S)-azetidinylmethoxy)pyridine ([125I]5-I-A-85380) was evaluated in the mouse as a potentialin vivoimaging ligand for central nicotinic acetylcholine receptors (nAChRs). After i.v. administration of [125I]5-I-A-85380, peak brain levels of radioactivity were measured within 1 h and declined slowly over 4 h. [125I]5-I-A-85380 binding was saturable, and both its pharmacology, based upon inhibition studies, and its pattern of accumulation in brain regions having high nAChR densities were consistent with an interaction at α4β2 nAChR agonist binding sites. The thalamus:cerebellum radioactivity ratio, a measure of specific labeling, reached 37. Therefore, radiolabeled 5-I-A-85380 has excellent potential as an imaging radiotracer for nAChRs, particularly with single photon emission computed tomography, when123I is incorporated into the molecule.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID