摘要:

Nandrolone, an anabolic androgenic steroid, reduced delta opioid receptor (DOR) mRNA and the number of DOR binding sites in two neuronal hybrid cell lines: NG 108-15 and the GT1-1 cells. Both cell lines express DOR but only GT1-1 cells express androgen receptors (AR). DOR mRNA levels were maximally decreased by ∼45% in NG 108-15 cells and by ∼38% in GT1-1 cells exposed for 24 h to 10−6M nandrolone. This action was partly due to a decrease in the rate of transcription of DOR mRNA and was not blocked by the androgen antagonist flutamide. Flutamide antagonized the repression of AR mRNA induced by nandrolone. The synthetic glucocorticoid dexamethasone (10−6M) did not modify DOR steady-state transcripts in either cell line. These results suggest that nandrolone presumably regulate DOR mRNA levels through mechanisms independent of the androgen and glucocorticoid receptors.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Activation of the amyloid β-protein precursor, secretary pathway through α-secretase has been reported to increase the secretion of neuroprotective amyloid precursor protein and preclude the formation of amyloid β-protein. Activation of protein kinase C has been shown to accelerate this secretory pathway. These results prompted us to focus on a potential links between protein kinase C and the amyloid β-protein-related pathology of Alzheimer disease (AD). Although protein kinase C is reported to occur in senile plaques, its catalytic activity has not been investigated. As the phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS) has been used as a marker for activation of protein kinase Cin vivo, we examined its phosphorylation in brain tissues obtained from seven AD patients and five non-demented subjects using an antibody that specifically recognized MARCKS phosphorylated by protein kinase C. Phosphorylation of MARCKS in cortical neurons in AD brains was weaker than that in control brains. Interestingly, however, phosphorylation of MARCKS was detected in microglia and dystrophic neurites within neuritic plaques, a mature form of amyloid β-protein deposits. These results suggest that protein kinase C alteration is associated with AD pathology and that protein kinase C is activated in microglia and dystrophic neurites by amyloid β-protein in AD brains.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Auditory evoked potentials were recorded while participants attended to visually presented digits. The difficulty of the visual task was manipulated by requiring participants to process only the current digit (0-back) or both the current and the preceding digit (1-back). Tones deviating in frequency from standard tones elicited a frontal mismatch negativity peaking around 200 ms which did not vary with visual task. However, decreasing the visual task load enhanced a right-temporal positive wave peaking around 200 ms when tones were presented slowly, and a frontocentral negative wave peaking around 450 ms when tones were presented more rapidly. The degree to which task-irrelevant sounds are processed therefore depends on the degree to which a visual task engages attentional resources.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Animals emerging from hibernation or daily torpor show an initial increase in electroencephalogram slow-wave activity (SWA, power density between 0.75 and 4.0 Hz) in non-REM sleep, which subsequently declines. These typical features of sleep following prolonged waking led to the interpretation that the animals incur a sleep deprivation (SD) during torpor. This hypothesis has recently been questioned because the increase in SWA disappears in ground squirrels when sleep deprived immediately following hibernation. Here we show that in Djungarian hamsters subjected to SD immediately after daily torpor a predictable increase in SWA occurs during recovery. This supports the notion that the hamsters must sleep to dissipate the pressure for SWA incurred during torpor. The similarity between sleep after waking and torpor may provide a key for understanding sleep regulation.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Bulbospinal sympathoexcitatory neurons in the rostral ventrolateral medulla are inhibited by activation of delta opioid receptors. However, it is not known whether this opioidergic effect is pre- or post- synaptic. Here, using retrograde tracing and immunocytochemistry in adult rats, we provide evidence that the delta opioid receptor is located on boutons that are presynaptic to both catecholaminergic and non-catecholaminergic neurons that project to the spinal cord. We suggest that the sympathoinhibitory action of delta opioid receptor activation in the rostral ventrolateral medulla is mediated presynaptically, resulting in a reduction of excitatory neurotransmitter release from boutons that appose sympathoexcitatory bulbospinal neurons.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

When a food is eaten to satiety, its reward value decreases. This decrease is usually greater for the food eaten to satiety than for other foods, an effect termed sensory-specific satiety. In an fMRI investigation it was shown that for a region of the orbitofrontal cortex the activation produced by the odour of the food eaten to satiety decreased, whereas there was no similar decrease for the odour of a food not eaten in the meal. This effect was shown both by a voxel-wise SPM contrast (p< 0.05 corrected) and an ANOVA performed on the mean percentage change in BOLD signal in the identified clusters of voxels (p< 0.006). These results show that activation of a region of the human orbitofrontal cortex is related to olfactory sensory-specific satiety.

ISSN:0959-4965    

出版商:OVID    

年代:2000

数据来源: OVID