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1.

Purpose

The purpose was to study the effect of estrogen deficiency on contrast agent diffusion into intervertebral disc in a rat model.

Materials and Methods

Seven-month-old female Sprague–Dawley rats were used. Fourteen rats had ovariectomy, and nine rats had sham surgery. Magnetic resonance imaging (MRI) of sagittal midsection of lumbar spine was performed with a 1.5-T magnet. Dynamic MRI was performed after a bolus injection of Gd-DOTA (0.3 mmol/kg) through tail vein. Eight hundred images were acquired at 0.6 s per acquisition. Regions of interests were drawn over three discs per rat. Maximum enhancement (Emax) and enhancement slope (Eslope) were evaluated. MRI was carried out at baseline and 8 weeks postsurgery.

Result

All disc enhancements demonstrated an initial fast wash-in phase followed by a second slower wash-in phase. For initial wash-in phase, E1max and E1slope of all rats remained unchanged at the two time points. For second wash-in phase, E2max and E2slope of control rats remained unchanged, while with ovariectomized rats, E2max showed reduction at 8 weeks (4.5%±5.6%) compared to baseline (10.3%±6.3%, P=.037), and E2slope was lower at 8 weeks (0.015±0.017) than the baseline (0.029±0.022), although it was not statistically significant (P=.101).

Conclusion

Ovariectomy induced detectable decrease in second wash-in phase of contrast agent into lumbar disc.  相似文献   

2.
The forced swimming test (FST) is a useful paradigm that is relatively quick and simple to perform and has been utilized to predict antidepressant activity based on learned helplessness as a model of depression. To date, few studies have used proton magnetic resonance spectroscopy (1H-MRS) to assess antidepressant effects in rats. The purpose of this study was to assess desipramine (DMI) effects on the left dorsolateral prefrontal cortex (DLPFC) of the rats, which were randomly assigned to three groups (control, n=10; FST+saline, n=10; FST+DMI, n=10), using single-voxel localization technique. All 1H-MRS experiments were performed on a Bruker 4.7-T scanner with 400 mm bore magnet, allowing for acquisition of in vivo 1H point-resolved spectroscopy spectra (TR/TE=3000/30 ms, number of data points=2048, NEX=512, voxel volume=27 μl, scan time=25 min). Proton metabolites were quantified automatically using LCModel software and were expressed as ratios to total creatine (Cr+PCr). Major target metabolites such as N-acetyl aspartate (NAA)+N-acetylaspartylglutamate (NAAG), glutamate+glutamine (Glu+Gln), glycerophosphorylcholine+phosphorylcholine (GPC+PCho), myo-inositol (mIns) and taurine (Tau) were successfully quantified with Cramer–Rao lower boundary ≤10%. There were significantly higher mIns/(Cr+PCr) and mIns/(NAA+NAAG) ratios in the FST+saline group compared to the control group. In the FST+DMI group, both mIns/(Cr+PCr) and mIns/(NAA+NAAG) ratios were significantly decreased to the level similar to those in the control group. No other metabolite ratios were significantly different among the three groups. Our findings suggest a possible role of altered mIns level within the left DLPFC of the rat model for depression.  相似文献   

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