Aim: Aim of this study was to evaluate the effect of acute stress on rat brain metabolism using PET [18F]FDG and Foot-Shock (FS) paradigm. Regional stress effect was evaluated both by a statistical voxelbased analysis using a rat-model version of Statistical Parametric Mapping (SPM) optimized in our facility. Materials & Methods: 16 male CD rats, randomly assigned into two groups, 8 rats for Control Group (CG) and 8 rats for Stressed Group (SG), were injected with [18F]FDG in a lateral tail vein. Following the FS protocol, the SG was exposed, immediately after radiotracer injection, to the shock session. One hour after [18F]FDG injection, CG and SG were then subjected to a PET brain study for 30 minutes. All animals have been then sacrificed and corticosterone and circulating glucose were measured. A rat template was created using a control rat, outside of the two groups, who performed, in addition to the PET study, an and MRI study: the PET images for this rat, co-registered to his MRI, was used as [18F]FDG/MRI template. Statistical analysis were performed setting p<0.05, a threshold of 100 voxels and rescaling data to a mean glucose consumption value of 28mol/100g/min. In particular three SPM design were used: 1) a single subject design was used both to perform a Jack-Knife analysis on CG and to evaluate each SG rat with respect to CG; 2) a compare-populations model was used to evaluate differences in SG with respect to CG; 3) a simple regression model allowed to evaluate correlations between cerebral glucose metabolism and corticosterone levels in different brain regions. Results: Jack-Knife analysis on CG showed that one rat had a pattern of altered metabolism in comparison to the other control rats, suggesting a different susceptibility to experimental handling. This rat was excluded from analysis. Single-subject analysis on stressed rats revealed a similar pattern, except for one animal. Interestingly this rat escaped from box during stress paradigm. Group analysis showed a relative reduction of regional brain metabolism at the level of thalamus, hypothalamus, entorhinal and piriform cortex, and cerebellum, while an increase was observed in motor, somato-sensory cortex, olfactory bulb regions and hippocampal subregions. A negative correlation was observed between cerebral glucose metabolism and corticosterone levels in different brain regions. Conclusion: Results of the study indicated that acute stress modifies regional brain functions and these modifications are associated with circulating level of stress markers like corticosterone.
Statistical voxel-based analysis of [F-18]FDG PET animal studies for the estimation of glucose metabolism in stress conditions
Di Grigoli G;Gallivanone F;Valtorta S;Castiglioni I;Gilardi M C;Moresco R M;Fazio F
2012
Abstract
Aim: Aim of this study was to evaluate the effect of acute stress on rat brain metabolism using PET [18F]FDG and Foot-Shock (FS) paradigm. Regional stress effect was evaluated both by a statistical voxelbased analysis using a rat-model version of Statistical Parametric Mapping (SPM) optimized in our facility. Materials & Methods: 16 male CD rats, randomly assigned into two groups, 8 rats for Control Group (CG) and 8 rats for Stressed Group (SG), were injected with [18F]FDG in a lateral tail vein. Following the FS protocol, the SG was exposed, immediately after radiotracer injection, to the shock session. One hour after [18F]FDG injection, CG and SG were then subjected to a PET brain study for 30 minutes. All animals have been then sacrificed and corticosterone and circulating glucose were measured. A rat template was created using a control rat, outside of the two groups, who performed, in addition to the PET study, an and MRI study: the PET images for this rat, co-registered to his MRI, was used as [18F]FDG/MRI template. Statistical analysis were performed setting p<0.05, a threshold of 100 voxels and rescaling data to a mean glucose consumption value of 28mol/100g/min. In particular three SPM design were used: 1) a single subject design was used both to perform a Jack-Knife analysis on CG and to evaluate each SG rat with respect to CG; 2) a compare-populations model was used to evaluate differences in SG with respect to CG; 3) a simple regression model allowed to evaluate correlations between cerebral glucose metabolism and corticosterone levels in different brain regions. Results: Jack-Knife analysis on CG showed that one rat had a pattern of altered metabolism in comparison to the other control rats, suggesting a different susceptibility to experimental handling. This rat was excluded from analysis. Single-subject analysis on stressed rats revealed a similar pattern, except for one animal. Interestingly this rat escaped from box during stress paradigm. Group analysis showed a relative reduction of regional brain metabolism at the level of thalamus, hypothalamus, entorhinal and piriform cortex, and cerebellum, while an increase was observed in motor, somato-sensory cortex, olfactory bulb regions and hippocampal subregions. A negative correlation was observed between cerebral glucose metabolism and corticosterone levels in different brain regions. Conclusion: Results of the study indicated that acute stress modifies regional brain functions and these modifications are associated with circulating level of stress markers like corticosterone.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
