MicroPET-CT study of the association between odor stimulation and olfactory related brain activation in rats

Abstract

Objective: Using (18)F-fluorodeoxyglucose ((18)F-FDG) and microPET-CT to test the feasibility of (18)F-FDG PET-CT for validation of olfactory function of rats with standard phenethyl alcohol (PEA) and isovaleric acid (IVA) odors stimulation. To verify the possibility of (18)F-FDG PET-CT as a new objective examination method for olfactory function. Methods: Six healthy Sprague-Dawley (SD) male rats were selected with a weight of 250-300 g. First of all, buried food pellet test (BFT) was used to confirm the normal olfactory function of rats. Then in the next 3 days, after the intravenous injection of (18)F-FDG (18 MBq/100 g), awaken rats were placed in a ventilated plexiglas cage for 30 min. Subsequently, pure air (the first day), PEA (the second day) and IVA (the third day) were delivered. After odor stimulation for 30 min, rats were performed by a static PET-CT under anesthesia. Images reconstructed were assessed by SPM method and analyzed by VBM method. Data was analysied by paired t test. Results: Activation regions of rat's brain after PEA stimulation included bed nucleus and insula. Activation regions of rat's brain after IVA stimulation included olfactory bulb, anterior olfactory nucleus, amygdala, entorhinal cortex, olfactory cortex, piriform cortex, insula, prefrontal cortex, cingulate cortex and bed nucleus (P<0.005, Ke>20 voxels). Conclusions: Through microPET-CT, we can observe that olfactory stimulation with different odors can induce metabolic activation in different regions of rat's brain, which was in concordance with olfactory regions. The olfactory related brain regions of rats have strong responses to odor stimulation of IVA.