Visualization of Activated BAT in Mice, with FDG-PET and Its Relation to UCP1

Abstract

<span>The visualization of symmetric structure by [₁₈F]-FluoroDeoxyGlucose-Positron Emission Tomography (FDG-PET), corresponding to adipose density in computed tomography (CT), has led to the idea that Brown Adipose Tissue (BAT) could be present in adult human. This article studies the FDG uptake in a mice model deficient on Uncoupling Protein 1 (UCP1), in a simple thermal activation protocol.</span><span> </span><b><span>Methods:</span></b><span> FDG were injected in mice, control and knock out (K.O.) for the UCP1. Before imaging mice were placed either in cold or warm environment. BAT uptake was evaluated by ratio named RISC. <b>Results:</b> In warm condition, mean value of the Ratio of Inter-Scapular uptake (RISC) was 1.34 +/﹣</span></a><span> 0.27. After cold exposure, RISC increased 2 fold for control mice, male K.O. did not increase their RISC, female K.O. increased their RISC up to 2.45.</span><span> </span><b><span>Conclusion: </span></b><span>Our study brought a further confirmation that FDG-PET visualised activated Brown Adipose Tissue. It gives a direct proof of the role of UCP1 in this process. The FDG uptake by cold female K</span><span>.</span><span>O</span><span>.</span><span> mice was unexpected.</span><span></span

Dissociation Between Brown Adipose Tissue 18F-FDG Uptake and Thermogenesis in Uncoupling Protein 1–Deficient Mice

“…The discordance with the findings from the present study could be explained by our use of female UCP1 KO mice. Indeed, coldstimulated BAT 18 F-FDG uptake is diminished in male UCP1 KO mice but not in female counterparts (16).…”

Differences in 18F-Fluorodeoxyglucose uptake in BAT of UCP1 -/- and UCP1+/+ during Adrenergic Stimulation of Non-Shivering Thermogenesis

“…BAT thermogenesis is believed to be contingent upon the expression of the protein UCP1, but con icting results have been reported in the literature concerning 18 F-FDG uptake within BAT of mice with and without UCP1. Differences in animal handling techniques such as feeding status, type of anesthetic, type of BAT stimulation, and estrogen levels were identi ed as possible confounding variables for 18 F-FDG uptake. In this study, we aimed to assess differences in BAT 18 F-FDG uptake between wildtype and UCP1knockout mice using a protocol that minimizes possible variations in BAT stimulation caused by different stress responses to mouse handling.…”

“…Brown adipose tissue (BAT) is a fat tissue found in most mammals that helps regulate energy balance and core body temperature through a sympathetic process known as non-shivering thermogenesis. BAT activity is commonly detected and quanti ed in 18 F-uorodeoxyglucose ( 18 F-FDG) positron emission tomography/computed tomography (PET/CT) scans, and radiotracer uptake in BAT during adrenergic stimulation is often used as a surrogate measure for identifying thermogenic activity in the tissue. BAT thermogenesis is believed to be contingent upon the expression of the protein UCP1, but con icting results have been reported in the literature concerning 18 F-FDG uptake within BAT of mice with and without UCP1.…”

“…BAT activity is commonly detected and quanti ed in 18 F-uorodeoxyglucose ( 18 F-FDG) positron emission tomography/computed tomography (PET/CT) scans, and radiotracer uptake in BAT during adrenergic stimulation is often used as a surrogate measure for identifying thermogenic activity in the tissue. BAT thermogenesis is believed to be contingent upon the expression of the protein UCP1, but con icting results have been reported in the literature concerning 18 F-FDG uptake within BAT of mice with and without UCP1. Differences in animal handling techniques such as feeding status, type of anesthetic, type of BAT stimulation, and estrogen levels were identi ed as possible confounding variables for 18 F-FDG uptake.…”

“…Differences in animal handling techniques such as feeding status, type of anesthetic, type of BAT stimulation, and estrogen levels were identi ed as possible confounding variables for 18 F-FDG uptake. In this study, we aimed to assess differences in BAT 18 F-FDG uptake between wildtype and UCP1knockout mice using a protocol that minimizes possible variations in BAT stimulation caused by different stress responses to mouse handling.…”