PD Dr. Anke Tönjes, Prof. Dr. Swen Hesse, Dr. Kerstin Krause
Interaction of thyroid hormones and brown adipose tissue
There is a growing interest in brown adipocytes since it has been demonstrated that a notable amount brown adipose tissue (BAT) can be detected also in adults. Furthermore, disseminated adipocytes with typical features of brown adipocytes, termed “brite” or “beige” cells, have been found in white adipose tissue (WAT). This “novel cell type” may either derive from phenotypic transdifferentiation or from de-novo differentiation of white or beige progenitor cells. Recently, BAT has become a potential target for pharmacological and genetic manipulation to treat human obesity since positron emission tomography (PET) has provided evidence that adult humans retain metabolically active BAT depots which can be induced in response to cold and sympathetic nervous system activation, particularly by the thyroid hormone (TH) T3. In contrast to effects on BAT activity, there are no data about the effect of T3 on the formation and molecular origin of new brown adipocytes.
The aim of this study is I.) to investigate if there is an effect of thyroid hormone on BAT formation and II.) to clarify the origin of newly formed adipocytes occurring in the course of hyperthyroidism.
We will apply I) an in-vivo model on hypo- and hyperthyroid mice to assess the nature of BAT by measuring a range of well-established as well as newly identified markers for brown and beige fat under TH treatment as well as measuring BAT-activation using F18-FDG-PET/MRI with newest hybrid technology. II) a human study focussing on the investigation of thyroid function and BAT activity using F18-FDG-PET/CT and F18-FDG-PET/MRI.
(III) Furthermore, we will investigate the differential gene expression of human BAT from supraclavicular regions, in comparison to white adipose tissue (WAT) from subcutaneous abdominal biopsies in patients before and after thyreostatic treatment or thyreoid operation in overt hyperthyroidism. Perspectively, stimulating conversion of white into brown adipocytes through the influence of TH might be translated into an effective therapy to raise energy expenditure.
This project is further integrated in the IFB AdiposityDiseases and the CRC Obesity Mechanisms in Leipzig.
Figure legend: Imaging activated brown adipose tissue with F18-FDG and PET (A), PETCT (B), by data segmentation for quantification (C) and with PETMR (D).
PD Dr. Anke Tönjes
Medical Department of Nuclear Medicine and Molecular NeuroImaging
Phone: +49 341 971 3380
Fax: +49 341 971 3380
Prof. Dr. Swen Hesse
Universität Leipzig, Medizinische Fakultät
Department of Nuclear Medicine, Molecular Neuroimaging IFB Adiposity Diseases
Phone: +49 341 971 8081/ -8242
Fax: +49 341 971 8069
Dr. Kerstin Krause
Department für Innere Medizin
Phone: +49 341 971 32 00
Fax: +49 341 971 32 39
Prof. Dr. Osama Sabri
Karen Geva Steinhoff
+49 341 971 8265