Journal Club

1. Journal Club Brundel M1, Reijmer YD, van Veluw SJ, Kuijf HJ, Luijten PR, Kappelle LJ, Biessels GJ; on behalf of the Utrecht Vascular Cognitive Impairment (VCI) Study Group. Cerebral microvascular lesions on High-Resolution 7T MRI in patients with type 2 diabetes. Diabetes. 2014 Apr 23. [Epub ahead of print] Fonseca TL1, Werneck-De-Castro JP, Castillo M, Bocco BM, Fernandes GW, McAninch EA, Ignacio DL, Moises CC, Ferreira A, Gereben B, Bianco AC. Tissue-specific inactivation of type 2 deiodinase reveals multilevel control of Fatty Acid oxidation by thyroid hormone in the mouse. Diabetes. 2014 May;63(5):1594-604. doi: 10.2337/db13-1768. Epub 2014 Jan 31. 埼玉医科大学　総合医療センター　内分泌・糖尿病内科 Department of Endocrinology and Diabetes, Saitama Medical Center, Saitama Medical University 松田　昌文　 Matsuda, Masafumi 2014年5月1日8:30-8:55 ８階　医局

2. Members of the Utrecht Vascular Cognitive Impairment Study Group involved in the Utrecht Diabetic Encephalopathy Study (in alphabetical order by department): the department of Neurology: E. van den Berg, G.J. Biessels, M. Brundel, W. Bouvy, S. Heringa, L.J.Kappelle; the Department of Radiology/Image Sciences Institute: J. de Bresser, H.J. Kuijf, A.Leemans, P.R. Luijten, W.P.Th.M. Mali, M.A. Viergever, K.L. Vincken, J. Zwanenburg; Julius Center for Health Sciences and Primary Care: A. Algra, G.E.H.M. Rutten

3. BACKGROUND Cerebral small vessel disease, including microvascular lesions, is considered to play an important role in the development of type 2 diabetes mellitus (T2DM) associated cognitive deficits. With ultra-high field MRI microvascular lesions (e.g. microinfarcts and microbleeds) can now be visualized in vivo.

4. METHODS For the present study, 48 nondemented older individuals with T2DM (mean age 70.3±4.1 years) and 49 age-, sex-, and education-matched control subjects underwent a 7T brain MRI scan and a detailed cognitive assessment. The occurrence of cortical microinfarcts and cerebral microbleeds was assessed on FLAIR and T1-weighted images and T2*-weighted images respectively, compared between the groups and related to cognitive performance.

5. Data are presented as mean ± SD or n (%) unless otherwise specified. * Estimated by the Dutch version of the National Adult Reading Test. † Mean values for three measurements; for one control subject blood pressure was not examined. ‡Defined as a clinical history of myocardial infarction, stroke (not including TIA) or endovascular or surgical treatment of carotid, coronal or peripheral arterial disease. §Rated with the Toronto Clinical Neuropathy Scoring System (8) || Defined as an albumin-to-creatinine ratio of >300 μg/mg ¶Data are presented as mean standardized z-scores ± SD.

6. Figure 1. An example of a cortical microinfarct, which appears hyperintense on FLAIR(A) and hypointense on T1-weighted (B) 7 tesla MR images.

7. Data are presented as mean ± SD, n (%), or median (range). ICV = intracranial volume * Determined at 7T field strength † Determined at 3T field strength

8. Figure 2. Number of microinfarcts (A) and microbleeds (B) in controls and patients with T2DM. The number of microvascular lesions did not differ between the groups (Mann Whitney U test for number of microinfarcts: p=0.35; for number of microbleeds: p=0.55).

9. RESULTS Microinfarctswere found in 38% of controls and 48% of patients with T2DM. Microbleeds were present in 41% of control participants, and 33% of patients (all p>0.05). Presence and number of microinfarcts or microbleeds were unrelated to cognitive performance.

10. CONCLUSIONS This study showed that microvascular brain lesions on ultra-high field MRI are not significantly more common in well-controlled patients with T2DM than in controls.

11. Message 7T の脳MRIでの解析。やはり糖尿病患者で障害部位が多いようだが有意差はなし。そして認識には影響が出ていないという。 7Tの磁力は相当なものだと思うが頭は大丈夫なのだろうか。

13. 安静時には脳以外の組織はブドウ糖よりも主に脂肪酸をエネルギー源として用いる。「油」の方がエネルギー効率はよく合目的である。ただし脂肪酸は脳脊髄関門を通れない。脂肪酸とブドウ糖利用の比率は呼吸商(respiratory quotient; RQ)に反映され，尿中窒素量を測定すると酸化されたブドウ糖の利用率は推定できる。 基質1gあたりの発生・消費量表 C6H12O6 + 6O2 → 6CO2 + 6H2O + エネルギー (糖質はブドウ糖換算で計算する) A,B,Cの３人の早朝空腹時のRQ(呼吸商)を測定したところAは0.72, Bは0.81, Cは0.95であった。このうち１名は測定直前におにぎり１個食べていたという。A,B,Cのうち誰か？

14. 1Division of Endocrinology, Diabetes, and Metabolism, Miller School of Medicine, University of Miami, Miami, FL 2Biophysics Institute and School of Physical Education and Sports, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil 3Department of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary

15. OBJECTIVEType 2 deiodinase (D2) converts the prohormonethyroxine (T4) to the metabolically active molecule 3,5,3′-triiodothyronine (T3), but its global inactivation unexpectedly lowers the respiratory exchange rate (respiratory quotient [RQ]) and decreases food intake.

16. RESEARCH DESIGN AND METHODS Here we used FloxD2 mice to generate systemically euthyroid fat-specific (FAT), astrocyte-specific (ASTRO), or skeletal-muscle-specific (SKM) D2 knockout (D2KO) mice that were monitored continuously.

17. Supplementary Figure 1. Energy expenditure (EE) in GLOB-D2KO, ASTRO-D2KO, FAT-D2KO and SKM-D2KO measured under different conditions. The KO and WT controls were acclimated to individual metabolic cages in the comprehensive lab animal monitoring system (C.L.A.M.S.) for 48 hours before measurements were recorded. A) Energy expenditure (EE) during 12h light and dark cycles recorded on the second day after acclimatization in the GLOB-D2KO and WT mice at room temperature; B) Same as in A, except measurements were recorded during acute cold (4oC) exposure of 24hs duration; C) Same as in A, except measurements were recorded on the first day of a 48hs interval of fasting; D) EE in the ASTROD2KO and controls at room temperature; E) EE in the FAT-D2KO and controls at room temperature; F) Same as in E, except measurements were recorded during chronic (15 days) exposure to thermoneutrality (30oC); G) Same as in E, except measurements were recorded on the first day of a 48hs interval of fasting; H) Same as in E, except easurements were recorded in the animals kept at room temperature after 8 weeks on HFD; I) Same as in H, however the animals were kept at thermoneutrality (30oC); J) EE in the SMK-D2KO and controls at room temperature; L) Same as in J, except measurements were recorded in the animals kept at room temperature after 8 weeks on HFD; Entries are mean ± SEM. Statistical significance is shown in each graph and was set as p < 0.05. Student’s t test was used to compare KO animals and the respective controls.

18. Figure 1—Metabolic phenotype of the GLOB-D2KO mouse. GLOB-D2KO and WT controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. (A) Oxygen consumption (VO2) during 12-h light and dark cycles recorded at the second day after acclimatization. (B) Same as in A, except that what is shown is RQ. (C) Contribution of fat oxidation to daily EE during the light cycle. (D) Food intake during light and dark cycles of animals kept on regular chow diet at room temperature (22°C). Entries are mean ± SEM of 3–7 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare WT and GLOBD2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

19. Figure 1—Metabolic phenotype of the GLOB-D2KO mouse. GLOB-D2KO and WT controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. (E) VO2 during 12-h light and dark cycles recorded during acute cold (4°C) exposure. (F) Same as in E, except that what is shown is RQ. (G) Food intake during light and dark cycles of animals kept on regular chow diet during the period of cold (4°C) exposure. Entries are mean ± SEM of 3–7 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare WT and GLOBD2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

20. Figure 1—Metabolic phenotype of the GLOB-D2KO mouse. GLOB-D2KO and WT controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. (H) VO2 register during chronically (15 days) cold exposed, where the environment temperature was gradually and progressively decreased every 3–4 days. (I) Same as in H, except that what is shown is RQ. Entries are mean ± SEM of 3–7 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare WT and GLOBD2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

21. Figure 1—Metabolic phenotype of the GLOB-D2KO mouse. GLOB-D2KO and WT controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. (J) VO2 during 12-h light and dark cycles recorded on the first day of 48 h of fasting. (K) Same as in J, except that what is shown is RQ. Entries are mean ± SEM of 3–7 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare WT and GLOBD2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

22. Figure 2—Metabolic phenotype of the ASTRO-D2KO mouse kept on regular chow diet at room temperature (22°C). (A) Body weight evolution during the 2-month period. (B) Body weight of the animals right before admission to CLAMS. (C) Body composition measured by DEXA 48 h before the animals were admitted to CLAMS. (D) VO2 during 12-h light and dark cycles. ASTRO-D2KO mouse and controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. Data shown are from the second day after acclimatization. (E) Same as in D, except that what is shown is RQ. (F) Contribution of fat oxidation to daily EE during the light cycle. (G) Food intake of the same animals during light and dark cycles. Entries are mean ± SEM of 4–5 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and ASTRO-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

23. Figure 2—Metabolic phenotype of the ASTRO-D2KO mouse kept on regular chow diet at room temperature (22°C). (A) Body weight evolution during the 2-month period. (B) Body weight of the animals right before admission to CLAMS. (C) Body composition measured by DEXA 48 h before the animals were admitted to CLAMS. (D) VO2 during 12-h light and dark cycles. ASTRO-D2KO mouse and controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. Data shown are from the second day after acclimatization. (E) Same as in D, except that what is shown is RQ. (F) Contribution of fat oxidation to daily EE during the light cycle. (G) Food intake of the same animals during light and dark cycles. Entries are mean ± SEM of 4–5 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and ASTRO-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

24. Figure 2—Metabolic phenotype of the ASTRO-D2KO mouse kept on regular chow diet at room temperature (22°C). (A) Body weight evolution during the 2-month period. (B) Body weight of the animals right before admission to CLAMS. (C) Body composition measured by DEXA 48 h before the animals were admitted to CLAMS. (D) VO2 during 12-h light and dark cycles. ASTRO-D2KO mouse and controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. Data shown are from the second day after acclimatization. (E) Same as in D, except that what is shown is RQ. (F) Contribution of fat oxidation to daily EE during the light cycle. (G) Food intake of the same animals during light and dark cycles. Entries are mean ± SEM of 4–5 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and ASTRO-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

25. Supplementary Figure 2. Characterization of FAT-D2KO mouse. A) Dio2 expression in the BAT of FAT-D2KO mouse and Controls (n=5) ; B) D2 activity in sonicate of BAT in WT, Cre Fabp4, FloxD2 and FAT-D2KO mouse (n=4-6); C) D2 activity in sonicate of cortex in control and FAT-D2KO mouse (n=4) and D) Serum TSH, E) T4 and F) T3 levels of control and Fat-D2KO mice (n=10-11). Entries are mean ± SEM. Statistical significance is shown in each graph and was set as p < 0.05. Student’s t test was used to compare controls and FAT-D2KO. (*, p<0.05 and ***, p<0.001 vs. control).

26. Figure 3—Metabolic phenotype of the FAT-D2KO mouse kept on regular chow diet. (A) Body weight evolution during the 5-month period of animals kept at room temperature (22°C). The FAT-D2KO mouse and controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. (B) Body weight of the animals right before the animals were admitted to CLAMS Entries are mean ± SEM of 5–12 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of day (12 h). *, P < 0.05; **, P < 0.01; ***, P < 0.001 vs. control; AUC, area under the curve; IP, intraperitoneal.

27. Figure 3—Metabolic phenotype of the FAT-D2KO mouse kept on regular chow diet. (C) Body composition measured by DEXA 48 h before the animals were admitted to CLAMS. (D) VO2 during 12-h light and dark cycles recorded the second day after acclimatization of animals kept on regular chow diet at room temperature (22°C). Entries are mean ± SEM of 5–12 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of day (12 h). *, P < 0.05; **, P < 0.01; ***, P < 0.001 vs. control; AUC, area under the curve; IP, intraperitoneal.

28. Figure 3—Metabolic phenotype of the FAT-D2KO mouse kept on regular chow diet. (E) Same as in D, except that what is shown is RQ. (F) Contribution of fat oxidation to daily EE during the light cycle in the same animals. (G) Food intake during light and dark cycles in the same animals. Entries are mean ± SEM of 5–12 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of day (12 h). *, P < 0.05; **, P < 0.01; ***, P < 0.001 vs. control; AUC, area under the curve; IP, intraperitoneal.

29. Figure 3—Metabolic phenotype of the FAT-D2KO mouse kept on regular chow diet. (H) Blood glucose concentrations at the indicated time points after intraperitoneal glucose injection (2 g/kg) in 2-month-old FAT-D2KO and control animals. (I) Blood glucose concentration at the indicated time points before and after intraperitoneal injection of regular human insulin (0.75 units/kg body weight) in 2-month-old FAT-D2KO and control animals. Entries are mean ± SEM of 5–12 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of day (12 h). *, P < 0.05; **, P < 0.01; ***, P < 0.001 vs. control; AUC, area under the curve; IP, intraperitoneal.

30. Figure 3—Metabolic phenotype of the FAT-D2KO mouse kept on regular chow diet. (J) VO2 during 12-h light and dark cycles recorded during chronic (15 days) exposure to thermoneutrality (30°C). (K) Same as in E, except that what is shown is RQ. (L) Food intake during light and dark cycles of animals kept at thermoneutrality. Entries are mean ± SEM of 5–12 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of day (12 h). *, P < 0.05; **, P < 0.01; ***, P < 0.001 vs. control; AUC, area under the curve; IP, intraperitoneal.

31. Figure 3—Metabolic phenotype of the FAT-D2KO mouse kept on regular chow diet. (M) VO2 during 12-h light and dark cycles recorded on the first day of 48 h of fasting. (N) Same as in J, except that what is shown is RQ. Entries are mean ± SEM of 5–12 animals. Area under the curve was calculated during light and dark cycles for each individual animal. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of day (12 h). *, P < 0.05; **, P < 0.01; ***, P < 0.001 vs. control; AUC, area under the curve; IP, intraperitoneal.

32. Figure 4—Effect of HFD in the FAT-D2KO mice at room temperature and thermoneutrality. The FAT-D2KO and controls were fed with HFD for 8 weeks. (A) Body weight evolution during 8 weeks of treatment of animals kept at room temperature (22°C). *P < 0.05 vs. control. (B) Area under the curve from the body weight shown in A was calculated from each individual animal. *P < 0.05 vs. control. (C) Food intake during light and dark cycles in the same animals Entries are mean ± SEM of 5–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

33. Figure 4—Effect of HFD in the FAT-D2KO mice at room temperature and thermoneutrality. The FAT-D2KO and controls were fed with HFD for 8 weeks. (D) Body composition measured by DEXA in the animals kept at room temperature before (day 1) and after (day 60) HFD. *P < 0.05 vs. day 1. (E) D% of fat measured by DEXA in D, calculated by the difference between days 1 and 60. *P < 0.05 vs. control. (F) Contribution of fat oxidation to daily EE during the light cycle in the same animals. Entries are mean ± SEM of 5–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

34. Figure 4—Effect of HFD in the FAT-D2KO mice at room temperature and thermoneutrality. The FAT-D2KO and controls were fed with HFD for 8 weeks. (G) VO2 during 12-h light and dark cycles in the animals kept at room temperature after 8 weeks on HFD. The FAT-D2KO mouse and controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. Data shown are from the second day after acclimatization. (H) Same as in G, except that what is shown is RQ. Entries are mean ± SEM of 5–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

35. Figure 4—Effect of HFD in the FAT-D2KO mice at room temperature and thermoneutrality. The FAT-D2KO and controls were fed with HFD for 8 weeks. (I) Body weight evolution during 8 weeks of treatment of animals kept at thermoneutrality (30°C). (J) Area under the curve from the body weight represented in I, calculated from each individual animal. (K) Food intake during light and dark cycles in the same animals. Entries are mean ± SEM of 5–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

36. Figure 4—Effect of HFD in the FAT-D2KO mice at room temperature and thermoneutrality. The FAT-D2KO and controls were fed with HFD for 8 weeks. (L) Body composition measured by DEXA in the animals kept at thermoneutrality before (day 1) and after (day 60) HFD. *P < 0.05 vs. day 1. (M) D%of fat measured by DEXA in L, calculated by the difference between days 1 and 60. (N) Contribution of fat oxidation to daily EE during the light cycle in the same animals. Entries are mean ± SEM of 5–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

37. Figure 4—Effect of HFD in the FAT-D2KO mice at room temperature and thermoneutrality. The FAT-D2KO and controls were fed with HFD for 8 weeks. (O) VO2 during 12-h light and dark cycles in the animals kept at thermoneutrality after 8 weeks on the HFD. (P) Same as in O, except that what is shown is RQ. Entries are mean ± SEM of 5–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and FAT-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

38. Figure 5—Metabolic phenotype of the SKM-D2KO mouse kept on regular chow diet and HFD at room temperature (22°C). (A) Body weight evolution during the 2-month period. (B) Body weight of the animals right before admission to CLAMS. (C) Body composition measured by DEXA 48 h before the animals were admitted to CLAMS. Entries are mean ± SEM of 3–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and SKM-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

39. Figure 5—Metabolic phenotype of the SKM-D2KO mouse kept on regular chow diet and HFD at room temperature (22°C). (D) VO2 during 12-h light and dark cycles. SKM-D2KO mouse and controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. Data shown are from the second day after acclimatization. (E) Same as in D, except that what is shown is RQ. Entries are mean ± SEM of 3–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and SKM-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

40. Figure 5—Metabolic phenotype of the SKM-D2KO mouse kept on regular chow diet and HFD at room temperature (22°C). (F) Contribution of fat oxidation to daily EE during the light cycle. (G) Food intake of the same animals during light and dark cycles. Entries are mean ± SEM of 3–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and SKM-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

41. Figure 5—Metabolic phenotype of the SKM-D2KO mouse kept on regular chow diet and HFD at room temperature (22°C). (H) Body weight evolution during 8 weeks of treatment with HFD in animals kept at room temperature (22°C). (I) Area under the curve from the body weight represented in H, calculated from each individual animal. Entries are mean ± SEM of 3–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and SKM-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

42. Figure 5—Metabolic phenotype of the SKM-D2KO mouse kept on regular chow diet and HFD at room temperature (22°C). (J) Body composition measured by DEXA in the animals kept at room temperature before (day 1) and after (day 60) HFD. (K) D% of fat measured by DEXA in J, calculated by the difference between days 1 and 60. Entries are mean ± SEM of 3–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and SKM-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

43. Figure 5—Metabolic phenotype of the SKM-D2KO mouse kept on regular chow diet and HFD at room temperature (22°C). (L) VO2 during 12-h light and dark cycles in the animals kept at room temperature after 8 weeks on HFD. The SKM-D2KO mouse and controls were acclimated to individual metabolic cages in the CLAMS for 48 h before measurements were recorded. Data shown are from the second day after acclimatization. (M) Same as in E, except that what is shown is RQ. Entries are mean ± SEM of 3–6 animals. Statistical significance is shown in each graph and was set as P < 0.05. Student t test was used to compare controls and SKM-D2KO groups within treatment conditions. Black horizontal bars denote the dark period of the day (12 h). AUC, area under the curve.

44. RESULTSThe ASTRO-D2KO mice also exhibited lower diurnal RQ and greater contribution of fatty acid oxidation to energy expenditure, but no differences in food intake were observed. In contrast, the FAT-D2KO mouse exhibited sustained (24 h) increase in RQ values, increased food intake, tolerance to glucose, and sensitivity to insulin, all supporting greater contribution of carbohydrate oxidation to energy expenditure. Furthermore, FAT-D2KO animals that were kept on a high-fat diet for 8 weeks gained more body weight and fat, indicating impaired brown adipose tissue (BAT) thermogenesis and/or inability to oxidize the fat excess. Acclimatization of FAT-D2KO mice at thermoneutrality dissipated both features of this phenotype. Muscle D2 does not seem to play a significant metabolic role given that SKM-D2KO animals exhibited no phenotype.

45. CONCLUSIONSThe present findings are unique in that they were obtained in systemically euthyroid animals, revealing that brain D2 plays a dominant albeit indirect role in fatty acid oxidation via its sympathetic control of BAT activity. D2-generated T3 in BAT accelerates fatty acid oxidation and protects against diet-induced obesity.

46. Message FT4とFT3の血中レベルはほとんど変化ないというが、組織でのFT3のレベルが低くなるような変異であると脳の変化でFFAの消費が増えるようである。褐色脂肪細胞でのFFAの燃焼に間接的に影響しているようである。 ただし、血中FT3低下などに結びつかないので生理的／病的な意義はよくわからないが。