Chronobiol Int. 2016;33(10):1369-1375.

Perturbation of the molecular clockwork in the SCN of non-obese diabetic mice prior to diabetes onset.

Ingenwerth M1, Reinbeck AL2, Stahr A1, Partke HJ2,3, Roden M2,3,4, Burkart V2,3, von Gall C1.

1 Institute of Anatomy II, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany.
2 Institute for Clinical Diabetology, German Diabetes Center , Düsseldorf.
3 German Center for Diabetes Research (DZD), München-Neuherberg , Germany.
4 Department of Endocrinology and Diabetology, Medical Faculty , Heinrich-Heine University , Düsseldorf , Germany.

 

Abstract

Circadian disruption is associated with the development of diabetes. Non-obese diabetic (NOD) mice show abnormal diurnal profiles in energy balance and locomotor activity suggesting circadian misalignment. Therefore, we analyzed cFos and mPER1 as markers for rhythmic neuronal activity within the suprachiasmatic nucleus (SCN) of wildtype (WT) and non-diabetic (nNOD) as well as acutely diabetic NOD (dNOD) mice. cFos levels show a day/night difference in both WT and nNOD but not in dNOD. mPER1 levels did not show a day/night difference in both nNOD and dNOD. This suggests that disruption of SCN rhythmicity in NOD mice precedes the actual onset of diabetes.

PMID: 27589389

 

Supplement:

Marc Ingenwerth1, 2 and Charlotte von Gall1

1 Institute of Anatomy II, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225 Duesseldorf, Germany

2 Institute of Pathology, University Hospital of Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45147 Essen, Germany

 

Timely coordinated organ and tissue functions are essential for health in general. A circadian system controls many rhythms in behavior, physiology and metabolism. Disruption of the circadian system is associated with many disorders such as metabolic diseases (Shi et al. 2013) . The endogenous circadian rhythm generator is located in the nucleus suprachiasmaticus (SCN) of the hypothalamus. On the cellular level, the circadian clockwork is composed of interactions between so called clock genes. The SCN orchestrates circadian rhythms by synchronizing subordinate oscillators in the periphery. The SCN itself receives light information from the eyes and thus can be entrained to the environmental light/dark conditions.

Diabetes mellitus is a metabolic disorder with many serious long-term complications such as cardiovascular diseases, stroke, kidney dysfunction, ulcers and eye problems. Both, type 1 and type 2 diabetes are due to environmental “lifestyle” factors and genetic predispositon. Disruption of the circadian system might be one of the lifestyle factors affecting the development of diabetes mellitus. Currently it is under debate whether deregulation of the SCN or misalignment of the SCN with subordinate clocks in the periphery leads to metabolic diseases. To approach this question, we studied photoentrainment and function of the molecular clockwork in a well established mouse model for type 1 diabetes, the non obese diabetic mouse (NOD). In these mice, diabetes develops as a result of a leukocytic infiltrate of the pancreatic islets and the manifestation of the disease can be detected around 10 weeks of age. The onset of diabetes is not only associated with glycosuria and hyperglycaemia but also with a loss of rhythmic spontaneous locomotor activity (Jelenik et al. 2014). As a marker for photoentrainment we used the immediate early gene cFos which is strongly expressed in the SCN during the light phase in regular wild type mice (C57BL6). We found a day (ZT02)/night (ZT14) difference in the number of cFOS-immunoreactive (Ir) cells in the SCN of C57BL6 and pre-diabetic (nNOD) mice (Fig. 1a). However, the number of c-FOS Ir cells was significantly reduced in nNOD mice (Fig. 1a). In acutely diabetic NOD mice (dNOD) there was no day/night difference in the number of cFOS-Ir cells in the SCN (Fig. 1a). As a marker for molecular clockwork function we used the clock gene mPER1 which is strongly expressed in the early dark phase (ZT14) of regular C57BL mice. Surprisingly, the day/night difference in the number of mPER1-Ir cells in the SCN was only present in C57BL6 but not in nNOD or dNOD (Fig. 1b). These data suggest impaired photoentrainment and affected molecular clockwork function in the SCN of NOD mice prior to the manifestation of diabetes. This indicates that deregulation of the SCN precedes the development of diabetes.

 

 

 

Figure 1 Quantitative analyses of the number of (a) cFOS- and (b) mPER1-Immunoreactive (Ir) cells in the SCN of wildtype (C57BL6), non-diabetic NOD (nNOD) and acutely diabetic (dNOD) mice sacrificed either 2 h after the onset of the light phase (ZT02) or 2 h after the onset of the dark phase (ZT14). ***: p<0.001, n.s.: not significantly different (Student’s T-test). n=3 C57BL mice per time-point; n=5 nNOD and dNOD per time-point.

 

References

Shi SQ, Ansari TS, McGuinness OP, Wasserman DH, Johnson CH (2013) Circadian disruption leads to insulin resistance and obesity. Curr Biol. 23:372-81.

Qian J, Scheer FA (2016) Circadian System and Glucose Metabolism: Implications for Physiology and Disease. Trends Endocrinol Metab. 27:282-93.

Jelenik T, Sequaris G, Kaul K, et al. (2014). Tissue-specific differences in the development of insulin resistance in a mouse model for type 1 diabetes. Diabetes. 63:3856–67.