Siewiera 2017 MiP2017

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Karolina Siewiera
Changes in blood platelet and brain mitochondrial respiration during short and long-lasting STZ-induced diabetes.

Link: MiP2017

Siewiera K, Labieniec-Watala M, Karolczak K, Wolska N, Polak D, Kassassir H, Watala C (2017)

Event: MiP2017

COST Action MITOEAGLE

Numerous reports suggest that chronic diabetes can lead to complications in the central nervous system and may result in cognitive dysfunction and dementia. These changes can be relatively subtle and can progress over time. Since neurons have a high energy demand, impaired mitochondrial function may result in diabetic encephalopathy. Due to rather poor availability of the brain tissue in the in vivo studies, in translational research easily accessible cells that could possibly act as the indicator(s) of these changes are looked for. Therefore, the idea and the aim of this study was to evaluate and compare changes in blood platelet mitochondrial respiration with those occurring in brain in the course of short and long-lasting STZ-induced diabetes. Our working hypothesis was that blood platelets may constitute good bioenergetic markers of metabolic brain impairments in severe hyperglycaemia.

For this purpose one hundred 8-week-old Sprague–Dawley rats were randomly allocated into healthy and diabetic groups. In order to induce diabetes, the animals were intraperitoneally injected with streptozotocin (STZ). After 1, 2.5 and 5-month of confirmed diabetes, the survived individuals were anaesthetised and the blood was collected from the abdominal aorta into 3.2% sodium citrate. Blood platelets were isolated using a multiple-stage centrifugation procedure. Immediately after the blood collection, cerebral hemispheres were removed post-mortem, placed in ice-cold MiR05 buffer, and then homogenized. The mitochondrial respiration parameters in intact blood platelets were monitored with the use of O2k high-resolution respirometry (Oroboros Instruments, Innsbruck, Austria), according to the protocol described by Gnaiger and Renner-Sattler [1], and the brain tissue homogenates were measured according to the Benani et al. [2] protocol with a small modification (FCCP titration).

After the first month of diabetes, diabetic animals demonstrated decreased brain mitochondrial respiration in E state (p< 0.05). However, we did not confirm these changes in the blood platelets, where no changes in respiration between 1 month-diabetic and control animals were observed. Longer-lasting diabetes (2.5 mo.) led to elevated respiration under conditions without addition of substrates (LEAK) (p< 0.05), while after glutamate addition (LEAKG) (p< 0.01) and after oligomycin addition (LEAKOmy) (p< 0.05) in brain mitochondria, indicating elevated electron and proton leak and only slightly elevated E state respiration in blood platelet mitochondria (p=0.0534).

Our results indicate that in a streptozotocin-diabetes model blood platelets are not a suitable markers of the changes in the brain mitochondria and that the changes in brain mitochondria seem to be much better marked compared to those observed in platelet mitochondria.


Bioblast editor: Kandolf G O2k-Network Lab: PL Lodz Watala C


Labels: MiParea: Respiration  Pathology: Diabetes 

Organism: Rat  Tissue;cell: Nervous system, Blood cells, Platelet  Preparation: Intact cells, Homogenate 


Coupling state: LEAK, ET  Pathway:HRR: Oxygraph-2k 


Affiliations

Siewiera K(1), Labieniec-Watala M(2), Karolczak K(1), Wolska N(1), Polak D(1), Kassassir H(1), Watala C(1)
  1. Dept Haemostasis Haemostatic Disorders, Chair Biomedical Sciences, Medical Univ Lodz
  2. Fac Biol Environm Protection, Dept Medical Biophysics, Univ Lodz; Poland. - ksiewiera@gmail.com

References and acknowledgements

Gnaiger E, Renner-Sattler K. (2009) High-resolution respirometry with cultured cells: a demonstration experiment, In: Gnaiger, E. (Ed.) Mitochondrial Pathways and Respiratory Control. 2nd ed. Oroboros MiPNet Publications, Innsbruck 62–73.
  1. Benani A, Barquissau V, Carneiro L, Salin B, Colombani A-L, Leloup C, Casteilla L, Rigoulet M, Pénicaud L (2009) Method for functional study of mitochondria in rat hypothalamus. J Neuroscience Methods 178:301–7.
The study supported by the National Centre of Science (NCN 2015/17/N/NZ5/02603 and NCN 2016/20/T/NZ3/00505) and by COST Action CA15203 MitoEAGLE Evolution - Age - Gender - Lifestyle – Environment: mitochondrial fitness mapping.