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Experimentally induced diabetes causes glial activation, glutamate toxicity and cellular damage leading to changes in motor function.

Nagayach A, Patro N, Patro I - Front Cell Neurosci (2014)

Bottom Line: Active caspase-3 positive apoptotic cells were profoundly present in all three cerebellar layers.Reduced co-labeling of GLT-1 and GFAP revealed the altered glutamate transportation in cerebellum following diabetes.These results, exclusively derived from histology, immunohistochemistry and cellular quantification, provide first insight over the associative reciprocity between the glial activation, cellular degeneration and reduced glutamate transportation, which presumably lead to the behavioral alterations following STZ-induced diabetes.

View Article: PubMed Central - PubMed

Affiliation: School of Studies in Neuroscience, Jiwaji University Gwalior, India.

ABSTRACT
Behavioral impairments are the most empirical consequence of diabetes mellitus documented in both humans and animal models, but the underlying causes are still poorly understood. As the cerebellum plays a major role in coordination and execution of the motor functions, we investigated the possible involvement of glial activation, cellular degeneration and glutamate transportation in the cerebellum of rats, rendered diabetic by a single injection of streptozotocin (STZ; 45 mg/kg body weight; intraperitoneally). Motor function alterations were studied using Rotarod test (motor coordination) and grip strength (muscle activity) at 2nd, 4th, 6th, 8th, 10th, and 12th week post-diabetic confirmation. Scenario of glial (astroglia and microglia) activation, cell death and glutamate transportation was gaged using immunohistochemistry, histological study and image analysis. Cellular degeneration was clearly demarcated in the diabetic cerebellum. Glial cells were showing sequential and marked activation following diabetes in terms of both morphology and cell number. Bergmann glial cells were hypertrophied and distorted. Active caspase-3 positive apoptotic cells were profoundly present in all three cerebellar layers. Reduced co-labeling of GLT-1 and GFAP revealed the altered glutamate transportation in cerebellum following diabetes. These results, exclusively derived from histology, immunohistochemistry and cellular quantification, provide first insight over the associative reciprocity between the glial activation, cellular degeneration and reduced glutamate transportation, which presumably lead to the behavioral alterations following STZ-induced diabetes.

No MeSH data available.


Related in: MedlinePlus

Persistent astroglial activation following diabetes. GFAP immunolabeled light microscopic images of both diabetic and control cerebellum depicting profound astroglial activation during diabetes. Astroglial activation was consistent in white matter and in all the three layers of the cerebellum upto the 12th week of diabetic duration bearing thick, dense, wavy and fragmented processes with a darkly stained large cell body (B–G; arrows). In controls astroglia were presenting resting morphology having thin, fine processes and lightly stained small cell body (A; arrowheads). ML, Molecular layer; PCL, Purkinje cell layer; GCL, Granule cell layer; WM, White matter. Scale bar = 50 μm. Quantitation and area fraction graphs were showing a significantly increased population (i) and volumetric fraction (ii) of GFAP + cells in the diabetic cerebellum upto the 12 weeks post-diabetic confirmation in comparison to controls. Same alphabets on bars indicate non-significant differences between groups at the given time points (p ≤ 0.001). Value represents mean ± s.e.m. of the 30 readings/ animal/ time point. **p ≤ 0.001 for comparison of diabetic group with the respective controls.
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Figure 4: Persistent astroglial activation following diabetes. GFAP immunolabeled light microscopic images of both diabetic and control cerebellum depicting profound astroglial activation during diabetes. Astroglial activation was consistent in white matter and in all the three layers of the cerebellum upto the 12th week of diabetic duration bearing thick, dense, wavy and fragmented processes with a darkly stained large cell body (B–G; arrows). In controls astroglia were presenting resting morphology having thin, fine processes and lightly stained small cell body (A; arrowheads). ML, Molecular layer; PCL, Purkinje cell layer; GCL, Granule cell layer; WM, White matter. Scale bar = 50 μm. Quantitation and area fraction graphs were showing a significantly increased population (i) and volumetric fraction (ii) of GFAP + cells in the diabetic cerebellum upto the 12 weeks post-diabetic confirmation in comparison to controls. Same alphabets on bars indicate non-significant differences between groups at the given time points (p ≤ 0.001). Value represents mean ± s.e.m. of the 30 readings/ animal/ time point. **p ≤ 0.001 for comparison of diabetic group with the respective controls.

Mentions: GFAP expression. An increased GFAP expression in the diabetic cerebellum upto 12th week of diabetes was immunohistochemically observed. In controls, the GFAP labeled Bergmann glial fibers were presenting intact, thin and erect morphology (Figure 3A) while in diabetic animals Bergmann glial fibers became hypertrophied, fragmented and disorganized at all the time points (Figures 3B–G). Similarly, the astroglia in the white matter and granule cell layer also presented activated morphology having thick, dense and fragmented processes with the darkly stained cell body as compared to resting astroglia with thin processes and lightly stained cell body in controls (Figure 4). Quantitation of GFAP positive cells showed a significant gradual increment (p ≤ 0.001) in astroglia population at all the diabetic points, i.e., 2nd week [F(11,359) = 18.548, p ≤ 0.001], 4th week [F(11,359) = 24.187, p ≤ 0.001], 6th week [F(11,359) = 23.972, p ≤ 0.001], 8th week [F(11,359) = 31.600, p ≤ 0.001], 10th week [F(11,359) = 33.203, p ≤ 0.001] and 12th week [F(11,359) = 33.246, p ≤ 0.001] as compared to the respective controls. A progressive escalation was also observed in the cerebellar astroglial population following diabetes (Figure 4i). Volumetric fraction (area fraction) assessment also showed a significant increment in the percentage of GFAP expression at all the diabetic points, i.e., 2nd week [F(11,359) = 9.292, p ≤ 0.001], 4th week [F(11,359) = 8.904, p ≤ 0.001], 6th week [F(11,359) = 9.714, p ≤ 0.001], 8th week [F(11,359) = 13.042, p ≤ 0.001], 10th week [F(11,359) = 16.788, p ≤ 0.001] and 12th week [F(11,359) = 19.489, p ≤ 0.001] as compared to the respective controls (Figure 4ii).


Experimentally induced diabetes causes glial activation, glutamate toxicity and cellular damage leading to changes in motor function.

Nagayach A, Patro N, Patro I - Front Cell Neurosci (2014)

Persistent astroglial activation following diabetes. GFAP immunolabeled light microscopic images of both diabetic and control cerebellum depicting profound astroglial activation during diabetes. Astroglial activation was consistent in white matter and in all the three layers of the cerebellum upto the 12th week of diabetic duration bearing thick, dense, wavy and fragmented processes with a darkly stained large cell body (B–G; arrows). In controls astroglia were presenting resting morphology having thin, fine processes and lightly stained small cell body (A; arrowheads). ML, Molecular layer; PCL, Purkinje cell layer; GCL, Granule cell layer; WM, White matter. Scale bar = 50 μm. Quantitation and area fraction graphs were showing a significantly increased population (i) and volumetric fraction (ii) of GFAP + cells in the diabetic cerebellum upto the 12 weeks post-diabetic confirmation in comparison to controls. Same alphabets on bars indicate non-significant differences between groups at the given time points (p ≤ 0.001). Value represents mean ± s.e.m. of the 30 readings/ animal/ time point. **p ≤ 0.001 for comparison of diabetic group with the respective controls.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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Figure 4: Persistent astroglial activation following diabetes. GFAP immunolabeled light microscopic images of both diabetic and control cerebellum depicting profound astroglial activation during diabetes. Astroglial activation was consistent in white matter and in all the three layers of the cerebellum upto the 12th week of diabetic duration bearing thick, dense, wavy and fragmented processes with a darkly stained large cell body (B–G; arrows). In controls astroglia were presenting resting morphology having thin, fine processes and lightly stained small cell body (A; arrowheads). ML, Molecular layer; PCL, Purkinje cell layer; GCL, Granule cell layer; WM, White matter. Scale bar = 50 μm. Quantitation and area fraction graphs were showing a significantly increased population (i) and volumetric fraction (ii) of GFAP + cells in the diabetic cerebellum upto the 12 weeks post-diabetic confirmation in comparison to controls. Same alphabets on bars indicate non-significant differences between groups at the given time points (p ≤ 0.001). Value represents mean ± s.e.m. of the 30 readings/ animal/ time point. **p ≤ 0.001 for comparison of diabetic group with the respective controls.
Mentions: GFAP expression. An increased GFAP expression in the diabetic cerebellum upto 12th week of diabetes was immunohistochemically observed. In controls, the GFAP labeled Bergmann glial fibers were presenting intact, thin and erect morphology (Figure 3A) while in diabetic animals Bergmann glial fibers became hypertrophied, fragmented and disorganized at all the time points (Figures 3B–G). Similarly, the astroglia in the white matter and granule cell layer also presented activated morphology having thick, dense and fragmented processes with the darkly stained cell body as compared to resting astroglia with thin processes and lightly stained cell body in controls (Figure 4). Quantitation of GFAP positive cells showed a significant gradual increment (p ≤ 0.001) in astroglia population at all the diabetic points, i.e., 2nd week [F(11,359) = 18.548, p ≤ 0.001], 4th week [F(11,359) = 24.187, p ≤ 0.001], 6th week [F(11,359) = 23.972, p ≤ 0.001], 8th week [F(11,359) = 31.600, p ≤ 0.001], 10th week [F(11,359) = 33.203, p ≤ 0.001] and 12th week [F(11,359) = 33.246, p ≤ 0.001] as compared to the respective controls. A progressive escalation was also observed in the cerebellar astroglial population following diabetes (Figure 4i). Volumetric fraction (area fraction) assessment also showed a significant increment in the percentage of GFAP expression at all the diabetic points, i.e., 2nd week [F(11,359) = 9.292, p ≤ 0.001], 4th week [F(11,359) = 8.904, p ≤ 0.001], 6th week [F(11,359) = 9.714, p ≤ 0.001], 8th week [F(11,359) = 13.042, p ≤ 0.001], 10th week [F(11,359) = 16.788, p ≤ 0.001] and 12th week [F(11,359) = 19.489, p ≤ 0.001] as compared to the respective controls (Figure 4ii).

Bottom Line: Active caspase-3 positive apoptotic cells were profoundly present in all three cerebellar layers.Reduced co-labeling of GLT-1 and GFAP revealed the altered glutamate transportation in cerebellum following diabetes.These results, exclusively derived from histology, immunohistochemistry and cellular quantification, provide first insight over the associative reciprocity between the glial activation, cellular degeneration and reduced glutamate transportation, which presumably lead to the behavioral alterations following STZ-induced diabetes.

View Article: PubMed Central - PubMed

Affiliation: School of Studies in Neuroscience, Jiwaji University Gwalior, India.

ABSTRACT
Behavioral impairments are the most empirical consequence of diabetes mellitus documented in both humans and animal models, but the underlying causes are still poorly understood. As the cerebellum plays a major role in coordination and execution of the motor functions, we investigated the possible involvement of glial activation, cellular degeneration and glutamate transportation in the cerebellum of rats, rendered diabetic by a single injection of streptozotocin (STZ; 45 mg/kg body weight; intraperitoneally). Motor function alterations were studied using Rotarod test (motor coordination) and grip strength (muscle activity) at 2nd, 4th, 6th, 8th, 10th, and 12th week post-diabetic confirmation. Scenario of glial (astroglia and microglia) activation, cell death and glutamate transportation was gaged using immunohistochemistry, histological study and image analysis. Cellular degeneration was clearly demarcated in the diabetic cerebellum. Glial cells were showing sequential and marked activation following diabetes in terms of both morphology and cell number. Bergmann glial cells were hypertrophied and distorted. Active caspase-3 positive apoptotic cells were profoundly present in all three cerebellar layers. Reduced co-labeling of GLT-1 and GFAP revealed the altered glutamate transportation in cerebellum following diabetes. These results, exclusively derived from histology, immunohistochemistry and cellular quantification, provide first insight over the associative reciprocity between the glial activation, cellular degeneration and reduced glutamate transportation, which presumably lead to the behavioral alterations following STZ-induced diabetes.

No MeSH data available.


Related in: MedlinePlus