199
Neuroscience Letters, 128 (1991) 199-202 © 1991 Elsevier Scientific Publishers Ireland Ltd. 0304-3940/91/$ 03.50 ADONIS 030439409100356C NSL 07874
Local action of the diabetogenic drug, streptozotocin, on glucose and energy metabolism in rat brain cortex Roger Nitsch* and Siegfried H o y e r Department of Pathochemistry and GeneralNeurochemistry, University of Heidelberg, Heidelberg ( F.R.G.) (Received 21 February 1991; Revised version received 12 April 1991; Accepted 15 April 1991)
Key words: Brain energy metabolism; ATP; Glucose; Brain cortex; Streptozotocin; Animal model Glucose is the principal source for energy production in the brain, and undisturbed glucose metabolism is pivotally significant for normal function of this organ. Peripheral glucose metabolism is impaired by streptozotocin (STZ), which induces diabetes mellitus. In this investigation, we have studied the local effects of intracerebroventricular (i.c.v.) STZ on glucose and energy metabolism in cerebral cortex. Three weeks after one single i.c.v, administration of STZ, ATP and phosphocreatine (CrP) concentrations as well as the ATP/ADP ratio and the enery charge potential were decreased, while the concentrations of glucose and ADP were increased, in cerebral cortex. Arterial blood glucose levels were not altered by i.c.v. STZ. It is concluded that brain energy metabolism is locally impaired by i.c.v. STZ. We propose that the disturbance of brain energy metabolism by i.c.v, STZ administration may provide a model for the study of prolonged metabolic neuronal stress.
Perturbations in the supply of glucose to the brain as well as impairments of brain glucose and energy metabolism may be expected to alter normal brain function [24]. Brain glucose and energy metabolism is in fact impaired in neurodegenerative brain disorders such as Alzheimer's disease. In particular, brain glucose utilization and brain tissue levels of energy rich phosphates are reduced in patients with Alzheimer's disease [9, 25]. In experimental animals, glucose metabolism in nonneural tissues is disturbed by streptozotocin (STZ), a glucosamine derivative of nitrosourea, which produces hyperglycemia when injected peripherally. The resulting diabetes mellitus is caused by inhibition of pancreatic insulin secretion [3] and decreased insulin receptor signalling in the target cells [11]. STZ is therefore most frequently used to induce insulin-dependent diabetes mellitus in experimental animals [10, 12, 13, 23]. To our knowledge, there is only one report on the local effect of STZ on brain insulin levels [6], and the local action of STZ on glucose and energy metabolism in the brain has not yet been evaluated. In order to test the hypothesis that i.c.v.
*Present address: Department of Neurology, Harvard Medical School, Massachusetts General Hospital, ACC 830, Fruit Street, Boston, MA 02114, U.S.A. Correspondence: S. Hoyer, Department of Pathochemistry and General Neurochemistry, University of Heidelberg, Im Neuenheimer Feld 220-221, D-6900 Heidelberg, F.R.G.
STZ induces prolonged impairment of brain glucose and energy metabolism in brain cortex, we measured brain tissue levels of energy rich phosphates, as well as intermediates of glycolysis and the tricarboxylic acid cycle, 21 days after one single i.c.v, administration of STZ. One-year-old male Han:WlST rats (486 + 55 g b.wt.) were purchased from the Central Institute for Laboratory Animal Breeding (Hanover, F.R.G.) and divided into two groups after randomization (n = 10 per group). Animals of the experimental group were anaesthesized (240 mg/kg 4 % chloral hydrate, i.p.) and injected stereotaxically in the cerebral ventricular system with 1.25/tg/g body weight STZ (Sigma, St. Louis, MO) dissolved in a final volume of 9 /tl phosphate/bicarbonate-buffered artificial cerebrospinal fluid (120 mM NaC1, 3 mM KC1, 1.15 mM CaC12, 0.8 mM MgCI2, 0.33 mM NaH2PO4, 27 mM NaHCO3, pH 7.2 adjusted by CO2 insufflation). Control animals were injected with 9 /tl vehicle only. Stereotaxical coordinates for the ventricular system were 2.00 mm lateral, 0.70 mm caudal and 4.00 mm ventral from the bregma at the piamatral level [21]. 21 days after i.c.v, injection, the rats were placed under controlled intubation anaesthesia with 0.5% halothane, 70% N20 and 29.5% oxygen. The femoral artery and vein were cannulated and the animals were monitored over a 20 min steady state period of normal arterial blood pressure, normoxemic and normocapnic arterial blood gases and normal acid-base parameters (measured using a Corning
200 0.6
TABLE I
r--, 5 E ~4
A R T E R I A L BLOOD PARAMETERS 3 WEEKS A F T E R ONE I.C.V. APPLICATION OF STZ (1.25 mg/kg) Values are given as means + S.D. MAP, mean arterial blood pressure; Hb, hemoglobin; Hct, hematocrit; Temp, body temperature. No significant differences between the two groups, n = 10 per group.
Glucose (mM) Lactate (mM) MAP(mmHg) pO2 (mmHg) pCO2(mmHg) pH Hb(g/100ml) Hct(%) TempCC)
Control
STZ i.c.v.
9.10__ 1.08 1.17 + 0.43 111.9 _+ 6.0 123.5 + 18.2 36.6 _ 2.6 7.44__+ 0.03 12.2 + 1.4 33.7 + 0.4 37.0 _+ 0.4
9,43+ 0.54 1,16 + 0.47 108.8 _+ 6.2 118.1 +24.4 36,2 + 2.7 7,42+ 0.06 11.3 +__ 1.1 31.8 + 2.8 37.0 _+ 0.2
A.
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0.5 XIX KX KX ~X
0
E 3 E
KX KX KX KX KX ~X
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0.4
0.3 3 0
0.2 ~
3
I
0.1 ~ 0.0
ATP
ADP
15
12
B.
4
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Neuroscience Letters, 128 (1991) 199-202 © 1991 Elsevier Scientific Publishers Ireland Ltd. 0304-3940/91/$ 03.50 ADONIS 030439409100356C NSL 07874
Local action of the diabetogenic drug, streptozotocin, on glucose and energy metabolism in rat brain cortex Roger Nitsch* and Siegfried H o y e r Department of Pathochemistry and GeneralNeurochemistry, University of Heidelberg, Heidelberg ( F.R.G.) (Received 21 February 1991; Revised version received 12 April 1991; Accepted 15 April 1991)
Key words: Brain energy metabolism; ATP; Glucose; Brain cortex; Streptozotocin; Animal model Glucose is the principal source for energy production in the brain, and undisturbed glucose metabolism is pivotally significant for normal function of this organ. Peripheral glucose metabolism is impaired by streptozotocin (STZ), which induces diabetes mellitus. In this investigation, we have studied the local effects of intracerebroventricular (i.c.v.) STZ on glucose and energy metabolism in cerebral cortex. Three weeks after one single i.c.v, administration of STZ, ATP and phosphocreatine (CrP) concentrations as well as the ATP/ADP ratio and the enery charge potential were decreased, while the concentrations of glucose and ADP were increased, in cerebral cortex. Arterial blood glucose levels were not altered by i.c.v. STZ. It is concluded that brain energy metabolism is locally impaired by i.c.v. STZ. We propose that the disturbance of brain energy metabolism by i.c.v, STZ administration may provide a model for the study of prolonged metabolic neuronal stress.
Perturbations in the supply of glucose to the brain as well as impairments of brain glucose and energy metabolism may be expected to alter normal brain function [24]. Brain glucose and energy metabolism is in fact impaired in neurodegenerative brain disorders such as Alzheimer's disease. In particular, brain glucose utilization and brain tissue levels of energy rich phosphates are reduced in patients with Alzheimer's disease [9, 25]. In experimental animals, glucose metabolism in nonneural tissues is disturbed by streptozotocin (STZ), a glucosamine derivative of nitrosourea, which produces hyperglycemia when injected peripherally. The resulting diabetes mellitus is caused by inhibition of pancreatic insulin secretion [3] and decreased insulin receptor signalling in the target cells [11]. STZ is therefore most frequently used to induce insulin-dependent diabetes mellitus in experimental animals [10, 12, 13, 23]. To our knowledge, there is only one report on the local effect of STZ on brain insulin levels [6], and the local action of STZ on glucose and energy metabolism in the brain has not yet been evaluated. In order to test the hypothesis that i.c.v.
*Present address: Department of Neurology, Harvard Medical School, Massachusetts General Hospital, ACC 830, Fruit Street, Boston, MA 02114, U.S.A. Correspondence: S. Hoyer, Department of Pathochemistry and General Neurochemistry, University of Heidelberg, Im Neuenheimer Feld 220-221, D-6900 Heidelberg, F.R.G.
STZ induces prolonged impairment of brain glucose and energy metabolism in brain cortex, we measured brain tissue levels of energy rich phosphates, as well as intermediates of glycolysis and the tricarboxylic acid cycle, 21 days after one single i.c.v, administration of STZ. One-year-old male Han:WlST rats (486 + 55 g b.wt.) were purchased from the Central Institute for Laboratory Animal Breeding (Hanover, F.R.G.) and divided into two groups after randomization (n = 10 per group). Animals of the experimental group were anaesthesized (240 mg/kg 4 % chloral hydrate, i.p.) and injected stereotaxically in the cerebral ventricular system with 1.25/tg/g body weight STZ (Sigma, St. Louis, MO) dissolved in a final volume of 9 /tl phosphate/bicarbonate-buffered artificial cerebrospinal fluid (120 mM NaC1, 3 mM KC1, 1.15 mM CaC12, 0.8 mM MgCI2, 0.33 mM NaH2PO4, 27 mM NaHCO3, pH 7.2 adjusted by CO2 insufflation). Control animals were injected with 9 /tl vehicle only. Stereotaxical coordinates for the ventricular system were 2.00 mm lateral, 0.70 mm caudal and 4.00 mm ventral from the bregma at the piamatral level [21]. 21 days after i.c.v, injection, the rats were placed under controlled intubation anaesthesia with 0.5% halothane, 70% N20 and 29.5% oxygen. The femoral artery and vein were cannulated and the animals were monitored over a 20 min steady state period of normal arterial blood pressure, normoxemic and normocapnic arterial blood gases and normal acid-base parameters (measured using a Corning
200 0.6
TABLE I
r--, 5 E ~4
A R T E R I A L BLOOD PARAMETERS 3 WEEKS A F T E R ONE I.C.V. APPLICATION OF STZ (1.25 mg/kg) Values are given as means + S.D. MAP, mean arterial blood pressure; Hb, hemoglobin; Hct, hematocrit; Temp, body temperature. No significant differences between the two groups, n = 10 per group.
Glucose (mM) Lactate (mM) MAP(mmHg) pO2 (mmHg) pCO2(mmHg) pH Hb(g/100ml) Hct(%) TempCC)
Control
STZ i.c.v.
9.10__ 1.08 1.17 + 0.43 111.9 _+ 6.0 123.5 + 18.2 36.6 _ 2.6 7.44__+ 0.03 12.2 + 1.4 33.7 + 0.4 37.0 _+ 0.4
9,43+ 0.54 1,16 + 0.47 108.8 _+ 6.2 118.1 +24.4 36,2 + 2.7 7,42+ 0.06 11.3 +__ 1.1 31.8 + 2.8 37.0 _+ 0.2
A.
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0
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KX KX KX KX KX ~X
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0.4
0.3 3 0
0.2 ~
3
I
0.1 ~ 0.0
ATP
ADP
15
12
B.
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C) qO
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