Sporadic Dementia Of Alzheimer's Type Research Articles

Exendin-4 Prevents Memory Loss and Neuronal Death in Rats with Sporadic Alzheimer-Like Disease.

This study investigated the neuroprotective effects of exendin-4 (EXE-4), an analog of the glucagon-like peptide 1 receptor (GLP-1R) on memory and on the neuronal populations that constitute the hippocampus of rats submitted to a sporadic dementia of Alzheimer's type (SDAT). Male Wistar rats received streptozotocin (STZ icv, 3mg/kg diluted in aCFS, 5µl/ventricle) and were treated for 21days with EXE-4 (10µg/kg, ip; saline as the vehicle). Four groups were formed: vehicle, EXE-4, STZ, and STZ + EXE-4. The groups were submitted to Y-Maze (YM), object recognition (ORT), and object displacement tasks (ODT) to assess learning and memory. The brains were used for immunohistochemical and immunofluorescent techniques with antibodies to NeuN, cleaved caspase-3 (CC3), PCNA, doublecortin (DCX), synaptophysin (SYP), and insulin receptor (IR). STZ worsened spatial memory in the YMT, as well as short-term (STM) and long-term (LTM) memories in the ORT and ODT, respectively. EXE-4 protected against memory impairment in STZ animals. STZ reduced mature neuron density (NeuN) and increased cell apoptosis (CC3) in the DG, CA1, and CA3. EXE-4 protected against neuronal death in all regions. EXE-4 increased PCNA+ cells in all regions of the hippocampus, and STZ attenuated this effect. STZ reduced neurogenesis in DG per se as well as synaptogenesis induced by EXE-4. EXE-4 increased immunoreactivity to IR in the CA1. From these findings, EXE-4 showed a beneficial effect on hippocampal pyramidal and granular neurons in the SDAT showing anti-apoptotic properties and promoting cell proliferation. In parallel, EXE-4 preserved the memory of SDAT rats. EXE-4 appears to enhance synapses at CA3 and DG. In conclusion, these data indicate that agonists to GLP-1R have a beneficial effect on hippocampal neurons in AD.

Tannic Acid Ameliorates STZ-Induced Alzheimer's Disease-Like Impairment of Memory, Neuroinflammation, Neuronal Death and Modulates Akt Expression.

Tannic acid (TA) is a hydrolysable glycosidic polyphenol polymer of gallic acid, which possesses neuroprotective properties. The aim of this study was to evaluate the effect of TA treatment on cognitive performance and neurochemical changes in an experimental model of sporadic dementia of Alzheimer's type (SDAT) induced by intracerebroventricular (ICV) injection of streptozotocin (STZ) and to explore the potential cellular and molecular mechanisms underlying these effects. Adult male rats were divided into four groups: control, TA, STZ, and TA + STZ. Animals from TA and TA + STZ groups were treated with TA (30mg/kg) daily, by gavage, for 21days; others groups received water (1mL/kg). Subsequently, an ICV injection of STZ (3mg/kg) was administered into the lateral ventricles of animals from STZ and TA + STZ groups, while other groups received citrate buffer. Cognitive deficits (short-term memory), neuronal survival, neuroinflammation as well as expression of SNAP-25, Akt, and pAkt were evaluated in the cerebral cortex. TA treatment protected against the impairment of memory in STZ-induced SDAT. STZ promoted an increase in neuronal death and the levels of proinflammatory cytokines (IL-6 and TNF-α) and a decrease in Akt and pAkt expression; TA was able to restore these changes. Neither STZ nor TA altered SNAP-25 expression or the levels of IL-12 and IL-4 in the cerebral cortex. Our study highlights that treatment with TA prevents memory deficits and reestablishes Akt and pAkt expression, protecting against neuronal death and neuroinflammation in STZ-induced SDAT in rats.

Protection of cholinergic and antioxidant system contributes to the effect of Vitamin D3 ameliorating memory dysfunction in sporadic dementia of Alzheimer’s type

ABSTRACTObjective: Investigate Vitamin D3 (VD3) effect on the Acetylcholinesterase (AChE), oxidative damage and behavioral tests in animals subjected to Intracerebroventicular injection of Streptozotocin (ICV-STZ) simulating a Sporadic Dementia of Alzheimer's Type (SDAT) and treated with VD3 (21 days).Methods: Animals were divided into eight groups: Vehicle, VD12.5 μg/kg, VD42 μg/kg, VD125 μg/kg, STZ, STZ+VD12.5 μg/kg, STZ+VD42 μg/kg, STZ+VD125 μg/kg.Results: VD3 prevented the increase in AChE in groups of VD42 µg/kg and VD125 µg/kg; in AChE of synaptossomes and TBARS levels prevented the increase in group VD125 µg/kg; in ROS levels there was not a significant difference; for the Carbonyl Content all doses prevented the increase. Total Thiols prevent the decrease in VD42 µg/kg and VD125 µg/kg, and Reduced Glutathione prevented the decrease in VD125 µg/kg, Oxidized Glutathione prevented the increase in VD125 µg/kg. In relation to behavioral tests, the VD3 prevented the increase in time to find (days 2 and 3), in the time to find the platform (day 3) and in time spent in the quadrant (day 2). However, in relation to crossings there was not difference in groups. These results indicated the therapeutic effect of the VD3 in model of STZ in rats.

Anthocyanins as a potential pharmacological agent to manage memory deficit, oxidative stress and alterations in ion pump activity induced by experimental sporadic dementia of Alzheimer's type

Anthocyanins (ANT) are polyphenolic flavonoids with antioxidant and neuroprotective properties. This study evaluated the effect of ANT treatment on cognitive performance and neurochemical parameters in an experimental model of sporadic dementia of Alzheimer's type (SDAT). Adult male rats were divided into four groups: control (1 ml/kg saline, once daily, by gavage), ANT (200 mg/kg, once daily, by gavage), streptozotocin (STZ, 3 mg/kg) and STZ plus ANT. STZ was administered via bilateral intracerebroventricular (ICV) injection (5 μl). ANT were administered after ICV injection for 25 days. Cognitive deficits (short-term memory and spatial memory), oxidative stress parameters, and acetylcholinesterase (AChE) and Na+-K+-ATPase activity in the cerebral cortex and hippocampus were evaluated. ANT treatment protected against the worsening of memory in STZ-induced SDAT. STZ promoted an increase in AChE and Na+-K+-ATPase total and isoform activity in both structures; ANT restored this change. STZ administration induced an increase in lipid peroxidation and decrease in the level of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), in the cerebral cortex; ANT significantly attenuated these effects. In the hippocampus, an increase in reactive oxygen species (ROS), nitrite and lipid peroxidation levels, and SOD activity and a decrease in CAT and GPx activity were seen after STZ injection. ANT protected against the changes in ROS and antioxidant enzyme levels. In conclusion, the present study showed that treatment with ANT attenuated memory deficits, protected against oxidative damage in the brain, and restored AChE and ion pump activity in an STZ-induced SDAT in rats.

Anthocyanins restore behavioral and biochemical changes caused by streptozotocin-induced sporadic dementia of Alzheimer's type

AimsThe aim of this study was to analyze if the pre-administration of anthocyanin on memory and anxiety prevented the effects caused by intracerebroventricular streptozotocin (icv-STZ) administration-induced sporadic dementia of Alzheimer's type (SDAT) in rats. Moreover, we evaluated whether the levels of nitrite/nitrate (NOx), Na+,K+-ATPase, Ca2+-ATPase and acethylcholinesterase (AChE) activities in the cerebral cortex (CC) and hippocampus (HC) are altered in this experimental SDAT. Main methodsMale Wistar rats were divided in 4 different groups: control (CTRL), anthocyanin (ANT), streptozotocin (STZ) and streptozotocin+anthocyanin (STZ+ANT). After seven days of treatment with ANT (200mg/kg; oral), the rats were icv-STZ injected (3mg/kg), and four days later the behavior parameters were performed and the animals submitted to euthanasia. Key findingsA memory deficit was found in the STZ group, but ANT treatment showed that it prevents this impairment of memory (P<0.05). Our results showed a higher anxiety in the icv-STZ group, but treatment with ANT showed a per se effect and prevented the anxiogenic behavior induced by STZ. Our results reveal that the ANT treatment (100μM) tested displaces the specific binding of [3H] flunitrazepam to the benzodiazepinic site of GABAA receptors. AChE, Ca+-ATPase activities and NOx levels were found to be increased in HC and CC in the STZ group, which was attenuated by ANT (P<0.05). STZ decreased Na+,K+-ATPase activity and ANT was able to prevent these effects (P<0.05). SignificanceIn conclusion, these findings demonstrated that ANT is able to regulate ion pump activity and cholinergic neurotransmission, as well as being able to enhance memory and act as an anxiolytic compound in animals with SDAT.

Therapeutic effect of organoselenium dietary supplementation in a sporadic dementia of Alzheimer's type model in rats

It is known that selenium (Se) might play different roles in the progression of Alzheimer's disease (AD), but there is a lack of evidence that proves whether supplementation with Se is beneficial or not for the treatment of AD. Thus, the aim of the current study was to investigate the therapeutic effect of p,p'-methoxyl-diphenyl diselenide [(MeOPhSe)2], an organoselenium compound, against streptozotocin (STZ)-induced sporadic dementia of Alzheimer's type (SDAT) in rats. Male Wistar rats received STZ twice daily (1.0 mg/8 μl; 4 μl/ventricle) for 21 days. After 21 days of STZ injection, regular-diet-fed rats were supplemented with 10 ppm of (MeOPhSe)2 during 30 days. At the end of this period, the rats were challenged in the Morris water maze and step-down passive avoidance tasks. The activity of acetylcholinesterase (AChE), deficit in cerebral energy metabolism (measurement of adenosine 5-triphosphate and adenosine 5-diphosphate levels), and oxidative and nitrosative stress were determined in the cortex and hippocampus of rats. The results demonstrated that (MeOPhSe)2 dietary supplementation reverted STZ-induced memory impairment of rats in both cognitive tasks. The findings also indicated that (MeOPhSe)2 dietary supplementation reverted oxidative stress in the STZ group (decreased reactive species and tyrosine nitration levels and enhanced nonprotein thiol levels). Moreover, (MeOPhSe)2 dietary supplementation normalized AChE activity, which was enhanced by STZ injection, but did not revert the deficit in cerebral energy metabolism caused by STZ. The results of the present study indicated the therapeutic effect of the (MeOPhSe)2-supplemented diet in a rat model of SDAT.

Rutin prevents cognitive impairments by ameliorating oxidative stress and neuroinflammation in rat model of sporadic dementia of Alzheimer type

The objective of the present study was to assess the neuroprotective role of rutin (vitamin P) and delineate the mechanism of action. Recent evidence indicates that rutin exhibits antioxidant potential and protects the brain against various oxidative stressors. More precisely, the aim of the present study was to examine the modulating impacts of rutin against cognitive deficits and oxidative damage in intracerebroventricular-streptozotocin (ICV-STZ)–infused rats. Rats were injected bilaterally with ICV-STZ (3 mg/kg), whereas sham rats received the same volume of vehicle. After 2 weeks of streptozotocin (STZ) infusion, rats were tested for cognitive performance using Morris water maze tasks and thereafter euthanized for further biochemical, histopathological, and immunohistochemical studies. Rutin pretreatment (25 mg/kg, orally, once daily for 3 weeks) significantly attenuated thiobarbituric acid reactive substances (TBARS), activity of poly ADP-ribosyl polymerase, and nitrite level and decreased level of reduced glutathione (GSH) and activities of its dependent enzymes (glutathione peroxidase [GPx] and glutathione reductase [GR]) and catalase in the hippocampus of ICV-STZ rats. ICV-STZ rats showed significant cognitive deficits, which was improved significantly by rutin supplementation. The results indicate that rutin attenuates STZ-induced inflammation by reducing the expression of cyclooxygenase-2 (COX-2), glial fibrillary acidic protein (GFAP), interleukin-8 (IL-8), inducible nitric oxide synthase (iNOS), nuclear factor-kB, and preventing the morphological changes in hippocampus. The study thereby suggests the effectiveness of rutin in preventing cognitive deficits and might be beneficial for the treatment of sporadic dementia of Alzheimer type (SDAT).

Sporadic dementia of Alzheimer's type induced by streptozotocin promotes anxiogenic behavior in mice

Alzheimer disease, a form of dementia in which loss of memory is the first and the most characteristic symptom, is frequently accompanied by affective symptoms. Intracerebroventricular (i.c.v.) injection of streptozotocin (STZ) to rodents has been reported as an appropriate model for sporadic dementia of Alzheimer's type (SDAT), characterized by a progressive impairment of memory. However, very little or nothing is known about non-cognitive behavioral effects (e.g. anxiety-like behavior) in the STZ model. In this context, the hypothesis to be tested in this study is if i.c.v. injection of STZ (0.1 mg/site, 4 μl) induces anxiety-like behavior in mice. The findings of the present study indicate that i.c.v. injection of STZ in mice resulted in an anxiogenic behavior. Mice spent less time and decreased the number of entries in the open arms in the elevated plus-maze task. The latency to the first entry in the dark side in the light–dark box task was reduced by STZ. No difference was found in anxiety-like behavior between early and late time (i.e., at 7 and 21 days after infusion, respectively). These results indicate that i.c.v. STZ injection caused an anxiogenic behavior in mice.

Neuroprotector effect of p,p'‐methoxyl‐diphenyl diselenide in a model of sporadic dementia of Alzheimer's type in mice: contribution of antioxidant mechanism

The present study investigated whether the antioxidant activity of p,p'-methoxyl-diphenyl diselenide [(MeOPhSe)(2)] is involved in its protective effect against cognitive impairment induced by streptozotocin (STZ) in a model of sporadic dementia of Alzheimer's type (SDAT). Swiss mice were treated with STZ or vehicle [2 µl of 2·5 mg ml(-1) solution; intracerebroventricularly (i.c.v.)] twice, 48 h apart. (MeOPhSe)(2) (25 mg kg(-1)) or vehicle was orally administered 30 min prior to each STZ treatment. Neuroprotector effect of (MeOPhSe)(2) on the behavioral performance of mice on spatial recognition memory consolidation was investigated in the Y-maze test. After that, mouse brains were removed for measuring antioxidant parameters. (MeOPhSe)(2) protected against the impairment in learning and memory caused by i.c.v. administration of STZ in mice. (MeOPhSe)(2) protected against the increase in reactive species and the reduction of glutathione levels, as well as, the increase in superoxide dismutase and glutathione S-transferase activities caused by STZ in whole brain. These results suggest that antioxidant property is involved, at least in part, in the neuroprotective effect of (MeOPhSe)(2) on SDAT induced by STZ in mice.

Organoselenium improves memory decline in mice: Involvement of acetylcholinesterase activity

The present study was designed to investigate the possible neuroprotective effect of p, p′-methoxyl-diphenyl diselenide [(MeOPhSe) 2] in a model of sporadic dementia of Alzheimer's type (SDAT) induced by intracerebroventricular (i.c.v.) injection of streptozotocin (STZ) in mice. Mice were divided into four groups: (I) control, (II) (MeOPhSe) 2, (III) STZ, and (IV) (MeOPhSe) 2 + STZ. Mice were exposed to (MeOPhSe) 2 (25 mg/kg, by gavage) and STZ (2 μl of 2.5 mg/ml solution; i.c.v.) or vehicles. 48 after that the exposure was repeated. Learning and memory were assessed with the step-down-type passive-avoidance (SDPA) and Morris water-maze (MWM) tests at the days 5–6 and 6–9, respectively. At the end of the experimental protocol animals were euthanized and cerebral cortex was removed for acetylcholinesterase (AChE) activity assay. Our results confirmed that i.c.v. STZ caused learning and memory deficits in mice, which were verified using the MWM and SDPA tasks. Furthermore, this study showed that AChE activity was increased in mice that received i.c.v. STZ. The most important findings of the present study are that (MeOPhSe) 2 was able to reverse the learning and memory impairments induced by STZ, and to protect against the increase in AChE activity. All these findings support the neuroprotective role of (MeOPhSe) 2 in a mice model of SDAT induced by i.c.v. STZ.

Selenium prevents cognitive decline and oxidative damage in rat model of streptozotocin-induced experimental dementia of Alzheimer's type

Selenium (Se), a nutritionally essential trace element with known antioxidant potential, protects the brain from oxidative damage in various models of neurodegeneration. Intracerebroventricular-streptozotocin (ICV-STZ) in rats causes impairment of brain glucose and energy metabolism along with oxidative damage and cholinergic dysfunction, and provides a relevant model for sporadic dementia of Alzheimer's type (SDAT). The present study demonstrates the therapeutic efficacy of Se on cognitive deficits and oxidative damage in ICV-STZ in rats. Male Wistar rats were pre-treated with sodium selenite, a salt of Se (0.1 mg/kg; body weight) for 7 days and then were injected bilaterally with ICV-STZ (3 mg/kg), while sham rats received the same volume of vehicle. After two ICV-STZ infusions, rats were tested for memory deficits in passive avoidance and Morris water maze (MWM) tests and then were sacrificed for biochemical and histopatholgical assays. ICV-STZ-infused rats showed significant loss in learning and memory ability, which were significantly improved by Se supplementation. A significant increase in thio-barbituric acid reactive species (TBARS), protein carbonyl (PC) and a significant decrease in reduced glutathione (GSH), antioxidant enzymes (glutathione peroxidase [GPx] and glutathione reductase [GR]) and adenosine triphosphate (ATP) in the hippocampus and cerebral cortex and choline acetyltransferase (ChAT) in hippocampus were observed in ICV-STZ rats. Se supplementation significantly ameliorated all alterations induced by ICV-STZ in rats. Our study reveals that Se, as a powerful antioxidant, prevents cognitive deficits, oxidative damage and morphological changes in the ICV-STZ rats. Thus, it may have a therapeutic value for the treatment of SDAT.

Amelioration of cognitive deficits and neurodegeneration by curcumin in rat model of sporadic dementia of Alzheimer's type (SDAT)

Recent evidence indicates that curcumin (CUR), the principal curcuminoid of turmeric, exhibits antioxidant potential and protects the brain against various oxidative stressors. The aim of the present study was to examine the modulating impacts of CUR against cognitive deficits and oxidative damage in intracerebroventricular–streptozotocin (ICV–STZ) infused rats. Rats were injected bilaterally with ICV–STZ (3 mg/kg), while sham rats received the same volume of vehicle and then supplemented with CUR (80 mg/kg) for three weeks. After two weeks of ICV–STZ infusion, rats were tested for cognitive performance using passive avoidance and water maze tasks and then sacrificed for biochemical and histopathological assays. ICV–STZ rats showed significant cognitive deficits, which were significantly improved by CUR supplementation. CUR supplementation significantly augmented increased 4-hydroxynonenal (4-HNE) and malonaldehyde (MDA), thiobarbituric reactive substances (TBARS), hydrogen peroxide (H 2O 2), protein carbonyl (PC) and oxidized glutathione (GSSG); decreased levels of reduced glutathione (GSH) and its dependent enzymes (Glutathione peroxidase [GPx] and glutathione reductase [GR]) in the hippocampus and cerebral cortex; and increased choline acetyltransferase (ChAT) activity in the hippocampus of ICV–STZ rats. The study suggests that CUR is effective in preventing cognitive deficits, and might be beneficial for the treatment of sporadic dementia of Alzheimer's type (SDAT).

A disturbance in the neuronal insulin receptor signal transduction in sporadic Alzheimer's disease.

Disturbances of glucose and energy metabolism are hypothesized as pathogenetic factors in sporadic dementia of Alzheimer type (SDAT). Insulin and is receptors play an important role in the regulation of brain glucose metabolism and neuronal growth. In postmortem brain cortex in SDAT, the densities of brain insulin receptors were decreased compared to adult controls, but were increased in relation to aged controls. Tyrosine kinase activity, a signal transduction mechanism common to insulin and IGF-1 receptors, was reduced in SDAT in comparison to middle-aged and age-matched control groups. The data are consistent with a neurotrophic role of insulin in the human brain and an upregulation of insulin receptors is SDAT brain as a compensatory mechanism, possibly due to impaired signal transduction mechanism.

Intracerebroventricular injection of streptozotocin induces discrete local changes in cerebral glucose utilization in rats

The purpose of the present study was to investigate whether or not cerebral glucose utilization is changed locally after damage of the neuronal insulin receptor by means of intracerebroventricular (icv) streptozotocin (STZ) administered in a subdiabetogenic dosage (1.5 mg/kg bw.). STZ was administered at the start of the study, and 2 and 21 days later bilaterally into the cerebral ventricles in rats of a mean age of 18 months. The local distribution of cerebral glucose utilization was analyzed in conscious rats on the 42nd day after the first STZ injection using the quantitative (14C)-2-deoxyglucose method. Of the 35 brain structures investigated from autoradiograms of brain sections, 17 showed a reduction in glucose utilization. Decreases in glucose utilization were observed in the frontal, parietal, sensory motor, auditory and entorhinal cortex and in all hippocampal subfields. In contrast, glucose utilization was increased in two white matter structures. The decrease in cerebral glucose utilization observed in cortical and hippocampal areas in the present study may correspond to changes in morphobiological parameters which have been found in patients with Alzheimer's disease. The present data are in accordance with the hypothesis that an impairment in the control of neuronal glucose metabolism at the insulin receptor site may exist in sporadic dementia of Alzheimer type (DAT), and can be studied by the icv STZ animal model.

Sporadic dementia of Alzheimer type: role of amyloid in etiology is challenged.

Alzheimer's disease is a heterogeneous neurodegenerative disorder. Whereas only a minority is due to genetic abnormalities and mostly with early onset, the majority of all Alzheimer cases is sporadic and with late onset. Therefore, in the latter, age-related disturbances in cellular metabolism may come into focus with respect to the etiopathogenesis rather than the primary formation of amyloid. In this "Editor's note for debate", the role of amyloid as a causative factor of sporadic Alzheimer's disease is challenged. Instead, as a possible primary abnormal event in sporadic Alzheimer's disease, the perturbations in neuronal glucose metabolism and the subsequent ATP deficit with its impacts on the secondary amyloid formation are discussed to open a new field of research and another aspect for debate.

Abnormalities in brain glucose utilization and its impact on cellular and molecular mechanisms in sporadic dementia of Alzheimer type.

Brain glucose utilization and ATP formation were found to be reduced to 54% and 81%, respectively, of control values in incipient sporadic dementia of Alzheimer type, causing reduced availability of the glucose-derived neurotransmitter acetylcholine. With respect to energy shortage, impacts on energy-dependent processes such as synaptic transmission, ion homeostasis, protein processing and degradation, extracellular transmission, and extracellular phosphorylation may be expected. Normal processing of the amyloid precursor protein was demonstrated to occur via a muscarinergic acetylcholine M1 and M3 receptor-mediated signal transduction pathway. Since both the muscarinergic acetylcholine receptors on pyramidal neurons and G proteins were found to be unaltered in DAT, the possibility is discussed that the diminution of glucose utilization and the energy shortage in DAT brain may contribute considerably to abnormal amyloid precursor protein processing and thus to secondary amyloid formation.

Action of the diabetogenic drug streptozotocin on glycolytic and glycogenolytic metabolism in adult rat brain cortex and hippocampus

In sporadic Alzheimer's disease (AD), a number of metabolic alterations to the brain have been observed soon after the onset of the initial clinical symptoms. In particular, impairments of glucose utilization and related metabolic pathways are prominent and well-established findings in incipient AD, resembling metabolic abnormalities such as have been found in noninsulin-dependent diabetes mellitus. To mimic these abnormalities, we administered an intracerebroventricular (icv) injection of streptozotocin (STZ) to rats and studied the effects on glucose and glycogen metabolism in the cerebral cortex and hippocampus compared with controls. The enzymatic activities studied dropped significantly by 10–30% in brain cortex (cort.) and hippocampus (hc) 3 and 6 weeks after icv STZ injection: hexokinase (15% 3 weeks cort.; 14% 6 weeks cort.; 12% 3 weeks hc; 28% 6 weeks hc), phosphofructokinase (15%; 15%; 24%; 15%), glyceraldehyde-3-phosphate dehydrogenase (10%; 12%; 30%; 19%), pyruvate kinase (22%; 13%; 22%; 28%), glucose-6-phosphatase (10%; 23%; 14%; 19%) and phosphorylase a (22%; 11%; 30%; 15%).The content of glycogen was significantly higher in STZ-treated rats than in control animals (7% 3 weeks and 15% 6 weeks in cortex).In contrast to the reduced enzymatic activities, we observed no changes in the concentrations of the glycolytic intermediates glucose, glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-diphosphate, pyruvate, lactate and glucose-1-phosphate. These data clearly indicate reduced glycolytic enzyme activity after icv administration of STZ and suggest gluconeogenesis consequent on abnormalities in glucose breakdown. This model may thus be assumed to be a useful tool to investigate pathogenetic factors involved in sporadic dementia of Alzheimer type.