Retraction Note to: Honokiol suppresses the development of post-ischemic glucose intolerance and neuronal damage in mice.

This article [1] has been retracted at the request of the corresponding author because an Investigation Committee established by Kobe Gakuin University (Kobe, Japan) has found numerous discrepancies between the raw data and the data presented in Figs. 6b, d. Statistical analysis of the raw data showed no significant difference between conditions. Authors S. Harada, K. Nakamoto, W. Fujita-Hamabe, H.-H. Chen, M.-H. Chan, and S. Tokuyama agree with this retraction. Authors M. Kishimoto and M. Kobayashi could not be reached for comment about this retraction.

RhoA affects oral morphine analgesia depending on functional variation in intestinal P-glycoprotein induced by repeated etoposide treatment.

In early palliative care, drug-drug interactions between opioids and anticancer agents may be caused by combined treatment with these drugs. We previously reported that repeated administration of oral etoposide (ETP), an anticancer drug that is a substrate of P-glycoprotein (P-gp), caused attenuation of the analgesic effect of oral morphine through up-regulation of intestinal P-gp. Recent studies have revealed that RhoA, a small G-protein, is involved in the regulation of P-gp expression and activity. Moreover, RhoA is known to be involved in various signaling pathways in response to anticancer drugs. Here, we examined the involvement of RhoA in the changes in ileal P-gp protein expression and activity induced by repeated orally administered ETP. Ileal P-gp and RhoA protein expression levels were analyzed using western blot analysis. The efflux activity of ileal P-gp was measured using the in situ closed loop method. The analgesic effect of oral morphine was determined with a tail-flick test. Repeated oral ETP significantly increased the activity of RhoA in association with up-regulation of P-gp protein expression and activity in the ileum. Interestingly, inhibition of RhoA activation by rosuvastatin prevented these effects. Furthermore, ETP-induced attenuation of the analgesic effect of oral morphine was also suppressed by rosuvastatin. RhoA activation induced by repeated oral ETP administration may be involved in the up-regulation of ileal P-gp protein expression and activity, leading to a decrease in the analgesic effect of oral morphine.

The involvement of cleavage of neural cell adhesion molecule in neuronal death under oxidative stress conditions in cultured cortical neurons.

Neural cell adhesion molecule (NCAM) is a member of the immunoglobulin superfamily with an important function in the central nervous system, particularly in synapse stabilization and neurite outgrowth. Our recent study clearly demonstrated that cleavage of NCAM-180 by matrix metalloproteinase-9 (MMP-9) exacerbated the neuronal damage induced by in vivo ischemic stress. In the present study, we investigated the effect of oxidative stress on the expression levels of full-length NCAM-180 and NCAM-cleavage product (65 kDa) and the relationship between NCAM-180 and MMP-9 in cultured cortical neurons. Primary cultured cortical neurons were exposed to oxidative stress by administration of hydrogen peroxide into the culture medium. After exposure to oxidative stress, cell death of cultured cortical neurons was gradually increased in a time-dependent manner. In parallel to the cell death, levels of full-length NCAM-180 and its cleavage product (65 kDa) were gradually and significantly decreased and increased, respectively, in a time-dependent manner. These changes completely disappeared following addition of an MMP-9 inhibitor, while MMP-9 protein levels were increased only in the early phase of oxidative stress. We conclude that oxidative stress can induce cleavage of NCAM-180 through up-regulation of MMP-9 during the early phase of oxidative stress. These changes might be related to the neuronal death observed under oxidative stress conditions.

Involvement of ubiquitination in the decrease of intestinal P-glycoprotein in a streptozotocin-induced diabetic mouse model.

P-Glycoprotein (P-gp), one of the drug efflux pumps, is expressed in some tissues and may affect the pharmacokinetics of its substrates. We have previously reported that a decrease of intestinal P-gp expression affects the pharmacokinetics of orally-administered P-gp substrate drugs in a streptozotocin (STZ)-induced type 1 diabetic mice model. Although we have found the participation of nitric oxide synthase (NOS) activation as a mechanism of the decrease in intestinal P-gp expression under diabetic conditions, more detailed mechanisms other than NOS remain unknown. Here, we studied the involvement of the ubiquitin-proteasome system in the mechanism of the decrease in intestinal P-gp expression under diabetic conditions. Nine days after STZ administration (diabetic condition), ubiquitination levels of ileal P-gp were significantly increased, accompanied by an decrease of intestinal P-gp protein expression levels. Furthermore, treatment with an NO donor could increase the intestinal ubiquitinated P-gp levels. On the other hand, activity of 26S proteasome, an important enzyme in ubiquitin-proteasome system, did not change, suggesting the first step of the system (i.e., ubiquitination) but not the second step (i.e., degradation)-specific up-regulation under diabetic conditions. Our results reveal the participation of the acceleration of the ubiquitin-preotasome system by NO in the decrease of intestinal P-gp expression levels under diabetic conditions.

Involvement of matrix metalloproteinase-9 in the development of morphine tolerance.

Matrix metalloproteinase-9 (MMP-9) is involved in tissue remodeling or neural plasticity in various clinical states (e.g. inflammation, neuropathic pain). We focused on the effect of MMP-9 on development of morphine tolerance after repeated morphine treatment. To develop morphine tolerance, mice were given morphine (10mg/kg; s.c.) once daily for 5 days. The antinociceptive effect of morphine was measured by the tail flick method. Development of morphine tolerance was significantly inhibited by daily treatment of the non-specific MMP inhibitor GM6001 (5 µg/mouse, i.c.v.). A MMP-9 inhibitor (5 µg/mouse, i.c.v.) partially, yet significantly, inhibited the development of morphine tolerance. Intrathecal treatment of a MMP-9 inhibitor did not affect morphine tolerance. In MMP-9((-/-)) mice, the development of morphine tolerance was partially, yet significantly, inhibited compared with wild-type mice. MMP-9 protein expression levels in the midbrain gradually increased 12h to 24h after morphine treatment on day 1, but were unchanged on days 3-5. In the spinal cord, MMP-9 protein expression levels were unchanged. In gelatin zymography analyses, MMP-9 activity in the midbrain gradually increased 12 to 24h after morphine treatment. Increment in MMP-9 activity in the midbrain was also observed on days 3-5. Our findings suggest that persistent MMP-9 activation observed after the transient increment in MMP-9 expression from the early phase of morphine treatment may contribute to the development of morphine tolerance.

Etoposide modulates the effects of oral morphine analgesia by targeting the intestinal P-glycoprotein.

OBJECTIVES: Opioids and anticancer compounds such as etoposide (ETP) are substrates of P-glycoprotein (P-gp), an ATP-dependent efflux pump. Chemotherapy compounds may impact on the analgesic effect of opioids such as morphine when the two drugs are co-administered. In this study, we used a mouse model to determine if there is a pharmacological interaction between ETP and morphine, focusing on the involvement of intestinal P-gp. METHODS: P-gp drug efflux activity was measured by an in-situ closed loop method with Rhodamine 123, a P-gp substrate. The analgesic effect of morphine was determined by the tail-flick test. Intestinal P-gp expression levels were determined by Western blot. KEY FINDINGS: ETP and morphine significantly decreased the intestinal Rhodamine 123 efflux activity of P-gp. Oral morphine analgesia was significantly enhanced when co-administered with ETP. However, repeated pretreatment (7 days) with oral ETP significantly decreased the oral morphine-induced analgesia, in a cyclosporine A (a P-gp inhibitor) reversible manner. Furthermore, repeated ETP significantly up-regulated intestinal P-gp expression. CONCLUSIONS: It may be important to consider aspects of therapeutic design such as the administration route or scheduling of drugs in patients receiving concurrent chemotherapy and opioid therapy to avoid pharmacokinetic interactions between the two agents.

[Altered intestinal P-glycoprotein expression levels affect pharmacodynamics under diabetic condition].

P-glycoprotein (P-gp), one of the important drug-efflux pumps, is known to affect pharmacokinetics and pharmacodynamics of P-gp substrate drugs. We have previously reported that intestinal P-gp expression levels are transiently decreased in streptozotocin (STZ)-induced type 1 diabetic mouse model. Herein, we examined the analgesic effects of orally administered morphine and its pharmacokinetic properties under diabetic conditions, specifically focusing on the involvement of intestinal P-gp in a type 1 diabetic mouse model. Type 1 diabetes was induced in male ddY mice by an i.p. injection of STZ (230 mg/kg). We assessed the oral morphine analgesia using the tail-flick test. Serum and brain morphine content were determined on a HPLC-ECD system. Intestinal P-gp expression levels were significantly decreased on day 9 after STZ administration. On the other hands, oral morphine analgesia, and serum and brain morphine content were significantly increased on day 9 after STZ administration. The decrease in the intestinal P-gp expression levels were suppressed by aminoguanidine, a specific iNOS inhibitor. Interestingly, the increase in the analgesic effect of morphine, as well as serum and brain morphine content, was suppressed by aminoguanidine. Conversely, there was no change in the analgesic effect obtained with subcutaneous morphine in STZ-treated mice. In conclusions, our findings suggest that the oral morphine analgesia is dependent on intestinal P-gp expression, and that may be one of the problems against obtaining stable pharmacological effects of morphine in diabetic patients.

Honokiol suppresses the development of post-ischemic glucose intolerance and neuronal damage in mice.

Honokiol, a constituent of Magnolia obovata, has various pharmacological effects, including protection against cerebral ischemia. However, few studies have been conducted to evaluate the possible neuroprotective effects of honokiol against cerebral ischemia. We recently reported that cerebral ischemic neuronal damage could be triggered by glucose intolerance that develops after the onset of ischemic stress (i.e., post-ischemic glucose intolerance). In addition, suppression of post-ischemic glucose intolerance significantly ameliorated ischemic neuronal damage. Here, we investigated the effects of honokiol on the development of post-ischemic glucose intolerance and neuronal damage. Mice were subjected to middle cerebral artery occlusion (MCAO) for 2 h. The development of post-ischemic glucose intolerance on day 1 and neuronal damage on day 3 after MCAO were significantly reduced by intraperitoneal administration of honokiol (10 mg/kg) compared with the vehicle-treated group. Honokiol did not affect serum insulin or adiponectin levels. However, honokiol significantly decreased the expression of phosphoenolpyruvate carboxykinase and increased the expression of 5'-AMP-activated protein kinase (AMPK) on day 1 after MCAO, compared with the vehicle-treated MCAO group. The results of this study suggest that honokiol could prevent post-ischemic glucose intolerance in an AMPK-dependent manner, which may be involved in the neuroprotective effects of honokiol against cerebral ischemia.

Ischemic Stroke and Glucose Intolerance: a Review of the Evidence and Exploration of Novel Therapeutic Targets.

Stroke is one of the leading causes of death and disability worldwide. It is well known that hyperglycemia and/or diabetes potentially exacerbate the neuronal damage observed following ischemic stroke. Recent reports have shown that hyperglycemia/glucose intolerance may be induced by cerebral ischemic stress, and that normalization of blood glucose levels during the first 48 h of hospitalization appears to confer greater survival outcomes in stroke patients. However, the mechanisms underlying post-ischemic glucose intolerance remain unclear. Here, we review research to date on the mechanisms through which ischemic neuronal damage develops and on the role of post-ischemic glucose intolerance focusing on insulin and adiponectin signaling and communication between the brain and peripheral tissues. The relationship between ischemic neuronal damage and post-ischemic glucose intolerance is also discussed. With respect to therapeutic options, in addition to traditional post-stroke therapies, we also discuss the effect of anti-diabetic drugs and glucose-sensing neuropeptides on the development of the post-ischemic glucose intolerance and neuronal damage. In conclusion, we support the idea for focusing research on the development of post-ischemic glucose intolerance as a new therapeutic target for the stroke patients.

RETRACTED: Ameliorating Effect of Hypothalamic Brain-Derived Neurotrophic Factor Against Impaired Glucose Metabolism After Cerebral Ischemic Stress in Mice.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Authors. In Figure1C some of the numbers of the original raw data were changed. Hence, the Figures were different from real Figures obtained from original raw data and the significant difference in Figure 1C was not obtained.

Ischemic stroke and glucose intolerance: a review of the evidence and exploration of novel therapeutic targets.

Stroke is one of the leading causes of death and disability worldwide. It is well known that hyperglycemia and/or diabetes potentially exacerbate the neuronal damage observed following ischemic stroke. Recent reports have shown that hyperglycemia/glucose intolerance may be induced by cerebral ischemic stress, and that normalization of blood glucose levels during the first 48 h of hospitalization appears to confer greater survival outcomes in stroke patients. However, the mechanisms underlying post-ischemic glucose intolerance remain unclear. Here, we review research to date on the mechanisms through which ischemic neuronal damage develops and on the role of post-ischemic glucose intolerance focusing on insulin and adiponectin signaling and communication between the brain and peripheral tissues. The relationship between ischemic neuronal damage and post-ischemic glucose intolerance is also discussed. With respect to therapeutic options, in addition to traditional post-stroke therapies, we also discuss the effect of anti-diabetic drugs and glucose-sensing neuropeptides on the development of the post-ischemic glucose intolerance and neuronal damage. In conclusion, we support the idea for focusing research on the development of post-ischemic glucose intolerance as a new therapeutic target for the stroke patients.

Ameliorating effect of hypothalamic brain-derived neurotrophic factor against impaired glucose metabolism after cerebral ischemic stress in mice.

Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, has potent neuroprotective effects against brain injury. We recently reported that glucose intolerance/hyperglycemia could be induced by ischemic stress (i.e., post-ischemic glucose intolerance) following ischemic neuronal damage. Therefore, the aim of this study was to determine the effects of BDNF on the development of post-ischemic glucose intolerance and ischemic neuronal damage. Male ddY mice were subjected to middle cerebral artery occlusion (MCAO) for 2 h. On day 1, the expression levels of BDNF were significantly decreased in the cortex, hypothalamus, liver, skeletal muscle, and pancreas. The expression levels of tyrosine kinase B receptor, a BDNF receptor, decreased in the hypothalamus and liver and increased in the skeletal muscle and pancreas, but remained unchanged in the cortex. Intrahypothalamic administration of BDNF (50 ng/mouse) suppressed the development of post-ischemic glucose intolerance on day 1 and neuronal damage on day 3 after MCAO. In the liver and skeletal muscle, the expression levels of insulin receptors decreased, while gluconeogenic enzyme levels increased on day 1 after MCAO. These changes completely recovered to normal levels in the presence of BDNF. These results indicate that regulation of post-ischemic glucose intolerance by BDNF may suppress ischemic neuronal damage.

Altered intestinal P-glycoprotein expression levels in a monosodium glutamate-induced obese mouse model.

AIMS: P-glycoprotein (P-gp) is an important drug efflux transporter located in many tissues such as the blood-brain barrier, intestines, liver and kidneys. We have previously reported that ileal P-gp expression levels decrease via a nitric oxide synthase (NOS)-mediated pathway in a streptozotocin (STZ)-induced type 1 diabetic mouse model. Herein, our objective was to assess whether there are differences in the expression of intestinal P-gp in an obesity-induced hyperglycemic mouse model versus the type 1 diabetic mouse model. MAIN METHODS: The hyperglycemia-accompanied obese mouse model was developed through an injection of monosodium glutamate (MSG). We analyzed intestinal P-gp expression using Western blot analysis. KEY FINDINGS: Body weight, body mass index, blood glucose levels and serum insulin levels increased significantly with age in the MSG-treated mice. Furthermore, in 24week-old MSG-treated mice, while intestinal P-gp expression levels were tended to increase P-gp expression in the duodenum, it was only significant in the jejunum, but not in the ileum. Additionally, the hyperglycemia-accompanied increase in intestinal NOS activity of STZ-treated mice was not evident in the MSG-treated mice. SIGNIFICANCE: Our results suggest that P-gp expression levels in the upper part of the intestine increase with age in a hyperglycemia/hyperinsulinemia (i.e. type 2 diabetes) -associated MSG-treated obese mouse model, and that these results completely differ from those found in the STZ-induced type 1 diabetic mouse model.

Decreased expression of intestinal P-glycoprotein increases the analgesic effects of oral morphine in a streptozotocin-induced diabetic mouse model.

Morphine is one of the strongest analgesics and is commonly used for the treatment of chronic pain. The pharmacokinetic properties of morphine are, in part, modulated by P-glycoprotein (P-gp). We previously reported that intestinal P-gp expression levels are influenced via the activation of inducible nitric oxide synthase (iNOS) in streptozotocin (STZ)-induced diabetic mice. Herein, we examine the analgesic effects of orally administered morphine and its pharmacokinetic properties under diabetic conditions, specifically we focusing on the involvement of intestinal P-gp in a type 1 diabetic mouse model. We assessed the analgesic effect of morphine using the tail-flick test. Serum and brain morphine levels were determined using a HPLC-ECD system. Oral morphine analgesic effects and serum and brain morphine content were significantly increased 9 days after STZ administration. The increase in the analgesic effects of morphine, as well as serum and brain morphine content, was suppressed by aminoguanidine, a specific iNOS inhibitor. Conversely, there were no changes in the analgesic effects obtained with subcutaneous morphine in STZ-treated mice. Our findings suggest that the analgesic effects of oral morphine are dependent on intestinal P-gp expression, and this may be one of the reasons that it is difficult to obtain stable pharmacological effects of morphine in diabetic patients.

Aß and Aδ but not C-fibres are involved in stroke related pain and allodynia: an experimental study in mice.

OBJECTIVES: Cerebral ischaemia is a leading cause of death and disability, including severe complications such as memory disturbance, palsy, and spasticity. Central post-stroke pain (CPSP) is a complication of cerebral ischaemia, and is characterized clinically by spontaneous pain and attacks of allodynia and dysaesthesia. However, the detailed mechanisms of CPSP are not well established. Herein, we have examined alterations of the current stimulus threshold of primary afferent neurons or the nociceptive threshold against mechanical stimuli in mice receiving left middle cerebral artery occlusion (MCAO). METHODS: Alterations of current stimulus threshold and the development of mechanical allodynia in hind paws were measured after MCAO using a Neurometer and the von Frey filament test, respectively. KEY FINDINGS: Development of cerebral infarction was clearly observed on day 1 and day 3 after MCAO. For the estimation of current stimulus threshold measured by the Neurometer, the sensitivity of Aδ and Aß fibres (at 2000 and 250 Hz stimulation, respectively) was significantly increased on day 3 after MCAO, while that of C fibres (at 5 Hz stimulation) was unaltered. In addition, the paw withdrawal threshold of the left hind paw as measured by the von Frey filament test was significantly decreased on day 1 and day 3 after MCAO when compared with day 0, while that in the right hind paw was not different. CONCLUSIONS: The data suggested the development of bilateral hyperaesthesia in this model. Further, mechanical allodynia developed in the ipsilateral side to the MCAO. Potentially, myelinated A fibre-specific hypersensitization after stroke may have contributed to these symptoms.

Involvement of matrix metalloproteinase-mediated proteolysis of neural cell adhesion molecule in the development of cerebral ischemic neuronal damage.

Neural cell adhesion molecule (NCAM) is a membrane protein abundantly expressed in the central nervous system. Recently, it has been reported that dysfunction of NCAM is linked to human brain disorders. Furthermore, NCAM is one of the proteolysis targets of matrix metalloproteinase (MMP), whose activation is implicated in neuronal damage. The aim of this study was to elucidate the involvement of MMP-mediated proteolysis of NCAM in the development of ischemic neuronal damage. Male ddY and MMP-9 knockout (KO) C57BL/6J mice were subjected to 2 h of middle cerebral artery occlusion (MCAO). In MCAO model mice, development of infarction and behavioral abnormality were clearly observed on days 1 and 3 after MCAO. Protein levels of MMP-2 and MMP-9 were significantly increased on days 1 and 3 after MCAO. In addition, full-length NCAM (180 kDa) was significantly decreased, but its metabolite levels increased on day 1 by ischemic stress per se. NCAM small interfering RNA significantly increased the neuronal damage induced by MCAO. MMP inhibition or MMP-9 gene KO attenuated the infarction, behavioral abnormalities, and decrease of NCAM (180 kDa) observed after MCAO in mice. The present findings clearly suggest that MMP-2/MMP-9-mediated NCAM proteolysis is implicated in the exacerbation of ischemic neuronal damage.

Involvement of NCAM and FGF receptor signaling in the development of analgesic tolerance to morphine.

This study examined the involvement of neural cell adhesion molecule (NCAM), a member of the immunoglobulin superfamily, in the development of tolerance to morphine. Furthermore, we focused on fibroblast growth factor (FGF) receptor and protein kinase C (PKC)-α as part of the intracellular signal transduction pathways underlying NCAM stimulation. The development of analgesic tolerance to morphine was gradually observed during daily treatment of morphine (10mg/kg, s.c.) for 5 days. Morphine treatment gradually and significantly decreased the NCAM expression levels. However it returned to normal levels immediately after re-treatment of morphine. Treatment of AS-ODN against NCAM completely inhibited analgesic tolerance to morphine. Protein expression levels of PKC-α were significantly increased by repeated morphine treatment in a NCAM-AS-ODN-reversible manner. Interestingly, alterations of protein interactions between NCAM and FGF receptor were observed under repeated morphine treatment. In addition, SU5402 (2 µg/mouse, i.c.v.), an inhibitor of FGF receptor, completely abolished the development of analgesic tolerance to morphine. Furthermore, κ-opioid receptor stimulation using U-50,488H, a κ-opioid receptor agonist, or establishment of formalin-induced chronic pain can completely suppress these changes in protein expression levels of NCAM and PKC-α and inhibit development of analgesic tolerance to morphine. These findings suggest that NCAM and its interaction with FGF receptor in the mechanism of up-regulation of PKC-α may contribute to the development of analgesic tolerance to morphine. Chronic pain or κ-opioid receptor stimulation could modulate these phenomena and suppress the development of analgesic tolerance to morphine.

[Nitric oxide synthase-mediated alteration of intestinal P-glycoprotein under hyperglycemic stress].

P-glycoprotein (P-gp), one of the important drug-efflux pumps, is known to be affected by pathological conditions such as inflammation or infection. Recently, it is reported that high glucose or hyperglycemia can alter P-gp expression levels at the blood-brain barrier or in kidney, although the details are still unknown. Here, we analyzed the alteration of intestinal P-gp expression and function in the development of diabetes and elucidated the mechanisms. Type 1 diabetes was induced in male ddY mice by an i.p. injection of streptozotocin (STZ) (230 mg/kg). We analyzed ileal P-gp expression and drug efflux activity using western blot analysis and an in situ closed loop method, respectively. Additionally, we analyzed ileal nitric oxide synthase (NOS) activity using colorimetric method. A significant reduction of P-gp expression level in ileum was found on day 9 after STZ administration. In contrast, a remarkable decrease in drug efflux activity was observed on days 3 and 9. Interestingly, NOS activity in ilea was significantly increased on day 9. The decrease of P-gp expression levels observed on day 9 was completely suppressed by L-NG-nitroarginine methyl ester (L-NAME), a broad range NOS inhibitor, or aminoguanidine, a specific inducible NOS (iNOS) inhibitor. In addition, P-gp expression level in ileum was significantly decreased by administration of NOR5, a NO donor. These results indicate the possibility that NO, produced by iNOS in the ileum, is involved in the alteration of ileal P-gp expression and function under STZ-induced diabetic conditions.

[Effectiveness of metformin in prevention of development of hyperglycemia and neuronal damage caused by ischemic stress].

Hyperglycemia is a known exacerbating factor in ischemic stroke. It has been reported that hyperglycemia and post-ischemic glucose intolerance can develop after stroke and be involved in the development of neuronal damage, as we described previously. Here, we focus on the effectiveness of metformin, a hypoglycemic drug, in preventing the development of neuronal damage using the middle cerebral artery occlusion (MCAO) model mice. 5'-AMP-activated protein kinase (AMPK) is a serine/threonine kinase that plays a key role in the hypoglycemic effects of metformin. Recently, it has been reported that centrally activated AMPK is involved in the development of ischemic neuronal damage, while the effect of peripherally activated AMPK on ischemic neuronal damage is not known. In the liver, AMPK activity was not affected by MCAO, while the administration of intraperitoneal metformin (250 mg/kg), an AMPK activator, significantly activated hepatic AMPK and suppressed both the development of post-ischemic glucose intolerance and ischemic neuronal damage without alteration of central AMPK activity. On the other hand, the administration of intracerebroventricular metformin (100 µg/mouse) significantly exacerbated the development of neuronal damage observed on day 1 after MCAO. These effects were significantly blocked by compound C, a specific AMPK inhibitor. These results suggest that central AMPK is activated by ischemic stress per se, although peripheral AMPK is not altered. Furthermore, the regulation of post-ischemic glucose intolerance by metformin-induced activation of peripheral AMPK contributes to the reduction of cerebral ischemic neuronal damage.