Effect of pertussis toxin pretreated centrally on blood glucose level induced by stress

In the present study, we examined the effect of pertussis toxin (PTX) administered centrally in a variety of stress-induced blood glucose level. Mice were exposed to stress after the pretreatment of PTX (0.05 or 0.1 µg) i.c.v. or i.t. once for 6 days. Blood glucose level was measured at 0, 30, 60 and 120 min after stress stimulation. The blood glucose level was increased in all stress groups. The blood glucose level reached at maximum level after 30 min of stress stimulation and returned to a normal level after 2 h of stress stimulation in restraint stress, physical, and emotional stress groups. The blood glucose level induced by cold-water swimming stress was gradually increased up to 1 h and returned to the normal level. The intracerebroventricular (i.c.v.) or intrathecal (i.t.) pretreatment with PTX, a Gi inhibitor, alone produced a hypoglycemia and almost abolished the elevation of the blood level induced by stress stimulation. The central pretreatment with PTX caused a reduction of plasma insulin level, whereas plasma corticosterone level was further up-regulated in all stress models. Our results suggest that the hyperglycemia produced by physical stress, emotional stress, restraint stress, and the cold-water swimming stress appear to be mediated by activation of centrally located PTX-sensitive G proteins. The reduction of blood glucose level by PTX appears to due to the reduction of plasma insulin level. The reduction of blood glucose level by PTX was accompanied by the reduction of plasma insulin level. Plasma corticosterone level up-regulation by PTX in stress models may be due to a blood glucose homeostatic mechanism.

Effect of D-glucose feeding on mortality induced by sepsis

Sepsis is the life-threatening response to infection which can lead to tissue damage, organ failure, and death. In the current study, the effect of orally administered D-glucose on the mortality and the blood glucose level induced by D-Galactosamine (GaLN)/lipopolysaccharide (LPS)-induced sepsis was examined in ICR mice. After various amounts of D-glucose (from 1 to 8 g/kg) were orally fed, sepsis was induced by injecting intraperitoneally (i.p.) the mixture of GaLN /LPS. Oral pre-treatment with D-glucose dose-dependently increased the blood glucose level and caused a reduction of sepsis-induced mortality. The oral post-treatment with D-glucose (8 g/kg) up to 3 h caused an elevation of the blood glucose level and protected the mortality observed in sepsis model. However, D-glucose post-treated at 6, 9, or 12 h after sepsis induction did not affect the mortality and the blood glucose level induced by sepsis. Furthermore, the intrathecal (i.t.) pretreatment once with pertussis toxin (PTX; 0.1 microg/5 ml) for 6 days caused a reduction of D-glucose-induced protection of mortality and hyperglycemia. Furthermore, once the hypoglycemic state is continued up to 6 h after sepsis initiated, sepsis-induced mortality could not be reversed by D-glucose fed orally. Based on these findings, it is assumed that the hypoglycemic duration between 3 and 6 h after the sepsis induction may be a critical time of period for the survival. D-glucose-induced protective effect against sepsis-induced mortality appears to be mediated via activating PTX-sensitive G-proteins in the spinal cord. Finally, the production of hyperglycemic state may be critical for the survival against the sepsis-induced mortality.

Effect of Sulfonylureas Administered Centrally on the Blood Glucose Level in Immobilization Stress Model

Sulfonylureas are widely used as an antidiabetic drug. In the present study, the effects of sulfonylurea administered supraspinally on immobilization stress-induced blood glucose level were studied in ICR mice. Mice were once enforced into immobilization stress for 30 min and returned to the cage. The blood glucose level was measured 30, 60, and 120 min after immobilization stress initiation. We found that intracerebroventricular (i.c.v.) injection with 30 microg of glyburide, glipizide, glimepiride or tolazamide attenuated the increased blood glucose level induced by immobilization stress. Immobilization stress causes an elevation of the blood corticosterone and insulin levels. Sulfonylureas pretreated i.c.v. caused a further elevation of the blood corticosterone level when mice were forced into the stress. In addition, sulfonylureas pretreated i.c.v. alone caused an elevation of the plasma insulin level. Furthermore, immobilization stress-induced insulin level was reduced by i.c.v. pretreated sulfonylureas. Our results suggest that lowering effect of sulfonylureas administered supraspinally against immobilization stress-induced increase of the blood glucose level appears to be primarily mediated via elevation of the plasma insulin level.

The Modulatory Role of Spinally Located Histamine Receptors in the Regulation of the Blood Glucose Level in D-Glucose-Fed Mice

The possible roles of spinal histamine receptors in the regulation of the blood glucose level were studied in ICR mice. Mice were intrathecally (i.t.) treated with histamine 1 (H1) receptor agonist (2-pyridylethylamine) or antagonist (cetirizine), histamine 2 (H2) receptor agonist (dimaprit) or antagonist (ranitidine), histamine 3 (H3) receptor agonist (alpha-methylhistamine) or antagonist (carcinine) and histamine 4 (H4) receptor agonist (VUF 8430) or antagonist (JNJ 7777120), and the blood glucose level was measured at 30, 60 and 120 min after i.t. administration. The i.t. injection with alpha-methylhistamine, but not carcinine slightly caused an elevation of the blood glucose level. In addition, histamine H1, H2, and H4 receptor agonists and antagonists did not affect the blood glucose level. In D-glucose-fed model, i.t. pretreatment with cetirizine enhanced the blood glucose level, whereas 2-pyridylethylamine did not affect. The i.t. pretreatment with dimaprit, but not ranitidine, enhanced the blood glucose level in D-glucose-fed model. In addition, alpha-methylhistamine, but not carcinine, slightly but significantly enhanced the blood glucose level D-glucose-fed model. Finally, i.t. pretreatment with JNJ 7777120, but not VUF 8430, slightly but significantly increased the blood glucose level. Although histamine receptors themselves located at the spinal cord do not exert any effect on the regulation of the blood glucose level, our results suggest that the activation of spinal histamine H2 receptors and the blockade of spinal histamine H1 or H3 receptors may play modulatory roles for up-regulation and down-regulation, respectively, of the blood glucose level in D-glucose fed model.

Repaglinide, but Not Nateglinide Administered Supraspinally and Spinally Exerts an Anti-Diabetic Action in D-Glucose Fed and Streptozotocin-Treated Mouse Models

We have recently demonstrated that some anti-diabetic drugs such as biguanide and thizolidinediones administered centrally modulate the blood glucose level, suggesting that orally administered anti-diabetic drugs may modulate the blood glucose level by acting on central nervous system. The present study was designed to explore the possible action of another class of anti-diabetic drugs, glinidies, administered centrally on the blood glucose level in ICR mice. Mice were administered intracerebroventricularly (i.c.v.) or intrathecally (i.t.) with 5 to 30 microg of repaglinide or nateglinide in D-glucose-fed and streptozotocin (STZ)-treated models. We found that i.c.v. or i.t. injection with repaglinide dose-dependently attenuated the blood glucose level in D-glucose-fed model, whereas i.c.v. or i.t. injection with nateglinide showed no modulatory action on the blood glucose level in D-glucose-fed model. Furthermore, the effect of repaglinide administered i.c.v. or i.t. on the blood glucose level in STZ-treated model was studied. We found that repaglinide administered i.c.v. slightly enhanced the blood glucose level in STZ-treated model. On the other hand, i.t. injection with repaglinide attenuated the blood glucose level in STZ-treated model. The plasma insulin level was enhanced by repaglinide in D-glucose-fed model, but repaglinide did not affect the plasma insulin level in STZ-treated model. In addition, nateglinide did not alter the plasma insulin level in both D-glucose-fed and STZ-treated models. These results suggest that the anti-diabetic action of repaglinide appears to be, at least, mediated via the brain and the spinal cord as revealed in both D-glucose fed and STZ-treated models.

Effect of Cholera Toxin Administered Supraspinally or Spinally on the Blood Glucose Level in Pain and D-Glucose Fed Animal Models

In the present study, the effect of intrathecal (i.t.) or intracerebroventricular (i.c.v.) administration with cholera toxin (CTX) on the blood glucose level was examined in ICR mice. The i.t. treatment with CTX alone for 24 h dose-dependently increased the blood glucose level. However, i.c.v. treatment with CTX for 24 h did not affect the blood glucose level. When mice were orally fed with D-glucose (2 g/kg), the blood glucose level reached to a maximum level at 30 min and almost returned to the control level at 120 min after D-glucose feeding. I.c.v. pretreatment with CTX increased the blood glucose level in a potentiative manner, whereas i.t. pretreatment with CTX increased the blood glucose level in an additive manner in a D-glucose fed group. In addition, the blood glucose level was increased in formalin-induced pain animal model. I.c.v. pretreatment with CTX enhanced the blood glucose level in a potentiative manner in formalin-induced pain animal model. On the other hand, i.t. pretreatment with CTX increased the blood glucose level in an additive manner in formalin-induced pain animal model. Our results suggest that CTX administered supraspinally or spinally differentially modulates the regulation of the blood glucose level in D-glucose fed model as well as in formalin-induced pain model.

Effect of Agrimonia pilosa Ledeb Extract on the Antinociception and Mechanisms in Mouse

In the present study, the antinociceptive profiles of Agrimonia pilosa Ledeb extract were examined in ICR mice. Agrimonia pilosa Ledeb extract administered orally (200 mg/kg) showed an antinociceptive effect as measured by the tail-flick and hot-plate tests. In addition, Agrimonia pilosa Ledeb extract attenuated the writhing numbers in the acetic acid-induced writhing test. Furthermore, the cumulative nociceptive response time for intrathecal (i.t.) injection of substance P (0.7 microg) was diminished by Agrimonia pilosa Ledeb extract. Intraperitoneal (i.p.) pretreatment with yohimbine (alpha2-adrenergic receptor antagonist) attenuated antinociceptive effect induced by Agrimonia pilosa Ledeb extract in the writhing test. However, naloxone (opioid receptor antagonist) or methysergide (5-HT serotonergic receptor antagonist) did not affect antinociception induced by Agrimonia pilosa Ledeb extract in the writhing test. Our results suggest that Agrimonia pilosa Ledeb extract shows an antinociceptive property in various pain models. Furthermore, this antinociceptive effect of Agrimonia pilosa Ledeb extract may be mediated by alpha2-adrenergic receptor, but not opioidergic and serotonergic receptors.

Hop Extract Produces Antinociception by Acting on Opioid System in Mice

In the present study, the antinociceptive profiles of hop extract were characterized in ICR mice. Hop extract administered orally (from 25 to 100 mg/kg) showed an antinociceptive effect in a dose-dependent manner as measured in the acetic acid-induced writhing test. Antinociceptive action of hop extract was maintained at least for 60 min. Moreover, cumulative response time of nociceptive behaviors induced with intraplantar formalin injection was reduced by hop extract treatment during the 2nd phases. Furthermore, the cumulative nociceptive response time for intrathecal injection of substance P (0.7 microg) or glutamate (20 microg) was diminished by hop extract. Intraperitoneal pretreatment with naloxone (an opioid receptor antagonist) attenuated antinociceptive effect induced by hop extract in the writhing test. However, methysergide (a 5-HT serotonergic receptor antagonist) or yohimbine (an alpha2-adrenergic receptor antagonist) did not affect antinociception induced by hop extract in the writhing test. Our results suggest that hop extract shows an antinociceptive property in various pain models. Furthermore, the antinociceptive effect of hop extract may be mediated by opioidergic receptors, but not serotonergic and alpha2-adrenergic receptors.

Lactosylceramide Mediates the Expression of Adhesion Molecules in TNF-alpha and IFNgamma-stimulated Primary Cultured Astrocytes

Here we have investigated how lactosylceramide (LacCer) modulates gene expression of adhesion molecules in TNF-alpha and IFNgamma (CM)-stimulated astrocytes. We have observed that stimulation of astrocytes with CM increased the gene expression of ICAM-1 and VCAM-1. D-Threo-1-phenyl- 2-decanoylamino-3-morpholino-1-propanol (PDMP) and N-butyldeoxynojirimycin (NBDNJ), inhibitors of glucosylceramide synthase (GLS) and LacCer synthase (galactosyltransferase, GalT-2), inhibited the gene expression of ICAM-1 and VCAM-1 and activation of their gene promoter induced by CM, which were reversed by exogenously supplied LacCer. Silencing of GalT-2 gene using its antisense oligonucleotides also attenuated CM-induced ICAM-1 and VCAM-1 expression, which were reversed by LacCer. PDMP treatment and silencing of GalT-2 gene significantly reduced CM-induced luciferase activities in NF-KB, AP-1, GAS, and STAT-3 luciferase vectors-transfected cells. In addition, LacCer reversed the inhibition of NF-KB and STAT-1 luciferase activities by PDMP. Taken together, our results suggest that LacCer may play a crucial role in the expression of ICAM-1 and VCAM-1 via modulating transcription factors, such as NF-KB, AP-1, STAT-1, and STAT-3 in CM-stimulated astrocytes.

Antidepressant-like Effect of Kaempferol and Quercitirin, Isolated from Opuntia ficus-indica var. saboten

Opuntia ficus-indica var. saboten. is widely cultivated in Jeju Island (South Korea) for use in manufacture of health foods. This study described antidepressant effect of two flavonoids (kaempferol and quercitrin) isolated from the Opuntia ficus-indica var. saboten. The expression of the hypothalamic POMC mRNA or plasma beta-endorphin levels were increased by extract of Opintia ficus-indica var. saboten or its flavoniods administered orally. In addition, antidepressant activity was studied using tail suspension test (TST), forced swimming test (FST) and rota-rod test in chronically restraint immobilization stress group in mice. After restraint stress (2 hrs/day for 14 days), animals were kept in cage for 14 days without any further stress, bet with drugs. Mice were fed with a diet supplemented for 14 days and during the behavioral test period with kaempferol or quercitrin (30 mg/kg/day). POMC mRNA or plasma beta-endorphin level was increased by extract of Opintia ficus-indica var. saboten and its flavoniods. In addition, immobility time in TST and FST was significantly reduced by kaempferol or quercitrin. In rota-rod test, the time of permanence was maintained to the semblance of control group in turning at 15 rpm. Our results suggest that two flavonoids (kaempferol and quercitrin) isolated from the Opuntia ficus-indica var. saboten. show a potent antidepressant effect.

Activation of PPARalpha Attenuates IFNgamma and IL-1beta-induced Cell Proliferation in Astrocytes: Involvement of IL-6 Independent Pathway

The present study demonstrates the effect of fibrates, agonists of PPARalpha on cytokines-induced proliferation in primary cultured astrocytes. Alone or combination treatment with cytokines, such as IL-1beta (10 ng/ml), IFNgamma (10 ng/ml), and TNF-alpha (10 ng/ml) cause a significant increase of cell proliferation in a time-dependent manner. Treatment of astrocytes with bezafibrate and fenofibrate (0, 5, and 10 micrometer) reduced the IFNgamma and IL-1beta-induced cell proliferation in a dose-dependent manner. To address the involvement of IL-6 on the IFNgamma and IL-1beta-induced cell proliferation, released IL-6 level was measured. IFNgamma and IL-1beta cause an increase of released IL-6 protein level in a time-dependent manner. Furthermore, pretreatment with IL-6 antibody (0, 0.1, 1, 2.5, and 5 ng/ml) dose-dependently inhibited the IFNgamma and IL-1beta-induced cell proliferation. However, bezafibrate and fenofibrate did not affect increased mRNA and protein levels of IL-6 in IFNgamma and IL-1beta-stimulated astrocytes. Taken together, these results clearly suggest that activation of PPARalpha attenuates the IFNgamma and IL-1beta-induced cell proliferation through IL-6 independent pathway.

Neuroprotective Effect of Visnagin on Kainic Acid-induced Neuronal Cell Death in the Mice Hippocampus

Visnagin (4-methoxy-7-methyl-5H-furo[3,2-g][1]-benzopyran-5-one), which is an active principle extracted from the fruits of Ammi visnaga, has been used as a treatment for low blood-pressure and blocked blood vessel contraction by inhibition of calcium influx into blood cells. However, the neuroprotective effect of visnagin was not clearly known until now. Thus, we investigated whether visnagin has a neuroprotective effect against kainic acid (KA)-induced neuronal cell death. In the cresyl violet staining, pre-treatment or post-treatment visnagin (100 mg/kg, p.o. or i.p.) showed a neuroprotective effect on KA (0.1 microgram) toxicity. KA-induced gliosis and proinflammatory marker (IL-1beta, TNF-alpha, IL-6, and COX-2) inductions were also suppressed by visnagin administration. These results suggest that visnagin has a neuroprotective effect in terms of suppressing KA-induced pathogenesis in the brain, and that these neuroprotective effects are associated with its anti-inflammatory effects.

Antinociception Effect and Mechanisms of Campanula Punctata Extract in the Mouse

In the present study, the antinociceptive profiles of Campanula punctata extract were examined in ICR mice. The Campanula punctata contain a large dose of saponin. Campanula punctata extract administered orally (200 mg/kg) showed an antinociceptive effect as measured by the tail-flick and hot-plate tests. In addition, Campanula punctata extract attenuated the writhing numbers in the acetic acid-induced writhing test. Furthermore, the cumulative nociceptive response time for intrathecal (i.t.) injection of substance P (0.7 microgram) was diminished by Campanula punctata extract. Intraperitoneal (i.p.) pretreatment with yohimbine (alpha2-adrenergic receptor antagonist) attenuated antinociceptive effect induced by Campanula punctata extract in the writhing test. However, naloxone (opioid receptor antagonist) or methysergide (5-HT serotonergic receptor antagonist) did not affect antinociception induced by Campanula punctata extract in the writhing test. Our results suggest that Campanula punctata extract shows an antinociceptive property in various pain models. Furthermore, this antinociceptive effect of Campanula punctata extract may be mediated by alpha2-adrenergic receptor, but not opioidergic and serotonergic receptors.