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The possible role of dopamine D2 receptors located in the spinal cord in the regulation of the blood glucose level have not been investigated before. In the present study, the effect of D2 receptor agonist and antagonist administered intrathecal (it) injection on the blood glucose level were examined in the Institute of Cancer Research (ICR) mice. We found that it injection with carmoxirole (D2 receptor agonist) caused an elevation of the blood glucose level in a dose-dependent manner. Carmoxirole-induced increase of the blood glucose was significantly attenuated by L-741,626 (D2 receptor antagonist). Previously, we indicated that intrathecal (it) treatment with 0.1 μg/5 μl pertussis toxin (PTX, a Gi/Go inhibitor) produces a hypoglycemic effect in ICR in a long-term manner. In the present study, it pretreatment with PTX for 6 days almost abolished the hyperglycemic effect induced by carmoxirole. The plasma insulin level was elevated by carmoxirole, and L-741,626 or PTX pretreatment reduced carmoxirole-induced increment of the insulin level. In addition, the plasma corticosterone level was increased by carmoxirole but it pretreatment with L-741,626 or PTX did not affect carmoxirole-induced increment of the corticosterone level. Our results suggest that D2 receptors located in the spinal cord play an important role in the elevation of the blood glucose level. Spinally located inhibitory G-proteins appear to be involved in hyperglycemic effect induced by carmoxirole.

Osteoarthritis (OA) is a general joint disease. Cartilage damage is associated with a decrease in the density of chondrocytes. Mesenchymal stem cells (MSCs) differentiate into adipocytes, osteocytes and chondrocytes, and are an excellent source of cell therapy. Cartilage-derived extracellular matrix (ECM) promotes chondrogenesis of MSCs. However, the role of MSCs stimulated by ECM is not well known in OA. The purpose of this study is to determine the role of specific factors generated by the application of ECM and umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) in managing OA symptoms. Cartilage acellular matrix (CAM), which is a cartilage-derived ECM, was used to promote the chondrogenesis of UCB-MSCs. Induced MSCs were analyzed using chondrogenic markers (aggrecan, collagen type 2, and SOX9) and bone morphogenic protein 6 (BMP6). BMP6 is known to be involved in early chondrogenesis of MSCs. As a result, treatment with CAM significantly increased the expression of chondrogenic markers and BMP6 in UCB-MSCs. Treatment with recombinant human BMP6 also dramatically increased the levels of chondrogenic markers in UCB-MSCs. In addition, UCB-MSCs and CAM were used to evaluate OA symptom improvement in a rabbit articular cruciate ligament transection (ACLT) model. Application of UCB-MSCs and CAM enhanced not only the structure and synthesis of proteoglycan and collagen type 2 but also anti-inflammatory effects in both rabbit joint and synovial fluid. Moreover, the detection of human cells and involvement of BMP6 were confirmed in rabbit cartilage tissues. This study indicates that therapeutic potential of UCB-MSCs with CAM is mediated via BMP6 in OA.

Rheumatoid arthritis (RA) is a common inflammatory chronic disease. It has been reported that mesenchymal stem cells (MSCs) have the effect of immune suppression in collagen-induced arthritis (CIA) mice model. However, the in vivo therapeutic effect from the long-interval repeated intravenous administration of human umbilical cord blood-derived (hUCB)-MSCs had not been investigated in CIA mice model. This study was undertaken to investigate the effects of long-interval repeated intravenous administration of hUCB-MSCs at different doses in CIA mice model. Mice were intravenously injected with three different doses of hUCB-MSCs once every 2 weeks for three times. RA severity was assessed by clinical joint score and histologic analysis including hematoxylin and eosin staining, safranin-O staining, and toluidine blue staining. We used real-time polymerase chain reaction and flow cytometry to quantify differences in inflammatory cytokines and Tregs. Mice treated with hUCB-MSCs showed significant improvement in clinical joint score. Histologic analysis revealed that hUCB-MSCs definitely reduced joint inflammation, cartilage damage, and formation of pannus in multimedium and multihigh groups. These hUCB-MSCs also significantly decreased IL-1 beta protein levels in multimedium and multihigh groups and IL-6 protein levels in all hUCB-MSCs-treated groups. Furthermore, mRNA levels of IL-1 beta and IL-6 were decreased significantly in all hUCB-MSCs-treated groups, whereas the expression of anti-inflammatory cytokine IL-10 was increased in the multihigh group. Tregs known as suppressor T cells were also significantly increased in the multihigh group. Our findings suggest that long-interval repeated intravenous administration of hUCB-MSCs has therapeutic effects by improving symptoms of RA in CIA mice model in a dose-dependent manner.

Oxyntomodulin is known as a regulator of the blood glucose homeostasis and food intake. In the present study, the possible roles of oxyntomodulin receptor (GCGR/GLP-1) located in the spinal cord for the regulation of the blood glucose level was investigated in ICR mice. We found in the present study that intrathecal (i.t.) injection with oxyntomodulin (from 1 to 10 μg) or glucagon-like peptide-1 (GLP-1; from 1 to 10 μg) alone did not affect the blood glucose level. However, i.t. administration with oxyntomodulin, but not GLP-1, caused a reduction of the blood glucose level in D-glucose-fed model. The oxyntomodulininduced reduction of the blood glucose level in D-glucose-fed model is followed by reduction of insulin level. Furthermore, the i.t. co-administration of oxyntomodulin with GLP-1 caused a profound up-regulation of the blood glucose level. The profound hyperglycemic effect shown by co-treatment with oxyntomodulin and GLP-1 caused a profound up-regulation of plasma insulin level. Our results suggest that the activation of oxyntomodulin system present in the spinal cord may play significant modulatory roles in the reduction of the blood glucose level in D-glucose-fed model. Furthermore, GLP-1 located in the spinal cord shows a synergistic interaction with oxyntomodulin for producing hyperglycemia.

5,7-Dihydroxytryptamine (5,7-DHT) is a neurotoxin which causes the depletion of serotonin. Moreover, the serotonergic system is the regulator of the blood glucose level. However, the role of centrally located serotonergic system in blood glucose regulation after D-glucose feed and immobilization (IMO) stress was not clearly characterized yet. Thus the present study was designed to examine the effect of 5,7-DHT administered intracerebroventricularly (i.c.v.) or intrathecally (i.t.) on the blood glucose level in D-glucose-fed and immobilization stress models. Mice were pretreated once i.c.v. or i.t. with 5,7-DHT (from 10 to 40 µg) for 3 days and D-glucose (2 g/kg) was fed orally. The blood glucose level was measured at 0, 30, 60 and 120 min after D-glucose feeding and immobilization stress initiation. We found that i.c.v. or i.t. pretreatment with 5,7-DHT attenuated the blood glucose level in both animal models. D-glucose feeding causes an increase in plasma insulin level, whereas the plasma cortico...

In the present study, we characterized the expression and role of forkhead box O (FoxO3a) in kainic acid (KA)-induced hippocampal neuronal cell death. FoxO3a and pFoxO3a expression in the CA1, CA2, and dentate gyrus regions in the hippocampus increased 0.5 and 1 h after intracerebroventricular administration of KA. In addition, both FoxO3a and pFoxO3a expression in the hippocampal CA3 region increased significantly and equally for 1 h but decreased gradually for 24 h after KA administration. In particular, the KA-induced increases in FoxO3a and pFoxO3a expression in the hippocampal CA3 region were inhibited by pretreatment with the N-methyl-D-aspartate (NMDA) receptor antagonist (MK-801, dizocilpine, 1 µg/5 µl) or a non-NMDA receptor antagonist (CNQX, 6-cyano-7-nitroquinoxaline-2,3-dione, 0.5 µg/5 µl). Furthermore, dizocilpine and CNQX produced a neuroprotective effect against KA-induced neuronal death in the CA3 region of the hippocampus. Our results suggest that FoxO3a and pFoxO3 expression is upregulated by KA. Both FoxO3a and pFoxO3a expression appear to be responsible for KA-induced neuronal death in the CA3 region of the hippocampus.

Effects of histamine receptors agonists or antagonists administered centrally (supraspinally or spinally) on immobilization stress-induced blood glucose levels were studied in Institute for Cancer Research mice. Mice were pretreated intracerebroventricularly (i.c.v.) or intrathecally (i.t.) with histamine (H1, H2, H3 and H4) receptor agonists or antagonists 10 min prior to immobilization stress (IMO) stimulation for 30 min. We found that the increased blood glucose level induced by IMO was attenuated by the i.c.v. pretreatment with α-methylhistamine (H3 agonist). However, H3 antagonist, H1, H2 and H4 receptor agonists and antagonists did not affect the blood glucose level. Also, i.t. pretreatment with α-methylhistamine or VUF 8430 attenuated the increased blood glucose level induced by IMO. In addition, cetirizine and carcinine enhanced the increased blood glucose level induced by IMO. However, the blood glucose level was not affected by H1 and H2 receptor agonists, H2 and H4 receptor antagonists. Cortico...

We examined the role of spinally located β-adrenergic receptors in the regulation of the blood glucose level. The intrathecal (i.t.) injections with dobutamine (β1-adrenergic receptor agonist) or terbutaline (β2-adrenergic receptor agonist) caused an elevation of the blood glucose level, whereas metoprolol (β1-adrenergic receptor antagonist) or butoxamine (β2-adrenergic receptor antagonist) did not. In addition, i.t. pretreatment with pertussis toxin (PTX) attenuated the hyperglycemic effect induced by dobutamine or terbutaline. Moreover, plasma insulin level was increased by dobutamine but not by terbutaline, and PTX reduced dobutamine-induced up-regulation of the plasma insulin level. Terbutaline significantly increased plasma corticosterone level, and PTX further enhanced terbutaline-induced corticosterone level. Furthermore, intraperitoneal (i.p.) pretreatment with hexamethonium- (a preganglionic blocker) attenuated dobutamine- and terbutaline-induced hyperglycemic effects. Our results suggest that activation of spinal β1- and β2-adrenergic receptors produces hyperglycemic effects in a different manner. Spinally located PTX-sensitive G-proteins appear to be involved in hyperglycemic effect induced by terbutaline. Furthermore, dobutamine- or terbutaline-induced hyperglycemia appears to be mediated through the spinal nerves.

Kainic acid (KA) is a well-known excitatory neurotoxic substance. In the present study, effects of KA-injected intraperitoneally (i.p.), intracerebroventricularly (i.c.v.) or intrathecally (i.t.) on the blood glucose level were investigated in ICR mice. We found that KA administered intraperitoneally (i.p.), intracerebroventricularly (i.c.v.) or intrathecally (i.t.) increased the blood glucose and corticosterone levels, suggesting that KA-induced hyperglycemia appeared to be due to increased blood corticosterone level. In support of this finding, adrenalectomy causes a reduction of KA-induced hyperglycemia and neuronal cell death in CA3 regions of the hippocampus. In addition, pretreatment with i.c.v. or i.t. injection of CNQX (6-cyano-7-nitroquinoxaline-2, 3-dione; a non-NMDA receptor blocker) attenuated the i.p. and i.c.v. administered KA-induced hyperglycemia. KA administered i.c.v. caused an elevation of the blood corticosterone level whereas the plasma insulin level was reduced. Moreover, i.c.v. pretreatment with CNQX inhibited the decrease of plasma insulin level induced by KA i.c.v. injection, whereas the KA-induced plasma corticosterone level was further enhanced by CNQX pretreatment. Our results suggest that KA administered systemically or centrally produces hyperglycemia. A glucocorticoid system appears to be involved in KA-induced hyperglycemia. Furthermore, central non-N-methyl-D-aspartate receptors may be responsible for KA-induced hyperglycemia.

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 µg/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.

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.

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 µg 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.