Gastrodia Elata Bl Attenuates Cocaine-Induced Conditioned Place Preference and Convulsion, but not Behavioral Sensitization in Mice: Importance of GABA(A) Receptors.

It has been suggested that GABAergic neurotransmission can modulate cocaine dependence and seizure activity. Since Gastrodia elata Bl (GE), an oriental herb agent, has been shown to enhance GABAergic transmission, we examined whether GE affects cocaine-induced seizures, conditioned place preference (CPP), and behavioral sensitization in mice. Treatment with GE (500 or 1000 mg/kg, p.o.) significantly delayed seizure onset time and significantly shortened seizure duration induced by cocaine (90 mg/kg, i.p.). In addition, cocaine (15 mg/kg, i.p.)-induced CPP was significantly attenuated by GE in a dose-dependent manner. However, GE did not significantly alter behavioral sensitization induced by cocaine (15 mg/kg, i.p.). In order to understand whether GABAergic receptors are implicated in GE-mediated pharmacological action in response to cocaine, GABA(A) receptor antagonist bicuculline and GABA(B) receptor antagonist SCH 50911 were employed in the present study. GE-mediated attenuations on the cocaine-induced seizures and CPP were significantly reversed by bicuculline (0.25 or 0.5 mg/kg, i.p.), but not by SCH 50911 (1.5 or 3.0 mg/kg, i.p.). Therefore, our results suggest that GE attenuates cocaine-induced seizures and CPP via, at least in part, GABA(A) receptor activation.

Gastrodia elata bl attenuates methamphetamine-induced dopaminergic toxicity via inhibiting oxidative burdens.

It has been recognized that Gastrodia elata Bl (GE), an oriental herb medicine, ameliorates various neurological disorders, that GE modulates the monoaminergic and GABAergic systems, and that GE possess antioxidant activities. We examined whether GE affects methamphetamine (MA)-induced striatal dopaminergic toxicity in mice. Treatment with MA (7.5 mg/kg, i.p. × 4) resulted in significant decreases in behavioural activity (as shown by locomotor activity and rota rod performance), dopamine level, tyrosine hydroxylase (TH) activity, and TH protein expression (as evaluated by immunocytochemistry and western blot analysis). In addition, MA treatment showed significant increases in lipid peroxidation [as evaluated by 4-hydroxy-2-nonenal (4-HNE) expression and malondialdehyde formation], protein oxidation (as shown by protein carbonyl expression and its formation), and reactive oxygen species (ROS) formation. Treatment with GE significantly attenuates MA-induced behavioural and dopaminergic impairments, and oxidative stresses in a dose-dependent manner. Our results suggest that GE treatment shows anti-dopaminergic effects in response to MA insult via, at least in part, inhibiting oxidative stresses in the striatum of the mice.

Proinsulin C-peptide rapidly stimulates mitogen-activated protein kinases in Swiss 3T3 fibroblasts: requirement of protein kinase C, phosphoinositide 3-kinase and pertussis toxin-sensitive G-protein.

It has been demonstrated that proinsulin C-peptide possesses several biological activities and that its specific binding sites are present on the surface of cell membranes. However, the molecular and cellular mechanisms of C-peptide actions are poorly known. In the present study we examined the possible involvement of the mitogen-activated protein kinase (MAPK) pathway in C-peptide effects. C-peptide induced the phosphorylation of MAPK [p44 extracellular signal-regulated kinase 1 (ERK1) and p42 ERK2] in Swiss 3T3 and 3T3-F442A fibroblasts but not in 3T3-L1 fibroblasts and some other cell lines such as L(6)E(9) muscle cells. In Swiss 3T3 cells, C-peptide-induced phosphorylation of MAPK was dependent on time and concentration, being maximal at 1 min and at 1 nM C-peptide and was accompanied by an increase in MAPK activity and MAPK kinase (MEK) phosphorylation. The MAPK phosphorylation by C-peptide was abolished by treatment with pertussis toxin (PTX) and also with a MEK inhibitor, PD 98059. In addition, MAPK phosphorylation was attenuated by treatment with a phosphoinositide 3-kinase (PI-3K) inhibitor, wortmannin, and with a protein kinase C (PKC) inhibitor, GF109203X, and by down-regulation of PKC by prolonged treatment with PMA. Similar effects of the inhibitors and PTX were found on the MAPK phosphorylation induced by neuropeptide Y. These results suggest that C-peptide activates MAPK through a putative G(i)/G(o)-linked receptor for C-peptide and through PI-3K-dependent and PKC-dependent pathways.

Sympathetic activation of hepatic and splenic IL-1beta mRNA expression during oscillation stress in the rat.

Interleukin (IL)-1beta mRNA expression in the liver and spleen was examined after subjection to oscillation stress in the rat. Thirty-minute subjection to oscillation stress increased IL-1beta mRNA expression in the both organs. Prior treatment of rats with gadolinium chloride, which eliminates macrophages, prevented the stress-induced IL-1beta expression. Either adrenalectomy or treatment of guanethidine, a blocker of norepinephrine release in the sympathetic nerve endings, partially attenuated the stress-induced response, but the combined treatment completely blocked it. Injection of beta-adrenergic antagonist (propranolol) also suppressed the stress-induced response. These results suggest that oscillation stress induces IL-1beta mRNA expression in the liver and spleen, probably in Kupffer cells and splenic macrophages, and that stress-induced IL-1beta expression is elicited by catecholamines released from sympathetic nerve terminals and the adrenal gland.

Norepinephrine stimulates interleukin-6 mRNA expression in primary cultured rat hepatocytes.

Non-invasive immobilization stress causes an increase in the plasma interleukin (IL)-6 level accompanied by increased IL-6 mRNA expression and IL-6 immunoactivity in the liver [Biochem. Biophys. Res. Commun. (1997) 238, 707-711]. In the present study, using rat primary cultured hepatocytes and non-parenchymal liver cells, the effect of norepinephrine (NE) on IL-6 mRNA expression was determined. IL-6 mRNA expression in hepatocytes, but not in non-parenchymal liver cells, increased when the cells were treated with NE. The stimulatory effect of NE was inhibited by the combined use of alpha- and beta-adrenergic antagonists. IL-6 mRNA expression in hepatocytes also increased on incubation with the culture medium of non-parenchymal liver cells treated with NE. The effect of the medium was blocked by an IL-1 receptor antagonist. Moreover, exogenous IL-1beta stimulated IL-6 mRNA expression in hepatocytes. IL-1beta was present in the medium of non-parenchymal liver cells and increased with NE-treatment. These results suggest that NE released from sympathetic nerve terminals during stress can directly increase IL-6 mRNA expression in hepatocytes and indirectly through IL-1beta production from non-parenchymal liver cells.

Induction of uncoupling protein (UCP) 2 in primary cultured hepatocytes.

Uncoupling protein 2 (UCP2) mRNA expression and function was examined in rat primary cultured hepatocytes. UCP2 mRNA was not expressed in freshly isolated hepatocytes, but appeared during a 24-144 h primary culture period. Isolated mitochondria from 144 h cultured hepatocytes showed a lower oxygen consumption rate in the presence of succinate and ADP. However, the ratio of the oxygen consumption rate when media contained succinate alone to that with succinate and ADP was increased by 166% versus control mitochondria. Moreover, the mitochondrial potential in the presence of succinate was decreased by 60%, indicating the potential role of UCP2 in hepatocyte mitochondria as an active uncoupler.

Immobilization stress increases hepatic IL-6 expression in mice.

When mice were subjected to restriction of movement in a small cylinder (immobilization stress), the serum interleukin (IL)-6 level rose in 1 h, following increased expression of IL-6 mRNA in both the liver and the spleen. The IL-6 mRNA induction was much greater in the liver than in the spleen when compared on a whole-organ basis. Intraperitoneal injection of bacterial lipopolysaccharide (LPS) also increased IL-6 mRNA expression in these organs, but more preferentially in the spleen. Immunohistochemical examinations of liver tissue using an antibody against murine IL-6 revealed that immobilization stress induced IL-6 mainly in hepatic parenchymal cells, whereas LPS injection did so only in sinusoidal mononuclear cells. These results indicate that immobilization stress induces IL-6 production in the liver, especially in hepatic parenchymal cells, probably by a different mechanism from that for IL-6 induction by LPS.