OBJECTIVETo investigate the influence of najanalgesin on glutamate-glial transporter 1(GLT-1) in spinal cord of rats after L5 spinal nerve ligation and transection (SNL), and explore the spinal analgesic mechanism of najanalgesin.

METHODOne hundred male SD rats were randomly divided into 6 groups: sham(A), SNL(B), SNL + najanalgesin(C), SNL + saline (D), SNL + najanalgesin + liposome (E), SNL + najanalgesin + liposome + GLT-1 As-ODNs(F) and treated with intrathecal injections of 10 p.L saline (A and D), 40 ng X kg(-1) najanalgesin (C, E and F), qd, respectively. Besides intrathecal administration of najanalgesin the rats were intrathecally injected with 10 microL of GLT-1 antisense oligodeoxynucleotides (As-ODNs) (F) and 10 micdroL of liposome(E) once daily on day 3. The L4-L6 segments of the spinal cord were isolated in 1, 4 and 7 d(A,B,C and D), 7 d(E and F) after surgery. The mRNA and protein of GLT-1 were determined.

RESULTThe SNL model has successfully been set up. Compared to sham group, the expression of GLT-1 mRNA and protein level in group B and D both increased firstly and decreased later, the expression of GLT-1 in group C was significantly increased and kept stable, which were also higher when compared to group D in day 7th. Compared to SNL + najanalgesin group, after intrathecal injection of GLT-1 As-ODNs the GLT-1, expression of GLT-1 in F group significantly decreased. While intrathecal administration of liposome had no significant effect on the spinal GLT-1 expression.

CONCLUSIONNajanalgesin could increase the mRNA and protein expression of GLT-1 in spinal cord, which may be one of its spinal mechanisms of analgesia.

Animals ; Elapid Venoms ; pharmacology ; Elapidae ; Excitatory Amino Acid Transporter 2 ; genetics ; metabolism ; Gene Expression Regulation ; drug effects ; Male ; Neuralgia ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; drug effects ; metabolism

Dendroaspis natriuretic peptide (DNP), a new member of the natriuretic peptide family, is structurally similar to atrial, brain, and C-type natriuretic peptides. However, the effects of DNP on the cardiac function are poorly defined. In the present study, we examined the effect of DNP on the cardiac L-type Ca2+ channels in rabbit ventricular myocytes. DNP inhibited the L-type Ca2+ current (ICa,L) in a concentration dependent manner with a IC50 of 25.5 nM, which was blocked by an inhibitor of protein kinase G (PKG), KT5823 (1 microM). DNP did not affect the voltage dependence of activation and inactivation of ICa,L. The alpha1c subunit of cardiac L-type Ca2+ channel proteins was phosphorylated by the treatment of DNP (1 microM), which was completely blocked by KT5823 (1 microM). Finally, DNP also caused the shortening of action potential duration in rabbit ventricular tissue by 22.3 +/- 4.2% of the control (n = 6), which was completely blocked by KT5823 (1 microM). These results clearly indicate that DNP inhibits the L-type Ca2+ channel activity by phosphorylating the Ca2+ channel protein via PKG activation.
Action Potentials/drug effects ; Animals ; Biological Transport/drug effects ; Calcium/metabolism ; Calcium Channels, L-Type/*metabolism ; Carbazoles/pharmacology ; Cells, Cultured ; Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors ; Elapid Venoms/*metabolism/pharmacology ; Enzyme Activation ; Heart ; Heart Ventricles/drug effects ; Myocytes, Cardiac/drug effects ; Patch-Clamp Techniques ; Peptides/*metabolism/pharmacology ; Phosphorylation/drug effects ; Rabbits

Voltage-gated K+ (Kv) channels have been considered to be a regulator of membrane potential and neuronal excitability. Recently, accumulated evidence has indicated that several Kv channel subtypes contribute to the control of cell proliferation in various types of cells and are worth noting as potential emerging molecular targets of cancer therapy. In the present study, we investigated the effects of the Kv1.1-specific blocker, dendrotoxin-kappa (DTX-kappa), on tumor formation induced by the human lung adenocarcinoma cell line A549 in a xenograft model. Kv1.1 mRNA and protein was expressed in A549 cells and the blockade of Kv1.1 by DTX-kappa, reduced tumor formation in nude mice. Furthermore, treatment with DTX-kappa significantly increased protein expression of p21Waf1/Cip1, p27Kip1, and p15INK4B and significantly decreased protein expression of cyclin D3 in tumor tissues compared to the control. These results suggest that DTX-kappa has anti-tumor effects in A549 cells through the pathway governing G1-S transition.
Adenocarcinoma/drug therapy/genetics/pathology ; Animals ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Disease Models, Animal ; Elapid Venoms/*pharmacology ; Elapidae ; Humans ; Kv1.1 Potassium Channel/*antagonists & inhibitors/deficiency/genetics/metabolism ; Lung Neoplasms/*drug therapy/genetics/pathology ; Mice ; Mice, Nude ; Neoplasm Transplantation ; Potassium Channel Blockers/*pharmacology ; RNA, Messenger/genetics ; Transplantation, Heterologous