THE MECHANISMS OF IBMX AND CPT-cAMP ON THE REGENERATION OF RGCs / 解剖学报

Objective Use three inhibitors to block three different signaling pathway to explore the mechanisms of 3-isobutyl-1-methylxanthine(IBMX) and 8 (4 Chlorophenylthio) cAMP(CPT-cAMP) on the regeneration of retinal ganglion cells. Method Fluorescent retrogratde tracing method and quantitative anatomical techniques were used to measure the numbers of RGCs in control one,control two group and experiment groups. Results 1

The Effect of Local Delivery of IBMX on the Neointimal Proliferation in Rat Carotid Balloon Injury Model

BACKGROUND: Hyperplastic neointima is one of the major mechanisms of restenosis following balloon angioplasty in selected patients with symptomatic angina pectoris. Elevation of cellular cyclic nucleotide levels such as cAMP and cGMP are known to inhibit the proliferation of vascular smooth muscle cells. 3-isobutyl-1-methylxanthine (IBMX) increases intracellular cAMP and cGMP by nonselective inhibition of phosphodiesterases (PDEs). We conducted this study under the hypothesis that local delivery of IBMX could inhibit neointimal hyperplasia after balloon injury of the rat carotid artery. METHODS: Left common carotid artery of 10 week old male Sprague-Dawley rats were subjected to arterial injury by 2F Fogarty balloon catheter. After injury, animals were allocated to the control groups (control 1: injury control and control 2: pluronic gel plus DMSO control) and IBMX group, which received pluronic polymer gel, DMSO and IBMX mixture periadventitially. After 3 weeks, the rats were killed by overdose of ketamine, and the injured left arteries were pressure-fixed with 10% formalin and subjected to histomorphological analysis. RESULTS: Mean body weight of rats was not statistically different among study groups. The mean area of neointima (control group 1:0.28+/-0.05 mm2,Control group 2:0.27+/-0.08 mm2 , IBMX group:0.18+/-0.08 mm2 : p<0.05) and the mean ratio of neointima to medial area[versus (control group 1:1.89+/-0.37, control group 2:1.95+/-0.41, IBMX group: 1.41+/-0.47: p<0.05)] were significantly less in IBMX group. The mean area of external elastic lamina was significantly larger in control group 1 than IBMX group (0.57+/-0.07 mm2 versus 0.47+/-0.10 mm2 ) and mean luminal area showed no significant difference among groups (control group1:0.14+/-0.07 mm2 , control group 2: 0.10+/-0.05 mm2 , control group 3: 0.16+/-0.06 mm2). CONCLUSION: Peri-adventitial single administration of IBMX showed its effectiveness in reducing the neointimal proliferation in rat carotid balloon injury model. Furthermore we observed the positive correlation between intimal area and EELA suggesting vascular remodeling depending on the intima volume.

The Effect of Local Delivery of IBMX on the Neointimal Proliferation in Rat Carotid Balloon Injury Model

BACKGROUND: Hyperplastic neointima is one of the major mechanisms of restenosis following balloon angioplasty in selected patients with symptomatic angina pectoris. Elevation of cellular cyclic nucleotide levels such as cAMP and cGMP are known to inhibit the proliferation of vascular smooth muscle cells. 3-isobutyl-1-methylxanthine (IBMX) increases intracellular cAMP and cGMP by nonselective inhibition of phosphodiesterases (PDEs). We conducted this study under the hypothesis that local delivery of IBMX could inhibit neointimal hyperplasia after balloon injury of the rat carotid artery. METHODS: Left common carotid artery of 10 week old male Sprague-Dawley rats were subjected to arterial injury by 2F Fogarty balloon catheter. After injury, animals were allocated to the control groups (control 1: injury control and control 2: pluronic gel plus DMSO control) and IBMX group, which received pluronic polymer gel, DMSO and IBMX mixture periadventitially. After 3 weeks, the rats were killed by overdose of ketamine, and the injured left arteries were pressure-fixed with 10% formalin and subjected to histomorphological analysis. RESULTS: Mean body weight of rats was not statistically different among study groups. The mean area of neointima (control group 1:0.28+/-0.05 mm2,Control group 2:0.27+/-0.08 mm2 , IBMX group:0.18+/-0.08 mm2 : p<0.05) and the mean ratio of neointima to medial area[versus (control group 1:1.89+/-0.37, control group 2:1.95+/-0.41, IBMX group: 1.41+/-0.47: p<0.05)] were significantly less in IBMX group. The mean area of external elastic lamina was significantly larger in control group 1 than IBMX group (0.57+/-0.07 mm2 versus 0.47+/-0.10 mm2 ) and mean luminal area showed no significant difference among groups (control group1:0.14+/-0.07 mm2 , control group 2: 0.10+/-0.05 mm2 , control group 3: 0.16+/-0.06 mm2). CONCLUSION: Peri-adventitial single administration of IBMX showed its effectiveness in reducing the neointimal proliferation in rat carotid balloon injury model. Furthermore we observed the positive correlation between intimal area and EELA suggesting vascular remodeling depending on the intima volume.

Effects of cyclic-GMP on hyperpolarization-activated inward current (I|f) in sino-atrial node cells of rabbit

The aim of present study is to investigate the effects of cGMP on hyperpolarization activated inward current (If), pacemaker current of the heart, in rabbit sino-atrial node cells using the whole-cell patch clamp technique. When sodium nitroprusside (SNP, 80 muM), which is known to activate guanylyl cyclase, was added, If amplitude was increased and its activation was accelerated. However, when If was prestimulated by isopreterenol (ISO, 1 muM), SNP reversed the effect of ISO. In the absence of ISO, SNP shifted activation curve rightward. On the contrary in the presence of ISO, SNP shifted activation curve in opposite direction. 8Br-cGMP (100 muM), more potent PKG activator and worse PDE activator than cGMP, also increased basal If but did not reverse stimulatory effect of ISO. It was probable that PKG activation seemed to be involved in SNP-induced basal If increase. The fact that SNP inhibited ISO-stimulated If suggested cGMP antagonize cAMP action via the activation of PDE. This possibility was supported by experiment using 3-isobutyl-1-methylxanthine (IBMX), non-specific PDE inhibitor. SNP did not affect If when If was stimulated by 20 muM IBMX. Therefore, cGMP reversed the stimulatory effect of cAMP via cAMP breakdown by activating cGMP-stimulated PDE. These results suggest that PKG and PDE are involved in the modulation of If by cGMP: PKG may facilitate If and cGMP-stimulated PDE can counteract the stimulatory action of cAMP.

EFFECTS OF H-89 AND wortmannin ON THE PROMOTING EFFECTS OF forskolin AND IBMX ON THE REGENERATION OF INJURED RETINAL GANGLION CELLS / 解剖学报

Objective The present study was aimed at investigating the regeneration promoting mechanism of forskolin and IBMX on injured retinal ganglion cells(RGCs). Methods Fluorescent retrograde labeling and autologus sciatic nerve transplanting techniques were used to observe the effects of H 89 or/and wortmannin on the regeneration promoting effects of forskolin and IBMX on injured retinal ganglion cells by intravitreal injection. Results Both H 89 and wortmannin could partly block the promoting effects of forskolin and IBMX on regeneration of injured RGCs, the effects of wortmannin might be more powerful, if united, they could inhibit the effects of forskolin and IBMX completely.Conclusion The regeneration promoting effects of forskolin and IBMX on injured RGCs might be realized by PKA CREB and PI3 K Akt accesses.