BACKGROUND: Intercellular adhesion molecule(ICAM)-1 mediates cell to cell adhesion by acting as a receptor for leukocyte surface antigen. Increased ICAM-1 expression was observed in chronic inflammatory skin diseases, such as psoriasis, atopic dermatitis and allergic contact dermatitis. Adenosine is an endogenous antiinflammatory agent released by cells under metabolically unfavorable conditions, recently the studies about antiinflammatory effects of adenosine in various tissues were increased, but there are few studies about the effect of adenosine on epidermal keratinocytes. OBJECTIVE: We investigated the effects of adenosine on ICAM-1 expression in cultured human keratinocyte cell line HaCaT cells. METHODS: Our study analyses the ICAM-1 expression in HaCaT cells by various stimulants and the effects of adenosine, adenosine receptor agonist&antagonist and an inhibitor of cellular adenosine uptake on ICAM-1 expression of cells stimulated by IFN-gamma through the cell-ELISA (enzyme-linked immunosorbent assay)&FACS (fluorescence-activated cell sorter) analysis. RESULTS: The results are summerized as follows: 1. ICAM-1 expression was significantly increased by IFN-gamma(500U/ml), IFN-gamma&TNF-alpha(10-8M) and IFN-gamma&LPS(10-8M)(p<0.05), but not by TNF-alpha, LPS and TNF-alpha & LPS. 2. Incubation of HaCaT cells with IFN-gamma(1-2000U/ml) for 48 hours induced dose-dependent expression of ICAM-1 at above 500U/ml of IFN-gamma. 3. Adenosine had no effect on ICAM-1 expression of unstimulated cells. 4. Adenosine(esp. 10-4M) significantly inhibited ICAM-1 expression of cells stimulated by IFN-gamma(p<0.01). 5. Adenosine(10-4M) significantly inhibited ICAM-1 expression of cells stimulated by IFN-gamma(p<0.01), IFN-gamma & TNF-alpha(p<0.05) and IFN-gamma&LPS. 6. The inhibition of ICAM-1 expression was not observed when cells were preincubated with an adenosine A1 receptor agonist(R-PIA) or an adenosine A2 receptor agonist (NECA). 7. The inhibition of ICAM-1 expression of adenosine was not affected by pretreatment state with an adenosine A1 & A2 receptor antagonist(theophylline)(p<0.01). 8. The inhibition of ICAM-1 expression of adenosine was not observed by pretreatment state with an inhibitor of adenosine cellular uptake (dipyridamole). CONCLUSION: High concentration of adenosine inhibits enhanced ICAM-1 expression on HaCaT cells by stimulated with IFN-gamma and these inhibitory effects of adenosine are mediated through other adenosine receptors excect adenosine A1 and A2 receptors. And we suggest that there may be an unknown intracellular mechanism about inhibition of ICAM-1 expression via intracellular-uptaken adenosine.
Adenosine* ; Antigens, Surface ; Cell Adhesion ; Cell Line* ; Dermatitis, Allergic Contact ; Dermatitis, Atopic ; Humans* ; Intercellular Adhesion Molecule-1* ; Keratinocytes* ; Leukocytes ; Psoriasis ; Receptor, Adenosine A1 ; Receptors, Adenosine A2 ; Receptors, Purinergic P1 ; Skin Diseases ; Tumor Necrosis Factor-alpha

BACKGROUND: In two-kidney one clip Goldbaltt hypertensive rats(2K1C GHR), clipped kidney may be exposed to low pressure and unclipped kidney to high pressure. In addition, both kidneys may have a different amount of adenosine which is increased by ischemia and plays an important role for renin release. The aim of this study was to invstigate the responsmiveness for renin release to adenosine agonists and antagonist in clipped and unclipped kidney of 2K1C GHR. METHODS: Emplying kidney slices from both unclipped and unclipped kidney of 2K1C GHR, the alteration by adenosine agonists and antagonist of renin release was studied. RESULTS: The renal renin content and basal renin release from unclipped kidney slices were suppressed, whereas those from clipped kidney were augmented Adenosine Al receptor agonist, cyclohexyladenosne(CHA), phenylisopropyl adenosine(PIA) and adenosine caused a decrease in renin release from clipped kidney slices. Adenosine A2 receptor agonist, NECA, and nonspecific adenosine receptor aganist, 2-chloroadenosine(CA) caused an increase in renin release from clipped kidney slices. Adenosine receptor antagonist, 8-phenyltheophylline(8-PT) caused an increase in renin release from clipped kidney slices. In unclipped kidney, however, the renin release in response to NECA, CA or 8-PT was reversed and the decreasing effect of renin release to CHA and adenosine was slightly inereased. CONCLUSION: These results suggest that the responsiveness of adenosine receptors, which may participate in renin release is modified in clipped and unclipped kidney of 2K1C GHR.
Adenosine* ; Adenosine-5'-(N-ethylcarboxamide) ; Animals ; Hypertension, Renovascular ; Ischemia ; Kidney ; Rats* ; Receptors, Adenosine A2 ; Receptors, Purinergic P1 ; Renin*

Numerous studies have shown that adenosine or adenosine agonists can stimulate angiogenesis. However, the effect of caffeine (a known adenosine receptor antagonist) on angiogenesis has not been previously studied. Accordingly, this study was undertaken to examine the effect of caffeine on angiogenesis and to clarify the mechanism involved. Chick chorioallantoic membrane assays were used to investigate the effect of caffeine on angiogenesis and proliferation assays using human umbilical vein endothelial cells (HUVECs), were used to study its effects on specific aspects of angiogenesis. The expressions of caspase-3 and Bcl-2 were examined by western blotting, immunofluorescence staining was used to identify HUVEC morphological changes, and fluorescence activated cell sorting (FACS) and DAPI staining were used to detect HUVEC apoptosis. Caffeine was found to inhibit blood vessel formation dose-dependently and to inhibit the proliferation of HUVECs time- and dose-dependently. FACS analysis and DAPI staining showed that inhibitory effect of caffeine on HUVEC proliferation was the result of apoptosis and the up-regulation of thrombospondin-1 (TSP-1). Furthermore, TSP-1 levels were down-regulated by NECA but were unaffected by CGS21680, indicating that caffeine regulated TSP-1 expression via adenosine A2B receptor. In addition, caffeine up-regulated caspase-3 and down-regulated Bcl-2 at the protein level. These results suggest that the inhibitory effect of caffeine on angiogenesis is associated, at least in part, with its induction of endothelial cell apoptosis, probably mediated by a caspase-3 dependent mechanism.
Adenosine ; Adenosine-5'-(N-ethylcarboxamide) ; Apoptosis ; Blood Vessels ; Blotting, Western ; Caffeine ; Caspase 3 ; Chorioallantoic Membrane ; Endothelial Cells ; Flow Cytometry ; Fluorescent Antibody Technique ; Glycosaminoglycans ; Human Umbilical Vein Endothelial Cells ; Indoles ; Phenethylamines ; Receptor, Adenosine A2B ; Receptors, Purinergic P1 ; Thrombospondin 1 ; Up-Regulation

BACKGORUND: A nerve ligation injury may produce a pain syndrome including mechanical allodynia. Usually the antiallodynic effect of morphine is diminished in a neuropathic rat model. However, in a previous study, spinal morphine was found to have an antiallodynic effect in a neuropathic rat model. Therefore, the present study was performed to observe the mechanical antiallodynic effects of spinal morphine and R-PiA, and to investigate the relationship between the two. METHODS: Male SD rats were prepared by tightly ligating the left L5 and L6 spinal nerve and by implanting a lumbar intrathecal catheter. in study 1, each of the 5 groups (morphine at 3 or 10mug, adenosine A1 receptor agonist (R-PiA) at 3 or 10mug, or saline) were administered intrathecally to examine changes in the mechanical allodynia threshold. in study 2, selective adenosine A1 receptor antagonist (DPCPX 10mug) was administered to investigate the reversal of the mechanical antiallodynic effect in the 4 treated groups. in study 3, we observed the pretreatment effect of DPCPX 10mug. The mechanical allodynic thresholds for left hindpaw withdrawal to von Frey hairs were assessed and converted to %MPE. RESULTS: in study 1, the mechanical allodynic threshold was significantly increased in a similar pattern by intrathecal morphine (3, 10mug) and R-PiA (3, 10mug) (P<0.05). in study 2, the allodynic threshold of morphine was insignificantly decreased by intrathecal DPCPX pretreatment. The mechanical allodynic threshold of R-PiA 3mug was decreased by intrathecal DPCPX (P<0.05). in study 3, the antiallodynic effect of morphine was not influenced by DPCPX pretreatment. CONCLUSiONS: intrathecal morphine and R-PiA produced the antiallodynic effect. The antiallodynic effect of morphine was slightly decreased by DPCPX 10mug. Therefore, it was suggested that the antiallodynic effect of morphine might be, at least in part, mediated by adenosine in a rat model of spinal nerve ligation.
Adenosine ; Animals ; Catheters ; Hair ; Humans ; Hyperalgesia ; Ligation* ; Male ; Models, Animal ; Morphine* ; Rats* ; Receptor, Adenosine A1 ; Receptors, Purinergic P1 ; Spinal Nerves*

BACKGROUND: A Nerve ligation injury may produce a pain syndrome that includes tactile allodynia. Reversal effects on tactile allodynia have been demonstrated after an intrathecal administration of adenosine analogues or morphine. Adenosine receptor agonists have been known to have antinociceptive and antiallodynic effects in many animal and human studies. We examined the drug interactions between morphine and adenosine agonists in a rat model of a nerve ligation injury. METHODS: Male Sprague Dawley rats were prepared with a tight ligation of the left lumbar 5 th and 6 th spinal nerves and chronic lumbar intrathecal catheter implantation for drug administration. We measured the tactile allodynia by applying von Frey filaments ipsilateral to the lesioned hindpaw. Thresholds for paw withdrawal were assessed. Morphine (1 - 30ng), adenosine (1 - 30ng) and R-PIA (0.1 - 10ng) were administered to obtain the dose-response curves and the 50% effective dose (ED50). Fractions of ED50 values were administered to establish the ED50 of drug combinations. Drug interactions were evaluated by the fractional and isobolographic analyses. Allodynic thresholds for left lesioned hindpaw withdrawal to the von Frey hairs test were assessed and converted to % maximal possible effect (%MPE). RESULTS: The antiallodynic effect of morphine, adenosine, and R-PIA were produced in a dose dependent manner. The antiallodynic effects of combinations showed a similar pattern. Isobolographic analysis revealed a synergistic interaction for the morphine-R-PIA combination but not for the morphine-adenosine combination. However, fractional analysis produced a synergistic result for two combination groups. CONCLUSIONS: The results demonstrated that intrathecal co-administration of adenosine A1 receptors agonist and morphine showed the synergistic effect on nerve ligation injury induced allodynia.
Adenosine* ; Animals ; Catheters ; Drug Combinations ; Drug Interactions ; Hair ; Humans ; Hyperalgesia ; Injections, Spinal ; Ligation* ; Male ; Models, Animal ; Morphine* ; Purinergic P1 Receptor Agonists* ; Rats* ; Rats, Sprague-Dawley ; Receptor, Adenosine A1 ; Receptors, Purinergic P1* ; Spinal Nerves

BACKGROUND: Several types of receptors are found at neuromuscular presynaptic membranes. Presynaptic inhibitory A1 and facilitatory A2A receptors mediate different modulatory functions on acetylcholine release. This study investigated whether adenosine A1 receptor agonist contributes to the first twitch tension (T1) of train-of-four (TOF) stimulation depression and TOF fade during rocuronium-induced neuromuscular blockade, and sugammadex-induced recovery. METHODS: Phrenic nerve-diaphragm tissues were obtained from 30 adult Sprague-Dawley rats. Each tissue specimen was randomly allocated to either control group or 2-chloroadenosine (CADO, 10 μM) group. One hour of reaction time was allowed before initiating main experimental data collection. Loading and boost doses of rocuronium were sequentially administered until > 95% depression of the T1 was achieved. After confirming that there was no T1 twitch tension response, 15 min of resting time was allowed, after which sugammadex was administered. Recovery profiles (T1, TOF ratio [TOFR], and recovery index) were collected for 1 h and compared between groups. RESULTS: There were statistically significant differences on amount of rocuronium (actually used during experiment), TOFR changes during concentration-response of rocuronium (P = 0.04), and recovery profiles (P < 0.01) of CADO group comparing with the control group. However, at the initial phase of this experiment, dose-response of rocuronium in each group demonstrated no statistically significant differences (P = 0.12). CONCLUSIONS: The adenosine A1 receptor agonist (CADO) influenced the TOFR and the recovery profile. After activating adenosine receptor, sugammadex-induced recovery from rocuronium-induced neuromuscular block was delayed.
2-Chloroadenosine ; Acetylcholine ; Adenosine* ; Adult ; Data Collection ; Depression ; Humans ; Membranes ; Neuromuscular Blockade* ; Neuromuscular Junction ; Neuromuscular Nondepolarizing Agents ; Rats, Sprague-Dawley ; Reaction Time ; Receptor, Adenosine A1 ; Receptors, Purinergic P1*

BACKGROUND: Nerve ligation injury may produce mechanical allodynia, but this can be reversed after an intrathecal administration of adenosine analogues. In many animal and human studies, ATP-sensitive potassium channel blockers have been known to reverse the antinociceptive effect of various drugs. This study was performed to evaluate the mechanical antiallodynic effects of spinal R-PIA (Adenosine A1 receptor agonist) and the reversal of these effects due to pretreatment with glibenclamide (ATP-sensitive potassium channel blocker). Thus, the relationship between the antiallodynic effects of R-PIA and ATP-sensitive potassium channel were investigated in a neuropathic model. METHODS: Male Sprague Dawley rats were prepared by tightly ligating the left lumbar 5th and 6th spinal nerves and implantation of a chronic lumbar intrathecal catheter for drug administration. The mechanical allodynia was measured by applying von Frey filaments ipsilateral to the lesioned hind paw. And the thresholds for paw withdrawal assessed. In study 1, either R-PIA (0.5, 1 and 2microgram) or saline were administered intrathecally for the examination of the antiallodynic effect of R-PIA. In study 2, glibenclamide (2, 5, 10 and 20 nM) was administered intrathecally 5 min prior to an R-PIA injection for investigation of the reversal of the antiallodynic effects of R-PIA. RESULTS: The antiallodynic effect of R-PIA was produced in a dose dependent manner. In study 1, the paw withdrawal threshold was significantly increased with 2microgram R-PIA (P < 0.05). In study 2, the paw withdrawal threshold with 2microgram R-PIA was significantly decreased almost dose dependently by intrathecal pretreatment of 5, 10 and 20 nM glibenclamide (P < 0.05). CONCLUSIONS: These results demonstrated that an intrathecal injection of ATP-sensitive potassium channel blockers prior to an intrathecal injection of adenosine A1 receptors agonist had an antagonistic effect on R-PIA induced antiallodynia. The results suggest that the mechanism of mechanical antiallodynia, as induced by an intrathecal injection of R-PIA, may involve the ATP-sensitive potassium channel at both the spinal and supraspinal level in a rat nerve ligation injury model.
Adenosine ; Animals ; Catheters ; Glyburide ; Humans ; Hyperalgesia ; Injections, Spinal ; Ligation ; Male ; Neuralgia ; Potassium Channel Blockers ; Potassium Channels* ; Potassium* ; Rats* ; Rats, Sprague-Dawley ; Receptor, Adenosine A1 ; Receptors, Purinergic P1 ; Spinal Nerves

Some recent investigations revealed that vasodilatory action of adenosine is mainly not mediated by surface A2 receptor and suggested the existence of an intracellular action site. In the present study, we tried to differentiate intracellular from extracellular site of adenosine action in the regulation of coronary flow. In perfused rabbit hearts, concentration-response curve of coronary flow to exogenous adenosine was constructed in the presence or absence of dipyridamole, an inhibitor of transmembrane purine transport. Inhibition of cellular adenosine uptake by dipyridamole suppressed the increase of flow rate while enhancing the decrease in heart rate induced by exogenous adenosine. In another series of experiments, perfused rabbit hearts were subjected to energy deprivation in order to increase the production of endogenous adenosine. Energy deprivation along with dipyridamole administration resulted in higher coronary flow rate. Lower perfusate adenosine concentration was observed along with higher tissue adenosine content in this group. These results implied that coronary flow rate is determined not by interstitial adenosine concentration but by intracellular activity of adenosine. To confirm the effects of dypiridamole in vivo, direct measurement of interstitial adenosine concentration by mycrodialysis along with the assay of intracellular adenosine content was performed after intranenous dipyridamole administration. After dipyridamole infusion, intracellular adenosine content was markedly increased while interstitial adenosine concentration was not altered. In another series of experiments, the right shift of concentration-response curve of adenosine-induced vasodilation by 8-phenyltheophilline, a representative adenosine receptor antagonist, was mostly abolished by prior administration of prazosin, indicating that the influence of 8-PT on the adenosine action is not attributed to the inhibition of A2 receptor but related to the suppression of alpha-adrenoceptor activation. From these results, we concluded that adenosine acts intracellularly to regulate the coronary blood flow.
Adenosine ; Dipyridamole* ; Heart ; Heart Rate ; Prazosin ; Receptors, Purinergic P1 ; Vasodilation*

BACKGROUND/AIMS: Adenosine is an endogenous modulator of nociception. Its role in visceral nociception, particularly in visceral hyperalgesia, has not been studied. The aim of this study was to determine the effects of adenosine receptor agonists in a model of visceral hyperalgesia. METHODS: The visceromotor response (VMR) in rats to colorectal distension (CRD; 80 mmHg, 20 seconds) was quantified by electromyographic recordings from the abdominal musculature. Three hours after the intracolonic administration of zymosan (25 mg/mL, 1 mL), VMRs to CRD were measured before and after either subcutaneous or intrathecal administration of an adenosine receptor agonist. RESULTS: Subcutaneous injection of 5'-N-ethylcarboxyamidoadenosine (NECA; an A1 and A2 receptor agonist), R(-)-N6-(2-phenylisopropyl)-adenosine (R-PIA; a selective A1 receptor agonist), or CGS-21680 hydrochloride (a selective A2a receptor agonist) dose-dependently (10-100 mg/kg) attenuated the VMR to CRD, although hindlimb weakness occurred at the higher doses tested. Intrathecal administration of NECA or R-PIA dose-dependently (0.1-1.0 microgram/kg) decreased the VMR, whereas CGS-21680 hydrochloride was ineffective over the same concentration range. Higher intrathecal doses of the A1/A2 receptor agonist NECA produced motor weakness. CONCLUSIONS: Adenosine receptor agonists are antihyperalgesic, but also produce motor weakness at high doses. However, activation of the spinal A1 receptor significantly attenuates the VMR to CRD without producing motor weakness.
Adenosine ; Adenosine-5'-(N-ethylcarboxamide) ; Animals ; Hindlimb ; Hyperalgesia ; Injections, Subcutaneous ; Nociception ; Purinergic P1 Receptor Agonists ; Rats ; Receptors, Purinergic P1 ; Zymosan

The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands.
Adenosine* ; Classification ; Dataset ; Dermatoglyphics ; Felodipine* ; Ligands ; Receptors, G-Protein-Coupled ; Receptors, Purinergic P1* ; Subject Headings ; Vibration