kt-5720 and capsazepine

Paclitaxel chemotherapy is limited by a long-lasting painful neuropathy that lacks an effective therapy. In this study, we tested the hypothesis that paclitaxel may release mast cell tryptase, which activates protease-activated receptor 2 (PAR2) and, subsequently, protein kinases A and C, resulting in mechanical and thermal (both heat and cold) hypersensitivity. Correlating with the development of neuropathy after repeated administration of paclitaxel, mast cell tryptase activity was found to be increased in the spinal cord, dorsal root ganglia, and peripheral tissues in mice. FSLLRY-amide, a selective PAR2 antagonist, blocked paclitaxel-induced neuropathic pain behaviors in a dose- and time-dependent manner. In addition, blocking downstream signaling pathways of PAR2, including phospholipase C (PLC), protein kinase A (PKA), and protein kinase Cε (PKC), effectively attenuated paclitaxel-induced mechanical, heat, or cold hypersensitivity. Furthermore, sensitized pain response was selectively inhibited by antagonists of transient receptor potential (TRP) V1, TRPV4, or TRPA1. These results revealed specific cellular signaling pathways leading to paclitaxel-induced neuropathy, including the activation of PAR2 and downstream enzymes PLC, PKCε, and PKA and resultant sensitization of TRPV1, TRPV4, and TRPA1. Targeting one or more of these signaling molecules may present new opportunities for the treatment of paclitaxel-induced neuropathy.

Topics: Analysis of Variance; Anilides; Animals; Ankyrins; Antineoplastic Agents, Phytogenic; Capsaicin; Carbazoles; Central Nervous System; Cinnamates; Cyclic AMP-Dependent Protein Kinases; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Enzyme Inhibitors; Estrenes; Gene Expression Regulation; Hyperalgesia; Male; Mice; Mice, Inbred ICR; Neuralgia; Oligopeptides; Paclitaxel; Pain Measurement; Physical Stimulation; Protein Kinase C; Pyrroles; Pyrrolidinones; Receptor, PAR-2; Sulfonamides; Time Factors; TRPV Cation Channels; Tryptases; Type C Phospholipases

Sensory neurons release calcitonin-gene related peptide (CGRP) on stimulation. We have reported that topical application of capsaicin increases facial skin elasticity by increasing the production of dermal insulin-like growth factor-I (IGF-I) through stimulation of sensory neurons in mice and humans. In this study, we examined whether topical application of alpha-D-glucosylglycerol (GG), a compound found in Japanese traditional brewed foods such as sake (Japanese rice wine), increases the dermal production of IGF-I in mice and increases the facial skin elasticity in females. GG increased CGRP release and cAMP levels in dorsal root ganglion (DRG) neurons isolated from wild-type mice. Pretreatment with capsazepine, an inhibitor of vanilloid receptor-1 activation, and with KT5720, an inhibitor of protein kinase A, reversed GG-induced increases in CGRP release from DRG neurons. Topical application of GG increased dermal levels of IGF-I, IGF-I mRNA, and collagen in wild-type mice, but not in CGRP-knockout mice. Topical application of GG increased cheek-skin elasticity in 13 female volunteers. These observations strongly suggest that GG increases the production of IGF-I in the skin through sensory neuron stimulation, thereby increasing skin elasticity.

Topics: Administration, Topical; Animals; Capsaicin; Carbazoles; Dermis; Elasticity; Face; Female; Ganglia, Spinal; Genes; Glucosides; Humans; Insulin-Like Growth Factor I; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Neurons, Afferent; Pyrroles; RNA, Messenger; Sensory Receptor Cells; Skin; TRPV Cation Channels

We recently demonstrated that calcitonin gene-related peptide (CGRP) released from sensory neurons reduces spinal cord injury (SCI) by inhibiting neutrophil activation through an increase in the endothelial production of prostacyclin (PGI(2)). Carperitide, a synthetic alpha-human atrial natriuretic peptide (ANP), reduces ischemia/reperfusion (I/R)-induced tissue injury. However, its precise therapeutic mechanism(s) remains to be elucidated. In the present study, we examined whether ANP reduces I/R-induced spinal cord injury by enhancing sensory neuron activation using rats. ANP increased CGRP release and cellular cAMP levels in dorsal root ganglion neurons isolated from rats in vitro. The increase in CGRP release induced by ANP was reversed by pretreatment with capsazepine, an inhibitor of vanilloid receptor-1 activation, or with (9S, 10S, 12R)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]-benzodiazocine-10-carboxylic acid hexyl ester (KT5720), an inhibitor of protein kinase A (PKA), suggesting that ANP might increase CGRP release from sensory neurons by activating PKA through an increase in the cellular cAMP level. Spinal cord ischemia was induced in rats using a balloon catheter placed in the aorta. ANP reduced mortality and motor disturbances by inhibiting reduction of the number of motor neurons in animals subjected to SCI. ANP significantly enhanced I/R-induced increases in spinal cord tissue levels of CGRP and 6-keto-prostaglandin F(1alpha). a stable metabolite of PGI(2). ANP inhibited I/R-induced increases in spinal cord tissue levels of tumor necrosis factor and myeloperoxidase. Pretreatment with 4'-chloro-3-methoxycinnamanilide (SB366791), a specific vanilloid receptor-1 antagonist, and indomethacin reversed the effects of ANP. These results strongly suggest that ANP might reduce I/R-induced SCI in rats by inhibiting neutrophil activation through enhancement of sensory neuron activation.

Topics: 6-Ketoprostaglandin F1 alpha; Anilides; Animals; Atrial Natriuretic Factor; Calcitonin Gene-Related Peptide; Capsaicin; Carbazoles; Cells, Cultured; Cinnamates; Cyclic AMP; Dose-Response Relationship, Drug; Enzyme Inhibitors; Humans; Indoles; Indomethacin; Male; Neurons, Afferent; Peroxidase; Psychomotor Performance; Pyrroles; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Spinal Cord; Spinal Cord Diseases; TRPV Cation Channels; Tumor Necrosis Factor-alpha

We recently demonstrated that activation of the pulmonary sensory neurons plays a critical role in prevention of endotoxin-induced shock by releasing calcitonin gene-related peptide (CGRP) in rats. CGRP increased the endothelial production of prostacyclin (PGI(2)) in the lungs, thereby preventing endotoxin-induced shock response by inhibiting tumor necrosis factor-alpha (TNF-alpha) production. Since antithrombin (AT) enhances sensory neuron activation, we hypothesized that AT might reduce endotoxin-induced hypotension by enhancing the activation of pulmonary sensory neurons in rats. We examined this possibility using a rat model of endotoxin shock. AT-induced effects including reduction of hypotension (n = 5) and inhibition of induction of iNOS (n = 4 or 5) and TNF- alpha (n = 5) in the lungs of endotoxin-treated animals were completely reversed by pretreatment with capsazepine (CPZ) (n = 4 or 5), a vanilloid receptor antagonist, or CGRP(8-37), a CGRP receptor antagonist (n = 4 or 5). AT enhanced endotoxin-induced increases in lung tissue levels of CGRP (n = 4), but this effect of AT was not seen in animals pretreated with CPZ (n = 4). CGRP produced therapeutic effects (n = 5) similar to those induced by AT, and such therapeutic effects were completely abrogated by pretreatment with indomethacin (n = 4). AT increased CGRP release from cultured dorsal root ganglion neurons only in the presence of anandamide (n = 5), and AT-induced increase in CGRP release was not observed in the presence KT5720, an inhibitor of protein kinase A (n = 5). AT markedly increased intracellular levels of cAMP in the presence of anandamide (n = 5). These results strongly suggested that AT might reduce endotoxin-induced hypotension in rats by enhancing activation of sensory neurons via activation of protein kinase A.

Topics: Animals; Antithrombins; Arachidonic Acids; Blood Pressure; Calcitonin Gene-Related Peptide; Calcitonin Gene-Related Peptide Receptor Antagonists; Capsaicin; Carbazoles; Cells, Cultured; Cyclic AMP; Cyclic AMP-Dependent Protein Kinase Type II; Cyclic AMP-Dependent Protein Kinases; Cyclooxygenase Inhibitors; Disease Models, Animal; Endocannabinoids; Endotoxins; Ganglia, Spinal; Gene Expression Regulation; Hypotension; Indoles; Indomethacin; Lung; Male; Neurons, Afferent; Nitrates; Nitric Oxide Synthase Type II; Nitrites; Peptide Fragments; Polyunsaturated Alkamides; Protein Kinase Inhibitors; Pyrroles; Rats; Rats, Wistar; Receptors, Calcitonin Gene-Related Peptide; RNA, Messenger; TRPV Cation Channels; Tumor Necrosis Factor-alpha

We have reported previously that bradykinin (BK) induces potent and reproducible concentration-dependent contractions of the pig iris sphincter (PIS) muscle in vitro through the activation of BK B(2) receptors. Here we attempted to investigate additional mechanisms by which BK induces contraction of the PIS in vitro. BK-mediated contraction of the PIS relied largely on the external Ca2+ influx by a mechanism sensitive to the L-, N- and P-type of Ca2+ channel selective blockers. Likewise, BK-induced contraction of the PIS was greatly inhibited by the CGRP-(8-37), NK(2) or NK(3) receptor antagonists (SR 48968, SR 142801), and to a lesser extent by the NK(1) antagonist (FK 888). Capsaicin desensitization of PIS or capsazepine pre-incubation also significantly reduced BK-mediated contraction in the PIS. Furthermore, KT 5720 or GF 109203X (the protein kinase A and C inhibitors, respectively) also significantly inhibited BK-mediated contraction. Taken together, these results indicate that BK-mediated contraction of the PIS seems to be mediated primarily by the release of CGRP and tachykinins from sensory nerve fibers, and relies largely on extracellular Ca2+ influx via activation of L-, N- and P-type of Ca2+ channels. Finally, these responses are mediated by activation of both protein kinase A- and C-dependent mechanisms.

Topics: Animals; Benzamides; Bradykinin; Calcitonin Gene-Related Peptide; Calcitonin Gene-Related Peptide Receptor Antagonists; Calcium; Calcium Channels; Capsaicin; Carbazoles; Conotoxins; Dipeptides; Dose-Response Relationship, Drug; Egtazic Acid; In Vitro Techniques; Indoles; Iris; Maleimides; Muscle Contraction; Nicardipine; omega-Agatoxin IVA; Peptide Fragments; Piperidines; Protein Kinase Inhibitors; Protein Kinases; Pyrroles; Receptors, Calcitonin Gene-Related Peptide; Receptors, Drug; Receptors, Neurokinin-2; Receptors, Neurokinin-3; Swine; Tachykinins