limaprost and Disease-Models--Animal

Basic animal research.. Cervical spondylotic myelopathy is a common condition among elderly and often treated by surgery. To explore possibility of pharmacologic treatment, limaprost alfadex, a prostaglandin E1 derivative with vasodilatory and antiplatelet action, was tried in a rat chronic spinal cord compression model.. Limaprost increased the blood flow of cauda equina and improved motor functions in animal models of lumbar stenosis. The drug is clinically used to treat neurogenic intermittent claudication.. : Forty-two rats were allocated to four groups: (A) sham operation without permanent cord compression, given 5 mL/kg of distilled water twice a day (n = 6); (B) sham operation, receiving 300 μg/kg limaprost twice a day (n = 6); (C) cord compression, receiving the vehicle (n = 15); and (D) cord compression receiving the drug (n = 15). A thin polyurethane sheet that expands by absorbing water was implanted under the C5-C6 laminae to produce cord compression. For sham operation, the sheet was immediately removed. Exercise tests were repeated on a rotating treadmill until 26 weeks after surgery, and then the animals were killed and the spinal cord harvested for motor neurons counts. RESULTS.: Treadmill endurance (seconds, mean ± standard error of mean) 2 weeks after surgery was 497.7 ± 2.3, 434.5 ± 65.5, 423.1 ± 33.0, and 480.5 ± 19.5 in groups A, B, C, and D, respectively. At 26th week, the duration was 497.7 ± 2.3, 421.2 ± 78.8, 21.3 ± 11.7, and 441.3 ± 40.4 (P < 0.0001 for the decrease in C group, multivariate analysis of variance with correction for multiple measures.) The motor neuron counts were 38.3 ± 3.6, 38.2 ± 2.6, 32.6 ± 1.9, and 36.2 ± 2.3 in groups A, B, C, and D (P = 0.34), respectively.. Limaprost alfadex prevented decline of forced locomotion capability in rats with chronic compression of the cervical cord.

Topics: alpha-Cyclodextrins; Alprostadil; Animals; Cervical Vertebrae; Chronic Disease; Disease Models, Animal; Exercise Tolerance; Male; Physical Conditioning, Animal; Platelet Aggregation Inhibitors; Rats; Rats, Wistar; Spinal Cord Compression; Spondylosis; Vasodilator Agents

Calcitonin gene-related peptide (CGRP) released from sensory neurons increases the production of a neuroprotective substance insulin-like growth factor I (IGF-I), and sensory neuron stimulation contributes to a reduction of spinal cord injury (SCI) by inhibiting inflammatory responses in rats. Because receptors for prostaglandin E₂ (EP receptors) are present on sensory neurons, it is possible that prostaglandin E₁ analog limaprost reduces SCI by increasing IGF-I production through sensory neuron stimulation. We examined this possibility in rats subjected to compression-trauma-induced SCI. Limaprost increased the CGRP release from dorsal root ganglion (DRG) neurons isolated from rats, and this increase was reversed by pretreatment with the EP4 receptor antagonist ONO-AE3-208. Spinal cord tissue levels of CGRP and IGF-I were increased after the induction of SCI, peaking at 2 h postinduction. The intravenous administration of limaprost enhanced increases of spinal cord tissue levels of CGRP, IGF-I, and IGF-I mRNA at 2 h after the induction of SCI. Increases of spinal cord tissue levels of tumor necrosis factor, caspase-3, myeloperoxidase, and the number of apoptotic nerve cells were inhibited by the administration of limaprost. Motor disturbances of hind legs in animals subjected to the compression-trauma-induced SCI were reduced by the administration of limaprost. These effects of limaprost were reversed completely by pretreatment with a specific transient receptor potential vanilloid 1 inhibitor SB366791 and by sensory denervation. These observations strongly suggest that limaprost may increase the IGF-I production by stimulating sensory neurons in the spinal cord, thereby ameliorating compression-trauma-induced SCI through attenuation of inflammatory responses.

Topics: Alprostadil; Anilides; Animals; Calcitonin Gene-Related Peptide; Capsaicin; Caspase 3; Cells, Cultured; Cinnamates; Denervation; Disease Models, Animal; Drug Therapy, Combination; Ganglia, Spinal; Gene Expression; Insulin-Like Growth Factor I; Male; Movement; Neurons; Rats; Rats, Wistar; RNA, Messenger; Sensory System Agents; Specific Pathogen-Free Organisms; Spinal Cord; Spinal Cord Injuries; Vasodilator Agents

Extracellular signal-regulated protein kinase (ERK) is a mitogen-activated protein kinase (MAPK) that mediates several cellular responses to mitogenic and differentiation signals, and activation of ERK in dorsal horn neurons by noxious stimulation is known to contribute to pain hypersensitivity. In order to elucidate the pathophysiological mechanisms of the cauda equina syndrome, secondary to spinal canal stenosis, we evaluated walking dysfunction triggered by forced exercise and activation of ERK in the dorsal horn using a rat model of neuropathic intermittent claudication. Rats in the lumbar canal stenosis (LCS) group showed a shorter running distance from 1 to 14 days after surgery. Two minutes after running on the treadmill apparatus, phosphorylation of ERK was induced in neurons in the superficial laminae in the LCS group but not in the sham group, whereas there was no change in the deeper laminae. Intrathecal administration of the MAPK kinase inhibitor, U0126, 30 min before running, clearly increased the running distance, whereas there was no significant change in the vehicle control group 3 days after surgery. In addition, a prostaglandin E1 analog, OP-1206 alpha-CD, administered orally, improved the walking dysfunction, and further, inhibited activation of ERK following running 7 days after surgery. These findings suggest that intermittent claudication triggered by forced walking might affect the phosphorylation of ERK in the superficial laminae, possibly via transient (partial) ischemia of the spinal cord. ERK activation in the dorsal horn neurons may be involved in the transient pain in the neuropathic intermittent claudication model.

Topics: Alprostadil; Analysis of Variance; Animals; Butadienes; Disease Models, Animal; Enzyme Inhibitors; Immunohistochemistry; Intermittent Claudication; Male; MAP Kinase Signaling System; Mitogen-Activated Protein Kinases; Nitriles; Posterior Horn Cells; Rats; Rats, Sprague-Dawley; Spinal Stenosis; Walking

An orally active prostaglandin E1 analogue, OP-1206 alpha-CD improves walking dysfunction in the rat spinal stenosis model. Loxoprofen-Na, a non-steroidal anti-inflammatory drug, is used to relieve chronic pain in patients with lumbar spinal canal stenosis. To determine whether the OP-1206 alpha-CD in combination with loxoprofen-Na could induce a greater therapeutical effect on walking dysfunction and spinal cord blood flow (SCBF) than OP-1206 alpha-CD treatment alone after chronic spinal stenosis in the rat. Spinal stenosis was induced by placing two pieces of silicon rubber strips in the lumbar (L4 and L6) epidural space of rats. After surgery, walking function was measured using a treadmill apparatus and SCBF was measured using a laser-Doppler flow meter. Drugs were administered orally twice a day for 11 days from the day 3 post-surgery. OP-1206 alpha-CD elicited a significant improvement of walking dysfunction on days 7 and 14 post-surgery and significantly increased spinal cord blood flow on day 15, whereas walking dysfunction and SCBF of rats treated with loxoprofen-Na alone remained unchanged. Combined treatment of OP-1206 alpha-CD with loxoprofen-Na did not provide additive therapeutical effect. These results suggest that a significant improvement seen after OP-1206 alpha-CD treatment is primarily mediated by improvement of the local spinal cord blood flow. This effect is not ameliorated or potentiated by a combined treatment with loxoprofen-Na.

Topics: Administration, Oral; alpha-Cyclodextrins; Alprostadil; Animals; Cyclodextrins; Disease Models, Animal; Drug Therapy, Combination; Intermittent Claudication; Male; Phenylpropionates; Prostaglandins E, Synthetic; Rats; Rats, Wistar; Regional Blood Flow; Spinal Cord; Spinal Stenosis; Walking

The systemic treatment effects of OP-1206 alpha-CD (17S-20-dimethyl-trans-delta 2-PGE1 alpha-cyclodextrin clathrate), a prostaglandin E1 (PGE1) analogue, on walking dysfunction, spinal cord blood flow (SCBF) and skin blood flow (SKBF) were assessed in the rat neuropathic intermittent claudication (IC) model in comparison with nifedipine (dimethyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedicarboxylate), ticlopidine (5-[(2-chlorophenyl)methyl]-4,5,6,7-tetrahydrothieno[3,2-C]pyridine hydrochloride) and cilostazol (6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)-butoxy]-3,4-dihydro-2(1H)-quinolinone). Two pieces of silicone rubber strips were placed in the lumbar (L4 and L6) epidural space in rats. After surgery, walking function was measured using a treadmill apparatus. SCBF and SKBF were measured using a laser-Doppler flow meter. Drugs were administered orally twice a day for 11 days from day 3 post-surgery. Treatment with OP-1206 alpha-CD significantly improved walking dysfunction on days 5, 7 and 14, and improved SCBF on day 14 post-surgery. SKBF remained unaffected. Treatment with nifedipine, ticlopidine or cilostazol had no significant effects on any of the parameters measured in this model. These data suggest that the therapeutic effect of OP-1206 alpha-CD is primarily mediated by the improved local SCBF at the territory of spinal stenosis and not due to improvement of peripheral perfusion and/or antiplatelet activity.

Topics: Alprostadil; Animals; Body Weight; Cilostazol; Disease Models, Animal; Exercise Test; Intermittent Claudication; Male; Nifedipine; Platelet Aggregation; Rats; Rats, Wistar; Skin; Spinal Cord; Tetrazoles; Ticlopidine; Time Factors; Walking

We investigated the possible induction of apoptosis of dorsal root ganglion (DRG) neurons and the defect of nerve regeneration after crush injury with reference to the JNK/c-jun and cAMP pathway in streptozocin-induced diabetic rats. In addition, the effects of a PGE1 analogue were tested in diabetic rats. At day 0 (before axonal injury), no TUNEL-positive DRG neurons were observed in any group. From day 1 to 7 after axonal injury, TUNEL-positive DRG neurons were seen in diabetic rats, but not in non-diabetic or PGE1-treated diabetic rats. The regeneration distance at day 7 after crush injury was shorter in diabetic rats than in the other groups of rats. The time course of JNK/c-jun phosphorylation did not parallel apoptosis. At day 7, the cAMP content of DRG was higher than that at day 0 in non-diabetic and PGE1-treated rats, whereas it was not increased after 7 days in diabetic rats. These results indicate that in diabetic rats apoptosis of DRG neurons is induced by axonal injury independently of the JNK/c-jun and cAMP pathway and that PGE1 rescues DRG neurons from apoptosis and improves axonal regeneration in diabetic rats.

Topics: Afferent Pathways; Alprostadil; Animals; Apoptosis; Axons; Carrier Proteins; Cyclic AMP; Diabetes Mellitus, Experimental; Diabetic Neuropathies; Disease Models, Animal; Ganglia, Spinal; Immunohistochemistry; In Situ Nick-End Labeling; Male; Nerve Crush; Nerve Regeneration; Phosphorylation; Proto-Oncogene Proteins c-jun; Rats; Rats, Sprague-Dawley; Time Factors; Vasodilator Agents