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Objective: To investigate the role of p38MAPK signal pathway in spinal cord and dorsal root ganglion (DRG) in rats with phantom limb pain and the effects of specific inhibitors.
 Methods: Healthy adult male SD rats (n=48) were cut off one side of the sciatic under anesthesia to establish a model of phantom limb pain. In addition, the healthy rats were taken as a sham group (group S, n=24). The animals were scored by observing the action of chewing (0=no chewing, 13=the worst chewing) after the operation and were sacrificed on the following day after the operation. The successful model of phantom limb pain were randomly divided into 2 groups: a phantom limb pain group (group P, n=24) and a phantom limb pain plus inhibitor group (group P+I, n=24). SB203580 was given to the rat at 0.8 mg/kg on every Monday until the rats were sacrificed, the rest of the rats received an equal amount of saline. Eight rats from each group were randomly taken for the determination of levels of P-p38MAPK in spinal cord and DRG before administration and on the 4th, 6th, 8th weekend following the administration, respectively.
 Results: In the sham group, no animal developed chewing. Meanwhile, rats in successful model of phantom limb pain group began chewing from the 2nd day after operation with scores at eight to eleven. The chewing scores in the P+I group were reduced after the treatment. Compared with group S, P-p38MAPK levels were elevated in groups of P and P+I (P<0.05 or P<0.01). Compared with group P, P-p38MAPK level was decreased in the group P+I (P<0.05 or P<0.01).
 Conclusion: P38MAPK signal pathway involves in the development of phantom limb pain.

Objective: To observe the effect of electroacupuncture (EA) stimulation at "Dazhui" (GV 14) and "Mingmen" (GV 4) of the Governor Vessel at different time-points on spinal cord neuronal apoptosis and the expression of c-Jun N-terminal kinases (JNK) protein in spinal cord injury (SCI) rats, so as to reveal its mechanism underlying improving SCI., Methods: A total of 108 male SD rats were randomly divided into normal control, SCI model and EA groups which were further divided into 1, 3 and 7 d subgroups (12 rats/subgroup, 6 rats in each subgroup for TUNEL or Western blot, separately). SCI model was established by using the modified Allen's method. EA was applied to GV 14 and GV 4 for 20 min, once daily, for 1, 3 and 7 days, respectively. Basso-Beattie-Bresnahan (BBB) scale was adopted to assess the locomotor function of rats, the TUNEL method was used to examine neuronal apoptosis of injuried spinal cord, and the expression of phosphorylated (p)-c-Jun protein of T 9 -T 11 spinal cord was detected by using Western blot., Results: After modeling, the BBB scores of SCI rats on day 1, 3 and 7 were signi-ficantly decreased ( P <0.01), while the numbers of apoptotic neuronal cells and the expression levels of p-c-Jun protein in the spinal cord were considerably increased at the 3 time-points in the model group ( P <0.01, P <0.05). Following EA intervention, the decreased BBB scores on day 3 and 7, and the increased numbers of apoptotic neuronal cells on day 1, 3 and 7 and the up-regulated expression levels of p-c-Jun protein on day 3 and 7 were obviously suppressed ( P <0.05, P <0.01)., Conclusions: EA intervention can improve the locomotor function of SCI rats, which Feb be related to its effects in reducing neuronal apoptosis and down-regulating p-c-Jun protein in the injuried spinal cord.

Objective: To observe the effect of electroacupuncture (EA) stimulation of "Weizhong" (BL 40)-"Huantiao" (GB 30) on expression of phosphorylated calcium/calmodulin dependent protein kinase II (p-CaMK II) and cAMP response element binding protein (p-CREB) in the spinal cord in rats with spared nerve injury (SNI), so as to explore its mechanism underlying easing neuropathic pain., Methods: Sixty SD rats were randomly divided into five groups: control (sham-operation) , model, EA, AP-5 (a NMDA receptor antagonist) and L-NAME (a non-selective nitric oxide synthase, NOS inhibitor) (n = 12 in each group). The neuropathic pain model was established by sectioning the right tibal nerve and common peroneal nerve. EA intervention (2 Hz, 1 mA, increasing 1 mA/10 min) was applied to "Weizhong" (BL 40) and "Huantiao" (GB 30) on the injured side for 30 min, once a day for 7 days. Rats of the AP-5 and L-NAME groups were treated by intragastric administration of AP-5 (0.7 mg · kg(-1) · d(-1)) and L-NAME (60 mg · kg(-1) · d(-1)) respectively from the 11 th day after operation, once daily for 7 days. The mechanical pain thresholds were measured before the SNI procedure (baseline) and at the 10th and 16th day after the procedure. The expression of p-CaMK II protein and p-CREB protein and gene of the spinal cord (L4-L6 segments) was determined by Western blot and fluorescence quantitative-polymerase chain reaction (PCR), separately., Results: In comparison to the control group, the mechanical pain threshold was significantly decreased in the model group (P < 0.01). After EA intervention, the mechanical pain thresholds of the EA, AP-5 and L-NAME groups were obviously increased (P < 0.01, P < 0.05) on day 16 post SNI procedure. The expression levels of p-CaMK II and p-CREB proteins and CREB mRNA in the spinal cord were significantly higher in the model group than in the control group (P < 0.05). Compared with the model group, the expression levels of spinal p-CaMK II and p-CREB proteins and CREB mRNA were obviously down-regulated in the EA group (P < 0.05), but not in the AP-5 group and the L-NAME group (P > 0.055., Conclusion: EA intervention of BL 40-GB 30 may alleviate pain in neuropathic pain rats, which may be related to its effects in down-regulating spinal CaMK II-CREB pathway function.

Objective: To observe the effects of electroacupuncture (EA) stimulation of different tissues (nerve stem, muscular layer) at "Huantiao" (GB 30) acupoint on expression of hosphorylated c-jun N-terminal kinase (p-JNK) and c-jun (p-c-jun) proteins in the lumbar spinal cord in rats with sciatic nerve injury, so as to explore its mechanism underlying improvement of peripheral neuropathic damage., Methods: Forty-eight SD rats were randomly divided into normal, model (the left sciatic nerve severed), GB 30 deep needling (the acupuncture needle tip was inserted to the sciatic nerve trunk to elicit an instantaneous jerk of the hind limb) and GB 30 shallow needling (the needle tip was inserted to the muscle layer to evoke a local muscular contraction) groups (n = 12 rats in each group). EA stimuli were delivered at 2 Hz/100 Hz, 1 mA, 20 min in duration per treatment for 10 consecutive days. Histopathological changes were observed by Hematoxylin-eosin (HE) staining and immunohistochemical assay was carried out to examine the pathological change of spinal segments (L4-L5) and the expression of p-JNK and p-c-jun proteins, respectively., Results: For rats with the sciatic nerve severed, the spinal neurons became swelling, degeneration or even apoptosis. Acupuncture intervention reduced the number of apoptosic neurons and improved the pathological change, which was relatively better in the.deep needling group than in the shallow needling group. Likewise, the elevated spinal p-JNK and p-c-jun expression levels of the model group were significantly reduced by EA intervention (deep needling vs shallow needling, P < 0.01., Conclusion: Acupuncture can improve the spinal pathological changes in rats with sciatic nerve injury, which is probably achieved by decreasing the p-JNK and p-c-jun expression and inhibiting the JNK signaling pathway, and thereby, reducing the apoptosis of the spinal neurons. Deep needling results in greater benefits than shallow needling.

Objective: To observe the change of neuronal nitric oxide synthase (nNOS) expression in the spinal cord of diabetic rats with painful diabetic neuropathy., Methods: Sixty SD rats were randomized equally into painful diabetic neuropathy group (DM group) and control group. Painful diabetic neuropathy was induced by intraperitoneal injection with STZ (60 mg/kg) in DM group, and the rats in the control group received a solvent injection. Blood glucose levels were measured before and at 2, 7, 14, 21, and 28 days after STZ injection (T1-6 respectively). Responses to the mechanical stimulus were measured with von Frey filament, and 50% paw withdraw threshold (PWT) and body weight were recorded at T1 and T3-6. At T1 and T3-6, 6 rats from each group were sacrificed to examine the expression of nNOS in the lumbar segments of the spinal cord using Western blotting., Results: The level of blood glucose increased while the body weight decreased significantly after STZ injection in DM group (P<0.05). Comparing to those in the control group, PWT decreased while spinal nNOS expression increased significantly in DM group at T4-6 (P<0.05) showing an inverse correlation between them (P<0.01)., Conclusion: The enhanced expression of spinal nNOS might be involved in the pathogenesis of painful diabetic neuropathy in rats.

Objective: To investigate the changes of cyclooxygenase-2 (COX-2) expression in the spinal cord dorsal horn after intrathecal a specific p38MAPK inhibitor-SB203580 on neuropathic pain in rats induced by chronic constrictive injury (CCI) to the sciatic nerve., Methods: Twenty-four male SD rats after intrathecal catheter placement were randomly divided into 4 groups: a sham group with sham surgery, the neuropathic pain model of a NS group, a DMSO group and an SB group were established by CCI to sciatic nerve. NS or DMSO or SB203580 was injected IT NS or 2%DMSO or SB203580 twice a day for 5 consecutive days starting at 6th day when the model of chronic constrictive injury was established. Mechanical stimuli were measured before the surgery and on 1st, 3rd, 5th, 7th, 9th, and 11th day after the surgery. Then all rats were sacrificed and the lumbar segment of spinal cord was removed to determine the COX-2 expression in the dorsal horn by immunocytochemistry., Results: Day 1 to 11 after the surgery, the threshold to mechanical on the surgery side was significantly lower in the NS group and the DMSO group than in the sham group. Day 7 to 11 after the sugery, the threshold to mechanical on the surgery side was significantly lower in the SB group than in the NS group and the DMSO group. The expression of spinal COX-2 was higher in the NS group and the DMSO group than in the sham group, but lower in the SB group than in NS group and the DMSO group., Conclusion: Intrathecal administration of SB203580 has significant analgesic effect in the CCI rat model. Expression of COX-2 is significantly reduced when p38MAPK is inhibited by intrathecal SB203580, and p38MAPK stimulation is essential for COX-2 expression.

Objective: To investigate the effects of chronic morphine administration on pain behaviors in young rats and to explore the mechanisms involved., Methods: Sixteen SD young rats of 3-4 weeks were randomly divided into control and morphine administration groups. Young rats received saline (1 mL/kg) or morphine (10 mg/kg) subcutaneously. Each regimen was given once daily for 14 days. Pain behaviors were examined on day 1, 3, 5, 7, and 14 before the daily drug administration. Western blot was used to examine the expression of glutamate decarboxylase 65 (GAD65) in the spinal cord dorsal horn on day 14 after the last drug administration., Results: Following 14 days of morphine administration, mechanical hyperalgesia was induced in young rats. Compared with control group, the mechanical withdrawal threshold of morphine group significantly decreased on days 3, 5,7 and 14. Chronic administration of morphine downregulated the expression of GAD65 in the spinal cord dorsal horn of young rats., Conclusion: Chronic morphine administration could induce mechanical hyperalgesia in young rats, and the downregulation of GAD65 in the spinal cord dorsal horn might play a critical role in the molecular mechanisms of morphine-induced hyperalgesia.

Objective: To examine the analgesic effect of calpain inhibitor ALLN on the zymosan-induced paw inflammatory pain and its effect on the expression of cyclooxygenase-2 (COX-2) in the spinal dorsal horn., Methods: Forty-eight Sprague-Dawley rats were equally divided into three groups: control group, sham-operated group, and zymosan group. According to Meller's method, zymosan (1.25 mg) was injected intraplantarly to induce paw inflammation in zymosan group; an equal volume of PBS was administered in the sham-operated group. Mechanical withdrawal threshold (MWT) and maximum thickness of paw were tested or measured before and 0.5, 1, 2, 4, 8, and 24 hours after injection. All rats were killed at different occasions following surgery to examine calpain activity in the spinal dorsal horn with Western blot analysis. Another sixty-four Sprague-Dawley rats were divided into three groups: sham-operated group, zymosan-induced paw inflammation with intraperitoneal dimethyl sulphoxide (DMSO) treatment group, and zymosan-induced paw inflammation with intraperitoneal calpain inhibitor ALLN treatment group. MWT and maximum thickness of paw were tested or measured before and 0.5, 1, 2, 4, 8, and 24 hours after injection. All rats were killed at different occasions following surgery to examine the COX-2 expression in the spinal dorsal horn with Western blot analysis., Results: MWT significantly decreased in the rats with zymosan-induced paw inflammation, while the maximum thickness of paw significantly increased, compared with control and sham-operated rats (P < 0.05). Calpain in the ipsilateral spinal dorsal horn was dramatically activated after zymosan injection (P < 0.01). Intraperitoneal ALLN injection significantly increased zymosan-induced MWT and decreased paw edema at the same time points after zymosan injection compared with DMSO treatment group (P < 0.05). Meanwhile, calpain inhibitor ALLN treatment significantly decreased the COX-2 expression in the spinal dorsal horn compared with DMSO treatment (P < 0.01)., Conclusion: Administration of calpain inhibitor ALLN is effective to attenuate zymosan-induced paw inflammatory pain. Calpain activation may be one aspect of the signaling cascade that increases the COX-2 expression in the spinal cord and contributes to mechanical hyperalgesia after peripheral inflammatory injury.

Objective: To study the peripheral and central neural involvements of acupoint "Taixi" (KI 3) by using Horseradish Peroxidase (HRP)., Methods: Ten male SD rats were used in the present study. 5 pL of 1% HRP was injected into the excavate site between the apex of medial malleolus and the Achilles tendon of the left hind foot, a corresponding site of acupoint "Taixi" (KI 3) in the human body. After 36 surviving hours, the rat's brain, spinal cord and dorsal root ganglia (DRG) of the lumbar segments (L) were dissected from the perfused experimental animals, and their tissue sections were examined with 3, 3', 5, 5' -tetramethyl-benzidine histochemistry for revealing HRP-labeling., Results: All the HRP-labeling appeared ipsilaterally to the injection side. Numerous HRP-labeled neurons were detected in the DRGs of L4 - L6 segments with their number being L5> L4 >L6. A longitudinal column of HRP-labeled motoneurons was found in the dorsolateral and mediolateral portions of the spinal cord, distributing in the lamina IX from the caudal L4 to the rostral L6. Additionally, the transganglionic HRP-labeled central prolection axonal terminals were found to be dense in the central part of laminae I-II from L4 to the rostral L6, and to scatter in the central part of gracile nucleus., Conclusion: HRP-labeled primary afferent and efferent innervating acupoint "Taixi" (KI 3) are DRGs of L4-L6, the dorsolateral and mediolateral motoneuron columns of L4-L6, and the centrally projecting axonal terminals of laminae I-II of the spinal cord and the gracile nucleus.

Objective: To investigate the changes of protein kinase C (PKC) activity and its role in the development of presyrinx state in rabbits., Methods: Presyrinx state was established in 56 rabbits by intra-cisternal injection of kaolin. At 1, 3, 7, 14, and 21 days after the injection, the water content in the upper cervical spinal cord was measured, its pathological changes observed microscopically and the PKC activity determined with substrate phosphorolysis kinase assay., Results: Spinal cord edema occurred in rabbits one day after kaolin injection, with water content of (68.35-/+0.70)%, which increased to (72.70-/+0.88)% on day 3, reaching the peak level of (72.92-/+0.86)% on day 7, followed by gradual decline after 3 weeks [(70.03-/+0.77)%]. The membrane PKC activity increased from 5.67-/+0.26 pmol.mg(-1).min(-1) on day 1 after the injection to reach the peak level on day 7 (13.27-/+3.15 pmol.mg(-1).min(-1)), which was maintained till day 14 with subsequent decrease to 8.85-/+1.56 pmol.mg(-1).min(-1) on day 21. The cytoplasmic PKC activity showed changes of a reverse pattern., Conclusion: In rabbits with experimental presyrinx state, PKC translocation and activation is involved in ischemic spinal edema.

Objective: To examine the cellular distribution and location of p38alpha/beta isoforms in the lumbar spinal cord of the bone cancer pain rats., Methods: Twenty SD female rats weighing 180 - 220 g were randomly divided into 2 groups (n = 10 each): group A (control group): intra-tibial injection of 3 microl Hank's solution; group B (model group): intra-tibial injection of 3 microl MADB-106 mammary gland carcinoma cells of rats (4.8 x 10(3)/microl). Mechanical withdrawal threshold and radiant heat threshold of rats' hind paws were measured every other day from one day before operation until 14 days later. The lumbar 4 ~ 5 spinal cord was removed on the 14th day. The cellular distribution and location of the spinal p38alpha/beta immunoreactivity were detected by immunohistochemistry SABC and double immunofluorescence methods., Results: No significant differences in mechanical withdrawal threshold and radiant heat threshold were found at all time points in group A. During the first 6 days of post-operation there was obvious difference in radiant heat stimulus between group A and B (P < 0.05); on the 14th day after operation, mechanical pain threshold and radiant heat threshold in group B were significantly different from that of group A (P < 0.05). The p38alpha/beta immunoreactivity of group B in laminae I approximately IV of dorsal horn showed stronger staining than group A (P < 0.05). Double immunofluorescence confocal micrographs showed that spinal p38alpha and the neuronal marker neuronal N (NeuN) were colocalized in the dorsal horn, indicating that p38alpha was expressed in neurons. Double immunofluorescence micrographs demonstrated that antibodies against p38beta and the microglia marker OX42 labeled the same cell, indicating that p38beta was expressed in microglia., Conclusion: Our studies indicate that p38alpha and p38beta are involved in the generation and maintenance of bone cancer pain states. p38alpha is predominantly expressed in neurons, while p38beta is expressed in microglia.

Extracellular signal-regulated kinase (ERK), a mitogen-activated protein kinase (MAPK), transduces a broad range of extracellular stimuli into diverse intracellular responses. It has been reported that ERK is involved in the modulation of nociceptive information and central sensitization produced by intense noxious stimuli or peripheral tissue inflammation. Our previous studies showed that the spinal neurons sensitization was involved in morphine withdrawal response. This study was to investigate the role of the spinal ERK in morphine dependence and naloxone-precipitated withdrawal response. To set up morphine-dependent model, rats were subcutaneously injected with morphine (twice a day, for 5 d). The dose of morphine was 10 mg/kg on the first day and was increased by 10 mg/kg each day. On day 6, 4 h after the injection of morphine (50 mg/kg), morphine withdrawal syndrome was precipitated by an injection of naloxone (4 mg/kg, i.p.). Using anti-phospho-ERK (pERK) antibody, the time course of pERK expression was detected by Western blot. U0126, a mitogen-activated protein kinase kinase (MEK) inhibitor, or phosphorothioate-modified antisense oligonucleotides (ODN) was intrathecally injected 30 min or 36, 24 and 12 h before naloxone-precipitated withdrawal. The scores of morphine withdrawal symptom and morphine withdrawal-induced allodynia were observed. One hour after naloxone-precipitated withdrawal, pERK expression in the spinal dorsal horn was assessed by immunohistochemical analysis and Western blot was used to detect the expression of cytosolic and nuclear fraction of pERK in the rat spinal cord. The results showed that the expression of cytosolic and nuclear fraction of pERK, not non-phospho-ERK, in the spinal cord was gradually increased following the injection of morphine. When morphine withdrawal was precipitated with naloxone, the expression of the spinal pERK further increased. Intrathecal administration of U0126 or antisense ODN against ERK decreased the scores of morphine withdrawal, attenuated morphine withdrawal-induced allodynia and also inhibited the increase of pERK expression in the spinal cord of morphine withdrawal rats. These results suggest that activation of the spinal ERK is involved in morphine-dependent and naloxone-precipitated withdrawal response.

Objective: To examine the effects of 5-HT4 receptor partial agonist tegaserod on response to rectal distention (RD) and on nNOS expression in spinal cord, and to investigate the mechanism of tegaserod influencing visceral sensation., Methods: Neonatal SD rats randomLy received colonic irritation by acetic acid from postnatal day 8 to day 21 as visceral hypersensitive model (Group H); or by saline intrarectally as control group (Group C). Five subgroups of Group H were i.p. injected randomLy with saline, vehicle (1-methyl-2-thpyrrolidone) or tegaserod at doses of 0.1, 0.3 and 1.0 mg/kg, respectively. Two subgroups of Group C were i.p. injected with saline or tegaserod at dose of 1.0 mg/kg. Ten minutes after injection rectal distention was performed, AWR was recorded and nNOS expression in spinal cord (L6-S1) was analyzed quantitatively by NADPH-diaphorase histochemistry., Results: Tegaserod significantly inhibited AWR in Group H, but had no effect in Group C. Tegaserod (1.0 mg/kg) inhibited AWR more significantly in Group H than in Group C at the largest volume of distention (1.2 mL). In Group H, tegaserod (1.0 mg/kg) significantly decreased overall nNOS positive cells in spinal cord to 40% of saline. The greatest attenuation was in dorsal horn (31% of H-saline). Tegaserod (0.1 mg/kg) did not affect the overall nNOS(P>0.20), but decreased the number of nNOS positive cells in central canal (79% of H-saline P<0.01)., Conclusion: Tegaserod inhibits response to rectal distention in rats with visceral hypersensitivity and dose dependently attenuates spinal nNOS expression, especially in dorsal horn and central canal. nNOS may be involved in the modulation of visceral sensitivity by tegaserod.

To investigate the effect of N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 on the formalin-induced cyclooxygenase-2 (COX-2) expression in the dorsal horn of the rat spinal cord. Forty-eight male Sprague-Dawley rats were divided into 4 groups: control, formalin, formalin+normal saline (NS) and formalin+MK-801 groups. Rats in formalin, formalin+NS and formalin+MK-801 groups were subcutaneously injected with 0.2 ml 5% formalin into the plantar surface of the right hind paw. NS or MK-801 solution (10 microl) was intrathecally injected under transient ether anesthesia 15 min prior to the formalin injection in the formalin+NS and formalin+MK-801 groups, respectively. Flinch reflex was measured within 1 h after the formalin injection and expression of COX-2 in the dorsal horn of the L(5) segment of the spinal cord was assayed 24 h after the formalin injection using immunohistochemistry. Formalin evoked a biphasic flinch reflex. MK-801 produced a limited effect on the flinch reflex of phase 1, but produced significant and dose-dependent suppression on the flinch reflex of phase 2. The number and immunostaining density, shown by grey degree which was inversely proportional to the immunostaining density, of immunoreactive soma in the superficial (mainly I-II) and deep (IV-VI) laminae of the L(5) spinal cord in formalin and formalin+NS groups increased significantly, in contrast to those in the control group (p<0.01). The number and immunostaining density of immunoreactive soma decreased significantly in formalin+MK-801 group, in comparison with the formalin+NS group (p<0.05). The degree of the decrease was proportional to the dosage of MK-801 used. In addition, there were some immunoreactive processes especially in the superficial laminae, which extended as a continuous band across the dorsal horn after the formalin injection. Change in immunostaining density of the processes after administration of MK-801 was similar to that in the immunoreactive soma. The results showed that intrathecal injection of MK-801 significantly inhibited the increase of COX-2 expression in the spinal dorsal horn induced by the formalin injection in a dose-dependent manner, suggesting that the activation of NMDA receptor is one of the mechanisms for the formalin-induced increase of COX-2 expression in the spinal dorsal horn.

Our previous studies have shown that long-term potentiation (LTP) of C-fiber-evoked field potentials in the spinal dorsal horn is NMDA receptor dependent. It is known that elevation of Ca(2+) in the postsynaptic neurons through NMDA receptor channels during high-frequency stimulation of the afferent fibers is crucial for LTP induction, but how this leads to a prolonged potentiation of synaptic transmission in the spinal dorsal horn is not clear. In the hippocampus, a rise of Ca(2+) activates calcium/calmodulin-dependent protein kinase II (CaMK II) through autophosphorylation. Once this occurs, the kinase remains active, even when Ca(2+) concentration returns to baseline level. Phosphorylated CaMK II potentiates synaptic transmission by enhancement of AMPA receptor channel function via phosphorylation of GluR1 subunit of the receptor and the addition of AMPA receptors to synapses. Up to now, the role of CaMK II in the induction and maintenance of LTP of the C-fiber-evoked field potentials in spinal dorsal horn has not been evaluated. In the present study, we examined the expression of CaMK II and phospho-CaMK II in the lumbar segments (L4-L6) of the rat spinal dorsal horn at 30 min and 3 h after the establishment of LTP induced by tetanic electrical stimulation of the sciatic nerve (40 V, 0.5 ms pulses at 100 Hz for 1 s repeated four times at 10 s intervals) by using Western blot and electrophysiological techniques. To determine the role of the phospho-CaMK II in the induction and maintenance of the spinal LTP, a selective CaMK II inhibitor KN-93 (100 micromol/L) was applied directly onto the spinal cord at the recording segments before and after LTP induction. We found that (1) the protein level of phospho-CaMKII increased at both 30 min and 3 h after LTP induction, while the total protein level of CaMK II increased at 3 h but not at 30 min after LTP induction. (2) Spinal application of KN-93 at 30 min prior to the tetanus blocked both LTP induction and the increase in phospho-CaMK II. (3) 30 min after LTP induction, spinal application of KN-93 depressed LTP and the level of phospho-CaMK II (n=3). (4) Spinal application of KN-93 at 3 h after LTP, however, affected neither the amplitude of the spinal LTP nor the level of phospho-CaMK II in the spinal dorsal horn. These results suggest that activation of CaMK II is probably crucial for the induction and the early-phase maintenance of LTP of C-fiber-evoked field potentials in the spinal dorsal horn.

Objective: To investigate the different role of neuronal constitutive nitric oxide synthase (nc-NOS) in dynorphin (Dyn) A(1-17) spinal neurotoxicity and analgesia., Methods: The cNOS activity in ventral and dorsal spinal cord in rats was measured with H-L-arginine conversion, and ncNOS immunoreactivity(IR) was observed with strepavidin-peroxidase immunohisto-chemistry., Results: Intrathecal administration of Dyn A(1-17) produced dose-dependent paralysis of hindlimbs and tail as well as inhibition of tail flick (TF) and foot flinch (FF) reflexes. Dyn A(1-17) 10 nmol induced only transient paralysis and apparently reduced the ncNOS-IR in the superficial dorsal horn but did not induce any change of ncNOS-IR in the ventral horn cells as compared with saline control. Dyn A(1-17) 20 nmol produced permanent paraplegia with irreversible spinal cord damage, characterized by central and progressive necrosis. Dyn A(1-17) 20 nmol remarkedly induced the expression of ncNOS-IR in the ventral horn cells whereas inhibited ncNOS-IR in the superficial dorsal horn. Dyn A(1-17) 20 nmol also significantly increased the activities of cNOS in the ventral spinal cord but did not affect cNOS activities in the dorsal spinal cord. Intrathecal pretreatment with 7-nitroindazole (7-NI) 1 mumol, a selective ncNOS inhibitor 10 min prior to i.t. Dyn A(1-17) 20 nmol significantly ameliorated Dyn-induced neurological outcome, but TF and FF remained inhibited. 7-nitroindazole also significantly antagonized the increases of cNOS activities and ncNOS-IR in the ventral spinal cord at 4 h after i.t. Dyn A(1-17) 20 nmol, but did not affect or even potentiated Dyn-induced inhibition of cNOS activity and ncNOS-IR in the dorsal spinal cord., Conclusions: Over-expression or over-activation of ncNOS in the ventral spinal cord may be involved in Dyn spinal neurotoxicity, whereas as the reduction of ncNOS activities in the dorsal spinal cord might reflect Dyn spinal analgeisia or pain modulation.

It was studied the central role of nitric oxide(NO) during experimental teeth movement and the relation between nitric oxide synthetase (NOS) positive neurons and FOS like immunoreactivity (FLN) with the NADPH-diaphorase histochemistry and immunocytochemical reaction method. Results indicated that NOS positive neurons and FLN showed typical distribution in Vcx and there was some overlap between them. It suggests that NO is involved in the central modulation of the stimulating message of teeth movement, and which further explains the central modulation mechanism of experimental teeth movement in rats.

To investigate the relationship between mitochondrial enzyme activities and mitochondrial function after cervical cord injury, cervical cord model was prepared using Allen method in cats. Changes in mitochondrial Na+, K(+)-ATPase, Ca2+, Mg(2+)-ATPase, superoxide dismutase (SOD) activities, contents of malondialdehyde (MDA) and mitochondrial function in cervical cord were observed by different biochemical methods. The results showed that mitochondrial Na+, K(+)-ATPase, CA2+, Mg(2+)-ATPase, SOD activities decreased; mitichondral respiratory control rate (RCR), P/O ratio and oxidative phosphorylation rate (OPR) were also depressed is compared with control group (P < 0.05), but MDA level significantly increased compared to control group (P < 0.01). The results demonstrate that there is close correlation, between mitochondrial ATPase. SOD activities and mitochondral function, suggesting that mitochondrial pathophysiological alteration plays important roles in the secondary damage after cervical cord injury.

1.5% Capsaicin (Cap) or Vehicle was respectively used to treat the right or left sciatic nerve in 20 Sprague-Dawley rats. On the seventh day, the 20 rats were at random divided into electroacupuncture (EA) group and non-EA group, the spinal cord corresponding to the afferent segments of sciatic nerve was taken out for observing the changes of acetylcholinesterase (AChE) activity and [3H]-quinuelidinylbenzylate (QNB) binding sites in the spinal dorsal horn (SDH). The results were as follows: (1) EA "Huantiao" could enhance AChE activity in the SDH and decrease [3H]-QNB binding sites; (2) Cap treating sciatice nerve could weaken AChE activity in the SDH and merease [3H]-QNB binding sites; (3) Cap treatment could inhibit or partially inhibit the actions of EA as above. The results indicated that ACh participated in the primary afferent of acupuncture information and might exist in Cap-sensitive neurons.

In an attempt to elucidate the relationship between synapse formation and cell development, the morphology and cytochemistry of the endoplasmic reticulum and its enzymic marker, glucose-6-phosphatase (G-6-Pase), in cultured mouse spinal neurons were investigated ultrastructurally. It was found that in the early period of the development, neurons were characterized by scarceness of organelles; only a few of granular or agranular endoplasmic reticulum and mitochondria were seen. The endoplasmic reticulum and nuclear envelope were packed specifically with G-6-Pase resection product but the product was weak. After a period of culture, most of the neurons had well-developed endoplasmic reticulum, Golgi apparatus, mitochondria and microtubules, etc. The Golgi apparatus was relatively large, having some cisternae associated with vesicles. Either concave of convex face of the saccules was labeled by thiamine pyrophosphatase (TPPase) specifically. GERL, labeled by cytidine monophosphatase (CMPase), was also seen close to the inner or outer face of some Golgi apparatus. The endoplasmic reticulum at this stage was distributed throughout the cytoplasm, including that in dendrites; its enzyme marker (G-6-Pase) localized consistently within the lumen of all endoplasmic reticulum, nuclear space and subsurface cisternae, and frequently in the concave saccules of the Golgi apparatus. After a long-term culture, some neurons became "aged". The endoplasmic reticulum cisternae enlarged and G-6-Pase reaction reduced. Along with the neuronal development, especially maturation of the endoplasmic reticulum and its enzymic marker, synapse formation was begun at the neuropile area. The axo-dendritic synapses always occurred between the axonal terminals and dendrites where the endoplasmic reticulum had showed positive G-6-Pase reactions. Considering the fact, it suggests that the appearance and change of these specific enzymes may be related to the maturation of the neurons in vitro, and also related to the synapse formation between neurons.