Spinal cord edema, 5-hydroxytryptamine, lipid peroxidation, and lysosomal enzyme release after acute contusion and compression injury in primates

Surgical Decompression of Traumatic Cervical Spinal Cord Injury: A Pilot Study Comparing Real-Time Intraoperative Ultrasound After Laminectomy With Postoperative MRI and CT Myelography

BACKGROUND

Decompression of the injured spinal cord confers neuroprotection. Compared with timing of surgery, verification of surgical decompression is understudied.

OBJECTIVE

To compare the judgment of cervical spinal cord decompression using real-time intraoperative ultrasound (IOUS) following laminectomy with postoperative MRI and CT myelography.

METHODS

Fifty-one patients were retrospectively reviewed. Completeness of decompression was evaluated by real-time IOUS and compared with postoperative MRI (47 cases) and CT myelography (4 cases).

RESULTS

Five cases (9.8%) underwent additional laminectomy after initial IOUS evaluation to yield a final judgment of adequate decompression using IOUS in all 51 cases (100%). Postoperative MRI/CT myelography showed adequate decompression in 43 cases (84.31%). Six cases had insufficient bony decompression, of which 3 (50%) had cerebrospinal fluid effacement at >1 level. Two cases had severe circumferential intradural swelling despite adequate bony decompression. Between groups with and without adequate decompression on postoperative MRI/CT myelography, there were significant differences for American Spinal Injury Association motor score, American Spinal Injury Association Impairment Scale grade, AO Spine injury morphology, and intramedullary lesion length (IMLL). Multivariate analysis using stepwise variable selection and logistic regression showed that preoperative IMLL was the most significant predictor of inadequate decompression on postoperative imaging (P = .024).

CONCLUSION

Patients with severe clinical injury and large IMLL were more likely to have inadequate decompression on postoperative MRI/CT myelography. IOUS can serve as a supplement to postoperative MRI/CT myelography for the assessment of spinal cord decompression. However, further investigation, additional surgeon experience, and anticipation of prolonged swelling after surgery are required.

Dual-Functioning Scaffolds for the Treatment of Spinal Cord Injury: Alginate Nanofibers Loaded with the Sigma 1 Receptor (S1R) Agonist RC-33 in Chitosan Films

The present work proposed a novel therapeutic platform with both neuroprotective and neuroregenerative potential to be used in the treatment of spinal cord injury (SCI). A dual-functioning scaffold for the delivery of the neuroprotective S1R agonist, RC-33, to be locally implanted at the site of SCI, was developed. RC-33-loaded fibers, containing alginate (ALG) and a mixture of two different grades of poly(ethylene oxide) (PEO), were prepared by electrospinning. After ionotropic cross-linking, fibers were incorporated in chitosan (CS) films to obtain a drug delivery system more flexible, easier to handle, and characterized by a controlled degradation rate. Dialysis equilibrium studies demonstrated that ALG was able to form an interaction product with the cationic RC-33 and to control RC-33 release in the physiological medium. Fibers loaded with RC-33 at the concentration corresponding to 10% of ALG maximum binding capacity were incorporated in films based on CS at two different molecular weights-low (CSL) and medium (CSM)-solubilized in acetic (AA) or glutamic (GA) acid. CSL- based scaffolds were subjected to a degradation test in order to investigate if the different CSL salification could affect the film behavior when in contact with media that mimic SCI environment. CSL AA exhibited a slower biodegradation and a good compatibility towards human neuroblastoma cell line.

Serotonin 5-HT7 receptor agonist, LP-211, exacerbates Na(+), K(+)-ATPase/Mg(2+)-ATPase imbalances in spinal cord-injured male rats

BACKGROUND

The observed controversy that N-(4-cyanophenylmethyl)-4-(2-diphenyl)-1-piperazinehexanamide (LP-211), a selective serotonin (5-HT7) receptor agonist, may either modify or exacerbate imbalances in serum electrolyte concentrations and renal tissue of spinal cord trauma cases has not been reported yet. The aim of this study was to better understand the effects of a new 5-HT7 receptor agonist, LP-211, on serum electrolyte changes in spinal cord injured- (SCI) rats.

METHODS

Sixty male rats were assigned to the following groups: A) Intact (saline as vehicle, 1 ml/kg, i.p.), B) Intact [LP-211, (0.003-0.3 mg/kg, i.p.)], C) Sham-operated [laminectomy + vehicle (1 ml/kg, i.p.)], D) Sham-operated [laminectomy + LP-211 (0.003-0.3 mg/kg, i.p.)], E) Treatment [laminectomy + spinal trauma (SCI) + vehicle (1 ml/kg, i.p.)], F) Treatment [laminectomy + spinal trauma + LP-211 (0.003-0.3 mg/kg, i.p.)]. SCI was performed by placing an aneurysm clip, extradurally at the level of T10. After two weeks, LP-211 was administered cumulatively and each dose was injected (i.p.) with 20 min interval. At the end of the experiment, blood samples were collected for biochemical evaluations of the electrolytes employing standard commercial kits.

RESULTS

The present results indicate elevated serum levels of Na(+), K(+), and Mg(2+) in SCI rats and significant differences demonstrated between the groups [P < 0.001, F(5, 35) = 23.92], [P < 0.001, F(5, 35) = 67.63], [P < 0.001, F(5, 35) = 71.144], respectively. So that, in groups B, D and F, there was a significant increase in K(+) and Mg(2+) serum levels compared to the groups A, C, and E (P < 0.001). Furthermore, Na(+) serum levels in SCI (LP-211), laminectomy (LP-211), and intact (LP-211) groups tended to be statistically lower than SCI (saline), laminectomy (saline) and intact (saline) groups. Infact, hyponatremia, hyperkalemia and hypermagnesemia was obtained in group F. Nevertheless, in the remaining measured serum electrolytes such as calcium (Ca(2+)), iron (Fe(2+)) and phosphorus (P(3-)), chlorine (Cl(-)), copper (Cu(+)), and zinc (Zu(+)), no significant changes were observed.

CONCLUSION

It was shown that acute additive LP-211 treatments in the SCI group led to hyponatremia, hyperkalemia and hypermagnesemia, it may be stated that LP-211 treatment as a promising candidate for treating SCI complications in some systems especially urinary tract might take into consideration and further studies would be needed to clarify its benefits or drawbacks. The observed discrepancies, nevertheless; will also pose new questions. Altogether, this will ultimately contribute to further understanding the pathophysiological role regarding 5-HT7 receptor activation.

The recovery of 5-HT transporter and 5-HT immunoreactivity in injured rat spinal cord

STUDY DESIGN

Experimental spinal cord injury.

OBJECTIVE

To determine the role of serotonin (5-HT) and 5-HT transporter in recovery from spinal cord injury.

METHOD

We examined 5-HT and 5-HT transporter of spinal cord immunohistologically and assessed locomotor recovery after extradural compression at the thoracic (T8) spinal cord in 21 rats. Eighteen rats had laminectomy and spinal cord injury, while the remaining three rats received laminectomy only. All rats were evaluated every other day for 4 weeks, using a 0-14 point scale open field test.

RESULTS

Extradural compression markedly reduced mean hindlimbs scores from 14 to 1.5 +/- 2.0 (mean +/- standard error of mean). The rats recovered apparently normal walking by 4 weeks. The animals were perfused with fixative 1-3 days, 1, 2 and 4 weeks (three rats in each) after a spinal cord injury. The 5-HT transporter immunohistological study revealed a marked reduction of 5-HT transporter-containing terminals by 1 day after injury. By 4 weeks after injury, 5-HT transporter immunoreactive terminals returned to the control level. The 5-HT immunohistological study revealed a reduction of 5-HT-containing terminals by 1 week after injury. By 4 weeks after injury, 5-HT immunoreactive fibers and terminals returned to the control level.

CONCLUSION

We estimated the recovery of 5-HT transporter and 5-HT neural elements in lumbosacral ventral horn by ranking 5-HT transporter and 5-HT staining intensity and counting 5-HT and 5-HT transporter terminals. The return of 5-HT transporter and 5-HT immunoreactivity of the lumbosacral ventral horn correlated with locomotor recovery, while 5-HT transporter showed closer relationship with locomotor recovery than 5-HT. The presence of 5-HT transporter indicates that the 5-HT fibers certainly function. This study shows that return of the function of 5-HT fibers predict the time course and extent of locomotory recovery after thoracic spinal cord injury.

Effects of serotonin 1A agonist on acute spinal cord injury

STUDY DESIGN

We evaluated the effects of serotonin (5-HT) agonists on in vitro models of spinal cord compressive injury. Evoked potentials in injured rat spinal cords (n=24) were recorded during perfusion with 5-HT agonists.

OBJECTIVES

To evaluate the therapeutic effects of 5-HT agonists on the recovery of compound action potentials in injured spinal cords.

METHODS

Rat dorsal columns were isolated, placed in a chamber, and injured by extradural compression with a clip. Conducting action potentials were activated by supramaximal constant current electrical stimuli and recorded during perfusion with 5-HT agonists and antagonists.

RESULTS

After inducing compression injuries, mean action potential amplitudes were reduced to 33.9+/-5.4% of the pre-injury level. After 120 min of perfusion with Ringer's solution, the mean amplitudes recovered to 62.8+/-8.4% of the pre-injury level. At a concentration of 100 micro M, perfusion with tandospirone (a 5-HT1A agonist) resulted in a significantly greater recovery of mean action potential amplitudes at 2 h after the injury (86.2+/-6.9% of pre-injury value) as compared with the control Ringer's solution (62.8+/-8.4% of pre-injury value, P<0.05). In contrast, quipazine (a 5-HT2A agonist) accelerated the decrease of amplitude (54.5+/-11.7% of pre-injury value). 5-HT1A and 5-HT2A agonist did not consistently alter latencies of the action potentials.

CONCLUSION

The 5-HT1A receptor agonist was effective for the recovery of spinal action potential amplitudes in a rat spinal cord injury model.

Human brain plasticity: an emerging view of the multiple substrates and mechanisms that cause cortical changes and related sensory dysfunctions after injuries of sensory inputs from the body

Injuries of peripheral inputs from the body cause sensory dysfunctions that are thought to be attributable to functional changes in cerebral cortical maps of the body. Prevalent theories propose that these cortical changes are explained by mechanisms that preeminently operate within cortex. This paper reviews findings from humans and other primates that point to a very different explanation, i.e. that injury triggers an immediately initiated, and subsequently continuing, progression of mechanisms that alter substrates at multiple subcortical as well as cortical locations. As part of this progression, peripheral injuries cause surprisingly rapid neurochemical/molecular, functional, and structural changes in peripheral, spinal, and brainstem substrates. Moreover, recent comparisons of extents of subcortical and cortical map changes indicate that initial subcortical changes can be more extensive than cortical changes, and that over time cortical and subcortical extents of change reach new balances. Mechanisms for these changes are ubiquitous in subcortical and cortical substrates and include neurochemical/molecular changes that cause functional alterations of normal excitation and inhibition, atrophy and degeneration of normal substrates, and sprouting of new connections. The result is that injuries that begin in the body become rapidly further embodied in reorganizational make-overs of the entire core of the somatosensory brain, from peripheral sensory neurons to cortex. We suggest that sensory dysfunctions after nerve, root, dorsal column (spinal), and amputation injuries can be viewed as diseases of reorganization in this core.

Evidence for serotonin sensitivity of adult rat spinal axons: studies using randomized double pulse stimulation

We have recently shown both inhibitory and excitatory effects of serotonin on neonatal rat dorsal column axons. While neonatal rat dorsal column axons also respond to norepinephrine and GABA, adult rat dorsal columns are insensitive to the actions of both compounds. Therefore, we studied the effects of serotonin agonists on adult rat dorsal column axons using randomized double pulse stimuli at 0.2 Hz with random interpulse intervals of 3, 4, 5, 8, 10, 20, 30, 50 and 80 ms. The serotonin(1A) agonist, 8-hydroxy-dipropylaminotetralin-hydrobromide (8-OH-DPAT), significantly modulated test response amplitudes at 3, 4, 5 and 8 ms interpulse intervals by 29.6+/-4.0%, 17.4+/-2.1%, 9.6+/-2.3%, and 12.4+/-2.2% of conditioning pulse amplitudes, respectively. The mean latencies at 3, 4 and 5 ms interpulse intervals increased by 17.0+/-5.1%, 8.6+/-2.1%, and 5.1+/-1.4%, respectively (P<0.05). However, neither 10 microM 8-OH-DPAT nor 100 microM serotonin hydrochloride affected the compound action potentials evoked by conditioning or test pulses. In contrast, treatment with 100 microM quipazine dimaleate (a serotonin(2A) agonist) decreased the refractory period. While the response amplitudes to a 3-ms double pulse were reduced by 11.0+/-1.5% during the control period, the test response fell to only 2.4+/-1.8% of the conditioning response amplitudes after exposure to 100 microM quipazine. 8-OH-DPAT decreased the amplitude, prolonged the latency and increased the refractory periods of compound action potentials in the adult rat dorsal column, although a high concentration of the agonist (100 microM) was required for these effects. In contrast, the serotonin(2A) agonist, quipazine, decreased refractory periods. These results suggest that both serotonin(1A) and serotonin(2A) receptor subtypes are present on adult spinal dorsal column axons. Further, these receptors have opposing effects on axonal excitability, despite the fact that their sensitivities are relatively low.

Characterization of axonal ultrastructural pathology following experimental spinal cord compression injury

The present study characterizes axonal pathology associated with traumatic compression injuries of the spinal cord and quantitatively assesses subtypes of axonal pathology in the acute, post-injury period. Eighteen adult female Wistar rats underwent spinal cord compression injury with a 53 g modified aneurysm clip at the C8-T1 segment. Six additional rats served as sham controls. Six experimental animals were sacrificed at each of the three post-injury time points: 15 min, 2 h and 24 h. From all animals, the C8-T1 spinal cord was dissected and processed for both light and electron microscopy. Axonal pathology included periaxonal swelling, organelle accumulation, vesicular myelin, myelin invagination, myelin rupture, and giant axons. Early myelin rupture and the ultrastructural features of giant axons are described here for the first time in the context of spinal cord compression injury. The quantitative analysis characterizes the prevalence of types of axonal pathology over the acute post-injury period and provides evidence for the secondary injury hypothesis regarding the evolution of axonal pathophysiology following trauma.

Methylprednisolone and membrane properties of primary cultures of mouse spinal cord

The present study attempts to define the capacity of methylprednisolone sodium succinate (MP) to protect neuronal membranes against a free radical challenge in primary cultures of fetal mouse spinal cord. Incubation of these cultures with MP significantly increased the Na+,K(+)-ATPase activity, an effect that was blocked by the RNA synthesis inhibitor, actinomysin D and the protein synthesis inhibitor, cycloheximide, suggesting an induction of protein synthesis by MP. In contrast, incubation with FeCl2 for 1 or 2 h significantly inhibited Na+,K(+)-ATPase activity and elevated the levels of thiobarbituric acid-reactive substances (TBARS). Pretreatment with MP prevented the rise in TBARS and partially prevented the decrease in Na+,K(+)-ATPase activity for the first hour of FeCl2 incubation, an effect that was lost during the second hour. A second dose of MP after the first hour of incubation with FeCl2 partially restored Na+,K(+)-ATPase activity and reduced TBARS levels after the second hour of exposure to FeCl2. Co-incubation of MP with cycloheximide completely prevented the decrease in Na+,K(+)-ATPase activity seen after a 2-h incubation with FeCl2 and eliminated the need for a second dose of MP after the first hour of incubation with FeCl2. These findings suggest a capacity for rapid protein induction and antioxidant activity for MP in vitro.