Discrepancy between SEPs directly recorded from the dorsal column nuclei following upper and lower limb stimulation in patients with syringomyelia

Somatosensory evoked potentials (SEPs) in response to electrical stimulation of the median nerve (MN) and posterior tibial nerve (PTN) were studied in 2 patients with syringomyelia. Intraoperative recordings were made from the surface of the dorsal column nuclei as well as from the scalp. Following MN stimulation, there was a preservation of scalp-recorded P9, P11, P13 and N20, however, there was an absence of spinal N13-P13. The dorsal column SEPs to MN stimulation were normal, characterized by a major negativity (N1), preceded by a small positivity (P1) and followed by a large positivity (P2). On the other hand, there was little or no cortical response (P37) to PTN stimulation. The dorsal column SEPs to PTN stimulation showed a disappearance of the normal P1′-N1′-P2′ configuration, being replaced by a series of small spiky waves. The syringomyelic cavity may have thus compressed the gracile dorsal column which courses more medially than the cuneate pathway, causing desynchronization of the dorsal column SEPs. These findings suggest that dorsal column pathway arising from the lower limb is more vulnerable than that from the upper limb when a cervical syrinx is present.     

Quantitative assessment of gait determinants during single stance via a three-dimensional model--Part 2. Pathological gait

A three-dimensional model for normal gait formulated in Part 1 is now altered to simulate the dynamics of pathological walking. Mechanisms fundamental to the production of a normal gait pattern are systematically removed, in order to assess contributions from individual gait determinants. Four separate pathological cases are studied: a model neglecting ankle plantarflexor activity; absence of stance knee flexion-extension and foot and knee interaction; both pelvic list and transverse pelvic rotation removed; and finally, a model with all major gait determinants missing. These are used collectively to show that stance knee flexion-extension and foot and knee interaction successively dominate lower-extremity dynamical response during the single support phase of normal gait. The hip abductor muscles, while effecting pelvic list, serve to stabilize this limb, rather than actively determine whole-body vertical acceleration. Mechanisms compensating for a loss in joint motion are also explored. Complete ankle loss may be successfully compensated with increased hip abductor muscle activity; the loss of both ankle and knee, however, demand unacceptable levels of vertical pelvic displacement.     

Organ cross talk modulates pelvic pain

Interstitial cystitis (IC) is a chronic bladder inflammatory disease of unknown etiology that is often regarded as a neurogenic cystitis. IC is associated with urothelial lesions, voiding dysfunction, and pain in the pelvic/perineal area, and diet can exacerbate IC symptoms. In this study, we used a murine neurogenic cystitis model to investigate the development of pelvic pain behavior. Neurogenic cystitis was induced by the injection of Bartha's strain of pseudorabies virus (PRV) into the abductor caudalis dorsalis tail base muscle of female C57BL/6J mice. Infectious PRV virions were isolated only from the spinal cord, confirming the centrally mediated nature of this neurogenic cystitis model. Pelvic pain was assessed using von Frey filament stimulation to the pelvic region, and mice infected with PRV developed progressive pelvic pain. Pelvic pain was alleviated by 2% lidocaine instillation into either the bladder or the colon but not following lidocaine instillation into the uterus. The bladders of PRV-infected mice showed markers of inflammation and increased vascular permeability compared with controls. In contrast, colon histology was normal and vascular permeability was unchanged, suggesting that development of pelvic pain was due only to bladder inflammation. Bladder-induced pelvic pain was also exacerbated by colonic administration of a subthreshold dose of capsaicin. These data indicate organ cross talk in pelvic pain and modulation of pain responses by visceral inputs distinct from the inflamed site. Furthermore, these data suggest a mechanism by which dietary modification benefits pelvic pain symptoms.     

Distribution of lumbar spinal evoked potentials and their correlation with stimulation-induced paresthesiae

In 7 awake patients with neuropathic lower extremity pain, spinal somatosensory evoked potentials (SEP) were elicited from the non-painful leg by electrical stimulation of the peroneal nerve and mechanical stimulation of the hallux ball. Recording was made epidurally in the thoraco-lumbar region by means of an electrode temporarily inserted for trial of pain-suppressing stimulation.In response to peroneal nerve stimulation, two major SEP complexes were found. The first complex consisted, as has been described earlier, of an initial positivity (P12), a spike-like negativity (N14), a slow negativity (N16) and a slow positivity (P23). The second complex consisted of a slow biphasic wave, conceivably mediated by a supraspinal loop. Both complexes had a similar longitudinal distribution with amplitude maxima at the T12 vertebral body.The SEP evoked by mechanical hallux ball stimulation had a relatively small amplitude, and there was no significant second complex. The relationship between stimulus intensity and SEP amplitude was negatively accelerating.The longitudinal distribution of spinal SEP was compated with the somatotopic distribution of paresthesiae induced by stimulation through the epidural electrode. It was found that stimulation applied at the level of maximal SEP generally induced paresthesiae in the corresponding peripheral region. Therefore, spinal SEP may be used as a guide for optimal positioning of a spinal electrode for therapeutic stimulation when implanted under general anesthesia.An attempt was made to record the antidromic potential in the peroneal nerve elicited from the dorsal columns by epidural stimulation. The antidromic response was, however, very sensitive to minimal changes of stimulus strength and body position of the patient, and was also contaminated by simultaneously evoked muscular reflex potentials.Thus, peripheral responses evoked by epidural stimulation appeared too unreliable to be useful for the permanent implantation of a spinal electrode for therapeutic stimulation.     

Effects of lumbo-pelvic rhythm on trunk muscle forces and disc loads during forward flexion: A combined musculoskeletal and finite element simulation study

Previous in-vivo studies suggest that the ratio of total lumbar rotation over pelvic rotation (lumbo-pelvic rhythm) during trunk sagittal movement is essential to evaluate spinal loads and discriminate between low back pain and asymptomatic population. Similarly, there is also evidence that the lumbo-pelvic rhythm is key for evaluation of realistic muscle and joint reaction forces and moments predicted by various computational musculoskeletal models. This study investigated the effects of three lumbo-pelvic rhythms defined based on in-vivo measurements on the spinal response during moderate forward flexion (60°) using a combined approach of musculoskeletal modeling of the upper body and finite element model of the lumbosacral spine. The muscle forces and joint loads predicted by the musculoskeletal model, together with the gravitational forces, were applied to the finite element model to compute the disc force and moment, intradiscal pressure, annular fibers strain, and load-sharing. The results revealed that a rhythm with high pelvic rotation and low lumbar flexion involves more global muscles and increases the role of the disc in resisting spinal loads, while its counterpart, with low pelvic rotation, recruits more local muscles and engages the ligaments to lower the disc loads. On the other hand, a normal rhythm that has balanced pelvic and lumbar rotations yields almost equal disc and ligament load-sharing and results in more balanced synergy between global and local muscles. The lumbo-pelvic rhythm has less effect on the intradiscal pressure and annular fibers strain. This work demonstrated that the spinal response during forward flexion is highly dependent on the lumbo-pelvic rhythm. It is therefore, essential to adapt this parameter instead of using the default values in musculoskeletal models for accurate prediction of muscle forces and joint reaction forces and moments. The findings provided by this work are expected to improve knowledge of spinal response during forward flexion, and are clinically relevant towards low back pain treatment and disc injury prevention.     

盆神经和阴部神经传入在大鼠腰骶髓的相互作用

应用条件－检验刺激技术观察时间依赖性抑制现象是研究传入信息相互作用的方式之一。用１．５－３倍阈刺激强度的电脉冲交替刺激麻醉、麻痹的盆神经（Ｐｅ）和阴部神经（Ｐｕ）,以玻璃微电极在Ｌ６－Ｓ１节段脊髓背角会聚神经元上记录细胞外放电。条件输入可对深层（＞３００μｍ）单位的检验反应产生时间依赖性抑制效应,产生抑制的刺激间期为１－３６０ｍｓ,Ｐｅ为条件刺激时较长。浅层细胞（＜３００μｍ）发生抑制的间期为１－     

Modification of the gravitropic response of seedling roots of raneseed (Brassica napus) transformed by Agrobacterium rhizogenes A4

We have examined the growth and gravitropic response of seedling roots of rapeseed ( Brassica napus . CrGC5–1) transformed by Agrobacterium rhizogenes A4, in order to evaluate if this could constitute a new model system for the study of gravitropism. The transformed clone chosen for study had integrated full-length TL- and TR-DNA from pRi (the root inducing plasmid), and thus included all of the agrobacterial genes potentially involved in the modified phenotype of transformed plants. In the vertical position, the growth rate of transformed roots was higher than controls. During 24 h of continuous stimulation, the optimal angle for gravitropic bending in normal roots was 135° (with respect to the gravity axis), with decreasing response at 90° and 45°. For transformed roots, slight curvature developed at 45° and at 90°, and stronger curvature was observed at 135°, though transformed roots tips never reached the vertical position. The minimum stimulation time necessary to elicit a response (presentation time) was also determined: it was signficantly shorter in normal roots (80 s) than in transformed ones (120 s). The results show that pRi transformed roots are less sensitive to gravity than normal roots.     

Truncal changes in children with mild limb length inequality: a surface topography study

Background

Limb length Inequality (LLI) in children and adults may affect posture, gait, and several truncal parameters, and it can cause spinal scoliosis. In literature, however, there is a paucity of assessment of truncal and spinal changes due to mild LLI in children. This report presents children with LLI, and it aims to provide information in pelvic imbalance, spinal posture, and scoliotic curve, using surface topography analysis which is a novel methodological approach for this condition.

Study design

This is an ongoing prospective research study on patient series suffering LLI.

Material and method

Twenty children, attending the Scoliosis Clinic of the department, 7 boys, 13 girls, 9–15?years old, range 7.5–15, mean 15.5?years, having mild LLI, were assessed. The LLI was 0.5 to 2?cm, mean 1.2?cm. There was not any post-traumatic LLI. We evaluated the LLI in correlation to pelvic and spinal posture parameters. The 4D Formetric DIERS apparatus (4DF) was used for the surface topography assessment. The following were assessed: in the coronal plane, the coronal imbalance, the pelvic obliquity, the lateral deviation, and the 4DF scoliosis angle; in the sagittal plane, the sagittal imbalance, the 4DF kyphotic angle, the kyphotic apex, the 4DF lordotic angle, the lordotic apex, the pelvic tilt, and the trunk inclination; and in the transverse plane, the pelvis rotation, the pelvic torsion, the surface rotation, and the 4DF vertebral rotation. LLI was measured using a tape. The data were statistically analyzed, and reliability study for the LLI was also performed.

Results/discussion

The LLI was statistically significantly correlated to the 4DF reading of pelvis rotation, pelvic tilt (pelvic obliquity), and surface rotation. The scoliometer readings (angle trunk rotation ATR or trunk inclination ATI) in the lumbar region were statistically significantly correlated to the 4DF readings of pelvic tilt (pelvic obliquity). The normally symmetric truncal parameters were also statistically significantly changed (all these deviating from the line of gravity through the vertebral prominence). Interestingly, LLI was not correlated to the scoliosis angle and the scoliometer reading at the lumbar level.The following 4DF readings are presented: in the coronal plane, the coronal imbalance, pelvic obliquity, lateral deviation, and 4DF scoliosis angle; in the sagittal plane, the sagittal imbalance, kyphotic angle, kyphotic apex, lordotic angle, lordotic apex, pelvic tilt, and trunk inclination; and in the transverse plane, the pelvic rotation, pelvic torsion, surface rotation, and vertebral rotation.

Conclusions

Previous studies have reported the results after simulation of LLI in order to evaluate the effects on the pelvic balance and spinal posture parameters. This report is not a LLI simulation study but it presents the effects of mild LLI on truncal changes in the main cardinal planes in children suffering LLI. These changes undoubtedly affect not only the standing truncal posture but also the gait’s economy as well.As mild LLI affects the pelvic balance and spinal posture parameters, our therapeutic approach is that mild LLI (less than 2.0?cm) has to be corrected using shoe elevation, in order to equalize the pelvic obliquity and, consequently, the spinal posture parameters.

     

Brachially innervated ectopic hindlimbs in the chick embryo. I. Limb motility and motor system anatomy during the development of embryonic behavior

The functional status of brachially innervated hindlimbs, produced by transplanting hindlimb buds of chick embryos in place of forelimb buds, was quantified by analyzing the number and temporal distribution of spontaneous limb movements. Brachially innervated hindlimbs exhibited normal motility until E10 but thereafter became significantly less active than normal limbs and the limb movements were more randomly distributed. Contrary to the findings with axolotls and frogs, functional interaction between brachial motoneurons and hindlimb muscles cannot be sustained in the chick embryo. Dysfunction is first detectable at E10 and progresses to near total immobility by E20 and is associated with joint ankylosis and muscular atrophy. Although brachially innervated hindlimbs were virtually immobile by the time of hatching (E21), they produced strong movements in response to electrical stimulation of their spinal nerves, suggesting a central rather than peripheral defect in the motor system. The extent of motoneuron death in the brachial spinal cord was not significantly altered by the substitution of the forelimb bud with the hindlimb bud, but the timing of motoneuron loss was appropriate for the lumbar rather than brachial spinal cord, indicating that the rate of motoneuron death was dictated by the limb. Measurements of nuclear area indicated that motoneuron size was normal during the motoneuron death period (E6-E10) but the nuclei of motoneurons innervating grafted hindlimbs subsequently became significantly larger than those of normal brachial motoneurons. Although the muscle mass of the grafted hindlimb at E18 was significantly less than that of the normal hindlimb (and similar to that of a normal forelimb), electronmicroscopic examination of the grafted hindlimbs and brachial spinal cords of E20 embryos revealed normal myofiber and neuromuscular junction ultrastructure and a small increase in the number of axosomatic synapses on cross-sections of motoneurons innervating grafted hindlimbs compared to motoneurons innervating normal forelimbs. The anatomical data indicate that, rather than being associated with degenerative changes, the motor system of the brachial hindlimb of late-stage embryos is intact, but inactive. © 1993 John Wiley & Sons, Inc.     

Etude de l’erection chez le rat: un nouveau modele physiologique

Penile erection is a muscular and vascular event mediated by the autonomic nervous system. The neurophysiology of erection remains poorly understood and controversial, requiring a suitable model for in-vitro studies of erectile function. Such a model, based in the rat whose penile innervation is very similar to man, is described here. The first study using this model considers the influence of systemic blodd pressure (BP) on penile erection. In 33 anaesthetized rats the pelvic and cavernosal nerves were identified and dissected. Supra maximal electrical stimulation was delivered over 1 minute by a train of 1 ms pulses onto the pelvic nerve (10 V, 15 Hz) or the cavernosal nerve (6 V, 10 Hz). Systemic blood pressure and intracavernosal pressure (ICP) were monitored and stored on a computer. As in previous animal models (dog, monkey), four phases of the cavernosal response to neural electrical stimulation were observed: latency, tumescence, full erection, and détumescence. In all rats electrical stimulation of either the pelvic or cavernosal nerves significantly increased intracavernosal pressure. Complete erectile response (rigidity and unfolding of the penis) was only seen with intracavernosal pressures > 95 mm Hg. Intracavernosal pressure increased proportionally with blood preessure during the full erection phase according to the equation ICP=0.94 BP ? 31 mm Hg (r=0.94 BP ? 31 mm Hg (r=0.94) for electrical stimulation of the cavernosal nerve, or the alternative aquation ICP=0.76 BP ? 21 mm Hg (r=0.73) for electrical stimulation of the pelvic nerve. The rat is a readily available model for the study of erection and present obvious advantages over existing models such as the dog, cat and monkey. Cavernosal repsonse to neural stimulation was closely related to arterial blood pressure and the two linear equations presented above should be considered further in studies modifying autonomic neurotransmission as well as in relation to the effects of pharmacological compounds with vasomotor actions on erectile function.     

Daily energy expenditure in active and inactive persons with spinal cord injury.

Daily energy expenditure (DEE) was evaluated seventeen male subjects with spinal cord injury (SSCI), who had active (N = 9) and inactive (N = 8) lifestyles, and in seven normal males. DEE was estimated from the mean 24-hr heart rate and heart rate-energy expenditure relationship determined in an arm cranking exercise. The DEE of SSCI on active days did not differ from those of normal subjects. On inactive days, SSCI had significantly lower DEE than on active days and than normal subjects. In contrast, the mean 24-hr heart rates of SSCI on active days and inactive SSCI were significantly greater than those of normal subjects, suggesting that SSCI, particularly inactive SSCI, exhibited a slight degree of tachycardia when compared to normal subjects. On inactive days, the DEE was fairly independent of the level of spinal cord injury. However, on active days, there was a clear tendency for SSCI with a low lesion level to have a higher DEE. Even if a SSCI with a high lesion level engaged in active sports, his DEE was relatively small. This lower DEE was largely attributable to the smaller functional muscle mass due to the limitation of physical activity.     

Spinal cord injury-induced astrocyte migration and glial scar formation: effects of magnetic stimulation frequency

The effects of magnetic stimulation on spinal cord injury-induced migration of white matter astrocytes were studied using an established animal model. Ethidium bromide was injected into the dorsal spinal cord funiculus of adult Sprague-Dawley rats on the left side at T10-11. Animals then received 1.52 Tesla-pulsed magnetic stimulation for 5 min at different frequencies (0-20 Hz) for 14 consecutive days. Selected animals received the non-competitive MEK1/2 inhibitor U0126 (10 microM), prior to stimulation at 10 Hz. Lesion volumes were measured in hematoxylin/eosin-stained sections. Expression of glial fibrillary acidic protein (GFAP), microtubule associated protein-2 (MAP-2) and extra-cellular signal-regulated kinasel/2 (ERK1/2) near the epicenter of injury was examined by Western blotting with quantification using an image analysis system. Lesion volumes decreased and GFAP and p-ERK1/2 expression increased with increasing magnetic stimulation frequency (0-10 Hz). MAP-2 expression was not affected at any frequency. Pretreatment with U0126 reduced GFAP and ERK1/2 expression and increased lesion volumes in response to stimulation at 10 Hz. It is concluded that magnetic stimulation increases the migration of astrocytes to spinal cord lesions. Activation of the ERK1/2 signaling pathway is proposed to mediate astrocyte migration and glial scar formation in response to spinal cord injury.     

Ca(2+)/calmodulin-dependent protein kinase II is associated with pelvic pain of neurogenic cystitis

Interstitial cystitis/painful bladder syndrome is a chronic bladder inflammatory disease of unknown etiology that is often regarded as a neurogenic cystitis. Interstitial cystitis is associated with urothelial lesions, voiding dysfunction, and pain in the pelvic/perineal area. In this study, we used a murine neurogenic cystitis model to identify genes participating in the development of pelvic pain. Neurogenic cystitis was induced by the injection of Bartha's strain of pseudorabies virus (PRV) into the abductor caudalis dorsalis (tail base) muscle of female C57BL/6J mice. Mice infected with PRV developed progressive pelvic pain. The sacral spinal cord was harvested on postinfection days (PID) 2 and 4, and gene expression was analyzed by microarrays and confirmed by quantitative RT-PCR. On PID 2, the overall expression profile was similar to that of uninfected sacral spinal cord; by PID 4, there were substantial differences in expression of multiple functional classes of genes, especially inflammation. Analysis of pain-signaling pathways at the dorsal horn suggested that Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) contributes to neurogenic cystitis pelvic pain. Consistent with this, CaMKIIδ expression exhibited a mast cell-dependent increase in the sacral spinal cord at the mRNA level, and phospho-CaMKII immunoreactivity in the dorsal horn was increased on postinfection day (PID) 4 during PRV infection. Finally, intrathecal injection of the CaMKII inhibitor KN-93 attenuated the PRV pain response. These data suggest that CaMKII plays a functional role in pelvic pain due to neurogenic cystitis.     

Tachykinin release from rat spinal cord in vitro and in vivo in response to various stimuli

The aim of the present study was to establish an experimental model, previously used in cat, for studying tachykinin release from the rat spinal cord in vivo and to compare the results with those obtained in vitro. Stimulation with pulses of 40 mM potassium or 10 microM capsaicin in the spinal cord superfusion fluid increased the release of substance P (SP)- and neurokinin A (NKA)-like immunoreactivity (LI) both in vivo and in vitro. The amounts of SP-LI and NKA-LI released by potassium in vitro were 1.02 +/- 0.12 and 1.17 +/- 0.22 fmol/mg tissue, respectively. Also the ratio between the amounts released by two consecutive potassium stimulations were similar for SP-LI and NKA-LI. Reversed-phase high performance liquid chromatography of the NKA-LI released in vitro by potassium or capsaicin revealed a major immunoreactive component coeluting with synthetic NKA. Despite the use of highly sensitive radioimmunoassays, basal release of SP-LI and NKA-LI was found only in 9 of 31 in vivo experiments. In these, peripheral electrical stimulation of the sciatic nerves (50 Hz, 50 V and 0.05 ms or 10 Hz, 10 V and 5 ms) induced an increase of the SP-LI and NKA-LI levels in the superfusates. This increase persisted for more than 40 min after a 2 min stimulation. In most experiments, however, no SP-LI or NKA-LI could be detected in the superfusates, neither at basal conditions nor following electrical nerve stimulation. Similarly, no release of SP-LI could be detected in response to various noxious mechanical, thermal or chemical stimuli applied to the skin. The present results demonstrate that the superfused rat spinal cord may be used to study in vivo release of tachykinins in response to intense chemical stimulation of the entire spinal cord. However, the method seems to be less suitable for studies of tachykinin release in response to electrical activation engaging only a few spinal segments or in response to natural noxious stimuli. The results obtained in vitro suggest that SP and NKA are released in equimolar amounts from the spinal cord upon stimulation with potassium.     

Curvilinear Three-Dimensional Modeling of Spinal Curves with Dual Kriging

In spinal deformation studies, three-dimensional reconstruction of the spine is frequently represented as a curve in space fitted to the vertebral centroids. Conventional interpolation techniques such as splines, Bezier and the least squares method are limited since they cannot describe precisely the great variety of spinal morphologies. This article presents a more general technique called dual kriging, which includes two mathematical constituents (drift and covariance) to adjust the interpolated functions to spinal deformity better. The cross-validation technique was used to compare the parametric representations of spinal curves with different combinations of drift and covariance functions. Model validation was performed from a series of analytic curves reflecting typical scoliotic spines. Calculation of geometric torsion, a sensitive parameter, was done to evaluate the accuracy of the kriging models. The best model showed an absolute mean difference of 1.2 x 10(-5) (+/- 7.1 x 10(-5) ) mm(-1) between the analytical and estimated geometric torsions compared to 5.25 x 10(-3) (+/- 3.7 x 10(-2) ) mm(-1) for the commonly used least-squares Fourier series method, a significant improvement in spinal torsion evaluation.     

Pelvic kinematic method for determining vertical jump height

Sacral marker and pelvis reconstruction methods have been proposed to approximate total body center of mass during relatively low intensity gait and hopping tasks, but not during a maximum effort vertical jumping task. In this study, center of mass displacement was calculated using the pelvic kinematic method and compared with center of mass displacement using the ground-reaction force-impulse method, in experienced athletes (n = 13) performing restricted countermovement vertical jumps. Maximal vertical jumps were performed in a biomechanics laboratory, with data collected using an 8-camera motion analysis system and two force platforms. The pelvis center of mass was reconstructed from retro-reflective markers placed on the pelvis. Jump height was determined from the peak height of the pelvis center of mass minus the standing height. Strong linear relationships were observed between the pelvic kinematic and impulse methods (R2 = .86; p < .01). The pelvic kinematic method underestimated jump height versus the impulse method, however, the difference was small (CV = 4.34%). This investigation demonstrates concurrent validity for the pelvic kinematic method to determine vertical jump height.     

Ovarian blood flow responses to electroacupuncture stimulation depend on estrous cycle and on site and frequency of stimulation in anesthetized rats.

Electroacupuncture (EA) applied to the abdomen and hindlimb modulates the ovarian blood flow (OBF) response. The present study aimed to further elucidate the role of the site and the frequency of short-term EA stimulation and the influence of the estrous cycle on the OBF response using anesthetized rats. EA stimulation was applied to the abdominal or the hindlimb muscles at three different frequencies (2, 10, and 80 Hz) during the estrus or diestrus phase. Involvement of spinal and supraspinal reflexes in OBF responses to EA stimulation was investigated by spinal cord transection. Abdominal EA stimulation at 10 Hz increased the OBF response, whereas hindlimb EA stimulation at 10 Hz and abdominal and hindlimb stimulation at 80 Hz decreased the OBF response; 2-Hz EA caused no OBF response. The OBF response to abdominal EA was more pronounced in the estrus than the diestrus phase. The OBF response to abdominal and hindlimb EA stimulation at both 10 and 80 Hz was almost abolished, both after severance of the sympathetic nerves and after spinal cord transection. In conclusion, the OBF response to both abdominal and hindlimb EA stimulation was mediated as a reflex response via the ovarian sympathetic nerves, and the response was controlled via supraspinal pathways. Furthermore, the OBF response to segmental abdominal EA stimulation was frequency dependent and amplified in the estrous phase.     

Orexin-A modulates glutamatergic NMDA-dependent spinal reflex potentiation via inhibition of NR2B subunit

Glucose-sensitive neurons in the lateral hypothalamic area produce orexin-A (OxA) as well as orexin-B (OxB) and send their axons to the spinal dorsal horn, which predominantly expresses orexin receptor-1 (OX-1), showing a higher sensitivity to OxA. The purpose of the present study was to assess the effects of OxA on the induction of a novel form of activity-dependent reflex potentiation, spinal reflex potentiation (SRP), in the pelvic-urethral reflex activity. External urethra sphincter electromyogram in response to pelvic afferent nerve test stimulation (TS; 1/30 Hz) or repetitive stimulation (RS; 1 Hz) was recorded in anesthetized rats. TS evoked a baseline reflex activity, whereas RS produced SRP, which was abolished by intrathecal OxA (30 nM, 10 mul). Intrathecal SB-408124 (10 muM, 10 mul), an OX-1 antagonist, reversed the abolition on SRP caused by OxA. Although there is, so far, no NR2A- and NR2B-specific agonist available, N-methyl-d-aspartate (NMDA) reversed the abolition on the RS-induced SRP caused by the co-administration of OxA and Co-101244 (30 nM, 10 mul; an NMDA NR2B subunit antagonist), but it did not reverse the abolition by the co-administration of OxA and PPPA (300 nM, 10 mul; an NMDA NR2A subunit antagonist). In conclusion, the activation of descending orexinergic fibers may inhibit the repetitive afferent input-induced central sensitization of pelvic-urethral reflex activity and urethra hyperactivity, indicating that spinal orexinergic neural transmission may be a novel target for the treatment of patients with neuropathetic or postinflammatory pain of pelvic origin.     

Role of vasopressin V(₁A) receptor in the urethral closure reflex in rats

An enhanced urethral closure reflex via the spinal cord is related to urethral resistance elevation during increased abdominal pressure. However, with the exception of monoamines, neurotransmitters modulating this reflex are not understood. We investigated whether the vasopressin V(?A) receptor (V(?A)R) is involved in the urethral closure reflex in urethane-anesthetized female rats. V(?A)R mRNA was highly expressed among the vasopressin receptor family in the total RNA purified from lamina IX in the spinal cord L6-S1 segment. In situ hybridization analysis of the spinal L6-S1 segment confirmed that these positive signals from the V(?A)Rs were only detected in lamina IX. Intrathecally injected Arg?-vasopressin (AVP), an endogenous ligand, significantly increased urethral resistance during an intravesical pressure rise, and its effect was blocked by the V(?A)R antagonist. AVP did not increase urethral resistance in rats in which the pelvic nerves were transected bilaterally. Urethral closure reflex responses to the intravesical pressure rise increased by up to threefold compared with the baseline response after AVP administration in contrast to no increase by vehicle. In addition, intravenously and intrathecally injected V(?A)R antagonists decreased urethral resistance. These results suggest that V(?A)R stimulation in the spinal cord enhances the urethral closure reflex response, thereby increasing urethral resistance during an abdominal pressure rise and that V(?A)R plays a physiological role in preventing urine leakage.     

Effect of narcotic analgesics on excitatory transmission in the spinal cord]

As demonstrated on nonanesthetized curare-immobilized spinal cats morphine, promedol and fentanyl failed to alter the amplitude of induced potentials in the ventro-lateral columns of the lumbar spinal cord, evoked by a single or repetitive stimulation of the cutaneous or pelvic nerves. In some experiments the same drugs inhibited the nerurons of the posterior horns of the spinal cord activated by the nociceptive stimulation of the peripheral receptors in intraarterial administration of bradykinin. It is suggested that a spinal component was involved in the action of hypnotic analgetics.