L4-L5 Segments Research Articles

Spatial patterns of increased spinal cord membrane-bound protein kinase C and their relation to increases in 14C-2-deoxyglucose metabolic activity in rats with painful peripheral mononeuropathy.

1. Three-dimensional spatial patterns of changes in membrane-bound protein kinase C (PKC) were examined in the lumbar spinal cords (L1-L5) of rats with an experimental painful peripheral mononeuropathy. Painful peripheral mononeuropathy was produced by loosely ligating the rat's common sciatic nerve, resulting in chronic constrictive nerve injury (CCI). Changes in spinal cord membrane-bound PKC distribution were assayed by employing an established quantitative [3H]-phorbol-12,13-dibutyrate ([3H]PDBu) autoradiographic assay, which includes spinal cord sectioning, incubation of spinal cord sections with [3H]PDBu, production of autoradiographs, and computer-assisted image processing. 2. Sciatic nerve ligation induced demonstrable thermal hyperalgesia in response to radiant heat stimulation and spontaneous pain-related behaviors (such as lifting of the nerve-ligated hind paw) in CCI rats 3, 7, and 10 days after unilateral sciatic nerve ligation. 3. Consistent with behavioral changes, CCI rats examined 3 or 10 days after sciatic nerve ligation displayed a three-dimensional pattern of increased membrane-bound PKC in the lumbar spinal cord (L1-L5) strikingly different from that of sham-operated rats: in the dorsoventral dimension, reliable increases in membrane-bound PKC occurred mainly within spinal cord laminae I-IV and V-VI in CCI rats; in the ipsilateral-contralateral dimension, changes in membrane-bound PKC were seen on both sides of the spinal cord in CCI rats with reliably higher levels of membrane-bound PKC on the side ipsilateral than on the side contralateral to sciatic nerve ligation; in the rostrocaudal dimension, increases in membrane-bound PKC in the spinal cord dorsal horns of CCI rats extended from spinal segments L2-L5. 4. Both three-dimensional increases in spinal cord membrane-bound PKC and nociceptive behaviors (thermal hyperalgesia and spontaneous pain behaviors) in CCI rats were reliably reduced after three daily intrathecal treatments with 80 nmol GM1 ganglioside (a glycosphingolipid shown to prevent PKC translocation/activation), the first of which was given 1 h after sciatic nerve ligation. This reduction was seen 24 h but not 7 days after the last GM1 ganglioside treatment. 5. This three-dimensional increase in membrane-bound PKC in the spinal cord dorsal horn of CCI rats displayed high correlations with thermal hyperalgesia and with spontaneous pain-related behaviors in CCI rats observed both 3 and 10 days after sciatic nerve ligation. Similar correlations were observed between decreases in levels of membrane-bound PKC in the spinal cord dorsal horn and the attenuation of nociceptive behaviors in CCI rats after three daily intrathecal treatments with GM1 ganglioside.(ABSTRACT TRUNCATED AT 400 WORDS)

Neuronal responses to stimulation of the cervix, uterus, colon, and skin in the rat spinal cord.

1. Previous studies in the rat have shown that the hypogastric nerve conveys input from the cervix and uterus mainly to the T13-L3 segments of the spinal cord, whereas the pelvic nerve conveys input from the cervix and vaginal canal mainly to the L6-S2 segments. 2. To study the effects of this input, the dorsal horns of the T13-L1, L6-S2, and L4-L5 segments in 13 decerebrate, T10-spinalized, unanesthetized, and paralyzed adult female rats in estrus were searched for neurons responsive to gentle mechanical stimulation of the cervix. The 87 neurons found were then further tested for their responses to gentle mechanical stimulation of the skin and to distension of both uterine horns, distension of the colon, and shearing stimulation of the colon and vaginal canal. 3. Neurons responsive to cervix stimulation, primarily by excitation, were readily found in the ventral part of the dorsal horn in T13-L1 and throughout the dorsal horn in L6-S2. Cervix-responsive neurons were less readily found throughout the dorsal horn in L4-L5, where 25% were inhibited by the stimulation. All but one neuron had cutaneous receptive fields. 4. The 30 cervix-responsive neurons in T13-L1 had large bilateral cutaneous receptive fields covering the perineum and hind-limbs. Most (76%) also responded, primarily by excitation, to uterine distension, as well as to colonic stimulation (59%). More than half were activated by both types of stimulation. 5. The 33 cervix-responsive neurons in L6-S2 had cutaneous receptive fields in the same regions as those in T13-L1, but generally smaller, particularly for neurons in the dorsal part of the dorsal horn, many of whose receptive fields were confined to the perineum. The L6-S2 neurons also exhibited less convergent input from other visceral structures, particularly the uterus. Fewer neurons (42%) responded to uterine distension, mostly by being inhibited, whereas about the same proportion (51%) responded with excitation to colonic stimulation. Only 24% responded to both uterus and colon. 6. All 24 cervix-responsive neurons in medial L4-L5 had small cutaneous receptive fields on the toes, and the neurons received less convergent input from other visceral structures (25% from the uterus, 33% from the colon, 13% from both). 7. These results indicate the presence of an extensive system of neurons throughout the caudal spinal cord of the rat, concentrated in separated thoracolumbar and lumbosacral segments, that is concerned with input from the reproductive tract.(ABSTRACT TRUNCATED AT 400 WORDS)

Lumbar mobility in asymptomatic individuals.

A radiological study of angulatory and translational lumbar mobility and of lumbar scoliosis was performed on 56 persons aged 35-54 years who had no history of back pain. The measurements of mobility were based on extension-flexion views; the assessment of scoliosis was done using radiographs taken in the standing position. The results indicated that the largest range of angulatory motion occurred in the L5-S1 segment (mean, 17.3 degrees for women and 16.4 degrees for men). Five-millimeter translational motion was so common in the L3-L4 and L4-L5 segments, as was 4-mm in the L5-S1 segments, that these values cannot be considered with certainty as pathological. Ten subjects (18%) showed scoliosis of > or = 10 degrees. Although based on a small series, these results are a step toward a more objective and careful interpretation of extension-flexion and functional radiographs of low-back pain patients.

Changes in calcitonin gene-related peptide immunoreactivity in the rat dorsal horn following electrical stimulation of the sciatic nerve

Immunoreactive staining for calcitonin gene-related peptide (CGRP) in the rat superficial dorsal horn (L4-L5 segments) was examined following electrical stimulation of the sciatic nerve. Electrical stimulation for twenty minutes at an intensity to elicit both A and C fiber volleys resulted in a significant decrease in CGRP immunoreactivity in the medial two-thirds of the dorsal horn on the stimulated side as compared to the non-stimulated side of the spinal cord. The change was most pronounced in the medial area of the dorsal horn, with a 54% decrease in immunostaining density compared to the non-stimulated side. In contrast, when the sciatic nerve was stimulated for the same period at an intensity that stimulates only A fibers, there was no significant difference in the density of immunoreactive staining in the dorsal horn between the non-stimulated and stimulated sides of the spinal cord. These results suggest that activity in a specific population of primary afferent fibers causes a dramatic depletion of CGRP in the dorsal horn.

The Effects of Inversion Traction on Spinal Column Configuration, Heart Rate, Blood Pressure, and Perceived Discomfort

The therapeutic effectiveness of inversion traction has only recently come under investigation. The purpose of this study was to use noninvasive methods to determine traction, cardiovascular, and perceived effects of inversion. The Gravity Gym(R) and Gravity Boot(R) inversion systems were compared. Treatment order was randomized and 18 normal subjects between the ages of 22 and 31 were suspended in each inversion device for 7 minutes. A computerized method was used for assessing posture. Three-dimensional coordinates were determined for spinous processes C7 through L5 relative to the midpoint of a line drawn between posterior superior iliac spines (S2). Heart rate was palpated and blood pressure was recorded using a standard sphygmomanometer. Pre-, initial, late, and postinversion measurements were taken. Questionnaires administered following each inverted posture assessed levels of discomfort. One-way analysis of variance was conducted to test the significance of results (p < 0.05). Measurements for both systems revealed an increase in L5-S2 distance, a decrease in C7-T12 distance, and a decrease in depth of the thoracolumbar curves. Segments C7-S2, L 1 -S2, L 1 -L2, L3-L4, and L4-L5 were increased in length by the Gravity Gym but not the Gravity Boots. Heart rate decreased and blood pressure increased an average of 20 mm Hg for both systems as subjects were inverted. This pattern was observed throughout the inversion period. Upon return to stand, heart rate increased for both systems while blood pressure decreased only for the Gravity Boot system. Subjects indicated that the Gravity Gym was the more tolerable inversion system. lnversion can be an effective means of spinal traction but due to elevated blood pressure, inversion may be contraindicated for some patients.J Orthop Sports Phys Ther 1986;7(5):254-260.

The spinal distribution of sympathetic preganglionic and visceral primary afferent neurons that send axons into the hypogastric nerves of the cat.

The spinal distribution of sympathetic preganglionic neurons (PGN) and visceral primary afferent neurons sending axons into the hypogastric nerve of the cat has been studied with HRP tracing techniques. After application of HRP to the cat hypogastric nerve, labeled PGN were identified in segments L2-L5. Most of these neurons were oriented transversely and were divided approximately equally between two nuclei: the principal nucleus and the intercalated nucleus. Cells were distributed in clusters at 160-361-microns intervals along the length of the cord. Sensory neurons were labeled in dorsal root ganglia from T12 to L5. Central axons of these visceral afferents were observed in the medial half of Lissauer's tract from T13 to L7. Afferent axon collaterals extended through lamina I on both sides of the dorsal horn but were most prominent on the lateral side, where they continued into lateral lamina V and VII, often overlapping the dorsal dendrites of PGN in this region. Labeled afferent projections exhibited a periodic distribution in lamina I with clusters of axons occurring at 235-343-microns intervals in the rostrocaudal axis. The central projection of hypogastric nerve primary afferents was qualitatively similar to the distribution of visceral afferent projections at other levels of the spinal cord.

Lumbar spine loading during half-squat exercises

Evaluation of the compressive load acting on the lumbar spine (L3-L4) during half-squat exercises executed with a barbell resting on the subject's shoulders was undertaken. The kinematics of the upper body segments of two male and two female subjects as well as the barbell were described using data obtained by means of an optoelectronic system (CoSTEL). L3-L4 compressive load was calculated using a model of the anatomy of the trunk musculoskeletal system. Filtered surface electromyographic trunk flexor recordings from the obliquus externus and rectus abdominis and trunk extensor erectores spinae muscles as well as measurement of the ground reaction forces were also carried out for predicted result validation. During half-squat exercises with barbell loads in the range 0.8 to 1.6 times body weight the compressive loads on the L3-L4 segment vary between 6 and 10 times body weight. Erectores spinae contraction force was predicted to be between 30 and 50% of the relevant maximal isometric force. The magnitude of trunk flexion was found to be the variable which influenced most spinal compression load.

The afferent and sympathetic components of the lumbar spinal outflow to the colon and pelvic organs in the cat. II. The lumbar splanchnic nerves.

The cell bodies of the lumbar sensory and sympathetic pre- and postganglionic neurons that project to the inferior mesenteric ganglion in the lumbar splanchnic nerves of the cat have been labeled retrogradely with horseradish peroxidase applied to the central end of their cut axons near the inferior mesenteric ganglion. The numbers, segmental distribution, location, and size of these labeled somata have been determined quantitatively. After all the lumbar splanchnic nerves on one side of an animal were labeled, most labeled cell bodies were situated ipsilaterally in dorsal root ganglia, ganglia of the lumbar sympathetic trunk, and spinal cord segments L2-L5, with the maximum numbers in L3 and L4. A few labeled somata lay contralaterally or rostral to L2. After labeling of only one lumbar splanchnic nerve, the majority of cell bodies were found in the labeled segment, but a few were also present up to three segments rostral or caudal. These variations could always be attributed to extraspinal connections usually via the lumbar sympathetic trunk. Cross-sectional areas of labeled afferent somata were small relative to those of the entire population of dorsal root ganglion cells. Preganglionic cell bodies were labeled in the intermediate gray matter extending from its lateral border ventrolaterally across to the central canal. Two regions of high density were observed: one laterally just medial to the edge of the white matter and the other lateral to the central canal. The dorsolateral group lay somewhat medial and caudal to the usual limits of the intermediolateral column. Labeled preganglionic neurons were on the average larger than the unlabeled cells in the inferior mesenteric ganglion, with the group lying medially being larger than those that were laterally positioned. From the data, it is estimated that about 4,600 afferent axons, about 4,600 preganglionic axons, and about 2,800 postganglionic axons travel in the lumbar splanchnic nerves to the inferior mesenteric ganglion of the cat.

Histochemical changes of substance P, FRAP, serotonin and succinic dehydrogenase in the spinal cord of rats with adjuvant arthritis

Various histochemical changes were found in spinal segments L4–L5 of rats with adjuvant arthritis, predominantly 30 days after inoculation. A slight to marked increase of substance P immunoreactivity occured in laminae I, II and X. FRAP activity was enhanced in lamina II. Serotonin immunoreactivity was heavier in laminae I, VIII and IX in a few animals. The intensity of the histoenzymological reaction for succinic dehydrogenase increased in certain laminae VIII and X neurons. At day 15 of the disease the increase of substance P and FRAP activities was chiefly restricted to the medial portion of the superficial dorsal horn. There was a significant positive correlation between the scratching behaviour of arthritic rats and the substance P immunoreactivity in laminae X and I. If one accepts that scratching is pain-related, the data are consistent with a possible role of substance P in the chronic pain associated with adjuvant arthritis. They leave undetermined the significance of the other histochemical changes.

Inhibition of dorsal spinocerebellar tract cells by interneurones in upper and lower lumbar segments in the cat.

The topographical distribution of interneurones mediating disynaptic inhibition of dorsal spinocerebellar tract (d.s.c.t.) cells from group I muscle afferents in the cat was investigated using both physiological and morphological techniques. Lesions of either the dorsal funiculi or of the lateral and ventral funiculi were made between L4 and L5 segments in two groups of cats. I.p.s.p.s. evoked from group I afferents were seen after both these lesions, showing that the i.p.s.p.s were evoked by interneurones located more caudally as well as by interneurones in the same segments as Clarke's column. Distribution of the caudally located interneurones in the lower lumbar segments was investigated after marking these interneurones with horseradish peroxidase retrogradely transported from Clarke's column. The horseradish peroxidase was injected along L3-L4 segments of Clarke's column in two cats with transected dorsal funiculi. The marked cells were found in L5, L6, L7 and S1 segments, with a highest density in L6 and L7. They were seen in laminae V, VI and VII. A search was made for interneurones which could be antidromically invaded following stimuli applied in Clarke's column and were monosynaptically excited by group I afferents. Such interneurones were found at locations corresponding to laminae V-VI of Rexed. The latencies of antidromic and orthodromic responses were within ranges allowing them to mediate disynaptic inhibition of d.s.c.t. cells.

Load-bearing characteristics of lumbar facets in normal and surgically altered spinal segments.

An in-vitro experimental study was carried out to measure the induced loading on human lumbar facets due to varying amounts of compressive axial load. Testing was done on L2-L3 and L4-L5 spinal motion segments obtained from cadavers at autopsy. The compressive loading was applied to the spinal specimens in first a neutral position and then in an extended position. The motion segments were tested in a normal state and after facetectomy of the left facet. Contact pressures were quantified using pressure-sensitive film. This film was inserted between the articulating surfaces of the two facet joints prior to placing axial loads on the motion segments. In addition to recording pressure, the film was also used to quantify contact area. This provided sufficient information to compute the total facet loadings for all cases studied. Results of this study show how facet loads, peak pressures and contact areas change with respect to the various loads, positions and states studied. In particular this study shows that the absolute facet loads remain relatively constant with increasing segmental compressive loads such that the facet load expressed as a percent of load applied to the segment decreases with increasing axial loads. It also shows that the contact area moves cranially at L2-L3 and caudally at L4-L5 with increasing loads in extension. Furthermore, this study indicates that the load on the remaining facet is reduced substantially after a facetectomy although peak pressure increases. Finally, this study demonstrates the substantial difference in facet loadings between L2-L3 segments and L4-L5 segments.

Enzyme activities in the anterior horn of spinal cord after β,β-iminodipropionitrile

Four enzymes, representative for different steps of carbohydrate metabolism, were studied in L3–L4 segments of rat spinal cord. The ventral horns were dissected from frozen dried sections and the enzyme activities were measured microfluorometrically by their quantitative reduction of NADP. In control rats the enzyme activities remained constant during the growth of the animals from 4 to 16 weeks of age. In rats which had neurological symptoms and axonal lesions after feeding of β,β-iminodipropionitrile, the activity of glucose-6-phosphate dehydrogenase was constantly increased during the same age period, while other enzymes were not. These findings are considered in relation to the findings of other investigators that drugs, dehydration, nerve transection, and other procedures affect the same enzymes.