Gulgun Sengul

Vertebral landmarks for the identification of spinal cord segments in the mouse

Accurate identification of spinal cord segments in relation to vertebral landmarks is essential to surgery aimed at experimental spinal cord injury. We have analyzed a complete series of high-resolution magnetic resonance (MR) images from the mouse spine in order to delineate the boundaries of spinal cord segments in relation to vertebral landmarks. The resulting atlas can be used to plan experimental approaches that require the accurate identification of a target spinal cord segment.

Organization of brainstem nuclei

This chapter presents a classification of the human brainstem structures, including most of neuronal cell groups in the human brainstem. Human homologs of nuclei identified in the brainstem of other mammals are also described as are attempts to extend to the human the overall organizational schemata that have been proposed for the brainstem of other mammalian species. A glaring structural similarity of brainstem across species is reflected by an impressive number of homologies recognized between the brainstem of the human and that of other animals. While it can be hypothesized that there are human homologs to nearly every nucleus identified in the rat brainstem, species differences and even strain differences occur, and this compels us to establish homologies not by extrapolation but by direct observation of human tissue. Functional mechanisms of the human brainstem, on the other hand, remain hidden in connections, chemoarchitecture, and physiology of neuronal groups. These characteristics are emerging from encouraging non-invasive imaging studies and expanding creative application of chemical analysis of the human brain.

The effect of hyperbaric oxygen on neuroregeneration following acute thoracic spinal cord injury

AIMS Although hyperbaric oxygen (HBO) treatment following spinal cord injury (SCI) have been studied in terms of neurological function and tissue histology, there is a limited number studies on spinal cord tissue enzyme levels. MAIN METHODS The effect of HBO treatment in SCI was investigated by measuring superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), nitric oxide synthase (NOS) and nitric oxide (NO) activity in the injured tissue. SCI was induced by applying an aneurysm clip extradurally at the level of T9-T11 vertebrae. Preoperative HBO (preopHBO) treatment was applied for 5days and postoperative HBO (postopHBO) for 7days. KEY FINDINGS In the preopHBO group, a significant decrease was observed in NOS and NO compared to the SCI group. There was a decrease in SOD, NOS and NO in the postopHBO group when compared to the SCI group. In the pre-postHBO group SOD, GPx, NOS and NO decreased significantly. There was a decrease in SOD in postopHBO compared to preopHBO. In the prepostopHBO, SOD decreased significantly compared to that in the preopHBO group. The prepostopHBO presented a significant decrease in GPx compared to postopHBO (p<0.05 for all parameters). No significant difference was observed for catalase for all groups. Significant improvement was found in BBB scores for both postopHBO and prepostHBO groups when compared to the SCI group (p<0.05). SIGNIFICANCE HBO treatment was found to be beneficial following SCI in terms of biochemical parameters and functional recovery in the postoperative period.

Musculotopic organization of the motor neurons supplying forelimb and shoulder girdle muscles in the mouse

We identified the motor neurons (MNs) supplying the shoulder girdle and forelimb muscles in the C57BL/6J mouse spinal cord using Fluoro-Gold retrograde tracer injections. In spinal cord transverse sections from C2 to T2, we observed two MN columns (medial and lateral) both with ventral and dorsal subdivisions. The dorsolateral column consisted of the biceps brachii, forearm extensors, forearm flexors, and hand MNs, and the ventrolateral column consisted of the latissimus dorsi, trapezius, teres major, deltoid, and triceps MNs. The supraspinatus muscle MNs were located in the dorsomedial column, and pectoralis major and serratus anterior MNs were located in the ventromedial columns. MNs of the dorsolateral column innervated the biceps brachii in mid-C4 to mid-C7, forearm extensors in caudal C4 to mid-T1, forearm flexors in rostral C5 to mid-T1, and hand muscles in mid-C8 to mid-T2 segments. The MNs innervating the trapezius were located in mid-C2 to mid-C4, triceps brachii in mid-C6 to rostral T1, deltoid in rostral C4 to mid-C6, teres major in rostral C5 to mid-C8, and latissimus dorsi in mid-C5 to caudal C8. In addition, MNs innervating the supraspinatus were located from rostral C4 to caudal C8, pectoralis major in mid-C6 to mid-T2, and serratus anterior in rostral C5 to caudal C7/rostral C8 segments. While the musculotopic pattern of MN groups was very similar to that documented for other species, we found differences in the position and cranio-caudal extent of some MN pools compared with previous reports. The identification of mouse forelimb MNs can serve as an anatomical reference for studying degenerative MN diseases, spinal cord injury, and developmental gene expression.

The spinal precerebellar nuclei: calcium binding proteins and gene expression profile in the mouse.

We have localized the spinocerebellar neuron groups in C57BL/6J mice by injecting the retrograde neuronal tracer Fluoro-Gold into the cerebellum and examined the distribution of SMI 32 and the calcium-binding proteins (CBPs), calbindin-D-28K (Cb), calretinin (Cr), and parvalbumin (Pv) in the spinal precerebellar nuclei. The spinal precerebellar neuron clusters identified were the dorsal nucleus, central cervical nucleus, lumbar border precerebellar nucleus, lumbar precerebellar nucleus, and sacral precerebellar nucleus. Some dispersed neurons in the deep dorsal horn and spinal laminae 6-8 also projected to the cerebellum. Cb, Cr, Pv, and SMI 32 were present in all major spinal precerebellar nuclei and Pv was the most commonly observed CBP. A number of genes expressed in hindbrain precerebellar nuclei are also expressed in spinal precerebellar groups, but there were some differences in gene expression profile between the different spinal precerebellar nuclei, pointing to functional diversity amongst them.

Cytoarchitecture of the Spinal Cord of the Postnatal (P4) Mouse

Interpretation of the new wealth of gene expression and molecular mechanisms in the developing mouse spinal cord requires an accurate anatomical base on which data can be mapped. Therefore, we have assembled a spinal cord atlas of the P4 mouse to facilitate direct comparison with the adult specimens and to contribute to studies of the development of the mouse spinal cord. This study presents the anatomy of the spinal cord of the P4 C57Bl/6J mouse using Nissl and acetyl cholinesterase‐stained sections. It includes a detailed map of the laminar organization of selected spinal cord segments and a description of named cell groups of the spinal cord such as the central cervical (CeCv), lateral spinal nucleus, lateral cervical, and dorsal nuclei. The motor neuron groups have also been identified according to the muscle groups they are likely to supply. General features of Rexeds laminae of the P4 spinal cord showed similarities to that of the adult (P56). However, certain differences were observed with regard to the extent of laminae and location of certain cell groups, such as the dorsal nucleus having a more dispersed structure and a more ventral and medial position or the CeCv being located in the medial part of lamina 5 in contrast to the adult where it is located in lamina 7. Motor neuron pools appeared to be more tightly packed in the P4 spinal cord. The dorsal horn was relatively larger and there was more white matter in the P56 spinal cord. Anat Rec, 2012.

Spinal cord projections to the cerebellum in the mouse

The projections from the spinal cord to the cerebellar cortex were studied using retrograde neuronal tracers. Thus far, no study has shown the detailed topographic mapping of the projections from the spinal neuron clusters to the cerebellar cortex regions for experimental animals, and there are no studies for the mouse. Tracers Fluoro-Gold and cholera toxin B were injected into circumscribed regions of the cerebellar cortex, and retrogradely labeled spinal cord neurons were mapped throughout the spinal cord. Spinal projections to the cerebellar cortex were mainly from five neuronal columns—central cervical nucleus, dorsal nucleus, lumbar and sacral precerebellar nuclei, and lumbar border precerebellar cells—and from scattered neurons located in the deep dorsal horn and laminae 6–8. The spinocerebellar projections to the cortex were mainly to the vermis. All five precerebellar cell columns projected to both anterior and posterior parts of the cerebellar cortex. Results of this study provide an amendment to the known rostral and caudal boundaries of the precerebellar cell columns in the mouse. Scattered precerebellar neurons in the most caudal deep dorsal horn and laminae 6–8 projected exclusively to the anterior part of the cerebellar cortex. In this study, no labeled spinal neurons were found to project to the lobules 6 and 7 of the cerebellar vermis, the flocculus, and the paraflocculus. Spinocerebellar neurons were located bilaterally, but the majority of the projections were contralateral for the central cervical nucleus, and ipsilateral for the remaining spinal precerebellar neuronal clusters.

The spinal cord of the common marmoset (Callithrix jacchus).

The marmoset spinal cord possesses all the characteristic features of a typical mammalian spinal cord, but with some interesting variation in the levels of origin of the limb nerves. In our study Nissl and ChAT sections of the each segment of the spinal cord in two marmosets (Ma5 and Ma8), we found that the spinal cord can be functionally and anatomically divided into six regions: the prebrachial region (C1 to C3); the brachial region (C4 to C8) - segments supplying the upper limb; the post-brachial region (T1 to L1) - containing the sympathetic outflow, and supplying the hypaxial muscles of the body wall; the crural region (L2 to L5) - segments supplying the lower limb; the postcrural region (L6) - containing the parasympathetic outflow; and the caudal region (L7 to Co4) - supplying the tail. In the rat, mouse, and rhesus monkey, the prebrachial region consists of segments C1 to C4 (with the phrenic nucleus located at the C4 segment), and the brachial region extends from C5 to T1 inclusive. The prefixing of the upper limb outflow in these two marmosets mirrors the finding in the literature that a large C4 contribution to the brachial plexus is common in humans.

Spinal Cord: Regional Anatomy, Cytoarchitecture and Chemoarchitecture

The spinal cord is composed of gray matter and white matter. The white matter is composed mostly of longitudinally running axons and also glial cells. The gray matter is composed of nine distinct cellular layers, or laminae, organized from dorsal to ventral, with the remaining area (area 10) surrounding the central canal. This lamination pattern was first defined by Rexed (1952, 1954) in the cat. Each lamina possesses different physiological, histochemical, and cytoarchitectonic characteristics. Laminae 1-6 constitute the dorsal horn, lamina 7 is the intermediate gray matter, laminae 8 and 9 constitute the ventral horn, and area 10 corresponds to the area around the central canal. There are also several named cell groups (nuclei) within the spinal cord. Most of these are located within the numbered gray laminae of the spinal cord. These are the dorsal nucleus (Clarkes column), the internal basilar nucleus, the central cervical nucleus, the intermediolateral cell column, the intermediomedial nucleus, the lumbar and dorsal commissural nuclei, the sacral precerebellar nucleus, and the sacral parasympathetic nucleus. There are also two significant neuronal groups in the white matter of the lateral columns of the spinal cord, the lateral cervical and lateral spinal nuclei.

NADPH-d and Fos reactivity in the rat spinal cord following experimental spinal cord injury and embryonic neural stem cell transplantation

AIMS The aim of this study is to determine the role of nitric oxide (NO) in neuropathic pain and the effect of embryonic neural stem cell (ENSC) transplantation on NO content in rat spinal cord neurons following spinal cord injury (SCI). MAIN METHODS Ninety adult male Sprague-Dawley rats were divided into 3 groups (n=30, each): control (laminectomy), SCI (hemisection at T12-T13 segments) and SCI+ENSC. Each group was further divided into sub-groups (n=5 each) based on the treatment substance (L-NAME, 75 mg/kg/i.p.; L-arginine, 225 mg/kg/i.p.; physiological saline, SF) and duration (2h for acute and 28 days for chronic groups). Pain was assessed by tail flick and Randall-Selitto tests. Fos immunohistochemistry and NADPH-d histochemistry were performed in segments 2 cm rostral and caudal to SCI. KEY FINDINGS Tail-flick latency time increased in both acute and chronic L-NAME groups and increased in acute and decreased in chronic L-arginine groups. The number of Fos (+) neurons decreased in acute and chronic L-NAME and decreased in acute L-arginine groups. Following ENSC, Fos (+) neurons did not change in acute L-NAME but decreased in the chronic L-NAME groups, and decreased in both acute and chronic L-arginine groups. NADPH-d (+) neurons decreased in acute L-NAME and increased in L-arginine groups with and without ENSC transplantation. SIGNIFICANCE This study confirms the role of NO in neuropathic pain and shows an improvement following ENSC transplantation in the acute phase, observed as a decrease in Fos(+) and NADPH-d (+) neurons in spinal cord segments rostral and caudal to injury.