Epimedium flavonoids ameliorate experimental autoimmune encephalomyelitis in rats by modulating neuroinflammatory and neurotrophic responses.

The present study was designed to determine whether epimedium flavonoids (EF) had effect on the development of experimental autoimmune encephalomyelitis (EAE) in rats and to elucidate its underlying mechanisms. EAE was induced by immunization of adult female Lewis rats with partially purified myelin basic protein (MBP) prepared from guinea-pig spinal cord homogenate. EF was administrated intragastrically once a day after immunization until day 14 post immunization (p.i.). Histopathological staining, enzyme-linked immunosorbent assay (ELISA), biochemical methods and western blotting approaches were used to evaluate the disease incidence and severity, neuroinflammatory and neurotrophic response in the central nervous system (CNS). Intragastrical administration of EF (20 and 60 mg/kg) significantly reduced clinical score of neurological deficit in EAE rats; alleviated demyelination and inflammatory infiltration; and inhibited astrocytes activation, production of proinflammatory molecules such as interleukin-1ß (IL-1ß), tumour necrosis factor-α (TNF-α), nitric oxide (NO) and nuclear transcription factor (NF-κB) in the spinal cord of EAE rats. Treatment with EF also enhanced the expression of 2', 3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) and nerve growth factor (NGF), increased the number of oligodendrocytes and protected the ultrastructure of myelin sheaths and axons in the spinal cord of EAE rats. Our results showed that EF inhibited the development of partial MBP-induced EAE in rats. This effect involved reducing neuroinflammation and enhancing myelination and neurotrophins and our findings suggest that EF may be useful for the treatment of multiple sclerosis.

Effect of Cerebellohypothalamic Glutamatergic Projections on Immune Function.

Our previous work has shown that lesions of the cerebellar interposed nuclei (IN) suppress immune cell functions. Since there is no direct structural connection between the cerebellum and immune system, we explored the pathway mediating the cerebellar immunomodulation at the profile of cerebellohypothalamic projections to understand this modulation. Anterograde tracing of nerve tracts from the cerebellar IN to the hypothalamus was conducted by injection of anterograde tracer dextran-texas red (dextran-TR) in the cerebellar IN. We observed that dextran-TR-labeled nerve fibers, which were sent by cerebellar IN neurons, traveled in the superior cerebellar peduncle (SCP), crossed in SCP decussation, and entered the hypothalamus. In the hypothalamus, the fibers mostly terminated in the lateral hypothalamic area (LHA). Retrograde tracing by injection of retrograde tracer fluoro-ruby (FR) in the LHA found that FR-labeled neurons appeared in contralateral cerebellar IN. Fluorescent immunohistochemistry for glutamate revealed that many of the FR-labeled neurons were glutamatergic. These results demonstrate a direct glutamatergic projection from the cerebellar IN to the LHA. Reduction of the cerebellohypothalamic glutamatergic projections by microinjection of 6-diazo-5-oxo- L-norleucine (DON), an inhibitor of glutaminase for glutamate synthesis, in bilateral cerebellar IN led to suppression of peripheral lymphocyte number, T lymphocyte proliferation, and serum anti-sheep red blood cell IgM level. But the DON injection in the cerebellar cortex that does not send axons to the hypothalamus did not significantly alter all the immune parameters. These findings suggest that cerebellohypothalamic glutamatergic projection modulates immune function, and that via the pathway, the cerebellum implements its immunoregulatory effect.

New drug therapies for multiple sclerosis.

PURPOSE OF REVIEW: Multiple sclerosis (MS) is an autoimmune and inflammatory disease of the central nervous system (CNS) that causes neurological disability in young adults and that to date has no cure. Until now, expensive and only partially efficacious therapies have become available. For this reason, researchers, clinicians and pharmaceutical companies are currently investigating new drugs for the treatment of MS. Here, we review the most recent data on drug candidates for MS. RECENT FINDINGS: In the preclinical phase, such drug candidates have shown a beneficial effect on the onset of experimental autoimmune encephalomyelitis (microtubule-stabilizing drugs, MS14, Lithium, GEMSP...), a decrease in CNS cell infiltrates (recombinant T cell receptor ligand, lovastatin-rolipram, ribavirin, GEMSP...), prevention of demyelination (lovastatin-rolipram, calpain inhibitor, lithium...); and a reduction of axonal loss (phenytoin, lovastatin-rolipram, calpain inhibitor). In clinical trials, drug candidates against MS have shown safety (rituximab, ustekinumab, intravenous immunoglobulin, laquinimod, BHT-3009, fumarate, chaperonin 10, GEMSP...), an improvement of gadolinium-enhanced lesions (protiramer, fingolimod, laquinimod, BHT-3009, fumarate, daclizumab...), and an improvement of the relapse rate (fingolimod, fumarate...). SUMMARY: Future research into MS should focus on a combination of therapies and on the development of drugs directed against the remitting and progressive phases of the disease. In this sense, MS is a very complex multifactorial disease that requires treatment able to cover all the aspects of MS and not only the anti-inflammatory aspect.

Localization and regulation of low affinity nerve growth factor receptor expression in the rat olfactory system during development and regeneration.

Nerve growth factor (NGF), a classic neurotrophic factor, promotes neuronal survival, maintenance, regeneration and differentiation in the peripheral nervous system and parts of the central nervous system. NGF activity is mediated by cell surface bound receptors including the low affinity NGF receptor (LNGFr) which is expressed by some peripheral and central neurons and is present on peripheral nerve Schwann cells during development and regeneration. The olfactory system is a useful model for the study of the role of LNGFr in neuronal development and regeneration. The growth of olfactory axons into the brain begins in the embryo and continues through the first few postnatal weeks. In mature animals there is persistent turnover and generation of olfactory receptor neurons (ORNs) and continuous growth of new axons into the olfactory bulb. These new axons grow along the preexisting olfactory pathway. In the mature olfactory system, LNGFr has been observed in the glomerular layer of the olfactory bulb, the target of ORNs. However, neither the cellular localization nor the developmental expression of LNGFr has been characterized. Here, we tested the hypothesis that LNGFr expression is developmentally regulated in the olfactory nerve and is reinduced following injury to the mature olfactory nerve. LNGFr-immunoreactivity (IR) was first observed in the olfactory mucosa at embryonic day (E)13 and in the olfactory nerve at E14. LNGFr-IR increased in the nerve during embryonic development, began to decrease at around postnatal day (P)5 and was scarcely detectable in normal adults. The staining pattern suggests that LNGFr is located on the olfactory nerve Schwann cells. Streaks of LNGFr-IR were present in the adult olfactory nerve. We reasoned that these streaks might represent transient reexpression of LNGFr associated with normal olfactory neuron turnover and replacement. Consistent with this hypothesis, LNGFr was robustly reexpressed in the adult olfactory nerve following lesion of the olfactory epithelium. Starting late in development (E21) and in the adult, LNGFr-IR was also observed on fibers in deep layers of the olfactory bulb. LNGFr-IR was also observed in neurons of the nucleus of the diagonal band (NDB) in the basal forebrain. NDB is the sole source of cholinergic afferents of the olfactory bulb. Thus, we tested the hypothesis that LNGFr in the deep layers of the olfactory bulb is located on NDB axons by making lesions of NDB. Following the lesion, LNGFr-IR disappeared in the deep layers of the olfactory bulb but remained in the glomerular layer.(ABSTRACT TRUNCATED AT 400 WORDS)

Postnatal development of parvalbumin immunoreactivity in axon terminals of basket and chandelier neurons in monkey neocortex.

1. Two classes of GABAergic inhibitory interneurons, chandelier and basket cells, are known regulators of pyramidal neurons. Parvalbumin (PV) a calcium binding protein, has been shown to be a marker for axon terminals of subpopulations of these interneurons. 2. Immunohistochemical methods were used in this study to examine changes in the distribution of PV-immunoreactive (IR) chandelier and basket axon terminals during postnatal development of monkey neocortex. 3. Our results indicate a differential effect of postnatal development on PV-IR axon terminals of chandelier and basket neurons that is region-specific. 4. The differential regional, laminar and developmental pattern of PV-IR axon terminals of chandelier and basket cells may provide insight into the functional role of these classes of inhibitory neurons in primate neocortex.

Development of brainstem and cerebellar projections to the diencephalon with notes on thalamocortical projections: studies in the North American opossum.

The North American opossum is born in a very immature state, 12 days after conception, and climbs into an external pouch where it remains attached to a nipple for an extended period of time. We have taken advantage of the opossum's embryology to study the development of brainstem and cerebellar projections to the diencephalon as well as the timing of diencephalic projections to somatosensory motor areas of neocortex. The techniques employed included immunocytochemistry for serotonin, the retrograde and orthograde transport of wheat germ agglutinin conjugated to horseradish peroxidase, and the selective impregnation of degenerating axons. Our results suggest that serotoninergic axons, presumably from the dorsal raphe and superior central nuclei, are present in the diencephalon at birth. Axons from the bulbar reticular formation, the vestibular complex, the trigeminal sensory nuclei, and the dorsal column nuclei reach at least mesencephalic (and probably diencephalic) levels by postnatal day (PND) 3, whereas those from the cerebellar nuclei may not grow into comparable levels until PND 5. The dorsal column and cerebellar nuclei innervate the ventral nuclei of the thalamus by estimated postnatal day (EPND) 17 and all of the diencephalic nuclei supplied in the adult animal by EPND 26. Diencephalic axons enter ventrolateral (face) areas of presumptive somatosensory motor cortex by PND 12, but do not reach dorsomedial (limb) regions until EPND 21. At both ages, diencephalic axons are limited to the cortical subplate and marginal zone; they do not innervate an identifiable internal granular layer until considerably later. Our results suggest that axons from the brainstem and cerebellum grow into the diencephalon early in development, but that they do not influence the cerebral cortex until relatively late. When the results of the present study are compared with those reported previously on the development of ascending spinal (Martin et al., '83) and corticofugal (Martin et al., '80; Cabana and Martin, '85b,c) projections, it appears that specific components of major somatosensory and motor circuits develop according to different timetables.

A monoclonal antibody to limbic system neurons.

A monoclonal antibody produced against hippocampal cell membranes labeled the surface of neurons in the rat limbic system. With a few exceptions, all nonlimbic components were unstained. This specific distribution of immunopositive neurons provides strong evidence of molecular specificity among functionally related neurons in the mammalian brain and supports the concept of a limbic system.

Distribution of immunoreactive somatostatin in the primate hypothalamus.

Immunocytochemical methods were used to compare the localization of somatostatin (SRIF) in the human and rhesus monkey hypothalamus. The distribution of SRIF-containing cell bodies and fibers is similar in the two species. Perikarya are located predominantly in the periventricular region and to a lesser extent in the ventromedial nucleus. Fibers occur in dense clusters within the periventricular region, ventromedial nucleus, arcuate nucleus, median eminence, and pericommissural area of both species. Analysis of serial sections suggests that fibers originate from cells in the periventricular region, extend ventrally through the ventromedial and arcuate nuclei to terminate around the portal vessels of the infundibular stalk, and thereby participate in the regulation of anterior pituitary function. Somatostatinergic fibers are also found surrounding non-immunoreactive perikarya in the ventromedial nucleus and periventricular region of both primates. This arrangement may support somatostatin's postulated role as a neurotransmitter or neuromodulator. The strong similarity between the localization of hypothalamic SRIF in the human and rhesus monkey supports the use of the rhesus monkey as a model for the study of somatostatin as a neuroendocrine regulatory in the human.