Journal of Neurobiology 

About: Journal of Neurobiology is an academic journal. The journal publishes majorly in the area(s): Neuron & Axon. It has an ISSN identifier of 0022-3034. Over the lifetime, 2919 publications have been published receiving 165284 citations.

Excitotoxic cell death

Abstract: Excitotoxicity refers to the ability of glutamate or related excitatory amino acids to mediate the death of central neurons under certain conditions, for example, after intense exposure. Such excitotoxic neuronal death may contribute to the pathogenesis of brain or spinal cord injury associated with several human disease states. Excitotoxicity has substantial cellular specificity and, in most cases, is mediated by glutamate receptors. On average, NMDA receptors activation may be able to trigger lethal injury more rapidly than AMPA or kainate receptor activation, perhaps reflecting a greater ability to induce calcium influx and subsequent cellular calcium overload. It is possible that excitotoxic death may share some mechanisms with other forms of neuronal death.

The Trk family of neurotrophin receptors.

Abstract: Accumulating evidence indicates that the Trk family of tyrosine protein kinase receptors, Trk (also known as TrkA), TrkB, and TrkC, are responsible for mediating the trophic effects of the NGF family of neurotrophins. Nerve growth factor (NGF) specifically recognizes Trk, a receptor identified in all major NGF targets, including sympathetic, trigeminal, and dorsal root ganglia as well as in cholinergic neurons of the basal forebrain and the striatum. Brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4) specifically activate the TrkB tyrosine kinase receptor. trkB transcripts encoding this receptor are found throughout multiple structures of the central and peripheral nervous system. Neurotrophin-3 (NT-3) primarily activates the TrkC tyrosine protein kinases, four related isoforms encoded by alternative splicing of trkC, a gene also widely expressed throughout the mammalian nervous system. Unlike the other neurotrophins, NT-3 appears to be somewhat promiscuous since it can activate Trk and TrkB kinase receptors, at least in certain cell systems. The trkB and trkC genes also encode noncatalytic neurotrophin receptor isoforms of an as yet, unknown function. Recently, strains of mice lacking each of these tyrosine kinase receptors have been generated. Preliminary characterization of these mutant mice has provided significant information regarding the role of these receptors in the ontogeny of the mammalian nervous system. For instance, mice deficient for Trk receptors lack most sympathetic neurons and do not display nociceptive and temperature sensations, two defects likely to result from severe neuronal cell loss in their trigeminal and dorsal root ganglia. Mice lacking TrkB tyrosine kinase receptors die postnatally due to their inability to intake food. Neuron cell loss in their trigeminal, nodose and petrosal sensory ganglia as well as in the facial motor nucleus are likely to contribute to this phenotype. Finally, TrkC-deficient mice display strikingly abnormal movements consistent with loss of proprioception, a defect likely to be a consequence of the complete loss of Ia muscle afferents observed in this mutant mice.

Ciliary neurotrophic factor

Abstract: The present invention relates to nucleic acid sequences encoding ciliary neurotrophic factor (CNTF) and to the proteins, peptides, and derivatives produced therefrom. In various embodiments of the invention, the nucleic acid sequences, proteins, and peptides of the invention may be used in the treatment of a variety of neurological diseases and disorders, including Alzheimer's disease. In a specific embodiment of the invention, CNTF may be used to support the growth of spinal cord neurons, thereby providing a method of treating spinal cord damage caused by trauma infarction, infection, nutritional deficiency or toxic agents. The present invention also relates to a novel method for producing substantially pure CNTF. The invention also relates to pharmaceutical compositions comprising effective amounts of CNTF gene products which may be used in the diagnosis and treatment of a variety of neurological diseases and disorders. The present invention relates to the cloning sequencing and expression of CNTF and provides, for the first time, a means for producing human CNTF utilizing human CNTF-encoding nucleic acid sequences. Furthermore, the CNTF nucleic acid sequences of the invention may be utilized to identify nucleic acid sequences encoding CNTF or CNTF-homologous molecules in a variety of species and tissues.

Enriched environment increases neurogenesis in the adult rat dentate gyrus and improves spatial memory.

Abstract: The fetal and even the young brain possesses a considerable degree of plasticity. The plasticity and rate of neurogenesis in the adult brain is much less pronounced. The present study was conducted to investigate whether housing conditions affect neurogenesis, learning, and memory in adult rats. Three-month-old rats housed either in isolation or in an enriched environment were injected intraperitoneally with bromodeoxyuridine (BrdU) to detect proliferation among progenitor cells and to follow their fate in the dentate gyrus. The rats were sacrificed either 1 day or 4 weeks after BrdU injections. This experimental paradigm allows for discrimination between proliferative effects and survival effects on the newborn progenitors elicited by different housing conditions. The number of newborn cells in the dentate gyrus was not altered 1 day after BrdU injections. In contrast, the number of surviving progenitors 1 month after BrdU injections was markedly increased in animals housed in an enriched environment. The relative ratio of neurogenesis and gliogenesis was not affected by environmental conditions, as estimated by double-labeling immunofluorescence staining with antibodies against BrdU and either the neuronal marker calbindin D28k or the glial marker GFAp, resulting in a net increase in neurogenesis in animals housed in an enriched environment. Furthermore, we show that adult rats housed in an enriched environment show improved performance in a spatial learning test. The results suggest that environmental cues can enhance neurogenesis in the adult hippocampal region, which is associated with improved spatial memory.

Overview of retinoid metabolism and function

Abstract: Retinoids (vitamin A) are crucial for most forms of life. In chordates, they have important roles in the developing nervous system and notochord and many other embryonic structures, as well as in maintenance of epithelial surfaces, immune competence, and reproduction. The ability of all-trans retinoic acid to regulate expression of several hundred genes through binding to nuclear transcription factors is believed to mediate most of these functions. The role of all-trans retinoic may extend beyond the regulation of gene transcription because a large number of noncoding RNAs also are regulated by retinoic acid. Additionally, extra-nuclear mechanisms of action of retinoids are also being identified. In organisms ranging from prokaryotes to humans, retinal is covalently linked to G protein-coupled transmembrane receptors called opsins. These receptors function as light-driven ion pumps, mediators of phototaxis, or photosensory pigments. In vertebrates phototransduction is initiated by a photochemical reaction where opsin-bound 11-cis-retinal is isomerized to all-trans-retinal. The photosensitive receptor is restored via the retinoid visual cycle. Multiple genes encoding components of this cycle have been identified and linked to many human retinal diseases. Central aspects of vitamin A absorption, enzymatic oxidation of all-trans retinol to all-trans retinal and all-trans retinoic acid, and esterification of all-trans retinol have been clarified. Furthermore, specific binding proteins are involved in several of these enzymatic processes as well as in delivery of all-trans retinoic acid to nuclear receptors. Thus, substantial progress has been made in our understanding of retinoid metabolism and function. This insight has improved our view of retinoids as critical molecules in vision, normal embryonic development, and in control of cellular growth, differentiation, and death throughout life.