摘要:

&NA;Remyelination of demyelinated axons in the CNS is a regenerative process that, like many others, becomes less efficient with age. This article reviews a series of studies in which toxin models of demyelination have been used to characterize this phenomenon. The delayed rate of remyelination in older animals is associated with a decrease in the rate of oligodendrocyte progenitor recruitment and in the rate at which the recruited cells differentiate into remyelinating oligodendrocytes. The differences in the behaviour of oligodendrocyte lineage cells during remyelination in young and old animals are related to the age‐related changes that occur in the expression of growth factors that affect the proliferation, migration and differentiation of oligodendrocyte progenitors, and in the inflammatory process associated with toxin‐induced demyelination. Based on these differences, a conceptual framework is proposed to explain the age‐associated effects on remyelination, which we have called the dysregulation hypothesis, and the feasibility of reversing these effects is discussed.NeuroReport13:923‐928

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

&NA;The present study investigated whether serotonin (5‐HT) agonists could inhibit the ability of arginine‐vasopressin (AVP) to induce a form of scent marking called flank marking by their actions in the medial preoptic‐anterior hypothalamus (MPOA‐AH). DOI, a 5‐HT2A,2B,2C receptor agonist, did not inhibit AVP‐induced flank marking, but mCPP a 5‐HT2A antagonist and 5‐HT2B,2C agonist inhibited AVP‐induced flank marking. In addition, the finding that 8‐OH‐DPAT, CGS‐12066A and SC53116 also inhibited AVP‐induced flank marking suggests that 5‐HT could also inhibit flank marking by acting through 5‐HT1A, 5‐HT7, 5‐HT1B and/or 5‐HT4 receptor subtypes. These data support the hypothesis that 5‐HTacts within the MPOA‐AH to inhibit the ability of AVP to induce flank marking.NeuroReport13:931‐933 © 2002 Lippincott Williams & Wilkins.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

&NA;Recent fMRI studies indicate that the anterior fusiform gyrus (the fusiform face area, FFA) is specialized for face recognition. However, the analyses used to determine face selectivity have not ruled out the possibility that other object categories produce significant activation in the FFA, relative to baseline. In the current fMRI study, we use a conservative hypothesis testing approach to show that FFA activation is not selective for faces. Rather, the FFA response is almost completely explained by a graded response in which faces produce more activation than either manufactured or natural objects, but those categories produce a statistically greater response than the baseline task. These findings question whether the FFA can be interpreted as a specialized module for face recognition.NeuroReport13:935‐938 © 2002 Lippincott Williams & Wilkins.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

&NA;The medial temporal lobe contains multiple structures whose mnemonic operations need further delineation. One model posits the function of the hippocampus as a relational binder, collaborating with overlying cortices that perform encoding and retrieval operations. For instance, lesions of the hippocampus leave intact the learning of paired‐associates while impairing the ability to synthesize information across pairs. We test this relational model with two PET studies of normal humans during a transitive inference task using faces that either have or lack relationships across the stimulus pairs. Both studies converge to support a relational processing model of hippocampal function.NeuroReport13:939‐944 © 2002 Lippincott Williams & Wilkins.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

&NA;Serotonin (5‐hydroxytryptamine; 5‐HT) is a regulator of feeding behavior. The effect of serotonin on food intake is believed to be primarily mediated via 5‐HT1Aand 5‐HT2Creceptors, which both are expressed in hypothalamic regions implicated in regulation of feeding behavior. Using an antiserum to the 5‐HT1Areceptor, immunoreactive neurons were observed in the rat supraoptic, paraventricular, arcuate and ventromedial nuclei and lateral hypothalamic area. 5‐HT1Areceptor immunoreactivity was demonstrated in neuropeptide Y‐, agouti‐related peptide‐, proopiomelanocortin‐ and cocaine‐ and amphetamine‐regulated transcript‐containing neurons of the arcuate nucleus. In the lateral hypothalamus, 5‐HT1Areceptor immunoreactivity was observed in melanin‐concentrating hormone‐ and orexin‐containing neurons. The results suggest that serotonin via postsynaptic 5‐HT1Areceptors affects the release of peptides regulating food intake.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

&NA;Current evidence indicates reorganization of motor cortex in association with motor behavior. To investigate the molecular basis for these changes rats were fitted with limb‐restricting vests which forced the use of one forelimb for 10 days. Using cDNA macroarrays, expression profiles of the corresponding motor cortices connected to the overused and immobilized limbs were analyzed. In the overused motor cortex up‐regulations were observed exclusively, including genes coding for voltage‐gated ion channels, trafficking and targeting proteins, and intracellular kinase net‐work members (10 genes). In the contralateral immobilized cortex changes were restricted to down‐regulation, mainly involving genes pertaining to DNA‐binding, translation, neuronal signaling and metabolic pathways (9 genes). At least some of these changes are likely to represent the molecular substrate of use‐dependent plasticity.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

&NA;We have studied the pharmacological regulation of mitochondrial activity in a human neuroblastoma cell line. Cyclosporin A was found to directly alter mitochondrial membrane potential and to decrease mitochondrial permeability as measured using calcein. The estrogen receptor ligands tamoxifen, nafoxidine and clomiphene were identified as agents which affect mitochondrial membrane potential in a cyclosporin A‐like manner. Also when mitochondrial permeability was measured using calcein, tamoxifen, nafoxidine and clomiphene were effective in inhibiting dye loss from mitochondria. Nafoxidine and cyclosporin A inhibit effects of mastoparan on SH‐SY5Y mitochondria. These studies indicate that estrogen receptor ligands appear to affect mitochondria in a cyclosporin A‐like manner in human neuroblastoma cells.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

&NA;Studies have shown nicotine is excreted into maternal milk, so that suckling offspring would be a target of the drug during the pre‐weaning period. Since nicotine exposure leads to an upregulation of neuronal nicotinic receptors, this study examines the hypothesis that nicotine delivered via maternal milk is capable of altering neuronal nicotinic receptor regulation in the drug‐exposed rat pups. The present study showed that postnatal nicotine exposure via maternal milk was sufficient to induce an upregulation in brain nicotinic receptors similar to that seen in adults that smoke. Such exposure may result in altered neuronal development and synaptic activity and structure, potentially leading to long‐term behavioral, learning, and memory deficits.

ISSN:0959-4965    

出版商:OVID    

年代:2002

数据来源: OVID