摘要:

WE report the distinct cellular distribution in the human cerebellar cortex of the mammalian mt1(Mel1a) and MT2(Mel1b) (1) melatonin receptor subtypes. Specific binding of the non-selective radioligand 2-[125I]iodomelatonin to the outer molecular layer was significantly higher than to the granule cell layer. Melatonin receptor subtype expression was assessed byin situhybridization using selective and specific digoxigenin-labeled antisense oligonucleotide probes. This is the first demonstration of MT2melatonin receptor mRNA expression in human cerebellar Bergmann glia and astrocytes. On the other hand, the mt1melatonin receptor mRNA was expressed in both basket-stellate cells and granule cells. We conclude that mt1and MT2melatonin receptors are heterogeneously expressed in human cerebellar cortex.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE offspring of diabetic mothers is at increased risk to develop obesity and diabetogenic disturbances during life. Pathophysiological mechanisms responsible are unclear. Neuropeptide Y (NPY) is an important hypothalamic stimulator of food intake and body weight gain, and its levels are decreased by elevated insulin. In neonatally hyperinsulinaemic offspring of diabetic mother rats, hypothalamic insulin level was significantly increased at birth (p< 0.01). At weaning, i.e. at the end of the critical hypothalamic differentiation period, a significantly increased number of NPY-positive neurons (p< 0.01) appeared in the arcuate hypothalamic nucleus. In conclusion, an increase in the number of NPYergic neurons in the hypothalamus, possibly due to hypothalamic malformation and/or perinatally acquired hypothalamic insulin resistance, might contribute to the development of obesity and metabolic disturbances in the offspring of diabetic mothers.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ASTROGLIOSIS is an important component of the response to injury of the central nervous system (CNS). The Id family of helix-loop-helix (HLH) transcription factors has been implicated in the regulation of cellular differentiation in several different lineages and may contribute to the regulation of astrogliosis. We examined the expression of Id genes in primary cultures of mouse forebrain astrocytes under experimental conditions in which astrogliosis was elicited by mechanical injury. Astrocyte cultures expressed the four known members of the Id gene family, Id1, Id2, Id3, and Id4. After injury, at a time when astrocytes developed the characteristic phenotypic changes of astrogliosis, Id4 expression decreased dramatically. Id1, Id2, and Id3 mRNA levels did not change. These results identify Id4 as a candidate marker of astroglial activation in culture and suggest that Id4 expression plays a role in the process of astrogliosis.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ACTIVATED mitogen-activated protein (MAP) kinases play an essential role controlling many neuronal functions. Dual specificity protein phosphatases (DS-PTPs) elicit selective inactivation of MAP kinases and are under tight transcriptional control. We have studied expression of four DS-PTPs (MKP-1, MKP-X, MKP-3 and B23) in rat brain and examined changes during post-natal development and following kainic acid induced seizure activity. In normal adult brain these DS-PTPs exhibit a strikingly different expression pattern. Only MKP-1 was regulated during development with levels increased transiently (P15-P21) within the thalamus and somatosensory cortex. Following kainate treatment, MKP-1, MKP-3 and B23 all exhibit striking changes in expression within hippocampal subfields CA1-3 and dentate gyrus. Regulated transcription of DS-PTPs may play a critical role controlling MAP kinase dependent processes including synaptic remodeling and neuronal death.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE compared the interaction between the metabotropic glutamate receptor agonist ACPD and arachidonic acid with the interaction between ACPD and nerve growth factor (NGF) on presynaptic function in hippocampus. ACPD interacted with both NGF and arachidonic acid to increase KCl-stimulated endogenous glutamate release and calcium concentration in synaptosomes prepared from whole hippocampus and synaptosomes prepared from untetanized dentate gyrus. The data indicate that prior induction of long-term potentiation (LTP) in perforant path granule cells synapses occluded the interaction between ACPD and both NGF and arachidonic acid, suggesting that these agents may play a role in the generation of LTP in dentate gyrus.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

FIBROBLAST growth factors (FGFs) are critical for normal development of the organ of Corti, and may also protect hair cells from ototoxic damage. Four different fibroblast growth factors are known, three of which have different splice variants in the extracellular immunoglobin-like (Ig) III FGF-binding domain, giving different patterns of sensitivity to the different FGFs. Analysis of a cDNA library of rat outer hair cells by the polymerase chain reaction, using isoform specific primers, showed expression only of FGF receptor 3, splice variant IIIc. This allows us to predict the pattern of sensitivity to applied FGFs, which may be useful in targeting outer hair cells selectively during an FGF-based strategy for cochlear therapy.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE cytokine IFN-γ was shown to regulate growth and differentiation of human embryonic forebrain astrocytes. This work investigated a signalling pathway used by IFN-γ during the process of growth regulation of human fetal astrocytes obtained from first trimester embryos. IFN-γ induced significantly higher cell survival compared to that of unexposed cultures, and this survival could be suppressed by incubation with the tyrosine protein kinase (TPK) specific inhibitor tyrphostin A47 at the non-toxic concentration of 10-6M. The signal transducer and activator of transcription (STAT)-1 was translocated into the nucleus upon IFN-γ stimulation, which was also blocked by incubation with A47. Our data demonstrate that TPKs are actively involved in growth regulation of the developing brain astrocytes induced by IFN-γ.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ODORANT receptor expression has been reported in a variety of non-olfactory cells and tissues in several animal models. We therefore investigated the possible expression of odorant receptor genes in taste tissue of channel catfish. Multiple odorant receptor transcripts were amplified by PCR from barbel.In situhybridization showed that receptors amplified from taste tissue, as well as receptors amplified from olfactory neurons, hybridized to taste epithelium with similar patterns. These results show that odorant receptor transcripts are expressed in catfish taste tissue. Taken with previous data, these results suggest that some members of the odorant receptor superfamily may mediate various chemoreceptive roles in non-olfactory cells.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

STUDIES of the interaction between long-term potentiation (LTP) and paired-pulse facilitation (PPF) may throw light on the role of presynaptic factors in LTP. We examine here, for the first time, the nature of PPF in the CA1-subiculum projection. PPF peaks at a05ms interstimulus interval (ISI) and is evident at ISIs from 10 to 500 ms. There is no PPF effect at a 1000 ms ISI. PPF decreases in magnitude post-LTP induction across the middle range of ISI values tested (30, 50 and 100 ms). There is a positive correlation between initial PPF values and LTP; this correlation increases as the ISI increases. Initial values and the change in PPF post-LTP are also negatively correlated

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE role of dopamine in the subthalamic nucleus to control motor behaviour was investigated in rats using bilateral microinfusions of the dopamine D1receptor antagonist SCH23390 and the dopamine D2receptor antagonist S(-)-sulpiride. Selective blockade of subthalamic D1receptors, but not of D2receptors, produced catalepsy. These findings suggest that dopamine D1receptors within the subthalmic nucleus play a prominent role in the regulation of motor functions. Furthermore, the data point to the possibility that a reduced dopaminergic tone at subthalamic dopamine D1receptors might contribute to akinesia in Parkinson's disease.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID