Abstract:
:Partial, unilateral nigrostriatal lesions of varying severity were produced in rats by injecting graded doses of 6-hydroxydopamine into the substantia nigra. Formation of the dopamine metabolites dihydroxyphenylacetic acid and homovanillic acid in each surviving nigrostriatal neuron (estimated by the ratios of dihydroxyphenylacetic acid to dopamine and homovanillic acid to dopamine in the striatum) increased significantly when dopamine concentrations in striata containing lesions had been reduced to 25% or less of control values, but remained unchanged in rats with less severe lesions. These findings suggest that, in rats with severe damage of nigrostriatal dopaminergic neurons, surviving neurons increase their firing rates and accelerate dopamine synthesis and release. In rats that had lesions and enhanced striatal dopamine release, but not in rats with lesser lesions (i.e., which reduced ipsilateral dopamine concentrations by less than 75%), administration of tyrosine (250 mg/kg) caused further significant increases in formation of dihydroxyphenylacetic acid and homovanillic acid. These findings provide further evidence that tyrosine availability can enhance dopamine synthesis in and release from nigrostriatal neurons if the firing rates of these neurons are accelerated.
journal_name
Proc Natl Acad Sci U S Aauthors
Melamed E,Hefti F,Wurtman RJdoi
10.1073/pnas.77.7.4305subject
Has Abstractpub_date
1980-07-01 00:00:00pages
4305-9issue
7eissn
0027-8424issn
1091-6490journal_volume
77pub_type
杂志文章abstract::This investigation was undertaken to determine the possible role of growth hormone (GH) in the hormonal regulation of hepatic low density lipoprotein (LDL) receptor expression. Treatment of normal rats with estrogen (ethynylestradiol, 5 mg/kg per day) increased the number of hepatic LDL receptors, and the LDL receptor...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.15.6983
更新日期:1992-08-01 00:00:00
abstract::Recent studies of human disease and transgenic animal experiments have clearly demonstrated the importance of desmosomes in normal tissue architecture. Furthermore, desmosomal components are down-regulated in certain types of carcinomas, suggesting a possible role for desmosomes in suppression of invasion and metastas...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.95.14.8064
更新日期:1998-07-07 00:00:00
abstract::Tactile-foraging ducks are specialist birds known for their touch-dependent feeding behavior. They use dabbling, straining, and filtering to find edible matter in murky water, relying on the sense of touch in their bill. Here, we present the molecular characterization of embryonic duck bill, which we show contains a h...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1708793114
更新日期:2017-12-05 00:00:00
abstract::Some trypanosomatid protozoa (order Kinetoplastida) are well known to harbor bacterial endosymbionts. Their phylogenetic positions and evolutionary relationships with the hosts were deduced by comparing the rRNA gene sequences. Earlier, we observed that these symbionts from three Crithidia spp. are identical and are c...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.18.8437
更新日期:1994-08-30 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0804861105
更新日期:2008-09-16 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.87.12.4833
更新日期:1990-06-01 00:00:00
abstract::Assessing temporal variability in extreme rainfall events before the historical era is complicated by the sparsity of long-term "direct" storm proxies. Here we present a 2,200-y-long, accurate, and precisely dated record of cave flooding events from the northwest Australian tropics that we interpret, based on an integ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1422270112
更新日期:2015-04-14 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0405759101
更新日期:2004-10-19 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.19.8787
更新日期:1991-10-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.83.11.3604
更新日期:1986-06-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.10.4567
更新日期:1993-05-15 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.93.20.10955
更新日期:1996-10-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2013-07-30 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.73.11.4205
更新日期:1976-11-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.91.11.4935
更新日期:1994-05-24 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2006-11-14 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.75.1.427
更新日期:1978-01-01 00:00:00
abstract::Antibodies from three different lines of monoclonal hybridomas crossreact with both the beta subunit of spectrin and the 90-kDa peptide present in highly purified preparations of the heme-controlled eIF-2 alpha (initiation factor 2 alpha-subunit) kinase from rabbit reticulocytes. Antibodies from two of the three lines...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:1985-08-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2001-07-31 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:2009-03-17 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.13.4010
更新日期:1982-07-01 00:00:00
abstract::The spectrum of cellular targets in the autoimmune diseases is both large and varied and includes among the nuclear components the so-called Sm and RNP antigens associated with systemic lupus erythematosus. The use of immunoaffinity chromatography with dual specificity for the Sm and RNP antigens has allowed for their...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.78.1.626
更新日期:1981-01-01 00:00:00
abstract::Dictyostelium actin was shown to become phosphorylated on Tyr-53 late in the developmental cycle and when cells in the amoeboid stage are subjected to stress but the phosphorylated actin had not been purified and characterized. We have separated phosphorylated and unphosphorylated actin and shown that Tyr-53 phosphory...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0606321103
更新日期:2006-09-12 00:00:00
abstract::Tolerance and resistance provide hosts with two distinct defense strategies against parasitism. In resistance the hosts "fight" the parasite directly, whereas in tolerance the hosts fight the disease by ameliorating the damage that infection causes. There is increasing recognition that the two mechanisms may exhibit v...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0809558105
更新日期:2008-12-30 00:00:00
abstract::The Zika virus (ZIKV) causes microcephaly and the Guillain-Barré syndrome. Little is known about how ZIKV causes these conditions or which ZIKV viral protein(s) is responsible for the associated ZIKV-induced cytopathic effects, including cell hypertrophy, growth restriction, cell-cycle dysregulation, and cell death. W...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1619735114
更新日期:2017-01-17 00:00:00
abstract::Toxoplasma gondii is a highly successful protozoan parasite that infects all warm-blooded animals and causes severe disease in immunocompromised and immune-naïve humans. It has an unusual global population structure: In North America and Europe, isolated strains fall predominantly into four largely clonal lineages, bu...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1117047109
更新日期:2012-08-14 00:00:00