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  • Proceedings of the National Academy of Sciences  (2)
  • 2005-2009  (2)
  • 1
    Online Resource
    Online Resource
    Thyroid hormone modulates glucose production via a sympathetic pathway from the hypothalamic paraventricular nucleus to the liver
    Proceedings of the National Academy of Sciences ; 2009
    In:  Proceedings of the National Academy of Sciences Vol. 106, No. 14 ( 2009-04-07), p. 5966-5971
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 106, No. 14 ( 2009-04-07), p. 5966-5971
    Abstract: Thyrotoxicosis increases endogenous glucose production (EGP) and induces hepatic insulin resistance. We have recently shown that these alterations can be modulated by selective hepatic sympathetic and parasympathetic denervation, pointing to neurally mediated effects of thyroid hormone on glucose metabolism. Here, we investigated the effects of central triiodothyronine (T 3 ) administration on EGP. We used stable isotope dilution to measure EGP before and after i.c.v. bolus infusion of T 3 or vehicle in euthyroid rats. To study the role of hypothalamic preautonomic neurons, bilateral T 3 microdialysis in the paraventricular nucleus (PVN) was performed for 2 h. Finally, we combined T 3 microdialysis in the PVN with selective hepatic sympathetic denervation to delineate the involvement of the sympathetic nervous system in the observed metabolic alterations. T 3 microdialysis in the PVN increased EGP by 11 ± 4% ( P = 0.020), while EGP decreased by 5 ± 8% (ns) in vehicle-treated rats (T 3 vs. Veh, P = 0.030). Plasma glucose increased by 29 ± 5% ( P = 0.0001) after T 3 microdialysis versus 8 ± 3% in vehicle-treated rats (T 3 vs. Veh, P = 0.003). Similar effects were observed after i.c.v. T 3 administration. Effects of PVN T 3 microdialysis were independent of plasma T 3 , insulin, glucagon, and corticosterone. However, selective hepatic sympathectomy completely prevented the effect of T 3 microdialysis on EGP. We conclude that stimulation of T 3 -sensitive neurons in the PVN of euthyroid rats increases EGP via sympathetic projections to the liver, independently of circulating glucoregulatory hormones. This represents a unique central pathway for modulation of hepatic glucose metabolism by thyroid hormone.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0805355106
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2009
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Interactive effects of age and estrogen on cognition and pyramidal neurons in monkey prefrontal cortex
    Proceedings of the National Academy of Sciences ; 2007
    In:  Proceedings of the National Academy of Sciences Vol. 104, No. 27 ( 2007-07-03), p. 11465-11470
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 104, No. 27 ( 2007-07-03), p. 11465-11470
    Abstract: We previously reported that long-term cyclic estrogen (E) treatment reverses age-related impairment of cognitive function mediated by the dorsolateral prefrontal cortex (dlPFC) in ovariectomized (OVX) female rhesus monkeys, and that E induces a corresponding increase in spine density in layer III dlPFC pyramidal neurons. We have now investigated the effects of the same E treatment in young adult females. In contrast to the results for aged monkeys, E treatment failed to enhance dlPFC-dependent task performance relative to vehicle control values (group young OVX+Veh) but nonetheless led to a robust increase in spine density. This response was accompanied by a decline in dendritic length, however, such that the total number of spines per neuron was equivalent in young OVX+Veh and OVX+E groups. Robust effects of chronological age, independent of ovarian hormone status, were also observed, comprising significant age-related declines in dendritic length and spine density, with a preferential decrease in small spines in the aged groups. Notably, the spine effects were partially reversed by cyclic E administration, although young OVX+Veh monkeys still had a higher complement of small spines than did aged E treated monkeys. In summary, layer III pyramidal neurons in the dlPFC are sensitive to ovarian hormone status in both young and aged monkeys, but these effects are not entirely equivalent across age groups. The results also suggest that the cognitive benefit of E treatment in aged monkeys is mediated by enabling synaptic plasticity through a cyclical increase in small, highly plastic dendritic spines in the primate dlPFC.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0704757104
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2007
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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