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| Research article summary (published 30 Dec 2001): |
Thyroid hormones, brain function and cognition: a brief review.
Full Abstract
In addition to their role in cellular metabolic activity, thyroid hormones (THs), also regulate neural development; the central nervous system is particularly dependent on TH for normal maturation and function. Specifically, there appears to be extensive inter-reliance between TH and acetylcholine (Ach), nerve growth factor and hippocampal function. These associations led us to investigate the possible effects of thyroxine (L-T4) on performance of a spatial learning task, where cholinergic activity and hippocampal function are known to be important. Groups of rats (n=20) received saline (controls) or L-T4 at 2.5 or 5mg/kg daily for 4 days as a sub-chronic treatment, or 0, 5 or 10mg/kg doses administered every third day for 28 days prior to testing as a chronic regimen. Rats were assessed in a water maze for their ability to find a submerged or visible platform. Forty minutes prior to water maze testing, half the animals in each group received 1mg/kg scopolamine to elicit a cognitive deficit. Following testing, rats were decapitated, blood samples taken, and the frontal cortex and hippocampus were dissected out for acetylcholinesterase (AChE) assay. The results showed that L-T4 treatment, administered both sub-chronically and chronically, significantly enhanced the ability of rats to learn a spatial memory task, compared with controls. Moreover, both short-term and long-term L-T4 treatment reduced the cognitive-impairing effects of scopolamine. Improvements in performance were shown to occur alongside significantly increased cholinergic activity in frontal cortex and in the hippocampus of treated animals.These findings demonstrate an augmentative effect of L-T4 upon cognitive function, possibly mediated by an enhancement of cholinergic activity. The results support previous findings of a relationship between L-T4 and acetylcholine, and underscore possible mechanisms by which disorders of thyroid function may be associated with cognitive decline.
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Author information
Author/s: Smith, Jeremy W (JW); Evans, A Tudor (AT); Costall, B (B); Smythe, James W (JW);
Affiliation: Postgraduate Studies in Neuropharmacology, School of Pharmacy, University of Bradford, Bradford BD7 1DP, UK.
Journal and publication information
Publication Type: Journal Article; Research Support, Non-U.S. Gov't; Review
Journal: Neuroscience and biobehavioral reviews (Neurosci Biobehav Rev), published in United States. (Language: eng)
Reference: 2002-Jan; vol 26 (issue 1) : pp 45-60
Dates: Created 2002/02/11; Completed 2002/04/29; Revised 2006/11/15;
PMID: 11835983, status: MEDLINE (last retrieval date: 11/6/2008)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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