Levothyroxine rescues the lead-induced hypothyroidism and impairment of long-term potentiation in hippocampal CA1 region of the developmental rats

Journal Article · Sat Oct 15 04:00:00 EDT 2011 · Toxicology and Applied Pharmacology

OSTI ID:21587864

Chuanyun, Wu; Bing, Liu; Huili, Wang

Lead (Pb) exposure during development has been associated with impaired long-term potentiation (LTP). Hypothyroidism happening upon subjects with occupational exposure to Pb is suggestive of an adverse effect of Pb on thyroid homeostasis, leading to the hypothesis that Pb exposure may alter thyroid hormone homeostasis. Hippocampus is one of the targets of Pb exposure, and is sensitive to and dependent on thyroid hormones, leading us to explore whether levothyroxine (L-T{sub 4}) administration could alter the thyroid disequilibrium and impairment of LTP in rat hippocampus caused by Pb exposure. Our results show that Pb exposure caused a decrease in triiodothyronine (T{sub 3}) and tetraiodothyronine (T{sub 4}) levels accompanied by a dramatic decrease of TSH and application of L-T{sub 4} restored these changes to about control levels. Hippocampal and blood Pb concentration were significantly reduced following L-T{sub 4} treatment. L-T{sub 4} treatment rescued the impairment of LTP induced by the Pb exposure. These results suggest that Pb exposure may lead to thyroid dysfunction and induce hypothyroidism and provide a direct electrophysiological proof that L-T{sub 4} relieves chronic Pb exposure-induced impairment of synaptic plasticity. - Highlights: > Lead may interfere with thyroid hormone homeostasis and induce hypothyroidism. > Levothyroxine decreases the hippocampal and blood Pb concentration. > Levothyroxine amends the T{sub 3}, T{sub 4} and TSH levels in blood. > Levothyroxine rescues the impaired LTP in CA1.

• OSTI ID: 21587864
• Journal Information: Toxicology and Applied Pharmacology, Journal Name: Toxicology and Applied Pharmacology Journal Issue: 2 Vol. 256; ISSN TXAPA9; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
AMINO ACIDS
ANIMALS
BIOLOGICAL MATERIALS
BLOOD
BODY
BODY FLUIDS
BRAIN
CARBOXYLIC ACIDS
CENTRAL NERVOUS SYSTEM
CEREBROSPINAL FLUID
DISEASES
ELEMENTS
ENDOCRINE DISEASES
ENDOCRINE GLANDS
GLANDS
HIPPOCAMPUS
HOMEOSTASIS
HORMONES
HYPOTHYROIDISM
LEAD
MAMMALS
MATERIALS
METALS
NERVOUS SYSTEM
OCCUPATIONAL EXPOSURE
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PEPTIDE HORMONES
PITUITARY HORMONES
PROTEINS
RATS
RODENTS
STIMULATION
THYROID
THYROID HORMONES
THYROXINE
TRIIODOTHYRONINE
TSH
VERTEBRATES