Related Experiment Video

Updated: Jul 4, 2026

Modeling Encephalopathy of Prematurity Using Prenatal Hypoxia-ischemia with Intra-amniotic Lipopolysaccharide in Rats
07:36

Modeling Encephalopathy of Prematurity Using Prenatal Hypoxia-ischemia with Intra-amniotic Lipopolysaccharide in Rats

Published on: November 20, 2015

Developmental neurotoxicity of propylthiouracil (PTU) in rats: relationship between transient hypothyroxinemia during

Marta Axelstad1, Pernille Reimar Hansen, Julie Boberg

  • 1Department of Toxicology and Risk Assessment, National Food Institute, Technical University of Denmark, Søborg, Denmark. maap@food.dtu.dk

Toxicology and Applied Pharmacology
|June 25, 2008
PubMed

Insights

Low thyroid hormone (T4) levels during development in rats negatively impacted behavior, learning, memory, and hearing. These long-lasting effects were linked to reduced T4, suggesting T4 levels predict developmental neurotoxicity.

Area of Science:

  • Developmental toxicology
  • Neuroendocrinology
  • Environmental health

Background:

  • Thyroid hormones are crucial for neurodevelopment, with even minor maternal thyroid status changes potentially affecting offspring.
  • Environmental chemicals disrupting thyroid hormones raise concerns for developmental neurotoxicity.

Purpose of the Study:

  • To investigate the relationship between thyroid hormone levels during development and long-lasting effects on behavior and hearing.
  • To assess the impact of propylthiouracil (PTU)-induced hypothyroxinemia on rat offspring development.

Main Methods:

  • Pregnant rats were administered PTU at varying doses from gestation day 7 to postnatal day 17.
  • Physiological parameters, thyroid gland status, and behavioral development of offspring were assessed.
  • Adult offspring were evaluated for learning, memory, and auditory function.

Main Results:

  • PTU exposure significantly decreased thyroxine (T4) levels in dams and pups, affecting thyroid gland weight and histology.
  • Offspring exhibited altered motor activity, impaired learning and memory, and reduced auditory function in higher dose groups.
  • All observed effects in adult offspring were significantly correlated with reduced T4 levels during development.

Conclusions:

  • PTU-induced hypothyroxinemia during development negatively impacts neurobehavioral and auditory functions in rats.
  • Reduced T4 levels during development serve as a predictor for long-lasting developmental neurotoxicity.
  • Findings highlight the critical role of thyroid hormone status for normal neurodevelopment and sensory function.

Related Concept Videos

Teratogenicity01:07

Teratogenicity

The ability of a drug to produce structural deformations and functional abnormalities in the developing embryo or the fetus is called teratogenicity, and the drug producing this effect is known as a teratogen. Teratogenic effects include stillbirth, miscarriage, intrauterine growth restriction, and neurocognitive delay. A teratogen may affect the embryo at different stages of development, which is important in determining the type and extent of the damage. During blastocyst formation, the early...
Drug Toxicity: Dose-Dependent Reactions01:24

Drug Toxicity: Dose-Dependent Reactions

Drug toxicities can be stratified into pharmacological, pathological, or genotoxic based on their mechanisms. The incidence and severity of these toxicities generally increase with the drug's concentration in the body and exposure time.Pharmacological toxicity is evident when the therapeutic effects of drugs overshoot into adverse reactions in a predictable, dose-dependent manner. Central nervous system (CNS) depression from barbiturates is a classic example, with effects escalating from...
Toxicity Testing in Animals01:23

Toxicity Testing in Animals

Toxicity tests in animals are grounded on two main assumptions: first, the effects observed in laboratory animals can be extrapolated to humans, especially when adjusted for body surface area; second, high-dose exposure in animals is essential to identify potential human hazards from lower doses. This is based on the quantal dose-response concept, which faces the challenge of extrapolating results from relatively few test animals to much larger human populations. For example, a 0.01% incidence...
Hypothyroidism II: Pathophysiology01:23

Hypothyroidism II: Pathophysiology

Hypothyroidism is a disorder characterized by insufficient production of thyroid hormones, which regulate metabolism, energy balance, and multiple organ systems.TypesHypothyroidism is classified based on the level of dysfunction. Primary hypothyroidism results from intrinsic thyroid gland dysfunction, causing reduced hormone production despite normal or increased stimulation. Secondary hypothyroidism arises from inadequate thyroid-stimulating hormone (TSH) secretion by the pituitary. Tertiary...
Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase01:27

Pharmacogenetics of Phase II Enzymes: N-acetyltransferase, Thiopurine S-methyltransferase, UDP-glucuronosyltransferase

Phase II biotransformation reactions are essential for detoxifying and eliminating xenobiotics, including many pharmaceutical compounds. These reactions typically involve conjugation, the covalent attachment of polar endogenous groups such as glucuronic acid, sulfate, methyl, or acetyl moieties to functional groups introduced during Phase I metabolism. The resulting conjugates are more water-soluble, enabling efficient renal or biliary excretion.The major classes of Phase II enzymes include...
Hyperthyroidism II: Pathophysiology01:27

Hyperthyroidism II: Pathophysiology

Hyperthyroidism is a hypermetabolic state caused by elevated levels of thyroid hormones, triiodothyronine (T3) and thyroxine (T4). It results from dysregulation at the thyroid, pituitary, or immune system level and affects multiple organ systems.PathophysiologyThe most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder in which antibodies, specifically thyroid-stimulating antibodies (TSAb), a subtype of TSH receptor antibodies (TRAb), bind to and activate TSH receptors...