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Age, dose, and time-dependency of plasma and tissue distribution of deltamethrin in immature rats

Kyu-Bong Kim1, Sathanandam S Anand, Hyo J Kim

  • 1Department of Pharmaceutical Engineering, Inje University, Gimhae, Gyongam 621-749, Korea.

Toxicological Sciences : an Official Journal of the Society of Toxicology
|March 10, 2010
PubMed

Insights

Immature rats show higher brain deltamethrin (DLT) levels and neurotoxicity due to limited metabolic inactivation. Age-dependent DLT disposition impacts brain dosimetry and potential long-term neurotoxicity risks.

Area of Science:

  • Toxicology
  • Neuroscience
  • Pharmacokinetics

Background:

  • Pyrethroids, like deltamethrin (DLT), are common insecticides.
  • Understanding DLT's age-dependent effects is crucial for assessing risks to developing organisms.
  • Immature brains may be particularly vulnerable to neurotoxicants.

Purpose of the Study:

  • To characterize the systemic disposition of deltamethrin (DLT) in immature rats.
  • To investigate the age-dependent relationship between DLT exposure, brain concentration, and neurotoxic effects.
  • To compare toxicokinetic data between immature and adult rats.

Main Methods:

  • Male Sprague-Dawley rats of different postnatal ages (PND 10, 21, 40, 90) were administered DLT via oral gavage.
  • Plasma, brain, liver, fat, and muscle samples were collected serially for DLT and metabolite analysis using HPLC.
  • Toxicokinetic data were analyzed to determine age- and dose-dependent disposition and metabolic clearance.

Main Results:

  • DLT plasma and tissue concentrations were inversely related to the age of the rats.
  • Immature rats (PND 10, 21) exhibited higher brain DLT levels, correlating with pronounced neurotoxic signs (salivation, tremors) and fatalities.
  • Limited hepatic metabolic inactivation of DLT was identified as the primary cause of elevated brain exposure and neurotoxicity in young rats.

Conclusions:

  • The immature rat's limited capacity for DLT metabolism leads to higher target organ doses and acute neurotoxicity.
  • Plasma DLT levels do not reliably predict brain concentrations or neurotoxicity severity in immature animals.
  • Elevated pyrethroid exposure in the developing brain may have significant short- and long-term neurotoxicological consequences.

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