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Developmental lead exposure alters the distribution of protein kinase C activity in the rat hippocampus
1Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson 39216, USA.
Insights
Chronic lead exposure in children impairs learning and memory by altering hippocampal protein kinase C (PKC) activity and distribution during development. These neurotoxic effects may contribute to cognitive deficits in early life.
Area of Science:
- Neuroscience
- Toxicology
- Developmental Biology
Background:
- Chronic low-level lead (Pb) exposure in children is linked to learning and memory deficits.
- In vitro studies suggest Pb exposure alters protein kinase C (PKC) activity, particularly in the hippocampus, which is crucial for learning.
- Hippocampal PKC activity is correlated with performance in various learning tasks.
Purpose of the Study:
- To investigate the effects of chronic Pb exposure on hippocampal PKC activity and distribution during different developmental stages in rats.
- To determine if developmental Pb exposure influences the subcellular localization of PKC in the hippocampus.
Main Methods:
- Pregnant and lactating rats were exposed to 0.2% lead acetate in drinking water, with exposure continuing to weanlings.
- Hippocampal PKC activity was measured in both membrane and cytosolic fractions at postnatal days 7, 14, 28, and 56.
- The ratio of membrane to cytosolic PKC activity was analyzed to assess PKC distribution.
Main Results:
- Lead exposure increased cytosolic PKC activity in postnatal day 56 (PN56) rats.
- Lead exposure decreased membrane-bound PKC activity at PN7.
- A significant decrease in the membrane to cytosolic PKC activity ratio was observed in Pb-exposed rats at PN28 and PN56, indicating altered PKC distribution.
Conclusions:
- Chronic lead exposure during development significantly influences hippocampal PKC activity and its subcellular distribution.
- These Pb-induced alterations in hippocampal PKC may underlie the subclinical neurotoxicity and cognitive deficits observed in children exposed to lead.
- The findings highlight the critical impact of early-life lead exposure on brain development and function.
Abstract:
Chronic low-level lead (Pb) exposure in children is known to cause a deficit in learning and memory. In vitro studies have demonstrated that Pb altered protein kinase C (PKC) activity. Especially, hippocampal PKC has been correlated with performance in several learning tasks. The effects of Pb exposure on hippocampal PKC were investigated during development at various postnatal ages: postnatal day (PN) 7, 14, 28, and 56. Two-tenth % Pb acetate was administered to pregnant and lactating dams and then administered to weanling rats in drinking water. PKC activity was measured in both membrane and cytosolic fractions from the hippocampi of the controls and Pb-exposed animals. Pb-induced increase in PKC activity in the cytosolic fraction was observed in the PN56 rats. In contrast, PKC activity was decreased by Pb at PN7 in the membrane fraction. Furthermore, a significant decrease in the ratio of membrane to cytosolic PKC activity which is representative of PKC distribution was observed in the PN28 and PN56 Pb-exposed rats relative to the same-age controls. This study indicates that chronic Pb exposure during development influences hippocampal PKC activity and distribution. These changes may be involved in the subclinical neurotoxicity of chronic Pb exposure in young children.