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Severe functional and structural changes caused by lithium in the developing rat kidney
Insights
Post-natal lithium exposure in rats significantly impairs kidney development, causing growth retardation and reduced kidney function. Prenatal lithium exposure had minimal effects on the developing kidney.
Area of Science:
- Nephrology
- Developmental Biology
- Toxicology
Background:
- Lithium (Li) is used to treat bipolar disorder.
- Its effects on the developing kidney are not fully understood.
- Assessing developmental toxicity is crucial for patient safety.
Purpose of the Study:
- To investigate the impact of lithium exposure during pregnancy and post-natal development on rat kidney function and structure.
- To determine the sensitivity of the developing kidney to lithium's nephrotoxic effects.
Main Methods:
- Rats were administered lithium during maternal pregnancy and/or for 8 weeks post-natally.
- Plasma lithium levels were monitored.
- Renal function (glomerular filtration rate, concentrating ability) and kidney structure were assessed.
- Morphometric analysis quantified tubular cell volume.
Main Results:
- Post-natal lithium exposure caused growth retardation, polyuria, reduced concentrating ability, and uremia.
- Glomerular filtration rate (GFR) decreased by up to 80% after post-natal lithium exposure.
- Severe structural changes included cortical cysts, interstitial fibrosis, and tubular atrophy.
- Prenatal lithium exposure alone had minimal effects on renal function and structure.
- Post-natal lithium exposure showed a significant correlation between structural changes and reduced GFR.
Conclusions:
- The developing rat kidney is highly sensitive to lithium's nephrotoxic effects during the post-natal period.
- Post-natal lithium exposure impairs renal function and leads to uremia.
- Prenatal lithium exposure has limited long-term effects on renal function and structure when evaluated post-natally.
Abstract:
Lithium (Li) was administered to rats during maternal pregnancy and/or 8 weeks post-natally, to study the effects on renal function and structure in the developing kidney. Plasma Li was 0.5-1.0 mmol/l 3 and 8 weeks post-natally. Functionally, post-natal Li leads to growth retardation, polyuria with lowering of renal concentration ability, and uremia associated with as much as 80% lowering of the normal glomerular filtration rate (GFR). Pre-natal Li alone did not affect the concentrating ability but caused a 20% increase in GFR when evaluated 8 weeks post-natally. Post-natal Li caused very severe structural changes, consisting of up to 3 mm cortical cysts (= dilated distal convoluted tubules), extensive interstitial fibrosis with cell infiltration, and atrophy of the cortical collecting ducts. Morphometric measurements showed a significant reduction in the volume of the proximal tubular cells. Pre-natal Li caused only slight structural changes, and animals treated both pre- and post-natally were less affected than animals treated post-natally only. The structural changes caused by post-natal Li were unrelated to changes in the concentrating ability but showed a significant correlation with the lowering of the GFR. It is concluded that the post-natally developing rat kidney is particularly sensitive to the nephrotoxic effects of Li, which in low concentrations causes impairment of renal function, leading to uremia. Pre-natal Li exposure by maternal lithium treatment had little effect on renal function and structure when evaluated post-natally.