Aging Mouse Basic Data Collection Study on Histopathological Evaluation of Liver and Kidney in C57BL/6J and C57BL/6N Mice at 78 Weeks of Age

Study Overview

This study evaluated histopathological changes in the liver and kidneys of aged C57BL/6J (B6J) and C57BL/6N (B6N) mice provided by CLEA Japan. The objective was to clarify structural changes at the organ level in geriatric mice and provide this information as a fundamental resource for age-related disease research.

With the extension of average lifespans, the need for research on age-related organ disorders, including liver and kidney diseases, is growing. However, there is a lack of fundamental histological information on aged mice. In this study, we selected mice with elevated values in blood biochemistry and urinalysis to conduct a detailed pathological analysis of the liver and kidneys.

Individual Selection - C57BL/6N

• Liver selection: Mouse Nos. 7 and 10, which showed high ALT and AST values.
• Kidney selection: Mouse Nos. 19 and 24, which showed high urinary protein.
• Mouse Nos. 1 and 2 were used as controls for both liver and kidney.

Individual Selection - C57BL/6J

• Liver selection: Mouse Nos. 5 and 8, which showed high ALT and AST values.
• Kidney selection: Mouse Nos. 27 and 28, which showed high urinary protein.
• Mouse Nos. 1 and 2 were used as controls for both liver and kidney.

Materials and Methods

Animals

• C57BL/6JJcl (B6J): 30 male mice, started at 62 weeks of age.
• C57BL/6NJcl (B6N): 30 male mice, started at 64 weeks of age.

Housing Conditions

• Diet: CE-2 (autoclaved), ad libitum
• Temperature: 20–26°C, Humidity: 45–70%
• Lighting: 12-hour light / 12-hour dark cycle
• Single-caged (M cage)
• Sterilized water, ad libitum

Study Design

• Regular body weight measurements: Once every two weeks.
• Dissection and organ collection/weight measurement at 78 weeks of age.
• For this study, the liver and kidneys were fixed in formalin for histopathological evaluation.

Individual Selection Criteria

• Liver evaluation: Two mice with high ALT and AST values, and two control mice.
• Kidney evaluation: Two mice with high urinary protein, and two control mice.

Evaluation Methods

• Scoring of pathological changes (+++: severe, ++: moderate, +: mild, ±: very mild, -: normal).
• Items observed: Liver (vacuolization, hypertrophy, focal necrosis), Kidney (adhesion, enlargement, etc.).

Results

Histopathological Evaluation of Liver and Kidney

Results: Histopathological Evaluation (Liver) C57BL/6N

Results: Histopathological Evaluation (Kidney) C57BL/6N

• Focal necrosis (moderate to severe) was observed in two mice with high ALT/AST values.
• Findings such as fatty liver and hepatocyte hypertrophy, which may be age-related, were also confirmed.

Results: Histopathological Evaluation (Liver) C57BL/6J

Results: Histopathological Evaluation (Kidney) C57BL/6J

• Focal necrosis was observed in the B6J strain as well, but no clear correlation with blood parameters was found.

Summary

Liver

• Focal necrosis was observed in two C57BL/6N mice that showed elevated liver function parameters.
• Focal necrosis was also confirmed in other individuals, including C57BL/6J mice, ranging from moderate to severe, but no correlation with liver function parameters was seen.
• ⇒ Fatty liver and hepatocyte hypertrophy may be age-related changes.

Kidney

• Effects on glomeruli were observed, but there was no correlation with urinary protein.
• (The degree of glomerular injury was more severe in C57BL/6J mice than in C57BL/6N mice.)
• ⇒ The glomerular findings may also be age-related.
• No tubular damage was observed in either strain.

Related Links

• [Study: Various Test Data]

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