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Spontaneous Age-Related Histopathological Changes in Microminipigs
Akihisa Kangawa1, Toshiaki Nishimura2, Takashi Nishimura2
1Swine and Poultry Department, Shizuoka Prefectural Research Institute of Animal Industry, Swine and Poultry Research Center, Shizuoka, Japan.
Abstract:
Microminipigs have become an attractive animal model for toxicology and pharmacology studies and for human disease models, owing to their manageable size. Although there are numerous reports of spontaneous age-related lesions in mice, rats, dogs, and monkeys, those in minipigs are scarce. In the present study, spontaneous age-related histopathological changes were investigated using 37 microminipigs (20 males and 17 females) that were 6 months to 10 years of age. Abnormal deposits of materials were evident in several animals from 6 years of age, and these deposits included amyloid in the renal medulla, thyroid gland, and adrenal gland, hyaline droplets in glomeruli, and fibrillar inclusions in neurons. Arterial sclerosing changes (intimal thickening, intimal proliferation, and medial mineralization) and proliferative lesions (hyperplasia of hepatocytes, follicular cells, Leydig cells, and uterine endometrial glands) were present at 4 years of age and beyond. Renal adenoma, uterine leiomyoma, and Leydig cell tumor were observed in several microminipigs. Moreover, glomerulosclerosis, renal interstitial fibrosis, thymic involution, and adrenocortical cell vacuolation were common in aging microminipigs. Since knowledge of age-related changes is helpful for pathologists, the basic information obtained in this study will be a useful reference for all future toxicity evaluations in microminipigs.
Insights
Microminipigs show spontaneous age-related lesions, including amyloid deposits and arterial changes, from 4-6 years old. This study provides essential histopathological data for future toxicity evaluations in this animal model.
Area of Science:
- Veterinary Pathology
- Comparative Pathology
- Toxicological Pathology
Background:
- Microminipigs are increasingly used in toxicology, pharmacology, and disease modeling.
- Spontaneous age-related lesions are well-documented in other species but scarce in minipigs.
Purpose of the Study:
- To investigate spontaneous age-related histopathological changes in microminipigs.
- To establish a baseline for age-associated pathology in this model.
Main Methods:
- Histopathological examination of 37 microminipigs (6 months to 10 years old).
- Analysis of spontaneous lesions across various organs.
Main Results:
- Amyloid deposits, hyaline droplets, and neuronal inclusions observed from 6 years of age.
- Arterial sclerosing and proliferative lesions noted from 4 years of age.
- Neoplasms (renal adenoma, uterine leiomyoma, Leydig cell tumor) and other degenerative changes (glomerulosclerosis, fibrosis, involution) identified in aging animals.
Conclusions:
- Microminipigs exhibit distinct spontaneous age-related histopathological changes.
- This data serves as a crucial reference for interpreting toxicity studies in microminipigs.
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