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C57 aged mice

Jiangsu Aniphe BioLab boasts highly standardized laboratory animal facilities and maintains an ample supply of aged mice, offering ready‑to‑use multi‑age mouse models. Supported by a robust inventory system, the company can swiftly meet customer demands, significantly shortening the timelines for aging‑related research and overcoming the time constraints inherent in animal studies on aging.

Strain Introduction

C57 elderly mice are a classic aging model generated through natural aging on the C57BL/6 genetic background. They effectively mimic the physiological and functional changes that occur with age and are widely used in studies of aging mechanisms, the development of age‑related disease models, the screening of anti‑aging drugs, and preclinical translational research.

With advancing age, C57 elderly mice exhibit hallmark aging phenotypes, including declining organ function, impaired immune responses, metabolic dysregulation, reduced muscle mass, decreased bone density, and deteriorating cognitive function, accompanied by chronic low-grade inflammation and diminished tissue repair capacity—features that closely resemble the natural aging process in humans.

Product Advantages

Natural aging model

It accurately reflects the aging process of the organism and exhibits high clinical relevance.

Genetic background is stable.

Based on the classic C57BL/6 strain, the experiment exhibits good reproducibility and data consistency.

Wide range of applications

It is applicable to multiple research areas, including aging biology, neurodegenerative diseases, osteoporosis, cancer, metabolic disorders, and immune senescence.

High conversion value

It can be used for studies on pharmacodynamics, pharmacokinetics, and mechanisms of action, providing a reliable in vivo research model for the development of anti‑aging drugs and preclinical evaluation.

Data parameters

Strain Name

Aged C57BL/6J mice
Targeted gene

None (non-GMO model)
Mutant site

None
Types of gene editing

None (natural aging)
Genetic background

C57BL/6J inbred strain
Microbial Grade

SPF grade

Validate data

C57BL/6 normal phenotypic changes

Tumor changes

In aged mice, body weight steadily increases with age, and inter‑individual variability also grows. By around 15 months of age, behaviors such as aggression, excessive grooming, rectal prolapse, cataracts, and spontaneous tumors become more common.

 

 

Hair changes

Grooming is a social behavior in mice, used to signal one’s rank within the group. Lower-ranking mice, due to frequent grooming, may experience hair loss or bald patches—most commonly on the whiskers and back. Females groom more often than males. As mice age, their coat color becomes progressively darker and lighter, with the appearance of some white hairs, and the fur thins—hair loss typically begins near the rump and gradually spreads to the back.

 

Changes in the dorsal fur of mice; image source: Aniphe BioLab.

As shown in the figure above, compared with young mice, aged mice exhibit reduced hair growth length and rate, along with an exceptionally prolonged telogen phase. This inability to re-enter the anagen phase is referred to as “telogen retention.”

The authors of J Invest Dermatol subsequently conducted transplantation experiments to verify whether the skin’s external environment influences hair growth, and then investigated at the molecular level the factors underlying this effect.

 

Transplantation of hair from C57 elderly mice into SCID mice to investigate the effects of the skin microenvironment on hair growth.

 

Experiment on the Effects of Follicle-Inhibiting Protein on Hair Growth in Aged Mice

Through a series of experiments, it has been determined that the thinning fur observed in aged mice results from their hair follicles being trapped in a prolonged “quiescent phase,” preventing them from re-entering the growth phase. Moreover, the skin microenvironment plays a critical role in hair growth; analysis revealed that, in aged mice, follistatin levels are downregulated, while the Wnt pathway inhibitors Dkk1 and Sfrp4 are upregulated—factors that collectively contribute to this phenomenon. It is hoped that these findings will help students and faculty better understand the mechanisms underlying hair growth in aging mice.

Changes in hearing

In old age, hearing (auditory function) gradually declines with advancing age, primarily due to the absence of the Ahl gene, which manifests as disruption of both inner and outer hair cells. Consequently, the auditory‑evoked brainstem response (ABR) threshold is elevated, making audiogenic seizures less likely to be triggered.

 

Comparison of hearing in C57BL/6J mice across different postnatal ages (n=5)

 

Phenotypic Changes in C57BL/6 Mice

Rectal prolapse

In mice, due to their relatively short rectum, age-related atrophy of the pelvic musculature can make the rectum more prone to prolapse.

Ocular lesions

Relatively speaking, mice have a larger corneal surface area, making them more susceptible to foreign-body exposure and subsequent inflammation. Furthermore, with aging, atrophy of the lacrimal glands and chronic inflammatory conditions can lead to reduced tear production and excessive corneal damage, ultimately resulting in ocular opacity and other pathological manifestations.

Palpable mass

Such subcutaneous or palpable masses within the body may be neoplastic lesions that develop with aging, or they may represent cysts. The most immediate consequence of the formation of an excessively large mass is impaired mobility in mice, which can, in turn, have adverse effects on their overall health.

 

 

Behavioral testing

Cognitive decline, depression, and anxiety-like behavioral changes

Experiments demonstrated that, compared with 2‑month‑old and 12‑month‑old mice, 24‑month‑old mice exhibited varying degrees of impairment in recognition memory, working memory, and spatial memory. In the forced swim test and the tail suspension test, aged mice showed a significantly prolonged immobility time, indicating the emergence of depression‑like behaviors. Both the open‑field test and the elevated plus maze test revealed pronounced anxiety‑like behaviors in aged mice.

 

Changes in Recognition Memory and Working Memory in Aged Rats

 

The Morris Water Maze Test Evaluates Changes in Spatial Memory Across Different Age Groups of Mice

 

Depression-like behavioral changes in aged mice

 

Anxiety-like behavioral changes in mice

 

Learning ability

Male C57 mice of advanced age typically exhibit higher activity levels and enhanced learning capabilities, making them more suitable than their female counterparts for research in neuroscience, behavioral science, and related fields.

 

 

Scores of C57BL/6 mice of different ages in the nest-building task

 

 

The digging weight of C57BL/6 mice of different ages and sexes

 

Body weight/survival curve of aged C57BL/6 mice

Survival curve

Many researchers, when conducting studies involving aged mice, often find themselves uncertain about the precise chronological age of these animals. Using human age as a reference, mice can be categorized into three stages—adult, middle-aged, and old—with an overall survival rate of approximately 50%.

01 The 3–6-month-old age range in mice corresponds to that of young adults (20–30 years old); at this stage, development is complete and the organism has not yet been affected by aging.

02 In mice, the age range of 10–15 months corresponds to middle age (38–47 years); aging-related changes can be detected for some but not all aging biomarkers.

03 In mice, the age range of 18–24 months corresponds to that of elderly humans (56–69 years); at this stage, nearly all aging‑related biomarkers exhibit detectable changes. According to published data, during the first month after birth, the growth rate of mice is approximately 150 times that of humans; from 1 to 6 months of age, it is about 45 times faster; and after 6 months, the growth rate is roughly 25 times that of humans.

 

 

Survival curve of C57BL/6J mice

 

Weight change

After 10 months of age, body weight typically increases to over 32 grams (note that mouse strain and diet can also influence body weight). By 15 months, most mice routinely reach a body weight of at least 33 grams. At 18 months, the body weight of aged male mice generally falls within the range of 32 to 38 grams. For females, it is standard practice to house retired animals in mixed-sex groups after eight months; normally, females weigh at least 23 grams. Once females exceed 18 to 21 months of age, their body weight usually remains above 29 grams, and by 22 months, their weight typically surpasses 30 grams, with some individuals reaching as much as around 40 grams.

 

 

Body weight ranges for female and male rats across age groups

 

Pathological examination

Increased CD8+ T cells

In the aging brain, there is a marked increase in CD8+ T cells. These cells accumulate with age, damage neurons, and contribute to the decline of cognitive and motor functions. When the number of CD8+ T cells is reduced, or when they fail to become activated or to express cytotoxic effector molecules, the age‑related damage to the brain is significantly attenuated, and the age‑induced impairment of motor function shows partial recovery.

 

 

 

 

Sex Differences in Cell-Specific Neurons of the Hypothalamic Defense System

Fluorescence in situ hybridization was used to label the vesicular glutamate transporter type 2 (Vglut2) and glutamic acid decarboxylase 2 (Gad2), thereby enabling the specific labeling of glutamatergic and γ‑aminobutyric acid (GABA)‑ergic neurons in multiple defense‑related subregions of the hypothalamus.

 

 

In female rats, the absolute number of Vglut2 mRNA‑positive neurons in the AHC was greater than that in the AHP (P<0.05), with a denser Vglut2 mRNA‑positive signal in the ventral region of the AHC adjacent to the caudal end; no statistically significant differences were observed in male rats.

 

 

In mice of both sexes, the DMHv and DMHc predominantly express Gad2 mRNA (P < 0.05). The relative proportion of neurons in the DMHd exhibits sex-specific differences: female mice show higher Gad2 mRNA expression in the DMHd (P < 0.05), whereas in male mice, the expression levels of Vglut2‑ and Gad2‑positive neurons are comparable.

Application areas

● C57BL/6J is used in a wide range of research areas, including cardiovascular biology, developmental biology, diabetes and obesity, genetics, immunology, neurobiology, and sensory neuroscience.
● It exhibits a low spontaneous incidence of mammary tumors, and chemical agents rarely induce mammary or ovarian neoplasms. It shows moderate tolerance to ionizing radiation, high complement activity, and a propensity to develop immune tolerance; it is susceptible to Mycobacterium tuberculosis and possesses some resistance to the mousepox virus. Interferon production is relatively high, it is sensitive to pertussis‑related histamine‑sensitive factors, has a strong preference for alcohol, and displays low concentrations of adrenal‑derived lipids. Often regarded as a “standard” inbred strain, it provides a genetic background for numerous genetically engineered mouse models.
● In addition, C57BL/6J mice are resistant to audiogenic seizures, exhibit relatively low bone mineral density, and develop age‑related hearing loss. They are also prone to diet‑induced obesity, type 2 diabetes, and atherosclerosis, and are frequently used in studies related to neurodegenerative diseases and bone density.

Breeding Techniques and Precautions

Strictly control inbreeding systems to mitigate genetic diversity.

 

When caging, avoid placing mice from different cages into the same box; it is recommended to house 2–3 individuals per cage. If aggression is severe, adopt a single‑mouse‑per‑cage housing regime.

Strictly control environmental stimuli to reduce experimental stress.

 

When replacing the bedding, set aside a small amount of the old bedding and place it on top of the new bedding to preserve the original scent.

Standardize breeding management to improve the survival rate of pups.

 

Place the animal housing cage in a quiet environment, ensuring adequate space between the cage and the walls to minimize excessive noise, vibration, and other disturbances.

 

Monitor age-related spontaneous lesions and eliminate experimental confounding.

 

Observe the experimental mice daily; if fighting is observed in the cage, isolate the strongest individual—free of injuries and with intact whiskers—and house it in a separate cage. At the same time, disinfect any injured animals daily with 75% ethanol or iodine tincture; they typically recover within 5–7 days.

Control male mouse fighting and standardize breeding practices.

 

Adding nesting materials to the bedding—such as shredded paper, cardboard tunnels, and shelters—and placing well‑wrung cotton balls soaked in povidone‑iodine inside the mouse cage can reduce grooming and fighting behaviors.

Control male mouse fighting and standardize breeding practices.

 

Sex differences in C57 mice of advanced age can influence experimental outcomes; therefore, when conducting experiments with aged animals, it is essential to gain prior knowledge of these differences and implement appropriate measures to ensure the accuracy and reliability of the results.

 

 

 

Literature support

Scientific papers published by Aniphe customers using this model are eligible for SCI-indexed publication. (Original paper link)
1.Nat Commun. 2024 Apr 5;15(1):2939.
2. Nat Commun. 2024 Jul 9;15(1):5761.

Frequently Asked Questions

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Q1. Compared with rapid aging models such as SAMP8 and D-galactose‑induced aging, how do C57老年 mice differ?

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A: SAMP8 mice, a rapid‑aging strain, harbor genetic mutations that primarily manifest as accelerated cognitive decline; however, their phenotypes are relatively limited and differ substantially from the etiologies of sporadic Alzheimer’s disease in humans.
D-galactose–induced model: This is a chemically induced oxidative stress–driven accelerated aging model that features a short modeling period; however, it mimics telomere‑independent aging and is subject to off‑target effects and toxicity inherent to the drug itself.
C57 natural aging model: exhibits synchronous decline across multiple systems and organs, accurately reflecting the cumulative progression of age‑related chronic diseases. It is particularly well suited for evaluating holistic anti‑aging strategies—such as dietary restriction and senolytics—and serves as the most reliable bridge for extrapolating findings to humans.

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Q2. How should the control group be set up in an experiment?

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A: It is strongly recommended to use young adult mice of the same strain, sex, and batch (typically 3–4 months old) as the baseline control. Historical data or animals that do not fully match are not advised. If the study examines the transition from middle age to old age, three groups can be established—3–4 months (young baseline), 10–14 months (middle age), and ≥18 months (old age)—to distinguish age‑related changes.

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