The phrase "middle aged mice" is correct and can be used in written English.
It refers to mice that are in the middle stage of their lifespan, typically between youth and old age. Example: The group of researchers studied the behaviors of middle aged mice to understand the effects of aging on their cognitive abilities.
Several differentially expressed genes in middle aged-mice were related to hepatocyte proliferation.
To determine data-relevant age cohorts, we tested young mice at 3-4 months-of-age, middle-aged mice at 10-12 months-of-age, and old mice at 18-24 months-of-age.
We also demonstrate that BECs synthesize more TGF-β1 as they are irradiated and that the increase in the TGF-β1 levels within vascular niches is an early molecular sign of aging in middle-aged mice.
In addition to our data implicating CD36 in age-induced NAFLD, we also report that middle-aged mice show a decline in the protein expression levels of the mitochondrial electron transport chain protein expression (complex I-IV), suggesting that fat oxidation is impaired in middle-aged mice irrespective of HF-feeding.
To further investigate the correlation between aging and hepatic CD36 expression, we assessed CD36 expression in middle-aged mice fed a chow-diet for one year.
By mining gateway genes related to hippocampal aging from networks made from gene expression in young and middle-aged mice, we provide a proof-of-concept of existence and importance of gateway nodes.
Moreover, liver to body weight ratio was significantly increased in middle-aged mice as compared to young mice fed a HFD (HF young: 2.1 ± 0.2; HF aged: 4.1 ± 0.2, p≤0.05).
However, we did not observe an age- or HFD-associated increase in Parkin expression in middle-aged mice compared to young mice.
And when middle-aged mice were injected with the gene, their muscles did not weaken in old age.
Moreover, CD36 gene- and protein expression levels were significantly increased by the combined effects of age and HFD feeding (Fig. 4A-C), suggesting enhanced CD36-mediated hepatic fat uptake in middle-aged mice fed a HFD.
