Dietary restriction reveals sex-specific expression of the mTOR pathway genes in Japanese quails

Abstract

Limited resources affect an organism’s physiology through the conserved metabolic pathway, the mechanistic target of rapamycin (mTOR). Males and females often react differently to nutritional limitation, but whether it leads to differential mTOR pathway expression remains unknown. Recently, we found that dietary restriction (DR) induced significant changes in the expression of mTOR pathway genes in female Japanese quails (Coturnix japonica). We simultaneously exposed 32 male and female Japanese quails to either 20%, 30%, 40% restriction or ad libitum feeding for 14 days and determined the expression of six key genes of the mTOR pathway in the liver to investigate sex differences in the expression patterns. We found that DR significantly reduced body mass, albeit the effect was milder in males compared to females. We observed sex-specific liver gene expression. DR downregulated mTOR expression more in females than in males. Under moderate DR, ATG9A and RPS6K1 expressions were increased more in males than in females. Like females, body mass in males was correlated positively with mTOR and IGF1, but negatively with ATG9A and RS6K1 expressions. Our findings highlight that sexes may cope with nutritional deficits differently and emphasise the importance of considering sexual differences in studies of dietary restriction.

Sex‐specific effects of dietary restriction on physiological variables in Japanese quails

“…While the observed effect trend in males aligned with the previously reported trend in body mass (Reda, Ndunguru, Csernus, Knop, Lugata, et al, 2024), females exhibited a different pattern, wherein the effect on body mass intensified with the severity of restriction .…”

“…As we have previously reported, DR substantially reduced body mass in both female and male birds, though the effect was more pronounced in females (Reda, Ndunguru, Csernus, Knop, Lugata, et al, 2024;.…”

“…Our previous report of gene expression patterns from the same experiment also indicated that hepatic IGF1 gene expression was consistently higher in females than males across dietary regimens (Reda, Ndunguru, Csernus, Knop, Lugata, et al, 2024). Other studies in sexually dimorphic lizards (Anolis sagrei and A. apletophallus) reported a male-dominated expression of hepatic IGF-1 network genes (Cox et al, 2017(Cox et al, , 2022.…”

“…Additionally, the physiological response to dietary restriction may vary among avian species. For instance, we previously found that DR decreased liver IGF1 gene expression in male and female Japanese quails (Coturnix japonica) (Reda, Ndunguru, Csernus, Knop, Lugata, et al, 2024), whereas other studies have reported that DR increased plasma IGF-1 in female canaries (Serinus canaria) (Hargitai et al, 2022), broiler chicken hens (Hocking et al, 1994) and male and female bearded reedlings (Panurus biarmicus) (Tóth et al, 2022). These mixed results indicate that, based on the existing evidence, it is difficult to draw a general conclusion about how changes in food availability affect the IGF-1 system.…”