Effect of feeding regimen on circadian activity rhythms of food anticipatory by ghrelin hormone in a pig model

ABSTRACT

Increasingly diverse meal patterns affect the internal body clock. Ghrelin secretion is closely associated with the anticipation of a regularly scheduled mealtime, leading ghrelin to be a putative candidate for food-related entraining signals that drive activity rhythms. Here, growing pigs with different meal frequencies were used to construct an irregular eating pattern model. We found that irregular eating patterns changed central ghrelin levels of pigs, affected the circadian entrainment and circadian rhythm pathways in hypothalamus tissue, and altered the daily behavior and food anticipatory activity (FAA). To determine whether ghrelin exerts an effect, growing pigs were intravenously injected with ghrelin antagonist [D-Lys3]-GHRP-6 for 7 days. We showed here that [D-Lys3]-GHRP-6 administration decreased locomotor activity of growing pigs in the 4-h window preceding onset of food availability. In addition, we also confirmed that the direct role of ghrelin in molecular mechanism of regulating clock genes expression via calcium mobilization through intracellular PKC/PLC and AC/PKA pathways in vitro. Collectively, irregular eating patterns affect the central circadian system by ghrelin, supporting ghrelin as a temporal messenger of food-entrainment in hypothalamic circadian functions.

KEYWORDS:

• Irregular eating pattern
• gene set enrichment analysis
• food anticipatory activity
• clock gene
• ghrelin
• hypothalamus
• calcium mobilization
• growing pig

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The RNA-seq datasets are available at NCBI project PRJNA718234.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (32072688 and 31872362) and the National Key R&D Program of China (2018YFD0500404).

Notes on contributors

He Zhang

He Zhang is a PhD. student at Nanjing Agricultural University; Master degree in Veterinary (South China Agricultural University).

Xiaoxi Yan

Xiaoxi Yan is a Master student at Nanjing Agricultural University.

Ailian Lin

AiLian is a Master student at Nanjing Agricultural University.

Pengke Xia

Pengke Xia is a Master student at Nanjing Agricultural University.

Menglan Jia

Menglan Jia is a Master student at Nanjing Agricultural University.

Yong Su

Yong Su is a Professor at Nanjing Agricultural University.