The Regulatory Mechanism of Feeding a Diet High in Rice Grain on the Growth and microRNA Expression Profiles of the Spleen, Taking Goats as an Artiodactyl Model

SIMPLE SUMMARY: Feeding with a diet high in rice often results in several adverse effects for animals, such as ruminal acidosis, the translocation of endotoxin into the bloodstream, gastrointestinal barrier impairment, liver injures, and inflammation. A high rice grain-based diet also provides excess energy for human beings, which usually induces obesity via an miRNA-based mechanism. Currently, whether high-rice diets affect spleen growth and related molecular events remains unknown. Therefore, we take goats as an artiodactyl model to investigate the effects of feeding a highly concentrated diet, based on rice grains, on the growth and microRNA expression profiles in the goat spleen. Here, we first report about the splenic microRNA profile in artiodactyls fed a highly concentrated diet based on rice. Our results shed light on the miRNA-based regulatory mechanism that contributes to the development of high calorie-induced metabolic diseases in mammals. ABSTRACT: Several researchers have testified that feeding with diets high in rice grain induces subacute ruminal acidosis and increases the risk of gastrointestinal inflammation. However, whether diets high in rice grain affect spleen growth and related molecular events remains unknown. Therefore, the present study was conducted to investigate the effects of feeding a high-concentrate (HC) diet based on rice on the growth and microRNA expression profiles in goat spleen. Sixteen Liuyang black goats were used as an artiodactyl model and fed an HC diet for five weeks. Visceral organ weight, LPS (lipopolysaccharide) concentration in the liver and spleen, and microRNA expression were analyzed. The results showed that feeding an HC diet increased the heart and spleen indexes and decreased the liver LPS concentration (p < 0.05). In total, 596 microRNAs were identified, and twenty-one of them were differentially expressed in the spleens of goats fed with the HC diet. Specifically, several microRNAs (miR-107, miR-512, miR-51b, miR-191, miR-296, miR-326, miR-6123 and miR-433) were upregulated. Meanwhile, miR-30b, miR-30d, miR-1468, miR-502a, miR-145, miR-139, miR-2284f, miR-101 and miR-92a were downregulated. Additionally, their target gene CPPED1, CDK6, CCNT1 and CASP7 expressions were inhibited (p < 0.05). These results indicated that the HC diet promoted the growth of the heart and spleen. The HC diet also regulated the expression of miR-326, miR-512-3p, miR-30b, miR-30d, miR-502a and their target genes (CPPED1, CDK6 and CCNT1) related to the enhancement of splenocyte proliferation. The HC diet also modulated the expression of miR-15b-5p, miR-1468 and miR-92a, related to the suppression of splenocyte apoptosis.