犊牦牛肾周棕色脂肪组织的发育及其产热相关基因的表达分析OA

Brown adipose tissue(BAT)serves as a primary heat-producing organ in non-shivering thermogenesis(NST)and plays a crucial role in the cold adaptation of neonatal animals.To investigate the development of kidney-adjacent brown adipose tissue(BAT)and the expression of thermogenesis-related genes in calves and yak calves,fat tissues were collected from the kidney-adjacent regions of 1-day-old,7-day-old,and 30-day-old animals.The study employed hematoxylin and eosin(H.E.)staining for observing fat cells,transmission electron microscopy for studying the ultrastructure of lipid droplets and mitochondria,immunohistochemical staining,real-time quantitative PCR,and Western blot to examine the expression of uncoupling protein 1(UCP1)in fat cells,as well as the mRNA expression levels of peroxisome proliferator-activated receptor alpha(PPARα)and peroxisome proliferator-activated receptor gamma coactivator 1-alpha(PGC-1α).The results showed the presence of two types of fat cells in the kidney-adjacent area:brown adipose cells with small lipid droplets and abundant mitochondria,and white adipose cells with large lipid droplets and fewer mitochondria.Compared to 1-day-old animals,the area and density of white adipose cells significantly increased(P＜0.05),while brown adipose cell area and density significantly decreased in 7-day-old and 30-day-old animals(P＜0.05).UCP1-positive expression was observed on the cytomembrane of brown and white adipose cells in different age groups.The intensity of UCP1-positive expression in fat cells significantly decreased in 7-day-old and 30-day-old animals compared to 1-day-old animals(P＜0.05).The mRNA expression levels of BAT thermogenesis-related genes(UCP1,PPARα,and PGC-1α)in kidney-adjacent fat tissue of 30-day-old animals significantly decreased compared to 1-day-old animals(P＜0.05).The protein expression level of UCP1 in kidney-adjacent fat tissue significantly decreased in 7-day-old and 30-day-old animals compared to 1-day-old animals(P＜0.05).The results indicate a gradual decrease in the number of brown adipose cells and an increase in white adipose cells in the kidney-adjacent area after birth,accompanied by a gradual decrease in the expression levels of thermogenesis-related genes.This study provides valuable information for further exploration of the cold adaptation mechanisms in calves and yak calves.