PDF(Pubmed)
Abstract：
UNASSIGNED: Glutamine in milk is believed to play an important role in neonatal intestinal maturation and immune function. For lactating mothers, glutamine utilization is increased to meet the demands of the enlarged intestine and milk production. However, the source of such glutamine during lactation has not been studied.
UNASSIGNED: We aimed to assess the effects of lactation on the expression of glutamine synthetase (GS) in the mammary gland and other tissues of lactating mice.
UNASSIGNED: Mouse tissues were sampled at 4 time points: 8-wk-old (virgin, control), post-delivery day 5 (PD5, early lactation), PD15 (peak lactation), and involution (4 days after weaning at PD21). We examined the gene expression and protein concentrations of GS and the first 2 enzymes of branched-chain amino acid catabolism: branched-chain aminotransferase 2 (BCAT2) and branched-chain ketoacid dehydrogenase subunit E1α (BCKDHA).
UNASSIGNED: The messenger RNA (mRNA) expression and protein concentrations of GS in mammary glands were significantly lower at PD5 and PD15 compared with the control but were restored at involution. Within the mammary gland, GS protein was only detected in adipocytes with no evidence of presence in mammary epithelial cells. Compared with the control, mRNA and protein concentrations of BCAT2 and BCKDHA in mammary glands significantly decreased during lactation and involution. No changes in GS protein concentrations during lactation were found in the liver, skeletal muscle, and lung. In non-mammary adipose tissue, GS protein abundance was higher during lactation compared with the virgin.
UNASSIGNED: This work shows that, within the mouse mammary gland, GS is only expressed in adipocytes and that the relative GS abundance in mammary gland sections is lower during lactation. This suggests that mammary adipocytes may be a site of glutamine synthesis in the lactating mouse. Identifying the sources of glutamine production during lactation is important for optimizing milk glutamine concentration to enhance neonatal and maternal health.
UNASSIGNED: We aimed to assess the effects of lactation on the expression of glutamine synthetase (GS) in the mammary gland and other tissues of lactating mice.
UNASSIGNED: Mouse tissues were sampled at 4 time points: 8-wk-old (virgin, control), post-delivery day 5 (PD5, early lactation), PD15 (peak lactation), and involution (4 days after weaning at PD21). We examined the gene expression and protein concentrations of GS and the first 2 enzymes of branched-chain amino acid catabolism: branched-chain aminotransferase 2 (BCAT2) and branched-chain ketoacid dehydrogenase subunit E1α (BCKDHA).
UNASSIGNED: The messenger RNA (mRNA) expression and protein concentrations of GS in mammary glands were significantly lower at PD5 and PD15 compared with the control but were restored at involution. Within the mammary gland, GS protein was only detected in adipocytes with no evidence of presence in mammary epithelial cells. Compared with the control, mRNA and protein concentrations of BCAT2 and BCKDHA in mammary glands significantly decreased during lactation and involution. No changes in GS protein concentrations during lactation were found in the liver, skeletal muscle, and lung. In non-mammary adipose tissue, GS protein abundance was higher during lactation compared with the virgin.
UNASSIGNED: This work shows that, within the mouse mammary gland, GS is only expressed in adipocytes and that the relative GS abundance in mammary gland sections is lower during lactation. This suggests that mammary adipocytes may be a site of glutamine synthesis in the lactating mouse. Identifying the sources of glutamine production during lactation is important for optimizing milk glutamine concentration to enhance neonatal and maternal health.
摘要：
■牛奶中的谷氨酰胺被认为在新生儿肠道成熟和免疫功能中起重要作用。对于哺乳期的母亲来说，增加谷氨酰胺利用率以满足扩大的肠道和牛奶生产的需求。然而,哺乳期间这种谷氨酰胺的来源尚未研究。
■我们旨在评估泌乳对泌乳小鼠乳腺和其他组织中谷氨酰胺合成酶（GS）表达的影响。
■在4个时间点对小鼠组织进行采样：8周龄（处女，control),分娩后第5天（PD5，早期泌乳），PD15（泌乳高峰），和退化（PD21断奶后4天）。我们检查了GS的基因表达和蛋白质浓度以及支链氨基酸分解代谢的前2种酶：支链氨基转移酶2（BCAT2）和支链酮酸脱氢酶亚基E1α（BCKDHA）。
■在PD5和PD15时，乳腺中GS的信使RNA（mRNA）表达和蛋白质浓度明显低于对照组，但在退化时恢复。在乳腺内，GS蛋白仅在脂肪细胞中检测到，在乳腺上皮细胞中没有存在的证据。与对照相比，在泌乳和退化期间，乳腺中BCAT2和BCKDHA的mRNA和蛋白质浓度显着降低。在哺乳期肝脏中没有发现GS蛋白浓度的变化，骨骼肌,还有肺.在非乳腺脂肪组织中，与处女相比，哺乳期GS蛋白丰度更高。
■这项工作表明，在小鼠乳腺内，GS仅在脂肪细胞中表达,并且在泌乳期间乳腺切片中的相对GS丰度较低。这表明乳腺脂肪细胞可能是泌乳小鼠中谷氨酰胺合成的位点。确定哺乳期间谷氨酰胺产生的来源对于优化乳谷氨酰胺浓度以增强新生儿和产妇健康是重要的。
■我们旨在评估泌乳对泌乳小鼠乳腺和其他组织中谷氨酰胺合成酶（GS）表达的影响。
■在4个时间点对小鼠组织进行采样：8周龄（处女，control),分娩后第5天（PD5，早期泌乳），PD15（泌乳高峰），和退化（PD21断奶后4天）。我们检查了GS的基因表达和蛋白质浓度以及支链氨基酸分解代谢的前2种酶：支链氨基转移酶2（BCAT2）和支链酮酸脱氢酶亚基E1α（BCKDHA）。
■在PD5和PD15时，乳腺中GS的信使RNA（mRNA）表达和蛋白质浓度明显低于对照组，但在退化时恢复。在乳腺内，GS蛋白仅在脂肪细胞中检测到，在乳腺上皮细胞中没有存在的证据。与对照相比，在泌乳和退化期间，乳腺中BCAT2和BCKDHA的mRNA和蛋白质浓度显着降低。在哺乳期肝脏中没有发现GS蛋白浓度的变化，骨骼肌,还有肺.在非乳腺脂肪组织中，与处女相比，哺乳期GS蛋白丰度更高。
■这项工作表明，在小鼠乳腺内，GS仅在脂肪细胞中表达,并且在泌乳期间乳腺切片中的相对GS丰度较低。这表明乳腺脂肪细胞可能是泌乳小鼠中谷氨酰胺合成的位点。确定哺乳期间谷氨酰胺产生的来源对于优化乳谷氨酰胺浓度以增强新生儿和产妇健康是重要的。
