Concentrations of hormones and metabolites in cerebrospinal fluid and plasma of dairy cows during the periparturient period
Concentrations of hormones and metabolites in cerebrospinal fluid and plasma of dairy cows during the periparturient period
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DOI：
10.3168/jds.2012-5909
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发表时间：
2013-05-01
影响因子：
3.5
通讯作者：
Kuhla, B.
中科院分区：
文献类型：
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作者：
Laeger, T.;Sauerwein, H.;Kuhla, B.
在泌乳早期，高产奶牛通常表现出采食量不足（FI），因此，它们进入与血浆代谢物和激素模式改变相关的负能量平衡。这些作为大脑中的短期和长期饥饿或饱足信号，在控制FI中发挥重要作用。脑脊髓液（CSF）中也存在代谢物和激素，CSF围绕着下丘脑和脑干，这是FT调节的两个主要中心。CSF激素和代谢物浓度主要受血脑屏障控制。因此，CSF激素和代谢物浓度与血液中的不同。然而，到目前为止，尚未研究可能导致高产奶牛泌乳早期FT不足的假定食欲和食欲刺激CSF信号的贡献。因此，本研究的目的是阐明在围产期期间血浆和CSF激素和代谢物之间存在的关联。对10头经产德国荷斯坦奶牛进行自由采食，并在产犊后第-20、-10、+1、+10、+20和+40天早晨饲喂前采集脊髓CSF和颈静脉血液样本。采食量从产犊前第5天开始下降，以后逐渐增加。葡萄糖、β-羟基丁酸酯（BHBA）、胆固醇、非酯化脂肪酸、尿素（所有酶），乳酸盐（比色法）、氨基酸（HPLC）、渗透压摩尔浓度（渗透压计），生长激素释放肽（RIA），瘦素（ELISA），（Western免疫印迹）在CSF和血浆中进行测量，而游离脂肪酸（气相色谱-质谱法）和挥发性脂肪酸（气相色谱-火焰离子化检测器）仅在血浆中测定。而瘦素浓度降低产犊后，血浆和CSF中，生长激素释放肽浓度没有改变，和总的BLORN和它的六聚体的丰度下降，只有在血浆中。虽然血浆中胆固醇和非酯化脂肪酸的浓度在围产期发生变化，但其浓度在CSF中不受影响。与此相反，CSF Gln浓度趋于增加，直到产犊，而BHBA，α-氨基丁酸，Cit，Gly，Ile，瓦尔和Leu的CSF浓度增加，在泌乳早期相比，发情期。因为已知Gln作为产生ATP的神经元底物，所以建议Gln在分娩前不久作为中枢促神经系统信号。此外，由于其已知的抑制作用，BHBA和Leu可能潜在地充当中枢信号，从而在泌乳早期抑制FT的充分增加。
During early lactation, high-yielding dairy cows often show insufficient feed intake (FI) and, as a consequence, they enter into a negative energy balance associated with an altered pattern of plasma metabolites and hormones. These act as short- and long-term hunger or satiety signals in the brain and play an important role in the control of FI. Metabolites and hormones also occur in cerebrospinal fluid (CSF), which surrounds the hypothalamus and brainstem, 2 major centers of FT regulation. The CSF hormone and metabolite concentrations are mainly under control of the blood-brain barrier. Consequently, CSF hormone and metabolite concentrations differ from those in blood. However, the contribution of putative orexigenic and anorexigenic CSF signals possibly leading to insufficient FT of high-yielding dairy cows during early lactation has not been studied so far. Therefore, the aim of this study was to elucidate associations existing between both plasma and CSF hormones and metabolites during the periparturient period. Ten multiparous German Holstein dairy cows were fed ad libitum and samples of CSF from the spinal cord and blood from the jugular vein were withdrawn before morning feeding on d -20, -10, +1, +10, +20, and +40 relative to calving. Feed intake started to decrease from d 5 before calving and increased thereafter. Glucose, beta-hydroxybutyrate (BHBA), cholesterol, nonesterified fatty acids, urea (all enzymatic), lactate (colorimetric), amino acids (HPLC), osmolality (osmometer), ghrelin (RIA), leptin (ELISA), and resistin (Western immunoblot) were measured in both CSF and plasma, whereas free fatty acids (gas chromatography-mass spectrometry) and volatile fatty acids (gas chromatography-flame-ionization detector) were determined in plasma only. Whereas leptin concentrations decreased after calving in both plasma and CSF, ghrelin concentrations were not altered, and abundances of total resistin and its hexamers decreased only in plasma. Although plasma concentrations of cholesterol and nonesterified fatty acids changed during the periparturient period, their concentrations were not affected in CSF. In contrast, CSF Gin concentration tended to increase until calving, whereas CSF concentrations of BHBA, alpha-aminobutyric acid, Cit, Gly, Ile, Val, and Leu were increased in early lactation compared with the preparturient period. Because Gin is known to serve as neuronal substrate generating ATP, Gln is suggested to act as a central anorexigenic signal shortly before parturition. Moreover, due to their known anorexic effect, BHBA and Leu may potentially act as central signals and thereby suppress a sufficient increase in FT during early lactation.