Koistinen H A, Karonen S L, Iivanainen M, Koivisto V A
Helsinki University Central Hospital, Helsinki, Finland.
Eur J Clin Invest. 1998 Nov;28(11):894-7. doi: 10.1046/j.1365-2362.1998.00386.x.
Leptin is an adipocyte-derived hormone that is thought to provide a negative feedback signal to control body fat mass by interacting with its hypothalamic receptor. The present study was undertaken to examine the uptake of leptin in cerebrospinal fluid (CSF) space in humans and whether the transport of leptin into CSF space is an active phenomenon or due to free access through the blood-CSF barrier.
We determined serum and CSF leptin concentrations by radioimmunoassay in 17 men [42 +/- 4 years, mean +/- SE; body mass index (BMI) 27.3 +/- 1.8 kg m-2] and 22 women (40 +/- 3 years, BMI 25.1 +/- 1.0 kg m-2). The function of the blood-CSF barrier was evaluated by determining the CSF/serum albumin ratio.
Serum leptin concentration was lower in male (5.8 +/- 1.6 microgram L-1) than in female subjects (13.1 +/- 1.7 microgram L-1, P = 0. 001), whereas the concentrations of leptin in CSF were virtually identical in male (0.34 +/- 0.03 microgram L-1) and female (0.36 +/- 0. 03 microgram L-1) subjects. Serum leptin was correlated positively with BMI both in men (r = 0.89, P < 0.01, n = 10) and in women (r = 0.61, P < 0.05, n = 14), whereas no correlation between CSF leptin concentration and BMI was found in either group. The CSF/serum leptin ratio correlated negatively with serum leptin concentration both in men (r = -0.93, P < 0.001) and in women (r = -0.77, P < 0. 001) and with BMI both in men (r = -0.75, P = 0.02, n = 10) and in women (r = -0.64, P < 0.02, n = 14). The CSF/serum albumin ratio was not correlated with the CSF/serum leptin ratio in either group. CSF leptin concentrations and the CSF/serum leptin ratio were virtually identical in subjects with impaired and normal blood-CSF barrier function.
Thus, our data support the presence of a saturable and active transporter of leptin from circulation into intrathecal space.
瘦素是一种由脂肪细胞分泌的激素，被认为通过与下丘脑受体相互作用来提供负反馈信号，以控制身体脂肪量。本研究旨在检测人体脑脊液（CSF）空间中瘦素的摄取情况，以及瘦素向脑脊液空间的转运是一种主动现象还是由于通过血脑屏障的自由通透。
我们采用放射免疫分析法测定了17名男性[42±4岁，平均±标准误；体重指数（BMI）27.3±1.8 kg/m²]和22名女性（40±3岁，BMI 25.1±1.0 kg/m²）的血清和脑脊液瘦素浓度。通过测定脑脊液/血清白蛋白比值来评估血脑屏障的功能。
男性血清瘦素浓度（5.8±1.6微克/升）低于女性（13.1±1.7微克/升，P = 0.001），而男性（0.34±0.03微克/升）和女性（0.36±0.03微克/升）脑脊液中的瘦素浓度几乎相同。男性（r = 0.89，P < 0.01，n = 10）和女性（r = 0.61，P < 0.05，n = 14）的血清瘦素均与BMI呈正相关，而两组中脑脊液瘦素浓度与BMI均无相关性。男性（r = -0.93，P < 0.001）和女性（r = -0.77，P < 0.001）的脑脊液/血清瘦素比值与血清瘦素浓度呈负相关，男性（r = -0.75，P = 0.02，n = 10）和女性（r = -0.64，P < 0.02，n = 14）的脑脊液/血清瘦素比值与BMI也呈负相关。两组中脑脊液/血清白蛋白比值与脑脊液/血清瘦素比值均无相关性。血脑屏障功能受损和正常的受试者脑脊液瘦素浓度及脑脊液/血清瘦素比值几乎相同。
因此，我们的数据支持存在一种可饱和的、将瘦素从循环转运至鞘内空间的主动转运体。
