Buff P R, Messer N T, Cogswell A M, Johnson P J, Keisler D H, Ganjam V K
Department of Veterinary Biomedical Sciences, University of Missouri-Columbia, MO 65211, USA.
Domest Anim Endocrinol. 2007 Nov;33(4):430-6. doi: 10.1016/j.domaniend.2006.08.007. Epub 2006 Sep 25.
The objective of this study was to determine if seasonal and/or pulsatile variations occur in plasma concentrations of thyrotropin (TSH) and leptin in mares while maintaining a constant energy balance. Blood samples were collected every 20 min during a 24h period in winter and again in summer from six Quarter Horse type mares. Plasma concentrations of TSH, leptin, and T(4) were determined by radioimmunoassay. No differences were observed in body weight between winter (388.1+/-12.5 kg) and summer (406.2+/-12.5 kg; P=0.11). Plasma concentrations of TSH were greater in the summer (2.80+/-0.07 ng/ml) when compared to winter (0.97+/-0.07 ng/ml; P<0.001). Pulse frequency of TSH was not different between winter (6.17+/-0.78 pulses/24h) and summer (5.33+/-0.78 pulses/24h; P=0.49). Mean TSH pulse amplitude, pulse area, and area under the curve were all greater in summer compared to winter (3.11+/-0.10 ng/ml versus 1.20+/-0.10 ng/ml, 24.86+/-0.10 ng/ml min versus 13.46+/-1.90 ng/ml min, 3936+/-72.93 ng/ml versus 1284+/-72.93 ng/ml, respectively; P<0.01). Mean concentrations of leptin were greater in summer (2.48+/-0.17 ng/ml) compared to winter (0.65+/-0.17 ng/ml; P<0.001). Pulsatile secretion patterns of leptin were not observed in any horses during experimentation. Mean concentrations of T(4) were greater in winter (20.3+/-0.4 ng/ml) compared to summer (18.2+/-0.4 ng/ml; P<0.001). These seasonal differences between winter and summer provide evidence of possible seasonal regulation of TSH and leptin.
本研究的目的是确定在维持能量平衡恒定的情况下，母马促甲状腺激素（TSH）和瘦素的血浆浓度是否存在季节性和/或脉冲式变化。在冬季和夏季的24小时内，每隔20分钟从6匹夸特马型母马采集血样。通过放射免疫分析法测定TSH、瘦素和T(4)的血浆浓度。冬季（388.1±12.5千克）和夏季（406.2±12.5千克；P = 0.11）的体重未观察到差异。与冬季（0.97±0.07纳克/毫升）相比，夏季TSH的血浆浓度更高（2.80±0.07纳克/毫升；P<0.001）。冬季（6.17±0.78次脉冲/24小时）和夏季（5.33±0.78次脉冲/24小时；P = 0.49）的TSH脉冲频率没有差异。与冬季相比，夏季的平均TSH脉冲幅度、脉冲面积和曲线下面积均更大（分别为3.11±0.10纳克/毫升对1.20±0.10纳克/毫升、24.86±0.10纳克/毫升·分钟对13.46±1.90纳克/毫升·分钟、3936±72.93纳克/毫升对1284±72.93纳克/毫升；P<0.01）。与冬季（0.65±0.17纳克/毫升）相比，夏季瘦素的平均浓度更高（2.48±0.17纳克/毫升；P<0.001）。实验期间在任何马匹中均未观察到瘦素的脉冲分泌模式。与夏季（18.2±0.4纳克/毫升）相比，冬季T(4)的平均浓度更高（20.3±0.4纳克/毫升；P<0.001）。冬季和夏季之间的这些季节性差异为TSH和瘦素可能存在季节性调节提供了证据。
