Bubenik G A, Schams D, White R G, Rowell J, Blake J, Bartos L
Department of Zoology, University of Guelph, Ont., Canada.
Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 1998 Aug;120(2):307-15. doi: 10.1016/s0742-8413(98)10010-5.
Seasonal levels of cortisol, growth hormone (GH), insulin like growth factor 1 (IGF-1), glucose, triiodothyronine (T3), free T3, thyroxine and free fatty acids (FFA) were measured every 3 weeks for 54 weeks in the plasma of five adult bulls, and four barren and five pregnant Alaskan reindeer (Rangifer tarandus) cows. Three consecutive samples were taken from each animal. Cortisol levels exhibited wide seasonal variation (9-45 ng/ml) [corrected] without any peak or difference in levels among groups. Rising levels were detected between the 3 consequent samples. Peak GH levels, detected during January and February, were higher in the non-pregnant group (54 ng/ml) than the pregnant (26 ng ml-1) and the male (27 ng ml-1) groups. Low GH levels (2-10 ng ml-1) were recorded between May and September. IGF-1 reached peak levels (715 ng ml-1) in males in August, in non-pregnant females in September (677 ng ml-1), and in the pregnant females in October (505 ng ml-1). Seasonal minima (404 in males, 172 and 93 in pregnant and non-pregnant groups) were detected in February. Glucose was fairly stable throughout the year (100-200 mg/100 ml). A rising levels were found between the three consecutive samples. Triiodothyronine (T3) (2.16-2.30 ng ml-1) peaked in all three groups during the spring and early summer, and minimal levels (0.61-0.97 ng ml-1) were detected from October to January. Conversely, thyroxine or free T3 did not exhibit seasonal variation. FFA fluctuated widely (97-1076 nmol l-1) throughout the year. Only in pregnant females were concentrations more stable (150-460 nmol l-1). Perhaps, because of ad libitum supply of food in captive reindeer, only T3 and GH exhibited pronounced seasonal fluctuations which could be related to the metabolic changes expected during the annual cycle.
在54周的时间里，每隔3周对5头成年公牛以及4头未怀孕和5头怀孕的阿拉斯加驯鹿（Rangifer tarandus）母牛的血浆进行检测，测量皮质醇、生长激素（GH）、胰岛素样生长因子1（IGF-1）、葡萄糖、三碘甲状腺原氨酸（T3）、游离T3、甲状腺素和游离脂肪酸（FFA）的季节性水平。从每只动物身上采集连续3个样本。皮质醇水平呈现出较大的季节性变化（9 - 45 ng/ml）[校正后]，各组之间没有任何峰值或水平差异。在连续的3个样本之间检测到水平上升。1月和2月检测到的GH峰值水平，未怀孕组（54 ng/ml）高于怀孕组（26 ng/ml）和雄性组（27 ng/ml）。5月至9月期间记录到较低的GH水平（2 - 10 ng/ml）。IGF-1在8月雄性中达到峰值水平（715 ng/ml），9月未怀孕雌性中达到峰值水平（677 ng/ml），10月怀孕雌性中达到峰值水平（505 ng/ml）。2月检测到季节性最低值（雄性为404，怀孕组和未怀孕组分别为172和93）。葡萄糖全年相当稳定（100 - 200 mg/100 ml）。在连续的3个样本之间发现水平上升。三碘甲状腺原氨酸（T3）（2.16 - 2.30 ng/ml）在所有三组中于春季和初夏达到峰值，10月至1月检测到最低水平（0.61 - 0.97 ng/ml）。相反，甲状腺素或游离T3没有呈现季节性变化。FFA全年波动很大（97 - 1076 nmol/l）。只有怀孕雌性的浓度更稳定（150 - 460 nmol/l）。也许是因为圈养驯鹿食物供应充足，只有T3和GH呈现出明显的季节性波动，这可能与年度周期中预期的代谢变化有关。
