Licht P, Breitenbach G L, Congdon J D
Gen Comp Endocrinol. 1985 Jul;59(1):130-9. doi: 10.1016/0016-6480(85)90427-7.
Plasma levels of testosterone (T), thyroxine (T4) and follicle-stimulating hormone (FSH) were measured in a field population of the painted turtle, Chrysemys picta, in Michigan. All three hormones showed pronounced seasonality; plasma luteinizing hormone (LH) remained nondetectable. Plasma T and FSH concentrations were highly correlated and exhibited biphasic cycles with peaks in spring and fall, whereas T4 showed a single peak in summer, coincident with the nadir in T. Hormone levels were minimal on the day that animals emerged from hibernation at the end of March; T and FSH then increased rapidly (in ca. 1 week after emergence) to a transient peak that persisted for only ca. 2 weeks. Plasma T and FSH rose again in September before the onset of hibernation and shortly after the late summer peak in spermatogenetic recrudescence. Plasma T4 increased more gradually after emergence in spring and did not peak for 1-2 months, coincident with the nadir in T. The profile in plasma FSH is consistent with the view that this gonadotropin may regulate androgen secretion but it did not show the expected relationship to the spermatogenetic cycle. Separate studies indicated that the turtles are sensitive to capture and handling; hormone levels (especially androgen) fall precipitously within a day of capture. These "stress" effects may account for discrepancies with previous studies of plasma T in this species.
在密歇根州对彩龟（锦龟）的一个野外种群测量了睾酮（T）、甲状腺素（T4）和促卵泡激素（FSH）的血浆水平。所有这三种激素都表现出明显的季节性；血浆促黄体生成素（LH）仍检测不到。血浆T和FSH浓度高度相关，并呈现双相周期，在春季和秋季出现峰值，而T4在夏季出现单峰，与T的最低点一致。在3月底动物从冬眠中苏醒的当天，激素水平最低；T和FSH随后迅速升高（在苏醒后约1周）至一个短暂峰值，仅持续约2周。在冬眠开始前的9月，以及夏末精子发生再生长高峰后不久，血浆T和FSH再次升高。春季苏醒后，血浆T4升高较为缓慢，1 - 2个月后才达到峰值，与T的最低点一致。血浆FSH的变化情况与这种促性腺激素可能调节雄激素分泌的观点一致，但它与精子发生周期并未呈现预期的关系。单独的研究表明，这些龟对捕捉和处理很敏感；激素水平（尤其是雄激素）在捕捉后一天内会急剧下降。这些“应激”效应可能是造成该物种之前血浆T研究结果存在差异的原因。
