Age, photoperiodic responses, and pineal function in meadow voles, Microtus pennsylvanicus.
Age, photoperiodic responses, and pineal function in meadow voles, Microtus pennsylvanicus.
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草地田鼠 (Microtus pennsylvanicus) 的年龄、光周期反应和松果体功能。
DOI：
10.1111/j.1600-079x.1989.tb00448.x
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发表时间：
1989
影响因子：
10.3
通讯作者：
Stetson,MH
中科院分区：
文献类型：
--
作者：
Donham,RS;Horton,TH;Rollag,MD;Stetson,MH
我们测试了幼年雄性宾夕法尼亚田鼠是否比成虫对短光周期的抑制作用更敏感。在20d或80d时将田鼠转移到短光周期(10L：14D)，60d后(即80d或140d)，昼夜间隔地处死动物。采集松果腺测定褪黑素，并称量睾丸重量。长期饲养的80日龄和140日龄动物的配对睾丸重量没有差异(睾丸重量中位数分别为1,953和1,843 mg)。相比之下，短日龄田鼠的睾丸重量中位数在80日龄和140日龄时分别为504和1112 mg；两组的睾丸重量与其年龄匹配的对照组相比差异显著(P.001，对数变换数据的两样本t检验)。两个年龄组的反应通过用各自的长日照对照的平均值和方差归一化个体值来比较。这一比较表明，动物对光周期的反应性随着年龄的增长而降低(t检验，P=0.01)。不同年龄的动物松果体褪黑素含量夜间升高的持续时间和幅度是相似的。在两个实验中，从20到80天或80到140天，每天给田鼠注射褪黑素。注射褪黑激素的动物的睾丸比注射生理盐水的对照组小(ANOVA：P=.01)，并且下午的注射比上午的注射更有效(P=.01)。对幼年和成年田鼠注射褪黑素和短日照的有效性比较表明，虽然短日照对幼年动物睾丸发育的抑制作用大于对成年田鼠的退化，但这种反应性的下降可能涉及夜间褪黑激素产生模式改变以外的其他因素。
We tested whether juvenile males ofMicrotus pennsylvanicuswere more sensitive than adults to the suppressive effects of short photoperiods. Voles were transferred to short photoperiods (10L:14D) at 20 or 80 d of age, and 60 d later (i.e., at 80 or 140 d) the animals were killed at intervals throughout the day and night. Pineal glands were collected for measurement of melatonin, and the testes were weighed. There were no differences in paired testicular weights of 80 and 140 d old animals held on long days (median testicular weights: 1,953 and 1,843 mg). In contrast, median testicular weights of voles held on short days were 504 and 1,112 mg, respectively, at 80 and 140 d of age; the testicular weights of both groups were significantly different from their age‐matched controls (P.001, two‐sample t‐tests on log transformed data). The responses of the two age groups were compared by normalizing the individual values by the mean and variance of the respective long‐day controls. This comparison suggests that the responsiveness to photoperiod decreases as the animals age (t‐test,P= .01). Duration and amplitude of the nocturnal rise in pineal melatonin content were similar in differently aged animals. In two experiments, voles were injected daily with melatonin from 20 to 80 or 80 to 140 d of age. Melatonin‐injected animals had smaller testes than did saline‐injected controls (ANOVA:P= .01), and injections were more effective in the afternoon than in the morning (P= .01). Comparison of the effectiveness of short day and melatonin injections in juvenile and adult voles suggests that while short days inhibited testicular development of young animals more than it induced regression of adults, this decrease in responsiveness may involve factors other than alterations in the nocturnal pattern of melatonin production.