Seasonal changes in the immunolocalization of steroidogenic enzymes in the testes of the Japanese black bear (Ursus thibetanus japonicus)
Seasonal changes in the immunolocalization of steroidogenic enzymes in the testes of the Japanese black bear (Ursus thibetanus japonicus)
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DOI：
10.1292/jvms.59.521
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发表时间：
1997-07-01
影响因子：
1.2
通讯作者：
Suzuki, Y
中科院分区：
文献类型：
--
作者：
Komatsu, T;Tsubota, T;Suzuki, Y
本文研究了日本黑熊(Ursus Thibetanus Japan Onicus)睾丸类固醇合成酶免疫染色部位的季节性变化。用放射免疫法测定血清睾酮和17β雌二醇的浓度，并与免疫染色结果进行比较。根据生精活动的形态观察，将其生殖周期划分为5个时期：5、6月份为活跃期；11月份为衰退期；1月份为休止期；3月份为早期恢复期；4月份为恢复后期。血清睾酮浓度因季节不同而不同，并伴有生精活性的差异，基线水平在11月和1月，在3月和4月上升，在5月和次年4月和6月达到较高水平。全年观察到间质细胞胆固醇侧链裂解细胞色素P450、17α-羟基酶细胞色素P450和3β-羟基类固醇脱氢酶(3β-HSD)的免疫反应。只有间质细胞对3βHSD免疫阳性的百分比显示出与血清睾酮浓度相关的季节性差异。芳香化酶细胞色素P450(P450arom)全年免疫定位于间质和支持细胞，5月、次年4月和6月在精子细胞，1月和3月在肌样细胞。间质细胞对该酶的免疫阳性百分率在5月和次年1月、3月和6月有所增加。另一方面，未观察到血清雌二醇-17β浓度的季节性变化。这些结果表明，3-β-HSD是睾丸间质细胞睾酮产生的关键酶。此外，间质细胞和肌样细胞产生的雌激素似乎通过负反馈作为旁分泌和/或自分泌介质对间质细胞起调节作用。
Seasonal changes in sites of immunostaining of steroidogenic enzymes were examined in testes of the Japanese black bear, Ursus thibetanus japonicus. In addition, serum concentrations of testosterone and estradiol-17 beta were investigated by radioimmunoassay, and the seasonal changes were compared with the results of immunostaining. On the basis of morphological observations of spermatogenic activity, the reproductive cycle was divided into five periods: an active period in May and June; a degenerative period in November; a resting period in January; an early-resumptive period in March; and a late-resumptive period in April. Serum concentrations of testosterone differed with season accompanied by differences in spermatogenic activity, with baseline levels in November and January, increasing levels in March and April, and high levels in May, and April and June of the next year. Immunoreactivities specific for cholesterol side-chain cleaving cytochrome P450, 17 alpha-hydroxylase cytochrome P450 and 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) were observed in Leydig cells throughout the year. Only the percentages of Leydig cells immunopositive for 3 beta HSD exhibited seasonal differences that correlated with serum concentrations of testosterone. Aromatase cytochrome P450 (P450arom) was immunolocalized in Leydig and Sertoli cells throughout the year, in spermatids in May, and April and June of the next year and in myoid cells in January and March. The percentages of Leydig cells immunopositive for this enzyme increased in May, and January, March and June of the next year. On the other hand, no pattern of seasonal change in serum estradiol-17 beta concentration was observed. These results suggest that 3 beta HSD is a key enzyme in the regulation of the testosterone production in Leydig cells. Furthermore, estrogen derived from Leydig and myoid cells seems to play a role in the regulation of Leydig cells by negative feedback as a paracrine and/or autocrine mediator.