鳥類正中隆起部に含まれるホルモン物質

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The neurohypophysial hormone activities of the extracts of pigeon median eminence region and posterior lobe were assayed with the rat uterus method and Sawyer's frog bladder method in vitro. The median eminence region possessed 1/35 rat uterus and 1/20 frog bladder activities of the posterior lobe. The ratio of the frog bladder activity to the rat uterus activity (in the Ringer's solution without Mg) was about 200 in the median eminence extract and about 160 in the posterior lobe extract. The former ratio coincides with the ratio obtained by Sawyer (1960) who used synthetic arginine vasotocin. The latter ratio is also similar to that of chick posterior lobe extract which represents the existance of both arginine vasotocin and oxytocin (Munsick et al., 1960). These findings suggest that the pigeon median eminence contains arginine vasotocin or a substance similar to it, and the pigeon posterior lobe contains both arginine vasotocin and oxytocin. The treatment with sodium thioglycolate nullified the rat uterus activity of both posterior lobe and median eminence region extracts. This fact also supports the assumption that the median eminence contains arginine vasotocin-like substance. Administration of 0.5 M NaCl solution to the pigeon as drinking water reduced the frog bladder activity of the posterior lobe to 1/8 that of normal level (from 60±9.6 units per individual to 7.2±0.37). However, the frog bladder activity of the median eminence of the same birds did not show any difference between normal control and salt water-treated birds. Exposure of the male wild duck, Anas platyrhyncos platyrhyncos, to long daily photoperiods (20 hours illumination a day) caused a significant decrease in the frog bladder activity of the median eminence region (14±1.5 units per individual in normal birds; 7.6±0.74 in long day birds) and a marked increase of the testicular weight (0.12±0.027 g in normal birds; 1.1±0.77 g in long day birds). However, the longday treatment did not affect the frog bladder activity of the posterior lobe of the male wild ducks. These experiments clarify the fact that the controlling mechanism of neurosecretion is independent of each other in the median eminence and the posterior lobe. The results of these experiments suggest that the arginine vasotocin-like substance may have some relationship to the hypothetical substance which is involved in the secretion of the gonadotrophin. This investigation was supported in part by Grant A-3678 from the United States Public Health Service to H. Kobayashi. and also by a grant from the Ministry of Education, Japan.
社団法人日本動物学会の論文
1962-06-15

鳥類正中隆起部に含まれるホルモン物質

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