Effects of thyroidectomy, hypophysectomy, temperature and humidity on the occurrence of nocturnal locomotor activity in the toad, Bufo japonicus, during the breeding season : Endocrinology

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Toads collected in October 1987 were thyroidectomized or hypophysectomized, and then released into an outdoor pen. Observations were made once a day between 2030 and 2130 hr for 19 days from February 27 to March 16, 1988. Toads found completely exposed above ground at the time of the observation were regarded as active individuals. In males thyroidectomy significantly reduced both the mean number of active individuals each day and the mean number of active days of each individual. Hypophysectomy significantly reduced both of these parameters in males. In females, the effects of the operations were not clear, since the number of active individuals was extremely small in all groups. Significant positive correlations (r =0.58-0.76) were observed between the number of active individuals and temperature in both sexes, and between the number of active individuals and the humidity of the air in males. When the temperature and humidity were combined as an independent variable, a highly significant multiple correlation (r >0.8) in both sexes was observed. The present results suggest that the pituitary gland plays some role in the migration of the toad toward the pond but thyroid hormone suppresses the migratory activity, and also that the combination of temperature and humidity is the external factor which initiates the migration
社団法人日本動物学会の論文
1990-02-15