2006 年 20 巻 2 号 p. 40-43
To investigate the effects of hypergravity on the pituitary gland and the target organs of amphibians, we raised frogs, Xenopus laevis under hypergravity environment (2 and 5G) environments from fertilization to the beginning of metamorphosis (St 57) and completion of metamorphosis (St 66). The frogs developed at 2G and 5G, but they were smaller than those raised at 1G. Moreover, the development of the frogs was delayed under both hypergravity conditions. The total volume, cell size and cell number of the pituitary of hypergravity-treated frogs were reduced. In the treated thyroid, the total volume and height of the epithelium were also reduced. Cell size was reduced in the adrenal grand of treated frogs. These morphological changes of the pituitary-target organs indicate that hypergravity alters their endocrinological functions. These results suggest that gravity different from the terrestrial environment causes dysfunction and hypofunction in the endocrine systems, and that the organisms may not be able to maintain their inherent life cycles under such conditions.
