|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1994 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1993 : ¥1,600,000 (Direct Cost : ¥1,600,000)
W already demonstrated that the neonatal treatment of female rats with danazol induced a true precocious puberty. We designed to investigate the developmental difference in the nuclear sizes of neurons of the hypothalamic nuclei between the sexual precocity and normal rats. The developmental changes of the nuclear sizes of the neurons in the hypothalamic nuclei of neonatal and infant control female rats were mainly classified into 3 groups. At 10 days of age, the nuclear sizes of neurons in the medial part of preoptic nucleus, anterior hypothalamic nucleus and medial part of vetromedial nucleus reached to the same levels as those at 20 days of age. At 15 days of age, the nuclear sizes of neurons in the suprachiasmatic nucleus and dorsomedial nucleus reached to the same levels as those at 20 day of age. In the suprachiasmatic (POSC) and periventricular (POP) parts of preoptic nucleus, supraoptic nucleus, paraventricular nucleus, arcuate nucleus and posterior part of ventromedial nucleus, the significant increases in nuclear sizes of neurons were observed until day 20. In the preococity rats induced by danazol, the nuclear sizes of neurons in the POSC nad POP at 10 days of age reached to the same levels as those of control rats at 15 days of age, and the nuclear sizes of neurons in these unclei at 15 days of age reached to the same levels as those of control rats at 20 days of age. However, there was no difference in the nuclear sizes of neurons in these nuclei between the 15th and 20th day. With the exception of POSC and POP,there was no difference in the developmental changes of nuclear sizes in the neurons of the hypothalamic nuclei between the precocious puberty and normal rats. These results suggest that the precoxity of POSC and POP are responsible for the induction of true precocious pubery, and the POSC and POP play an important role in the onset of puberty.