| Co-Investigator(Kenkyū-buntansha) |
MOBBS Charles The Rockefeller University, 助教授
KOIBUCHI Noriyuki The Rockeffeler University, 研究員
GIBBS Robert The Rockefeller University, 助教授
KATO Masakatsu Institute of Endocrinology, Gunma University, 内分泌研究所, 助手 (90143239)
ISHIKAWA Koichi Institute of Endocrinology, Gunma University, 内分泌研究所, 助手 (80143238)
MATSUZAKI Shigeru Institute of Endocrinology, Gunma University, 内分泌研究所, 助教授 (60008604)
PFAFF Donald W. The Rockefeller University, 教授
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| Budget Amount *help |
¥8,600,000 (Direct Cost: ¥8,600,000)
Fiscal Year 1990: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1989: ¥5,300,000 (Direct Cost: ¥5,300,000)
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| Research Abstract |
1. Neuronal networks of hypothalamic GRF and SRIF neurons in adult male rats and the role of SRIF in relation to growth hormone (GH) secretion.
(1) GRF neurons in the arcuate nucleus (Arc) were connected to the vasolateral amygdala (BLA) via the stria terminals, while SRIF neurons in the periventricular nucleus (Pe), have connections to noradrenergic neurons in the brain stem. (2) Pe lesion markedly reduced SRIF content in the median eminence and blunted the sensitivity of pituitary GH cells to GRF stimulation. (3) SRIF pretreatment facilitated 2-fold GH release from the dispersed cells and also the increase in intracellular free Ca^<2+> ions by GRF stimulation.
2. Effects of thyroid hormone on fos-like protein, thyroid hormone and SRIF receptors.
(1) A number of fos-like immunoreactivity (IR) was examined in adult male rat brains and the IRs were found in the magnocellular and parvocellular regions of the paraventricular nucleus (mPVN & pPVN), anterior hypothalamus, lateral hypothalamus,
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and pyriform cortex. Six days after thyroidectomy (Tx), the number of fos-like IR cells increased 2-fold in PVN. (2) The mRNA of erbA alfa2, one of thyroid hormone recepror family was widely distributed in rat brains, particularly a dense localization was observed in the PVN, hypothalamic ventromedial nucleus, Arc, the hippocampus, medical amygdala, cerebral cortex, and pyriform cortex. After Tx, there was no significant change in the receptor gene expression in these regions, except in PVN, suggesting a negative feedback interrelation between PVN-TRH neural activity and circulating thyroid hormone concentration. (3) Changes in gene expression of GRF by Tx is still under investigation. But recently Downs et al. (1990) reported that Tx or hypophysectomy stimulates GRF gene expression, while thyroid hormone or GH replacement suppresses the increase, proposing that there is a negative feedback mechanism between GH and GRF gene expression. (4) SRIF receptors in rat brains were widely distributed in the regions such as the cerebral cortex, endopyriform nucleus, hippocampus, habenular nucleus and BLA. The number of SRIF receptor in these regions and PVN significantly increased after Pe lesion. However, Tx caused no change in the receptor number except an increase in BLA and thyroxine replacement could not restore the change. Less
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