Dynamics of Growth Hormone Responsiveness to Growth Hormone Releasing Factor in Aging Rats: Peripheral and Central Influences
- 1 January 1991
- journal article
- research article
- Published by S. Karger AG in Neuroendocrinology
- Vol. 53 (5) , 439-446
- https://doi.org/10.1159/000125755
Abstract
The in vivo and in vitro dynamics of somatotroph responsiveness to rGRF(l-29) NH2 (rat growth hormone releasing factor) were evaluated in 2-, 4-, 8-, 12-, and 20-month-old male rats. In vivo, using pentobarbital-anesthetized animals, we observed that the rGH (rat growth hormone) responsiveness to 0.4 and 1.6 µg/kg rGRF started to decline at the higher dose in 12-month-old rats and was completely blunted at both rGRF doses in 20-month-old animals. In vitro, using freshly dispersed perifused pituitary cells, we also documented a decrease of rGRF-induced rGH secretion in 12- and 20-month-old rats. Moreover, as the animals aged, the rGRF-induced rGH secretion was differentially affected by the inhibiting action of somatostatin (pKeywords
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