Liver-derived IGF-I regulates GH secretion at the pituitary level in mice
| Autor: | Mia Umaerus, Kristina Wallenius, Olle Isaksson, Rhonda D. Kineman, Klara Sjögren, Jun-Li Liu, Xiao Ding Peng, Ville Wallenius, Lawrence A. Frohman, John-Olov Jansson, Seungjoon Park, Håkan Wennbo, Claes Ohlsson |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Male
Pituitary gland medicine.medical_specialty Receptors Prolactin Hypothalamus Receptors Cell Surface Growth Hormone-Releasing Hormone Mice Endocrinology Internal medicine medicine Animals RNA Messenger Insulin-Like Growth Factor I Receptor Mice Knockout Chemistry Somatostatin receptor Neuropeptides Proteins Organ Size Neuropeptide Y receptor Growth hormone secretion medicine.anatomical_structure Somatostatin Liver Growth Hormone Pituitary Gland Secretagogue Female |
| Zdroj: | Endocrinology. 142(11) |
| ISSN: | 0013-7227 |
| Popis: | We have reported that liver-specific deletion of IGF-I in mice (LI-IGF-I-/-) results in decreased circulating IGF-I and increased GH levels. In the present study, we determined how elimination of hepatic IGF-I modifies the hypothalamic-pituitary GH axis to enhance GH secretion. The pituitary mRNA levels of GH releasing factor (GHRF) receptor and GH secretagogue (GHS) receptor were increased in LI-IGF-I-/- mice, and in line with this, their GH response to ip injections of GHRF and GHS was increased. Expression of mRNA for pituitary somatostatin receptors, hypothalamic GHRF, somatostatin, and neuropeptide Y was not altered in LI-IGF-I-/- mice, whereas hypothalamic IGF-I expression was increased. Changes in hepatic expression of major urinary protein and the PRL receptor in male LI-IGF-I-/- mice indicated an altered GH release pattern most consistent with enhanced GH trough levels. Liver weight was enhanced in LI-IGF-I-/- mice of both genders. In conclusion, loss of liver-derived IGF-I enhances GH release by increasing expression of pituitary GHRF and GHS receptors. The enhanced GH release in turn affects several liver parameters, in line with the existence of a pituitary-liver axis. |
| Databáze: | OpenAIRE |
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