Evidence for a primary involvement of somatostatin in clonidine-induced growth hormone release in conscious rats
| Autor: | Gloria Shaffer Tannenbaum, R Lanzi, W Gurd, Martine Lapointe |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
Male
Agonist medicine.medical_specialty medicine.drug_class Endocrinology Diabetes and Metabolism medicine.medical_treatment Hypothalamus Pulsatile flow Alpha (ethology) Growth Hormone-Releasing Hormone Clonidine Rats Sprague-Dawley Endocrinology Internal medicine medicine Animals Saline Dose-Response Relationship Drug Chemistry Growth hormone secretion Rats Somatostatin Mechanism of action Growth Hormone Pituitary Gland Injections Intravenous medicine.symptom Secretory Rate medicine.drug |
| Zdroj: | Journal of Endocrinology. 141:259-266 |
| ISSN: | 1479-6805 0022-0795 |
| Popis: | The GH-releasing activity of the α2-adrenergic agonist clonidine has been extensively studied in the rat, but the mechanism(s) by which clonidine stimulates GH release remains controversial. In the present study, we examined the effects of various doses of clonidine on spontaneous pulsatile GH secretion in conscious rats, and tested the hypothesis that the GH-releasing activity of clonidine is mediated primarily by an inhibition of hypothalamic somatostatin (SRIF) release. In the first experiment, free-moving adult male rats were given either saline or various doses of clonidine i.v. (30, 50 and 125 μg/kg) at times of spontaneous peaks (1100 h) and troughs (1300 h) in the GH rhythm. Clonidine, at all doses tested, failed to stimulate GH release when administered at the time of a spontaneous peak. In contrast, injection of clonidine at trough times (when SRIF tone is high) consistently augmented plasma GH levels (mean ± s.e.m. integrated GH release; 30 μg/kg, 1843·0±484·0; 50 μg/kg, 1469·0± 490·3; 125 μg/kg, 1675·6 ± 513·4 vs 201·3 ± 100·1 ng/ml per 45 min in saline-injected controls; PP Journal of Endocrinology (1994) 141, 259–266 |
| Databáze: | OpenAIRE |
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