Effect of Thymosin α1 on Hypothalamic Hormone Release
| Autor: | L. Milenkovic, Aguila Mc, Samuel M. McCann, Krzysztof Lyson |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
endocrine system
medicine.medical_specialty Metergoline Pituitary gland Endocrine and Autonomic Systems Chemistry Endocrinology Diabetes and Metabolism Thyrotropin-releasing hormone Cellular and Molecular Neuroscience Corticotropin-releasing hormone chemistry.chemical_compound Endocrinology Somatostatin medicine.anatomical_structure Hypothalamus Internal medicine medicine hormones hormone substitutes and hormone antagonists 5-HT receptor Hormone |
| Zdroj: | Neuroendocrinology. 56:674-679 |
| ISSN: | 1423-0194 0028-3835 |
| DOI: | 10.1159/000126292 |
| Popis: | Thymosin α1 (Tα1) is a well-characterized immunopotentiating polypeptide originally isolated from calf thymus. We have recently shown in vivo, probable hypothalamic effects of Tα1 to decrease the release of the pituitary hormones, TSH, PRL and ACTH from the pituitary gland. Therefore, in the present study we evaluated the effect of the peptide on the release of hypothalamic regulatory hormones: thyrotropin-releasing hormone (TRH) and corticotropin-releasing hormone (CRH), as well as somatostatin (SRIH), from medial basal hypothalamic (MBH) fragments incubated in vitro. After a preliminary time-course study indicated that a 30-min incubation period was optimal, it was used for all the other experiments. At the end of the incubation the tissue was still able to respond to a depolarizing K+ concentration for 15 min by a 4-fold increase of TRH concentration compared to control basal release during the preceding 30 min. Tα1 was shown to inhibit the release of TRH and CRH from MBH fragments incubated in vitro with a minimal effective dose (MED) of 10-9M. SRIH and CRH release was also inhibited but the MED for these peptides was 10∼9M. The relative responsiveness to the action of Tα1 was TRH greater than CRH, which was greater than SRIH. This correlated with our previous in vivo results for pituitary hormone release, except in the case of SRIH since we previously did not detect any significant effect of the peptide on growth hormone release. Finally, we evaluated the possible involvement of other neurotransmitters in the effect of Tα1 on TRH release. A serotonin receptor blocker, metergoline, which blocked the inhibitory effect of serotonin on TRH release, also prevented the inhibitory effect of Tα1 on the release of TRH. These results suggest the possible involvement of a serotonergic mechanism in the inhibitory effect of Tα1 on TRH release. |
| Databáze: | OpenAIRE |
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