Thyrotropin releasing hormone (TRH) and a degradation stabilized analogue (RX77368) stimulate phosphoinositide turnover in cultured astrocytes in a regionally specific manner
| Autor: | Stephen L. Dickinson, Graham P. Wilkin, Alison M. McDermott |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
endocrine system
medicine.medical_specialty Cell type Receptor expression Neuropeptide Thyrotropin-releasing hormone Biology Phosphatidylinositols Rats Sprague-Dawley Cellular and Molecular Neuroscience Cerebellum Internal medicine medicine Animals Inositol phosphate Thyrotropin-Releasing Hormone Cells Cultured Cerebral Cortex chemistry.chemical_classification Brain Cell Biology Pyrrolidonecarboxylic Acid Rats Endocrinology medicine.anatomical_structure Animals Newborn Spinal Cord chemistry Organ Specificity Astrocytes Second messenger system Neuroglia hormones hormone substitutes and hormone antagonists Brain Stem Astrocyte |
| Zdroj: | Neurochemistry International. 20:307-313 |
| ISSN: | 0197-0186 |
| Popis: | Whilst the CNS effects of thyrotropin releasing hormone (TRH) may result from a direct action on neurones it is also a possibility that another cell type may mediate an indirect action. A potential candidate for such a role is the astrocyte. The ability of TRH and a stable analogue RX77368 (di-methyl proline TRH) to stimulate phosphoinositide turnover has been investigated in cultured astrocytes from a number of CNS regions. Significant increases in turnover were noted in three of the four regions studied. Percentage values were: in spinal cord, 33% TRH, 31% RX77368 (n = 15); in brain stem, 33% TRH, 37% RX77368 (n = 6); in cerebellum, 72% TRH, 73% RX77368 (n = 6); in cortex, 4% TRH, 13% RX77368 (n = 6). EC50 values for both peptides were in the picomolar range. These results indicate that some astrocytes in vitro possess functional TRH receptors linked to the phosphoinositide second messenger system and hence this cell type would potentially be capable of mediating an indirect action of the peptide. Also, because the response was limited to certain regions, heterogeneity in receptor expression is implied. Furthermore, in the light of other evidence to support astrocyte heterogeneity within a region, we suggest that certain characteristics of the response seen in our experiments may be the result of TRH receptors being restricted to a subpopulation of astrocytes within a given culture. Thus, our data show that astrocytes prepared from some CNS regions possess functionally coupled TRH receptors. |
| Databáze: | OpenAIRE |
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