[3-Me-His(2)]-TRH combined with dopamine withdrawal rapidly and transiently increases pyroglutamyl aminopeptidase II activity in primary cultures of adenohypophyseal cells
| Autor: | Julie Bourdais, Fidelia Romero, Miguel Cisneros, Jean-Louis Charli, Patricia Joseph-Bravo, B. Uriostegui |
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| Rok vydání: | 2000 |
| Předmět: |
Agonist
endocrine system medicine.medical_specialty medicine.drug_class Dopamine Thyrotropin-releasing hormone Aminopeptidases Prolactin cell Cellular and Molecular Neuroscience chemistry.chemical_compound Endocrinology Pituitary Gland Anterior Internal medicine medicine Animals Rats Wistar Neurotransmitter Thyrotropin-Releasing Hormone Cells Cultured biology Endocrine and Autonomic Systems General Medicine Prolactin Enzyme assay Pyrrolidonecarboxylic Acid Rats Neurology chemistry biology.protein Female Endocrine gland medicine.drug |
| Zdroj: | Neuropeptides. 34(2) |
| ISSN: | 0143-4179 |
| Popis: | TRH is hydrolyzed by pyroglutamyl aminopeptidase II (PP II), a highly specific ecto-enzyme which is localized on the surface of lactotrophs. To study whether PP II activity may be rapidly regulated during a burst of prolactin secretion, we used an in vitro model in which primary cultures of adenohypophyseal cells were incubated with 500 nM dopamine (DA) for 24 h prior to treatments. We observed a rapid increase of PP II activity when 100 nM [3-Me-His 2 ]-TRH, a TRH agonist, was added at removal of DA. PPII activity was maximal after 20 min of treatment and reduced to time 0 activity at 30 min. Dopamine withdrawal alone, slightly and transiently, modified the enzyme activity: an initial activation at 15 min was followed by a transient inhibition at 20 min. The specific contribution of [3-Me-His 2 ]-TRH in this paradigm was a transient enhancement of PP II activity. If DA was not removed, [3-Me-His 2 ]-TRH was ineffective. These data demonstrate that during in vitro conditions that mimic a suckling episode, adenohypophyseal PP II activity is rapidly and reversibly adjusted. |
| Databáze: | OpenAIRE |
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