Effect of glutamate and somatostatin-14 on basal and cAMP-stimulated steroidogenesis by rainbow trout (Oncorhynchus mykiss) ovarian follicles, in vitro
| Autor: | Lucy Lin, R.L. Renaud, John F. Leatherland |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
medicine.medical_specialty
N-Methylaspartate Physiology medicine.medical_treatment Glutamic Acid In Vitro Techniques Biochemistry Steroid chemistry.chemical_compound Ovarian Follicle Internal medicine Cyclic AMP medicine Animals Testosterone Ovarian follicle Molecular Biology Forskolin Estradiol Glutamate receptor Radioimmunoassay Glutamic acid medicine.anatomical_structure Endocrinology chemistry Oncorhynchus mykiss Pregnenolone Female Steroids Somatostatin medicine.drug |
| Zdroj: | Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 140:647-656 |
| ISSN: | 1096-4959 |
| DOI: | 10.1016/j.cbpc.2005.01.001 |
| Popis: | The effects of glutamate and somatostatin-14 (SRIF) on the in vitro basal and cAMP-stimulated steroid production of mid-vitellogenic rainbow trout (Oncorhynchus mykiss) ovarian follicles were investigated. cAMP-stimulation was achieved by the addition of the adenylyl cyclase activator, forskolin (FS), or a membrane permeate cAMP agonist, 8-bromo-cAMP (BA), to the incubation medium. Testosterone (T) and 17beta-estradiol (E(2)) secretion was measured using radioimmunoassay. Solid phase extraction (SPE) was used to measure the relative formation of unconjugated and conjugated steroids, and high performance liquid chromatography (HPLC) was used to examine the steroid metabolites formed from the metabolism of a tritium labelled precursor, pregnenolone (P(5)). The accumulations of T and E(2) in the medium were suppressed in the presence of the glutamate agonists, N-methyl-d,l-aspartate (NMA) or l-glutamic acid (GA), and by the presence of SRIF. The suppression was evident for both basal and cAMP-stimulated steroidogenesis except for T concentrations of GA treatments following basal steroidogenesis, when there were no treatment effects. No significant effects of treatment on conjugated:unconjugated steroid ratios were found. For all treatments E(2) was the major end product steroid synthesized from P(5), and the steroid profiles were similar except for trace amounts of radiolabelled androgens in the medium following cAMP-stimulated steroidogenesis that were not present following basal steroidogenesis. The findings suggest that glutamate and SRIF reduce end point steroid production, possibly by reducing P(5) production. However, since the inhibitory affect was found for basal and cAMP-stimulated steroidogenesis, the response does not appear to be due to the inhibition of cAMP synthesis. |
| Databáze: | OpenAIRE |
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