GABAB receptor subunit mRNAs are differentially regulated in pituitary melanotropes during development and detection of functioning receptors coincides with completion of innervation
| Autor: | Tracy D. Davis, Scott A. Sands, Maya Gadhvi Purisai, Bibie M. Chronwall, Jeffrey L. Price |
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| Rok vydání: | 2004 |
| Předmět: |
Gene isoform
Male medicine.medical_specialty Aging Protein subunit In situ hybridization GABAB receptor Biology Rats Sprague-Dawley Developmental Neuroscience Pregnancy Dig Internal medicine medicine Animals Tissue Distribution RNA Messenger Receptor Neurons Gene Expression Profiling Gene Expression Regulation Developmental Molecular biology Rats Blot Protein Subunits Endocrinology nervous system Receptors GABA-B Pituitary Gland Immunohistochemistry Female Developmental Biology |
| Zdroj: | International journal of developmental neuroscience : the official journal of the International Society for Developmental Neuroscience. 23(4) |
| ISSN: | 0736-5748 |
| Popis: | This study examines the developmental expression of GABA B receptor subunits (GABA B(1a), GABA B(1b), GABA B(2) ) in the pituitary intermediate lobe using in situ hybridization, reverse transcriptase-polymerase chain reaction, immunohistochemistry, and Western blots. Receptor functionality was studied by baclofen-stimulated GTPγS binding. In the adult rat pituitary all three transcripts were detected in melanotropes, but not in glia, of the intermediate lobe. No transcripts of any subunit were detected in the neural lobe. Transcripts of GABA B(1a) and GABA B(1b), but not of GABA B(2) , were detected in specific subpopulations of cells in the anterior lobe. All three transcripts were detected in melanotropes on gestational day 18 using in situ hybridization. Reverse transcriptase-polymerase chain reactions comparing postnatal day 2 and adult transcript levels in the neurointermediate lobe support in situ hybridization data that GABA B(1a) mRNA levels do not change, GABA B(1b) levels increase, and GABA B(2) levels decrease as the rat matures. Thus, GABA B receptor subunit transcripts are differentially regulated in melanotropes during development. In the adult rat both GABA B(1) and GABA B(2) proteins were detected in the neurointermediate lobe using Western blotting and in melanotropes by immunohistochemistry. Developmentally, GABA B(1) protein was not detected until postnatal day 7, but was clearly expressed by postnatal day 15 while GABA B(2) protein could not be detected until postnatal day 15. Functional receptors were found in the intermediate lobe at postnatal day 15 and in the adult. The demonstration of transcripts for GABA B(1a) , GABA B(1b) and GABA B(2) subunits at gestational day 18 contrasted with the failure to detect any protein before postnatal day 7, suggesting that the regulation of GABA B subunit isoforms occurs differentially at both the transcriptional and translational level as development progresses. The disparity in the regulation of the receptor subunits may suggest that GABA B(1) could have other functions besides being part of the GABA B receptor heterodimer. |
| Databáze: | OpenAIRE |
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