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Expression and functions of β1- and β2-adrenergic receptors on the bulbospinal neurons in the rostral ventrolateral medulla. Hypertens Res 2014; 37:976-83. [PMID: 24965172 DOI: 10.1038/hr.2014.112] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/28/2014] [Accepted: 04/13/2014] [Indexed: 11/08/2022]
Abstract
The expression and effects of β-adrenergic receptors (β-ARs) on the neurons of the bulbospinal rostral ventrolateral medulla (RVLM) have been limitedly examined to date. The objective of this study was to examine the expression of β1- and β2-ARs on the bulbospinal RVLM neurons electrophysiologically and histologically. To directly investigate whether RVLM neurons display sensitivity to metoprolol (a β1-AR antagonist), dobutamine (a β1-AR agonist), butoxamine (a β2-AR antagonist), and salbutamol (a β2-AR agonist), we examined changes in the membrane potentials of the bulbospinal RVLM neurons using the whole-cell patch-clamp technique during superfusion of these drugs. During metoprolol superfusion, 16 of the 20 RVLM neurons were hyperpolarized, and 5 of the 6 RVLM neurons were depolarized during dobutamine superfusion. During butoxamine superfusion, 11 of the 16 RVLM neurons were depolarized, and all of the 8 RVLM neurons were hyperpolarized during salbutamol superfusion. These results suggest the expression of β1- and β2-ARs on the RVLM neurons. To determine the presence of β1- and β2-ARs histologically, immunofluorescence examination was performed. Five metoprolol-hyperpolarized neurons were examined for β1-AR and tyrosine hydroxylase (TH) immunoreactivity. All of the neurons displayed β1-AR immunoreactivity, whereas three of the neurons displayed TH immunoreactivity. All of the five RVLM neurons that became depolarized during metoprolol superfusion and hyperpolarized during butoxamine superfusion displayed β1- and β2-AR immunoreactivity. Our findings suggest that β1-AR antagonists or β2-AR agonists may decrease blood pressure through decreasing the activity of the bulbospinal RVLM neurons.
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Timmusk S, Merlot E, Lövgren T, Järvekülg L, Berg M, Fossum C. Regulator of G protein signalling 16 is a target for a porcine circovirus type 2 protein. J Gen Virol 2009; 90:2425-2436. [DOI: 10.1099/vir.0.008896-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Interaction studies have suggested that the non-structural protein encoded by open reading frame 3 (ORF3) of porcine circovirus type 2 (PCV2) binds specifically to a regulator of G protein signalling (RGS) related to human RGS16 (huRGS16). The full-length clone of RGS16 was generated from porcine cells and sequence analysis revealed a close relationship to huRGS16 and murine RGS16. In vitro pull-down experiments verified an interaction between porcine RGS16 (poRGS16) and ORF3 from PCV2. Using GST-linked ORF3 proteins from three different genogroups of PCV2 and from porcine circovirus type 1 (PCV1) in the pull-down experiments indicated that there were differences in their ability to bind poRGS16. Quantitative RT-PCR demonstrated that the expression of poRGS16 mRNA could be induced by a number of cell activators including mitogens (LPS and PHA), interferon inducers (ODN 2216 and poly I : C) and the neurotransmitter norepinephrine. Immunofluorescence labelling confirmed the induced expression of poRGS16 at the protein level and suggested that the PCV2 ORF3 protein co-localized with poRGS16 in LPS-activated porcine PBMC. Furthermore, poRGS16 appeared to participate in the translocation of the ORF3 protein into the cell nucleus, suggesting that the observed interaction may play an important role in the infection biology of porcine circovirus.
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Affiliation(s)
- Sirje Timmusk
- Institute of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 12618, Estonia
- Department of Biomedical Sciences and Veterinary Public Health, Section of Immunology, Swedish University of Agricultural Sciences, Biomedical Center, Box 588, SE-751 23 Uppsala, Sweden
| | - Elodie Merlot
- INRA, UMR1079, F-35000 Rennes, France
- Department of Biomedical Sciences and Veterinary Public Health, Section of Immunology, Swedish University of Agricultural Sciences, Biomedical Center, Box 588, SE-751 23 Uppsala, Sweden
| | - Tanja Lövgren
- Department of Biomedical Sciences and Veterinary Public Health, Section of Immunology, Swedish University of Agricultural Sciences, Biomedical Center, Box 588, SE-751 23 Uppsala, Sweden
| | - Lilian Järvekülg
- Institute of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 12618, Estonia
| | - Mikael Berg
- Department of Biomedical Sciences and Veterinary Public Health, Section of Parasitology and Virology, Swedish University of Agricultural Sciences, PO Box 7036, SE-750 07 Uppsala, Sweden
| | - Caroline Fossum
- Department of Biomedical Sciences and Veterinary Public Health, Section of Immunology, Swedish University of Agricultural Sciences, Biomedical Center, Box 588, SE-751 23 Uppsala, Sweden
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