Endothelin-mediated in vivo pressor responses following TRPV1 activation.
*Blood Pressure/drug effects; *Vasoconstriction/drug effects; Adrenergic alpha-Agonists/administration & dosage; Analysis of Variance; Animal; Animals; Azepines/administration & dosage; Biphenyl Compounds/administration & dosage; Capsaicin/administration & dosage; Cells; Cultured; Diabetes Mellitus; Diabetic Angiopathies/genetics/*metabolism/physiopathology; Dipeptides/administration & dosage; Disease Models; Dose-Response Relationship; Drug; Endothelial Cells/metabolism; Endothelin A Receptor Antagonists; Endothelin A/metabolism; Endothelin B Receptor Antagonists; Endothelin B/metabolism; Endothelin-1/*metabolism; Enzyme-Linked Immunosorbent Assay; Femoral Artery/drug effects/*metabolism/physiopathology; Inbred C57BL; Indoles/administration & dosage; Infusions; Intravenous; Knockout; Male; Mice; Phenylephrine/administration & dosage; Receptor; TRPV Cation Channels/agonists/deficiency/genetics/*metabolism; Type 2/genetics/*metabolism/physiopathology; Vasoconstrictor Agents/administration & dosage
Transient receptor potential vanilliod 1 (TRPV1) channels have recently been postulated to play a role in the vascular complications/consequences associated with diabetes despite the fact that the mechanisms through which TRPV1 regulates vascular function are not fully known. Accordingly, our goal was to define the mechanisms by which TRPV1 channels modulate vascular function and contribute to vascular dysfunction in diabetes. We subjected mice lacking TRPV1 [TRPV1((-/-))], db/db, and control C57BLKS/J mice to in vivo infusion of the TRPV1 agonist capsaicin or the alpha-adrenergic agonist phenylephrine (PE) to examine the integrated circulatory actions of TRPV1. Capsaicin (1, 10, 20, and 100 mug/kg) dose dependently increased MAP in control mice (5.7 +/- 1.6, 11.7 +/- 2.1, 25.4 +/- 3.4, and 51.6 +/- 3.9%), which was attenuated in db/db mice (3.4 +/- 2.1, 3.9 +/- 2.1, 7.0 +/- 3.3, and 17.9 +/- 6.2%). TRPV1((-/-)) mice exhibited no changes in MAP in response to capsaicin, suggesting the actions of this agonist are specific to TRPV1 activation. Immunoblot analysis revealed decreased aortic TRPV1 protein expression in db/db compared with control mice. Capsaicin-induced responses were recorded following inhibition of endothelin A and B receptors (ET(A) /ET(B)). Inhibition of ET(A) receptors abolished the capsaicin-mediated increases in MAP. Combined antagonism of ET(A) and ET(B) receptors did not further inhibit the capsaicin response. Cultured endothelial cell exposure to capsaicin increased endothelin production as shown by an endothelin ELISA assay, which was attenuated by inhibition of TRPV1 or endothelin-converting enzyme. TRPV1 channels contribute to the regulation of vascular reactivity and MAP via production of endothelin and subsequent activation of vascular ET(A) receptors. Impairment of TRPV1 channel function may contribute to vascular dysfunction in diabetes.
Ohanyan Vahagn A; Guarini Giacinta; Thodeti Charles K; Talasila Phani K; Raman Priya; Haney Rebecca M; Meszaros J Gary; Damron Derek S; Bratz Ian N
American journal of physiology. Heart and circulatory physiology
2011
2011-09
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpheart.00082.2011" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.00082.2011</a>
Upregulation of thrombospondin-1 expression by leptin in vascular smooth muscle cells via JAK2- and MAPK-dependent pathways.
Animals; Cell Movement/physiology; Cells; Cultured; Gene Expression Regulation/physiology; Humans; Inbred C57BL; Janus Kinase 2/*biosynthesis; Knockout; Leptin/*physiology; Male; MAP Kinase Signaling System/*physiology; Mice; Muscle; Myocytes; Smooth; Smooth Muscle/enzymology/metabolism; Thrombospondin 1/*biosynthesis; Up-Regulation/*physiology; Vascular/enzymology/*metabolism
Hyperleptinemia, characteristic of diabetes and a hallmark feature of human obesity, contributes to the increased risk of atherosclerotic complications. However, molecular mechanisms mediating leptin-induced atherogenesis and gene expression in vascular cells remain incompletely understood. Accumulating evidence documents a critical role of a potent antiangiogenic and proatherogenic matricellular protein, thrombospondin-1 (TSP-1), in atherosclerosis. Although previous studies reported elevated TSP-1 levels in both diabetic and obese patients and rodent models, there is no direct information on TSP-1 expression in vascular cells in response to leptin. In the present study, we show that leptin upregulates TSP-1 expression in cultured human aortic smooth muscle cells (HASMC) in vitro, and this increase occurs at the level of transcription, revealed by mRNA stability and TSP-1 promoter-reporter assays. Utilizing specific pharmacological inhibitors and siRNA approaches, we demonstrate that upregulation of TSP-1 expression by leptin is mediated by JAK2/ERK/JNK-dependent mechanisms. Furthermore, we report that while ERK and JNK are required for both the constitutive and leptin-induced expression of TSP-1, JAK-2 appears to be specifically involved in leptin-mediated TSP-1 upregulation. Finally, we found that increased HASMC migration and proliferation in response to leptin is significantly inhibited by a TSP-1 blocking antibody, thereby revealing the physiological significance of leptin-TSP-1 crosstalk. Taken together, these findings demonstrate, for the first time, that leptin has a direct regulatory effect on TSP-1 expression in HASMCs, underscoring a novel role of TSP-1 in hyperleptinemia-induced atherosclerotic complications.
Chavez Ronaldo J; Haney Rebecca M; Cuadra Rene H; Ganguly Rituparna; Adapala Ravi K; Thodeti Charles K; Raman Priya
American journal of physiology. Cell physiology
2012
2012-07
Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).
<a href="http://doi.org/10.1152/ajpcell.00008.2012" target="_blank" rel="noreferrer noopener">10.1152/ajpcell.00008.2012</a>