Enhancement of mesenteric artery contraction to 5-HT depends on Rho kinase and Src kinase pathways in the ob/ob mouse model of type 2 diabetes.
OBJECTIVE
Arteries from hypertensive subjects are reportedly hyperresponsive to 5-hydroxytryptamine (5-HT), but it remains unclear whether this is true in chronic type 2 diabetes. We have assessed responses to 5-HT shown by mesenteric arteries from type 2 diabetic ob/ob mice (27-32 weeks old) and have identified the molecular mechanisms involved.


METHODS
Contractions of mesenteric rings to 5-HT were examined in vitro. Activation of mesenteric RhoA, Rho kinase and Src was measured by Western blotting or by modified enzyme-linked immunosorbent assay.


RESULTS
Concentration-dependent contractions to 5-HT were greater in mesenteric rings from the ob/ob than in those from the age-matched control ('Lean') group. In each group, there was no significant change in the 5-HT-induced contractions after inhibition of nitric oxide synthase (with N(G)-nitro-L-arginine), of cyclooxygenase (with indomethacin) or of protein kinase C (with chelerythrine). However inhibition of the MEK/ERK pathway (with PD98059) decreased the response to 5-HT. Although the diabetes-related enhancement of the 5-HT response was preserved with each of these inhibitors, enhancement was abolished by a Rho kinase inhibitor (Y27632) and by Src kinase inhibitors (PP1 analogue or Src kinase inhibitor I). 5-HT-induced activation of RhoA, Rho kinase and Src kinase in mesenteric arteries was greater in the ob/ob than in the Lean group, but the expression of RhoA, Rho kinase isoforms and Src did not differ between these groups.


CONCLUSIONS
These results suggest that the enhancement of 5-HT-induced contraction in mesenteric arteries from ob/ob mice may be attributable to increased activation of RhoA/Rho kinase and Src kinase.
Matsumoto
Takayuki
T
Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo, Japan. t-matsu@hoshi.ac.jp
Kobayashi
Tsuneo
T
Ishida
Keiko
K
Taguchi
Kumiko
K
Kamata
Katsuo
K
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008638:Mesenteric Arteries / Q000503:physiopathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D011451:Prostaglandin-Endoperoxide Synthases / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D012701:Serotonin / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D020742:rhoA GTP-Binding Protein / Q000502:physiology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
D004791:Enzyme Inhibitors; D012701:Serotonin; D019001:Nitric Oxide Synthase; D011451:Prostaglandin-Endoperoxide Synthases; D019061:src-Family Kinases; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D020742:rhoA GTP-Binding Protein