title: Altered clock gene expression and vascular smooth muscle diurnal contractile variations in type 2 diabetic db/db mice.
abstract: This study was designed to determine whether the 24-h rhythms of clock gene expression and vascular smooth muscle (VSM) contractile responses are altered in type 2 diabetic db/db mice. Control and db/db mice were euthanized at 6-h intervals throughout the day. The aorta, mesenteric arteries, heart, kidney, and brain were isolated. Clock and target gene mRNA levels were determined by either real-time PCR or in situ hybridization. Isometric contractions were measured in isolated aortic helical strips, and pressor responses to an intravenous injection of vasoconstrictors were determined in vivo using radiotelemetry. We found that the 24-h mRNA rhythms of the following genes were suppressed in db/db mice compared with control mice: the clock genes period homolog 1/2 (Per1/2) and cryptochrome 1/2 (Cry1/2) and their target genes D site albumin promoter-binding protein (Dbp) and peroxisome proliferator-activated receptor-γ (Pparg) in the aorta and mesenteric arteries; Dbp in the heart; Per1, nuclear receptor subfamily 1, group D, member 1 (Rev-erba), and Dbp in the kidney; and Per1 in the suprachiasmatic nucleus. The 24-h contractile variations in response to phenylephrine (α(1)-agonist), ANG II, and high K(+) were significantly altered in the aortas from db/db mice compared with control mice. The diurnal variations of the in vivo pressor responses to phenylephrine and ANG II were lost in db/db mice. Moreover, the 24-h mRNA rhythms of the contraction-related proteins Rho kinase 1/2, PKC-potentiated phosphatase inhibitory protein of 17 kDa, calponin-3, tropomyosin-1/2, and smooth muscle protein 22-α were suppressed in db/db mice compared with control mice. Together, our data demonstrated that the 24-h rhythms of clock gene mRNA, mRNA levels of several contraction-related proteins, and VSM contraction were disrupted in db/db mice, which may contribute to the disruption of their blood pressure circadian rhythm.
authors.affiliation: Departments of Physiology, University of Kentucky Medical Center, Lexington, KY 40536, USA.
authors.forename: Wen
authors.initials: W
authors.lastname: Su
authors.forename: Zhongwen
authors.initials: Z
authors.lastname: Xie
authors.forename: Zhenheng
authors.initials: Z
authors.lastname: Guo
authors.forename: Marilyn J
authors.initials: MJ
authors.lastname: Duncan
authors.forename: Jenny
authors.initials: J
authors.lastname: Lutshumba
authors.forename: Ming C
authors.initials: MC
authors.lastname: Gong
mesh_terms: D000818:Animals; D001011:Aorta / Q000502:physiology; D001794:Blood Pressure / Q000235:genetics; D002940:Circadian Rhythm / Q000235:genetics; D056931:Cryptochromes / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics* / Q000503:physiopathology; D015870:Gene Expression / Q000502:physiology; D006321:Heart / Q000502:physiology; D007668:Kidney / Q000502:physiology; D008297:Male; D008638:Mesenteric Arteries / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D047495:PPAR gamma / Q000235:genetics; D056950:Period Circadian Proteins / Q000235:genetics*; D013493:Suprachiasmatic Nucleus / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics; D014661:Vasoconstriction / Q000235:genetics
chemical_list: C538964:Cry1 protein, mouse; C538967:Cry2 protein, mouse; D056931:Cryptochromes; D004268:DNA-Binding Proteins; C498260:Dbp protein, mouse; D047495:PPAR gamma; C539023:Per1 protein, mouse; C513312:Per2 protein, mouse; D056950:Period Circadian Proteins; D014157:Transcription Factors