Influence of phenotype conversion of epicardial adipocytes on the coronary atherosclerosis and its potential molecular mechanism.

OBJECTIVE: To investigate the phenotype conversion of epicardial adipocytes and its potential molecular mechanism during the occurrence and development of coronary atherosclerosis. METHODS: A total of 30 health male New Zealand white rabbits were used. In experiment group (n=15), rabbits were fed with high fat food to establish atherosclerosis animal model; rabbits in control group (n=15) were fed with normal food. RESULTS: At week 0, UCP-1 and PPARγ mRNA expressions in EAT and sBAT were significantly higher than in eWAT, and leptin mRNA expression lower than (P<0.05). In experiment group, the mRNA expressions of UCP-1 and PPARγ reduced gradually, but leptin mRNA increased progressively in EAT (P<0.05). UCP-1 expression reduced gradually, the newly generated blood vessels reduced significantly, but leptin and RAM11 increased gradually (P<0.05). The adipocyte volume in EAT increased gradually, but the adipocyte number reduced progressively (P<0.05). The number of mitochondria with multiple crests reduced gradually in EAT; IL-6 reduced the mRNA expressions of UCP-1 and PPARγ in adipocytes of BAT in a dose dependent manner, but it increased the mRNA expressions of leptin and STAT3 (P<0.05). In the presence of IL-6, JSI-124 increased the mRNA expressions of UCP-1 and PPAR-γ in adipocytes of BAT in a dose dependent manner, but it reduced the mRNA expressions of leptin and STAT3 (P<0.05). CONCLUSION: During the progression of atherosclerosis, there is a phenotype conversion of EAT from BAT to WAT, which further promotes the focal occurrence and development of atherosclerosis; IL-6 may activate JAK-STAT3 pathway to induce this conversion.

Associations of C1q/TNF-Related Protein-9 Levels in Serum and Epicardial Adipose Tissue with Coronary Atherosclerosis in Humans.

OBJECTIVE: To investigate the correlation of CTRP9 with coronary atherosclerosis. METHODS: Coronary angiography confirmed CAD in 241 patients (62 received CABG) and non-CAD in 121 (55 received valve replacement). RESULTS: Serum levels of LDL-C, CRP, TNF-α, IL-6, and leptin in CAD patients were significantly higher than those in non-CAD patients (P < 0.05), but APN and CTRP9 were lower (P < 0.05). Serum levels of CTRP9 and APN were negatively related to BMI, HOMA-IR, TNF-α, IL-6, and leptin but positively to HDL-C (P < 0.05) in CAD patients. After adjustment of APN, CTRP9 was still related to the above parameters. Serum CTRP9 was a protective factor of CAD (P < 0.05). When compared with non-CAD patients, leptin mRNA expression increased dramatically, while CTRP9 mRNA expression reduced markedly in epicardial adipose tissue of CAD patients (P < 0.05). The leptin expression and macrophage count in CAD group were significantly higher than in non-CAD group, but CAD patients had a markedly lower CTRP9 expression (P < 0.05). CONCLUSIONS: Circulating and coronary CTRP9 plays an important role in the inflammation and coronary atherosclerosis of CAD patients. Serum CTRP9 is an independent protective factor of CAD.

[Membrane testosterone receptors in cultured vascular smooth muscle cells].

OBJECTIVE: To determine the presence of membrane testosterone receptors in cultured vascular smooth muscle cells (VSMC), and investigate their relationship with classical intracellular androgen receptors (iAR). METHODS: VSMCs were cultured from the thoracic aorta of male Sprague-Dawley rats by the explant method. Subconfluent VSMCs were incubated with serum-free medium for 24 h to obtain quiescent non-dividing cells, and then treated with the indicated agents. The aliquots of VSMCs were labeled with testosterone-BSA-FITC (T-BSA-FITC) and analyzed by flow cytometry. Classical iARs in intact- and permeabilized-cells were detected with anti-iAR antibodies and FITC-labeled secondary antibodies by immunofluorescence, followed by flow cytometry analysis. RESULTS: Incubation of VSMCs with T-BSA-FITC obviously increased their relative fluorescence intensity at 10 sec as compared with the untreated controls (P < 0.01), and so did it at 10 min in comparison with the treatment with BSA-FITC alone or together with free testosterone (P < 0.01). Pretreatment with iAR antagonist flutamide exhibited no significant influence on the relative fluorescence intensity of VSMCs (P = 0.318). Traditional iARs were not detectable on the surface of intact VSMCs, although permeabilized cells contained iARs. CONCLUSION: VSMCs contain testosterone receptors in the plasma membrane, and these membrane receptors are not identical to classical iARs.

[Testosterone at physiological level inhibits PGF2alpha-induced increase in intracellular Ca2+ in cultured vascular smooth muscle cells].

OBJECTIVE: To explore the acute effects of testosterone at the physiological level on PGF2alpha-induced increase in intracellular Ca2+ in cultured vascular smooth muscle cells (VSMCs). METHODS: VSMCs from the thoracic aorta of male Sprague-Dawley rats were cultured using the explant method. The subconfluent VSMCs were incubated with serum-free medium for 24 hours to obtain quiescent non-dividing cells and then treated with the indicated agents. For the measurement of [Ca2+]i, the VSMCs were loaded with fura-2. Changes of [Ca2+]i were determined ratiometrically with a Nikon TE-2000E system. RESULTS: The resting level of [Ca2+]i was around 100 nmol/L in the VSMCs. Exposing cells to perfusate containing 10 micromol/L PGF2alpha triggered an immediate and transient peak in [Ca2+]i, which gradually decreased afterwards. Interference at the peak with the physiological concentration (40 nmol/L) of testosterone significantly decreased the peak-to-baseline time of [Ca2+]i, compared with ethanol vehicle (104.9 +/- 27.0 s vs 153.5 +/- 40.4 s, P < 0.01). Pretreatment with testosterone at 40 nmol/L for 2 minutes also reduced the peak-to-baseline time of [Ca2+]i significantly in comparison with the ethanol control (120.6 +/- 32.0 s vs 151.4 +/- 27.4 s, P < 0.01), but it had no significant effect on the peak level of PGF2alpha-induced intracellular Ca2+ (390.0 +/- 126.0 nmol/L vs 403.4 +/- 160.7 nmol/L, P > 0.05). CONCLUSION: Testosterone at physiological concentration inhibits PGF2alpha-induced Ca2+ fluxes, probably via receptor-operated calcium channels by a non-genomic mechanism in VSMCs, which may be involved in the vasodilatory effect of testosterone.