Project Details
Abstract
Endothelial dysfunction, defined as imbalance of endothelial-derived vasorelaxants
and constrictors, is responsible for most cardiovascular diseases. This is considered
recently as an imbalance between bioavailable NO (nitric oxide) and oxidative stress (O2
.-
neutralizes NO rapidly). Both aging and male gender (or estrogen deficiency) are risks
factors for cardiovascular diseases that involve both endothelial dysfunction and oxidative
stress. We thus hypothesize that caloric restriction (CR) and estrogen/estrogen receptor
(ER) provide vascular protection via reducing oxidative stress to enhance available NO and
thus ameliorates endothelial dysfunction associated with aging and gender difference. CR
(reducing food intake to 50-70% of ad lib level) increases lifespan and reduces risk factor for
cardiovascular diseases. However, neither direct correlational study between endothelial
improvement and CR-induced benefits during aging nor mechanistic investigation of the
CR-induced vascular protection is available. There has been no study on gender difference
of CR (during aging) either. The first part of our proposal aims to explore these issues.
Although estrogen via ER confers vascular protection in general, the responsible ER subtype
(ERα or ERβ) is not clear and whether different mechanism(s) is involved for endothelial
protection for different ER subtype is unknown. The second part of our proposal thus will
examine these questions in ovariectomyzed (OVX) rats and the findings will also be useful
for the understanding of the CR studies. Our proposal consists of both
physiological/functional determination of CR-, gender-, estrogen (and agonists for ERα or
ERβ)-induced vascular effects, particularly the endothelial NO/O2
.- balance; and
biochemical analysis (mRNA/protein of target molecules, see below) of endothelial cells
(EC) obtained by laser capture microdissection (LCM) or whole aortic tissue derived from
CR-or estrogen-treated rats. The physiological parameters examined will include
endothelium-dependent relaxation (EDR), endothelium-derived NO (EDNO), vascular
production of NO and O2
.- (via lucigenin-enhanced chemiluminesence or LEC), as well as
blood analysis of glucose, cholesterol, insulin, and other important markers of
metabolic/vascular events. The biochemical analysis of molecular targets will consist of
vascular sources of NO and O2
.- as well as antioxidant enzymes, including mRNA/protein of
endothelial NO synthase (eNOS), inducible NOS (iNOS), BH4 synthase for cofactor BH4
(tetrahydrobiopterin), and heat shock protein (HSP-90) as positive regulators for NO
production; NADPH oxidase (NADPH Ox), xanthine oxidase (XO) and uncoupled eNOS
(low BH4) for O2
.- production and thus negative regulator for NO production; antioxidant
enzyme activities of superoxide dismutase (SOD), catalase (CAT), and glutathione
peroxidase (GPx) as negative regulator for O2
.- production. Quantative analysis of these
molecular targets under various experimental conditions (CR or control, male or female,
OVX or sham, and specific ERα or ERβ agonist/antagonist) can be compared with
physiological determinants (EDR, NO/ROS production, etc.) to allow a mechanistic
investigation of endothelial functions. For the aging study, rats of both genders under CR
treatment for 2, 8, or 20 months will be studied. For the ER study, sham, OVX, OVX
supplemented with E2 or specific ERα/ERβ agonist-treated rats will be studied. The results
will clarify NO/O2
.- mechanisms involved in endothelial dysfunction during two natural
processes, namely, aging and gender difference. These findings also will provide
functional test for important difference of beneficial effects of CR in different genders with
mechanistic analysis.
Project IDs
Project ID:PC9706-0159
External Project ID:NSC95-2320-B182-030-MY3
External Project ID:NSC95-2320-B182-030-MY3
Status | Finished |
---|---|
Effective start/end date | 01/08/08 → 31/07/09 |
Keywords
- endothelial dysfunction
- caloric restriction
- estrogen receptor
- nitric oxide,oxidative stress
- aging.
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