How Oleic Acid in Olive Oil
Reduces Blood Pressure.
Pablo V. Escribá, University of the Balearic
Islands, pablo.escriba@uib.es
John E. Halver, University of Washington
halver@u.washington.edu
REGULATION OF BLOOD PRESSURE
VASCULAR SMOOTH MUSCLE
PKA
VASODILATION
MUSCULAR
RELAXATION
CROSS-TALK
G proteins
PKG
AC
Endotheliumdependent
PKA
GPCR-associated signaling
Blood Pressure is tightly controlled by several signaling systems.
Many of them involve regulation of cell functions through G proteincoupled receptors (GPCRs). This slide shows a Gq protein-associated
pathway involved in the regulation of cytosolic Ca2+.
G proteins: peripheral membrane
proteins
G proteins propagate
messages from membrane
receptors to effectors that
control cytosolic levels of
second messengers
(cAMP, cGMP, IP3, DAG,
ions, etc.).
Lipid-protein interactions
regulate the localization
and activity of G proteins
and, therefore, cell
signaling.
G PROTEIN-COUPLED RECEPTORS (GPCRs)
INVOLVED IN THE REGULATION OF BP
CENTRAL NERVOUS SYSTEM :
ADRENOCEPTORS
α 2A α2B
• PERIPHERAL NERVOUS SYSTEM :
CARDIAC MUSCLE:
ADRENOCEPTORS
α 1 β1 β2
MUSCARINIC RECEPTORS M2
SMOOTH MUSCLE:
ADRENOCEPTORS
α 1 β2
MUSCARINIC RECEPTORS M3
CARDIAC CELL SIGNALING
1 adrenoceptor
1 adrenoceptor
Gs protein
Gq11 protein
(+) Adenylyl cyclase
(+) Phospholipase C
cAMP
(+) PKA
(+) Ca2+ channels
contractility
DAG
(+) PKC
IP3
(+) Ca2+
Muscarinic M2
Gi/Go proteins
(-) Adenylyl cyclase
(+) K+ Channels
Cell
hyperpolarization
contractility
contractility
VASCULAR CELL SIGNALING
2 adrenoceptor
1 adrenoceptor
Gs protein
Gq11 protein
(+) Adenylyl cyclase
(+) Phospholipase C
cAMP
(+) PKA
Intracellular Ca2+
Vasorelaxation
DAG
(+) PKC
Muscarinic M3
Nitric Oxide
(+) Guanylyl cyclase
IP3
cGMP
(+) Ca2+
(+) PKG
vasoconstriction
Intracellular Ca2+
Vasorelaxation
Membrane lipid structure and G
protein-membrane interactions
Binding of G proteins to model membranes (liposomes) determined by immunoblotting
G protein heterotrimers prefer nonlamellar-prone membrane regions
G protein -monomers prefer lamellar-prone regions (higher PC content)
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver
Membrane lipid structure and G
protein-membrane interactions
G protein g-dimers have a
huge preference for
nonlamellar-prone membrane
regions (higher PE content).
They take G protein monomers from nearby
GPCRs.
Binding of G proteins to model membranes (liposomes) determined by immunoblotting
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver
Gg protein-membrane interactions
FTIR analysis
X-ray analysis
DSC analysis
Membrane and aqueous phases
Only in membrane
Membrane on Gg structure
Gg on membrane structure
C-terminal region of Gg: Main player in G protein-lipid interactions.
Membrane lipids affect G protein structure and vice versa.
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver
A new model of G protein activity
based on their interactions with lipids
Two views of the same process. From the membrane
(above) or from the cytosol (right): receptors (R) are
activated by agonists (a or AG) in hexagonal phase-prone
regions (H), which are loaded with G proteins (G) thanks
to Gg. Upon activation, G goes to lamellar-prone
regions (L) to regulate the activity of effectors (E, E1).
Gg protein-membrane interactions
GFP
WT
MutC1
MutC3 MutC4
Gg2-GFP
Nuclei
Cells
Altered Gg protein
distribution after
point mutations
on the C-terminal
region (Gg2-GFP
fusion proteins)
Merge
Cellular localization of Gg protein-GFP constructs by confocal microscopy
C-terminal region of Gg: Main player in G protein-lipid interactions.
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver
Membrane fatty acids
OA
EA
Oleic Acid
18:1 n-9 cis
SA
Elaidic Acid
18:1 n-9 trans
Stearic Acid
18:0
Effect of OA and EA on membrane
structure by X-Ray diffraction
DEPE
DEPE:OA (20:1, mole:mole)
DEPE:EA (20:1, mole:mole)
Oleic acid but not the structurally related fatty acids, elaidic and
stearic acid, regulates membrane lipid structure.
Effect of OA and EA on G protein function
Oleic acid but not the structurally related fatty acids, elaidic and
stearic acid, regulates G protein function.
Acute effects of VOO, TO, and OA
on systolic BP
Normotensive rats
Olive oil also
induces shortterm
reductions of
BP. Triolein
and oleic acid
have similar
effects
V, vehicle; VOO, virgin olive oil; TO, triolein; OA, oleic acid
Chronic effects of OA, elaidic acid
and stearic acid on systolic BP
Normotensive rats
V, vehicle; OA, oleic acid; EA, elaidic acid; SA, stearic acid
Oleic acid, but
not elaidic and
stearic acids,
induces BP
reductions.
Oleic acid is
the fatty acid
present in
triolein and
the main
component of
olive oil (7080%).
Effects of VOO
treatment on
BP in SHRs
Olive oil and oleic acid (OA)
reduce BP in hypertensive
animals. Elaidic acid (EA) and
stearic acid (SA) failed to
reduce BP.
Hypertensive rats
Effects of VOO, TO, and OA treatments
on total G protein αi2, αi3 and αq/11
subunits and PKCβ1 levels in aorta
Olive oil, triolein and oleic
acid regulate Gi and Gq
protein levels and those of
downstream effectors, such
as phospholipase C (PLC).
V, vehicle; VOO, virgin olive oil; TO, triolein; OA, oleic acid
Correlations between BP reductions (mmHg) and decrease of L-to-HII
phase transition temperature (°C; A) or the dose of cis-MUFA (g/kg)
administered to animals (B)
Treatments: 1, VOO; 2, 2-hydroxyoleic
acid; 3, TO; 4; OA; 5, stearic acid; 6;
vehicle; 7, elaidic acid; 8, soybean oil.
Decrease of BP correlates with the dose
of cis-monounsaturated fatty acids (cisMUFA). Fatty acids, rather than
triacylglycerides, are involved in this
effect.
Consequences for human
health
1. Consumption of fats that contain cismonounsaturated fatty acids (e.g., oleic
acid) have positive effects on
cardiovascular health, compared with
saturated or trans-MUFA fats.
2. Because this effect has structural
molecular bases, we can design
molecules to regulate BP or reverse
other pathological processes.
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver
Then, I can control cell
functions by regulating
membrane lipid structure and
composition!!!
Sure. You may even
design nutritional or
pharmaceutical
approaches to treat
human pathologies!!!
Chronic effects of soybean oil, VOO,
or TO treatments on systolic BP
Normotensive rats
Olive oil, but
not soy oil,
reduces blood
pressure.
Triolein, the
main
triacylglyceride
in olive oil
reproduces this
effect.
VOO is the oil
obtained from
olives by
pressure at room
temperature.
V, vehicle; SO, soy oil; VOO, virgin olive oil; TO, triolein
OLEIC ACID ANALOGUES FOR
TREATMENT OF BLOOD
PRESSURE
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver
Rational design of 2hydroxyoleic acid
2-Hydroxyoleic acid (left) is an oleic acid (center) analog that keeps most structural properties
of oleic acid and differs from elaidic acid (pink) in its interaction with membranes (right).
2-Hydroxyoleic acid on BP
in hypertensive animals
Effect of olive oil
Effects of 2-hydroxyoleic acid (2-OHOA) treatment (600 mg/kg every 12 h) on blood pressure
(BP) and heart rate in spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver
2-Hydroxyoleic acid on BP
in hypertensive animals
Dose-dependent effects of 2-OHOA on systolic BP in SHRs
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver
2OHOA increases elasticity in aorta rings
Rat aorta rings were preincubated 1 hour in the presence (2OHOA) or absence
(control) of 2-hydroxyoleic acid. Then, the contraction in response to noradrenaline
was determined.
2-Hydroxyoleic acid has no cytotoxicity
Control
Control
2OHOA
Lung
Aorta
Kidney
Heart
Liver
S.I.
2OHOA
cGMP is not involved in the
effects of 2-hydroxyoleic acid
6
4
-1
(pmol ·mg protein)
cGMP levels in aorta
8
**
2
0
WKY
WKY
veh
2OHOA
SHR
veh
SHR
2OHOA
The levels of cGMP in normotensive (WKY) and hypertensive (SHR) rats were unrelated to 2hydroxyoleic acid effects on BP
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver
2-Hydoxyoleic acid on Gi proteins
48 h
10%FBS
Serum w/o
PDGF
OH50
OH100
Gi3
actin
BASAL
Serum with PDGF
PDGF
Gi3
actin
2-Hydroxyoleic acid induces reduced expression of G protein.
This effect is PDGF-independent.
Effects of 2-hydroxyoleic acid treatment (600 mg/kg every 12 h) for 7 days on
protein kinase A (PKA) subunit levels in aortas from SHRs and WKY rats
2-Hydroxyoleic acid regulates the expression of some PKA subunits
Effects of 2-hydroxyoleic acid treatment (600 mg/kg every 12 h) for 7 days on
adenylyl cyclase (AC) activities in SHRs and WKY rat aortas
2-Hydroxyoleic acid treatments induce restoration of Adenyly cyclase activity
in rat aorta. Adenyly cyclase produces cAMP, which in turn regulates PKA.
Effects of 2-OHOA treatment (600 mg/kg every 12 h) for 7 days on PKA activity in
aortas from SHRs and WKY rats
2-Hydroxyoleic acid treatments induce restoration of PKA activity in aorta of
hypertensive rats and do not change PKA activity in normotensive rats.
-Adrenoceptor signaling pathway
Epinephrine activates -adrenoceptors, which in turn activate a Gs protein. Gs
proteins activate adenylyl cyclase, that produce cAMP and activate PKA.
Effects of acute administration of the PKA inhibitor 8-bromo adenosine-3',5'cyclic monophosphorothioate, Rp isomer (Rp-8-Br-cAMP), on systolic BP in
vehicle-treated (control) and 2-OHOA-treated SHRs
The use of a specific PKA inhibitor in rats
treated with 2-hydroxyoleic acid reversed the
hypotensive effect of this drug. This result
demonstrates that the proposed mechanism of
the hypotensive effects of 2-hydroxyoleic
acid (via Gs protein, adenyly cyclase and
PKA) operates in vivo.
In normotensive animals (treated and
untreated) and hypertensive rats not treated
with 2-hydroxyoleic acid, no blood pressure
reductions were observed (data not shown),
indicating that the effect cannot be attributed
to the PKA inhibitor itself.
In addition, this effect was time- and
concentration-dependent.
Effects of withdrawal of 2-OHOA on systolic BP and
aortic PKA subunit levels in SHRs
After treatments with 2-hydroxyoleic
acid, blood pressure started to rise to
reach their initial high values about two
weeks after the administration of the last
dose. This slow recovery of blood
pressure indicates that the modification
induced by the fatty acid occurs on
membrane lipids, whose turnover is
slower.
Effects of 2-OHOA treatment (600 mg/kg every 12 h) for 7 days on Rho
kinase II levels in aortas from SHRs and WKY rats
Rho kinase also appeared to be
markedly increased in
hypertensive rats. Treatment
with 2-OHOA reduced the
expression of this protein to
normal levels. This result
indicates that besides PKA,
vascular cell’s cytoskeleton is
also regulated by this
compound.
CONCLUSION
The CIS structure of Oleic Acid fits
neatly into the phospholipid structure
of biomembranes, and alters receptor
sites on the membrane surface, to
regulate blood pressure. Q.E.D.
For references see:PNAS 105;13811(208)
How Oleic Acid in olive oil reduces blood pressure. P.V. Escribá & J.E. Halver