INVESTIGADORES
BUZALEH Ana Maria
congresos y reuniones científicas
Título:
Alterations in the expression of nitric oxide synthase due to porphyrinogenic drugs
Autor/es:
SAMPAYO, ROCIO; LAVANDERA JIMENA; BATLLE, ALCIRA; BUZALEH, ANA MARIA
Lugar:
Estocolmo
Reunión:
Congreso; PORPHYRINS AND PORPHYRIAS 2009; 2009
Institución organizadora:
Swedish Society of Medicine
Resumen:
The existence of heme as a functional prosthetic
group in a large variety of housekeeping proteins
is crucial for life and death. Under heme deficiency
conditions, cells fail to survive and subsequently die
because of impairment of major vital functions carried
out by hemeproteins. Porphyrias neuropathophysiology
could be related to low levels of heme, a
cofactor for nitric oxide synthase (NOS), enzyme
responsible of NO synthesis in mammalian tissues.
Four NOS isoforms have been described: neuronal
NOS (nNOS), endothelial NOS (eNOS), inducible
NOS (iNOS) and mitochondrial NOS (mtNOS).
To provide further understanding on the onset of the
porphyrias, we examined how anaesthetics and other
porphyrinogenic agents affect nitric oxide metabolism
in brain and liver of mice. A comparative study
in animals receiving 5-aminolevulinic acid (ALA) was
carried out.
Recently, we have reported that NOS activity response
depends on both the porphyrinogenic agent and
the cellular fraction analyzed. Ethanol, chronic enflurane
and isoflurane increased liver cytosolic and brain
mitochondrial activity; while oral griseofulvin enhanced
liver mitochondrial activity. ALA also produced a
diminution of NOS activity in both tissues.
In this work, the expression of nNOS, mtNOS and
iNOS was measured in brain. Western blot analysis
identified a protein of 157 kDa reacting with antinNOS
antibodies (amino terminus) in cytosolic
fraction and other protein of 144 kDa reacting with
anti-nNOS antibodies in mitochondrial fraction (mt-
NOS). nNOS expression was diminished after acute
(90%) and chronic (43%) enflurane, veronal (60%)
and ethanol (87%) and enhanced after acute isoflurane
(40%) (p<0.05, n=4). mtNOS expression was induced
after chronic enflurane (45%) and diminished after
ethanol (50%), topical Gris (80%) and starvation (75%)
(p<0.05, n=4). No induction of iNOS was detected in
any of the assayed treatments. In liver, NOS expression
also varied in function of the agent studied. ALA
affected liver nNOS expression.
NOS expression diminution could be a consequence
of free heme pool reduction. Results would also indicate
the development of nitrosative stress besides
the oxidative stress previously demonstrated and give
evidence about the widespread action of porphyrinogenic
drugs in brain.