EXPRESSÃO DAS MAPKs EM FOLÍCULOS OVARIANOS E CORPOS LUTEOS EM DIFERENTES FASES DO CICLO ESTRAL DE BOVINOS
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2009-08-21
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Universidade Federal de Goiás
Resumo
Bovine estrous cycle activates the pathways of MAPKs (mitogen activated
protein) via oscillation of hypothalamus-pituitary-gonad axis hormones. The objective
of this work was to evaluate in vivo the frequency of expression of active
(phosphorylated) form, of p-MEK 1/2 and p-ERK1/2 in all types of ovarian follicles and
corpora lutea in different phases of the estrous cycle of cattle. Bovine ovaries were
harvested in a local slaughterhouse and the phase of the estrous cycle was
determined, considering seven stages, defined as experimental groups: days 1-3 (n =
2), 4-6 (n = 5), 7-9 (n = 5), 10-12 (n = 3), 13-15 (n = 5), 16-18 (n = 5) and 19-21 (n =
5). After processing, the histological sections were subjected to
immunohistochemistry using antibodies that specifically recognize the phosphorylated
form of MEK 1/2 and ERK 1/2. Histological sections containing corpora lutea were
also subjected to immunohistochemistry with antibodies that recognize p-BCL2 (B cell
phospho lymphoma 2) and COX-2 (COX-2). The frequency of marked follicles was
evaluated for the presence or absence of markup for the two cellular enzymes. The
fragments of the corpus luteum were evaluated according to the scores of intensity for
positive staining of the four antibodies. The frequencies of the markers studied in the
follicles were compared using the chi-square. In preantral follicles, both MEK and
ERK 1/2 showed high levels between 16 to 18 days. In the case of p-MEK, the
greater activation of primordial follicles and primary held from 7 to 9. In secondary
follicles, the less marked for p-MEK occurred in group 4 to 6. Levels of p-ERK began
to rise from 13 to 15 days and subsequently decreased. Comparing the frequencies
of MEK and ERK, there was statistic difference (p <0.0001) in antral follicles
compared to other types of follicles. It was concluded that the intensity of activation of
MAPKs MEK / ERK varies with the phases of the estrous cycle and follicular class
studied. Since the corpora lutea were evaluated by analysis of variance after
transforming the data, it was observed that the proteins studied showed variation in
expression profile, in relation to the development, survival and death of the corpus
luteum. Since COX-2, a precursor of prostaglandin, is capable of activating the
pathways of MEK / ERK 1/2, it reduces the frequency of expression of cell survival factor BCL-2, leading to the corpus luteum at luteolysis. The in vivo evaluation of the
activation profile of MAPKs without the use of hormonal protocols demonstrated the
importance of this enzyme during the physiological reproductive process, raising new
inquiries and providing opportunities to expand knowledge about the functioning of
the hormone and its association with the cellular mechanisms activated by hormones
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FERREIRA, Mônica Rodrigues. EXPRESSION OF MAPKs IN ovarian follicles is
Lutea at different stages of estrous cycle
CATTLE. 2009. 88 f. Tese (Doutorado em Ciências Agrárias) - Universidade Federal de Goiás, Goiânia, 2009.