Dissertação
Rota de ação da prostaglandina F22α administrada via submucosa vulvar na luteólise de bovinos
Fecha
2011-09-16Registro en:
ROVANI, Monique Tomazele. ROUTE OF ACTION OF PROSTAGLANDIN F2α AFTER
INTRAVULVOSUBMUCOUS INJECTION IN BOVINE LUTEOLYSIS. 2011. 50 f. Dissertação (Mestrado em Medicina Veterinária) - Universidade Federal de Santa Maria, Santa Maria, 2011.
Autor
Rovani, Monique Tomazele
Institución
Resumen
The aim of this study was to verify if prostaglandin F2α (PGF2α) administered by
intravulvosubmucous (IVSM) injection induces luteolysis by reaching the corpus luteum (CL)
directly by a local absorption rote, preventing its metabolism in the lungs, or after absorption
and distribution via the systemic circulation. In a first trial, the estrus rate of 1,937 beef cows
was monitored for 5 days (25.6% of estrus). At day 5, the cows that did not show estrus
received 1/5 of the standard dose of dinoprost IVSM (5 mg; n = 1440) and resulted in 68.2%
of estrus in the next 5 days. However, in a second trial, the number of heifers detected in
estrus after dinoprost injected via the IVSM (47.4%; n = 97) or intramuscular route (IM;
54.7%; n = 95) at day 5 was not different (P > 0.05). Based on serum progesterone
concentrations, animals treated with 5 mg dinoprost at day 5 of the estrous cycle do not
present functional luteolysis regardless of the administration route. At day 10 of the estrous
cycle, luteolysis was variable in cows treated with 5 mg of dinoprost. Nevertheless, luteolysis
occurred in all animals treated with 25 mg dinoprost independent of the estrous cycle day.
After treatment, the PGF2α concentration did not differ in serum from uterine and jugular
veins. This was further confirmed by measuring the concentration of 13,14-dihydro-15-keto-
PGF (PGFM) after 5 mg dinoprost injection via the IM or IVSM route. Dinoprost IM- and
IVSM-administered resulted in a similar PGFM serum pattern over time, suggesting the same
absorption rate for both routes. Although anatomical evidences suggest that PGF2α injected
IVSM could be taken direct to the ovaries, avoiding the systemic circulation, the results do
not support this hypothesis. In summary, the route of PGF2α administration (IVSM or IM)
resulted in similar serum concentrations of PGF2α, PGFM, and luteolysis. Taking all the
results together, the PGF2α injection via IVSM reached the systemic circulation before
reaching the ovary, and the effectiveness of low doses of PGF2α was dependent on luteal
phase and not on the route of administration.