XXXX with a @entity935 antagonist in mares: different responses between ovariectomized and intact mares.

@entity1420 @entity2931 @entity935 @entity3216 @entity230 @entity5535
The aim of this study was to compare the effects of treatment with repeated injections of @entity3216 (a @entity935 D2 antagonist) on prolactin secretion and induced @entity5535 in ovariectomized and intact adult mares and to verify if this induction was possible at the beginning and at the end of the birth season. Two experiments were carried out in September [experiment (expt) 1], and in March (expt 2), in France (48 degrees N). In expt 1, three groups of five mares were tested: intact-control, intact-treated and ovariectomized-treated mares. In expt 2, mares previously subjected to artificial photoperiod were assigned in two groups: four intact-control and five intact-treated mares. The cyclicity of intact mares was previously synchronized with PGF2alpha injections, then all the mares were in the follicular phase at the beginning of treatment. @entity3216 was intramuscularly injected (0.5 mg/kg of BW), twice a day. Mares were milked at 7:30, 11:45, 16:00 and 20:15 hours. Blood samples were collected every day during the treatment for @entity1420 , total @entity2931 and prolactin assays. In the two experiments, only treated intact mares produced milk, with a large inter-animal variability. Prolactin increase after @entity3216 treatment was not so great in the ovariectomized-treated mares as in the intact-treated mares. The total correlations between prolactin, @entity1420 , @entity2931 plasma concentrations and daily milk production were significant (0.57, 0.25, 0.17 respectively). This induction of @entity5535 can be performed during the entire birth season in intact mares, but not in ovariectomized mares, indicating that @entity230 are necessary for this induction in mares treated by @entity935 D2 antagonist.
